FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Hipopinto on June 15, 2020, 12:49:20 PM
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Hello all
I have been reading on this page for several years but finally decided to join!
I have a 1966 galaxie Convertible 428 with a wide ratio Toploader gear vendors overdrive, 3.89 rear with a 31 spline locker this car is really fun to drive
My question is as follows if a pair of engines were comparably built meaning same heads, cam, compression ratio and bolt on components would a 427 be much more powerful than a 428?
I realize one is a short stroke screamer and one is a long stroke torque monster
I’m just looking to gather info as I have a few locals that ask “why didn’t you build this”
More nonsense than anything but I want to sound intelligent when asked
Thanks for listening
Dave
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All other things being equal (and they never are), a 428 and a 427 will make the same power, just at different RPM's. The 428 will make the power at a lower RPM then the 427. The torque will be very similar, but again, the 428 will make torque sooner in the RPM range, giving the perception of being a torque monster.
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Implicit in your question is the fact that these two engines will be built. Built using what block? Did you have a 428 block you think you could have blithely bored out to a 427 bore?
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Funny, your equipment is the same exact as what I'm building now. Same gear ratio, same trans, gear vendor OD. Only difference is mine will be a long stroke 428.
I'm interested in your feedback on the gear vendor. My dad and I were discussing this weekend how the gear vendor should be utilized.....do you push in the clutch before you bump it in? Or do you just pull it into OD under normal load? I know they are designed to handle the power but don't know what makes them live the best.
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There are a lot of little differences, all other things being equal.
The longer stroke, can create more friction, at higher rpm.
The bigger bore, shrouds the valves less, with potentially better intake flow.
The cam timing has MUCH more effect on the torque curve than the stroke.
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I have owned my galaxie since 1992 when I was 18
Fast forward 25 years and I finally am in the situation to be able to build it!
My car was originally a 289 2v auto car.
In 1993 I found a 66 country squire wagon with a 390 (c6me) and a three on the tree! I bought the whole drive train and the clutch pedals to make my car an FE
I did the drill bit test and that block had enough meat to go .080 over so I made it a standard bore 428 with a crank I picked up
The heads I had were C6AE-R but they had whipped valve guides and the guy that built my heads wouldn’t honor any warranty, so I put a set of Edelbrock RPMS on it along with a performer RPM intake, comp 270S, erson rockers, and a duraspark distributor worked over by Faron Rhodes I converted my module to HEI and it’s been great!
The transmission is a galaxie Toploader 4 speed but it needed rebuilt so I was going to rebuild it as a close ratio but David Kee convinced me to make it a wide ratio as it would be “better” on the street I am sure glad I did that!
Originally I had 3.25 gears but that is a heavy car and it seemed “doggy” and it was never in its power range the 3.89s changed that!!!! But man driving was awful so I added the gear vendor!
If you are building a galaxie ONLY BUY your vendor from David Kee! Gear vendors did not build the housing correct to fit the galaxie and David modifies it to work with the stock floor his price is like 100 bucks more but working with him is second to none!
Driving that thing is amazing! It is literally a 7 speed if you are “on it” (the vendor has to be rolling at 20 mph to activate)
To answer your question I do clutch it when shifting because without it it’s VERY violent!
I also machined my shifter face to hide the wire from the shift ball it’s a very clean install!
Also if you are running a 66 galaxie I mounted the vendor lights on each side of the clock on the dash! It looks as if it were built that way
My email is janowski@windstream.net I can send pics of anything you want
I’m game to help anyone!!!
Thanks guys and sorry for the long speak I just really like that car!
Dave
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Dumpling
I picked up a center Oiler block after I built my 428
It’s more of a “what if” question
I thought that similar displacements would make similar powers
Thanks
Dave
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Misread the post. Joe-JDC
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I built a 428 SCJ (R code mach I)for a friend in the early 90's.Similar build to my 427.He had a 268H cam and I have a 270S cam.Both engines used CJ manifolds and I pulled his 3.91 gears and installed 3.50's (same as my car).By then both of us had owned our cars along time..His car was a auto and mine a 4sp...He had a blue thunder intake and I had the C7-F...Both cars tuned by me...For the most part he could stay with me..Both cars were built for corner carving so a drag race was pointless...I drove the SCJ for hundreds of miles..A different car as a auto but felt similar to the 427.The biggest difference is I could seriously out rev him...And pull him on top end.
Now...his car is a factory SCJ with the original drive train...I stayed moderate on the engine..
My car 65 427 .017 over bore and std rods and crank.Engine built in 88.....I stayed moderate...
JMO.....Cory
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My question is as follows if a pair of engines were comparably built meaning same heads, cam, compression ratio and bolt on components would a 427 be much more powerful than a 428?
Nope. You wouldn't see a difference.
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I realize one is a short stroke screamer and one is a long stroke torque monster
The stroke has nothing to do with how quickly an engine revs, how high it can rev, or how much torque it will make. If you build a 427 and a 428 equally the same, with the same heads, same cam, same intake, same compression ratio, etc., you will end up with almost exactly the same horsepower and torque.
The stroke doesn't make for a lazy engine or a zippy engine. I've seen extremely lazy 352's and I've seen 4.500" stroke engines that will zip and rev to the moon.
Stroke = rev is a really big wives tale.
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Brent
This is exactly what I was looking for!
I “thought” that what you said about stroke was correct but I wasn’t sure
I see many folks stroking 390 engines that will walk all over factory 427s and 428s so there has to be some logic to it
Thanks for the reply
Dave
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Brent
This is exactly what I was looking for!
I “thought” that what you said about stroke was correct but I wasn’t sure
I see many folks stroking 390 engines that will walk all over factory 427s and 428s so there has to be some logic to it
Thanks for the reply
Dave
I can point you to some 5.500" stroke engines that pull 7500-8500 rpm. Yes, they are special race pieces, but my point is that stroke has nothing to do with rpms. Displacement determines torque and there are several variables that go into how quickly an engine will accelerate/rpm.
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For years I have been told “long stroke” engines can handle higher RPMs and the blow up
I have seen several 427 engines with windowed blocks and far less 428 engines that way
Brent in your opinion would you build as big as you can or is there a “recipe” or “formula” to get optimum performance for your vehicle?
Again just curious I love knowing answers to questions
Dave
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Never understood short stroke motors being described as quick rev'ing either. Engine is hooked to a car chassis, whatever revs quickest is accelerating faster, meaning whichever engine is creating more hp is "reving quicker" regardless of the stroke. I feel like there are many many many wives tales that are still circulating, and this is one of them.
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Any engine that's not built for the rpm will come apart. You can't really lump stroke into that argument at all. Most 427's have been twisted way higher than most 428's and with factory rods, you will find a weak link.
I see no reason to bypass the longest stroke crankshaft you can get, unless it's a rules engine or a restoration.
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The stroke has nothing to do with how quickly an engine revs, how high it can rev, or how much torque it will make. If you build a 427 and a 428 equally the same, with the same heads, same cam, same intake, same compression ratio, etc., you will end up with almost exactly the same horsepower and torque.
The stroke doesn't make for a lazy engine or a zippy engine. I've seen extremely lazy 352's and I've seen 4.500" stroke engines that will zip and rev to the moon.
Stroke = rev is a really big wives tale.
I respectfully have to disagree. Math and rotational forces say otherwise. Show me a 427 or 428 that can rev as high as a 289. I've seen 289's that run up to nearly 10,000 rpm. I don't believe you will EVER see a long stroke (or any stroke FE) that can go that high. Yes, they are different engines, but it's the rotational forces, side loading, piston speed, weight etc. that are the limiting factors.
As for nearly identical HP and TQ numbers, what about the RPM at which those numbers are made?
And comparing a "lazy" 352 to a 4.5 stroke engine that "zips to the moon", then obviously the 352 was not built to the level of the 4.5 stroke engine. And I'd venture to say that you could never make the same torque with that 352 as you would a 4.5" stroke, given the same general build criteria. Lots of general speak here that doesn't really hold water, in my opinion.
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I can show you a 4.180" stroke engine that will turn 9000 easily.
The only reason bore size should ever come into the equation is if the valves are really shrouded. Otherwise, displacement is displacement is displacement and the engine doesn't know that it's a 427 or a 428. We have to remember that an engine is just a fancy air pump. Displacement is volume and volume is just a combination of bore and stroke. If you get to 427 with a large bore and short stroke or a small bore and large stroke, it's still a 427 and will behave the same.
Now the caveat here is that it is dependent on the factors that you described: component weight, piston speed, etc. However, the *stroke length* doesn't make the engine rev or not rev.
Obviously a 352 won't make the same torque as a 4.5" stroke engine, but that wasn't the point that I was trying to make. Go grab the throttle of a factory 352 2V engine and wing it. Now go grab the throttle of a 12:1 4.250" stroke FE. You will instantly know the difference and the result isn't because of the stroke.
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Here's one that will put a few wives tales out to pasture.....
Not only is it a LOOONNNNGGG stroke, but it's grossly undersquare.
https://www.sonnysracingengines.com/engines/drag-racing-engines/extreme-pro-stock-2025-hp-racing-engine
5.750" stroke peaking at 7800, would probably go above 8000 in a race. No trouble making the long arms get up there and get with it.
Here's a 5.875" stroke peaking at 8000.
https://bangshift.com/general-news/mountain-motor-a-closer-look-at-the-1005ci-2100hp-naturally-aspirated-monster-from-sonny-leonard/
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Back in the heydey of the nostalgia super stock stuff, call it 2003 maybe? Pat Burke was turning an FE 9300+rpm, pretty amazing stuff. Booze Bros weren't far behind that RPM either, they all sounded insane in the burnout box
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Back in the heydey of the nostalgia super stock stuff, call it 2003 maybe? Pat Burke was turning an FE 9300+rpm, pretty amazing stuff. Booze Bros weren't far behind that RPM either, they all sounded insane in the burnout box
I called Pat for some random reason one time, maybe for a part I was looking for. We got to talking about his NSS engine. He said the class was limited to either 430 or 440 cubes. He ran a 4.0" stroke. Was an offset ground truck crank, small journals, aluminum rods.
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Yep, talked to him the pits a bit, full carbon fiber intake was pretty wild as well.
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Have to agree with cjshaker on this one. He stated that his explanation was "general speak" and his general observations are spot on.
While yes it is technically possible to create a long stroke motor that can achieve and withstand high rpms (ie 7800), it also comes at a cost ($91,000 in the example given), with every component being modified (we're not talking stock FE parts here) and many parts constructed from unobtainium (hence the 91k price tag).
I once viewed some engineering videos where 3 single cylinder engines were constructed identically with the exception of bore and stroke. One had an equal bore and stroke, one had a larger bore with shorter stroke, and one had a smaller bore with longer stroke. All 3 engines were identical in displacement, identical valve sizes, identical cams, carbs, and heads.
The engine with identical bore and stroke was tested first and used as a baseline. The test measured hp, torque, and max rpm. Compared with the square engine the short stroke version topped out at a higher max rpm, the long stroke version had a lower max rpm. I don't recall what the hp differences were between the three, but the long stroke version did make the most torque.
If the long stroke engine in this engineering video had been modified (larger valves, different cam, lighter rod & piston, head work, carb work, recurved ignition, etc.) then I imagine it too could have achieved the same rpm or higher than the short stroke motor. But when all things were equal, the short stroke motor achieved the higher rpm (as cjshaker was saying).
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Here's the thing though.....no one discussed the price tag, weights, etc. There's a general stigma floating around on the internet that "long stroke engines won't rev". Undersquare engines won't rev. Best scenario is big bore and short stroke. My general complaint is against those internet "generalizations". For every generalization, you can find opposing data....i.e. the 4" stroke FE up above turning 9300.
I'd be interested in seeing the engineering video that you were referring to. It would be easy to skew the results with a valve package that was more suited for a big bore.
I've built a lot of 428 and 427 combinations over the years. With similar head flow, cam specs, compression, etc., they are all right there with each other on hp and torque.
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I think this discussion went way off of the original discussion and Brent's original answer. In that case, the 3.98 stroke vs 3.78 stroke, or even a 4.25 stroke will all rev equally with IMHO very little additional cost. New pistons are a wash on all three combos, rods are likely MORE expensive for the 3.78 and 3.98 and crank cost depends on your tolerance for new or used. Certainly not much different on those builds to drive to 6500 rpm or so
It's not just the stroke that determines ability to rev, and in fact, the stroke can add benefit for a given deck height as well.
- Longer stroke uses a lighter piston
- Longer rod uses and even lighter piston given the same deck
Say we compared the two builds I have going on, a 456 side oiler 3.98 stroke and a 457 428-based 4.25 stroke. The bob weight on the 427 based motor is almost 2400 grams, the 428 based is 2000 grams, and I am using a heavy rod on the 428. I was in the low 1900s on the last one with a bigger dish and Molnar rod. Even without the lighter combo, the two in the garage now have a difference of .88 of a pound for each bobweight. That's 3 1/2 lbs difference across the entire crank......even with a more modern rod and piston on the short stroke motor, you won't gain back the difference. Now 3.98 to 3.78, the difference in piston weight is still an advantage to the long stroke, with minimal changes closer to crank centerline.
Comparing it to a 289, I can't see how this applies, hardly apples to apples as component weight is significantly different. In that case, too many different variables to say that a SBF stroke versus FE stroke defines RPM. Every single component on the SBF is drastically lighter.
I didn't chime in earlier, but within the limits of most of the FEs built here, go for as much stroke as your combo allows, unless you have a good reason. As far as the 427 vs 428, I think there may be some small differences due to valve shrouding, but it depends on the build, and there may be some gains in other areas with the longer stroke. Regardless, I would expect power to be very close to the same if all other components were the same between a 427 and 428
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I have a question and these are the specs:
427, 4.265 x 3.98 = 454.89 CI
428, 4.13 x 4.25 = 455.48 CI
Heads are the same @ 2.25 IN x 1.74 EX, as well as all other components other than rotating assy.
Will they have the same HP?
Same question for a SBF:
302
4.04 x 3.00 = 307.66
260
3.8 x 3.40 = 308.48
Heads, 2.05 x 1.6 valves.
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Great question Frank!
This is what I’m wondering but I’m thinking they should be very similar
Thanks
Dave
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I'd say years ago a 427 basically picked up where a 428 left off. A low riser head either be about the same. Want more power be a MR, HR, or TP head which requires the bigger bore of a 427. Today with good aftermarket heads can make the power that used to require a 427 with the good factory heads, actually many time even more, but not need the large bore.
Heck a 390 with a 4.125" stroke is about 430ci and will make the power with some TFS heads easier than say a 427 MR.
Now a 427 block is a stronger piece then a 428 block and the larger bore allows more cubes for a given stroke so I'd say a 427 still picks up where a 428 leaves off, just withe heads and strokers of today the that switchover point is a good bit higher then in 1970.
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So let me caveat this that all I did was plug some numbers into the Camquest software, which is free, easy to plug numbers in but I have no idea the assumptions associated with it, or how capable the "guesser" is. However, it is an easy one to get to on my desktop and had some saved files to lean on
Plugging no changes except for the bore and stroke Frank had, I got the that chart. Is it accurate? Who knows, but it does show what I suspect real world would show, ever so slight advantage to a bigger bore for breathing, but not really enough to make a wild difference
Keep in mind, I cannot validate the accuracy, I don't even use this one or compare it to real dynos, but it was an easy one to change data and copy/paste.
FE on top, SBF on bottom
(https://i.postimg.cc/hjNwSfF0/Charts.jpg)
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Just for laughs I did the FEs on Pipemax, came out almost the opposite. Pipemax is a pretty good program, but who knows now
(https://i.postimg.cc/BZccZjGQ/Pipemax.jpg)
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I personally wouldn't run valve sizes that big on a 428 bore or a 260 bore anyway. Way more than what's necessary to make power. Shrouding would be a big issue.
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I personally wouldn't run valve sizes that big on a 428 bore or a 260 bore anyway. Way more than what's necessary to make power. Shrouding would be a big issue.
Great point, I didn't either on those runs, I was going to add some other some points this morning too
1 - In both cases I used valves that were usable in the small bore. My thought was to see what the sims did with just bore and stroke. Knowing the big valves would hit, especially on the FE, I didn't even consider them
2 - The FEs in the Camquest and the Pipemax are not the same. It was late and I didn't feel like entering all the data in. I just used 2 builds from the Camquest package, made sure they made sense, and changed bore and stroke. For Pipemax, I used my all iron stroker build from last year, which was pretty close in the forecast numbers. Then changed bore and stroke. FWIW, Pipemax it the HP peak almost spot on for best and average based on our testing but torque was higher in the real engine.
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Here's a nice clip that gets into some of the nitty gritty about bore vs stroke. Kind of a tangent but.... A different perspective on things too. Generalization are sometimes the pitfall of a project but I totally get how those old wives tales make there way into shop talk.
https://youtu.be/UV3RwBPqznU
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Interesting stuff to think about from all. As a novice at best, I see the building method as a chosen path to the same result. Large cubic inches vs large amounts of RPM and some variations of both on the extreme end of performance.
I don't know if anyone else has seen or heard of it but the "valve-less" 302 built by Coates International (I think) that was an experimental engine using OHC style setup with ball valves machined into the cams to eliminate the poppet valve, pushrods, valves etc. Supposedly that engine would spin at 10,000 rpm with stock rotating assembly because the non-existent valve train restrictions. I only bring this up because how a traditional cam basically stops working at a certain rpm and the engine is done making power and torque.
Not only that but NASCAR builds are relatively mild as far as bore and stroke but specifically built for rpm. There's plenty of video of these engines on a Spintron winging 11,000 or 12,000 rpm without parts failures.
Again, I'm just a grease slinger and I got bit by the FE bug so this has been pretty cool to read and think about future builds.
***EDIT- I found the link for Coates-
http://www.coatesengine.com/csrv-system.html
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I personally wouldn't run valve sizes that big on a 428 bore or a 260 bore anyway. Way more than what's necessary to make power. Shrouding would be a big issue.
This was the question:
My question is as follows if a pair of engines were comparably built meaning same heads, cam, compression ratio and bolt on components would a 427 be much more powerful than a 428?
The answer will be yes, mostly because of the shrouding issue. That is why I offered the comparison builds. I'm not even sure that they (428 & 260) could be put together w/o notching the bores but, they are diffinitly possible.
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I ran into a guy at a dragstrip over 35 years ago that had two cars he ran regularly. A 67 427 Fairlane and a 1969 428 CJ Cobra. Something that has stuck with me all these years was his comment that both cars ran indentical times.
JWR
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I personally wouldn't run valve sizes that big on a 428 bore or a 260 bore anyway. Way more than what's necessary to make power. Shrouding would be a big issue.
This was the question:
My question is as follows if a pair of engines were comparably built meaning same heads, cam, compression ratio and bolt on components would a 427 be much more powerful than a 428?
The answer will be yes, mostly because of the shrouding issue. That is why I offered the comparison builds. I'm not even sure that they (428 & 260) could be put together w/o notching the bores but, they are diffinitly possible.
Well yeah, but there should have been an understanding that you don't try to cram stuff in there that's not logical. Obviously the 427 will make more power since the valves will be hitting the cylinder walls in the 428.
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Well yeah, but there should have been an understanding that you don't try to cram stuff in there that's not logical. Obviously the 427 will make more power since the valves will be hitting the cylinder walls in the 428.
Interesting "thinking" experiment.
Are cubic inches - large bore, short stroke - or small bore, long stroke equal as far as making power?
At lower rpm where there is no valve size limitation to power produced - they can make very similar power.
When smaller bore starts to impact air flow - the larger bore engine combination starts to look better and better.
Just my opinion.
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Well yeah, but there should have been an understanding that you don't try to cram stuff in there that's not logical. Obviously the 427 will make more power since the valves will be hitting the cylinder walls in the 428.
It is totally logical to put 2.25 x 1.74 valves in a 427, right? If you can't do that with a 390/428, then the bigger bore makes more HP, correct?
Regarding same for same, with smaller valves, the math gives the edge to the smaller rod/stroke ratio (cyl filling after TDC), i.e. 6.488 rod x 4.375 stroke (1.483) than say the 368 Linc/Merc, 7.065 x 3.66 (1.93). How much difference it will actually make on a dyno, I can not say but, I've played with it in a dyno sim that I have and it made 1.5 hp, for the lower ratio, for SB engines I've run but, at lower rpm, like under 2500 rpm, the higher ratio made about 1 more HP. The difference is so small that it would be VERY hard to find on a real dyno.
I like long rods though and for even 5, maybe even 10 hp difference, I'll take the long rod, for it's reduce friction and stress.
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Well yeah, but there should have been an understanding that you don't try to cram stuff in there that's not logical. Obviously the 427 will make more power since the valves will be hitting the cylinder walls in the 428.
It is totally logical to put 2.25 x 1.74 valves in a 427, right? If you can't do that with a 390/428, then the bigger bore makes more HP, correct?
No, not necessarily. Why do you think a bigger valve will always make more horsepower? Not true.
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Brent, I know that you know better than your trying to portray. A 2.09 valve, will not flow the same air as a 2.25 valve, you know that, right. Air mixed atomized fuel = HP, right?
Now then, if your talking about something other than max HP, you have a point but, as far as I can tell, the question was as stated and indicated (as I saw it) the potential for max hp.
All things being equal, that 2.25 valve, unshrouded, will create more hp than the 2.09 valve, as the flow demand increases. Not only that but, depending on the ports design (ability to keep velocity up) it can out do the smaller valve in the lower range, too. You know that, I know you do.
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Brent, I know that you know better than your trying to portray. A 2.09 valve, will not flow the same air as a 2.25 valve, you know that, right. Air mixed atomized fuel = HP, right?
Now then, if your talking about something other than max HP, you have a point but, as far as I can tell, the question was as stated and indicated (as I saw it) the potential for max hp.
All things being equal, that 2.25 valve, unshrouded, will create more hp than the 2.09 valve, as the flow demand increases. Not only that but, depending on the ports design (ability to keep velocity up) it can out do the smaller valve in the lower range, too. You know that, I know you do.
In that case, then we just need to fit the biggest valve we can fit in any head, right?
You need to think a little more about that one.
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For max attainable hp, with a good flowing port, yes.
Are you going to use 2.03 valves in your 352?
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I’m gonna use the valve that’s appropriate for the port and throat size.
I think I’m gonna see if a 2.450” will physically fit and then I’ll take a grinder and cut a chunk out of the cylinders. Whatcha think?
If you’re thinking of fitting the biggest valve in your SBF head that you can fit, the 2.08” or whatever it was, you really need to take some time to rethink that. Get away from that 60’s thinking of “I’m gonna make it as big as I can make it.”
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Unsteady, compressible airflow is a REALLY complex thing. Throw some atomized fuel into the mix and it's beyond crazy.
Some ports like tulip valves, some like nailhead. The valve seat angle(s) have a huge effect on flow. Bigger valves don't always work better, since the cylinder wall can get too close and back up the whole works.
You would think that the wall only affects a small area, so the big valve must flow better overall? Nope! That small area can trip up the flow over the entire cross section.
Despite spending a few years in wind tunnels during undergrad and grad school, I still only know enough about this to be dangerous. I worked on afterburners for F404 jet engines (F-14 Tomcat proposal). We found that adding restriction actually increased performance! The restriction was carefully shaped winglets on the fuel spray bars, which added swirl to better mix the fuel.
It's a black art. More is often less...
Edit - For the purists, we were working on an improved F404 proposal for the Tomcat. Ultimately they passed on that and GE developed the F110 (from the improved F404) for the F-14D. The F404 made its way into the F-18 Hornet.
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I’m gonna use the valve that’s appropriate for the port and throat size.
I think I’m gonna see if a 2.450” will physically fit and then I’ll take a grinder and cut a chunk out of the cylinders. Whatcha think?
If you’re thinking of fitting the biggest valve in your SBF head that you can fit, the 2.08” or whatever it was, you really need to take some time to rethink that. Get away from that 60’s thinking of “I’m gonna make it as big as I can make it.”
Hmmm, trying to side step the question?
Tell us what your your thoughts are, on putting 2.19 x 1.625 valves, in a 4.040 bore 352? You state in the thread that they are shrouded. Is that "going as big as you can" or “I’m gonna make it as big as I can make it.”?
BTW, my SBF heads are 2.02 x 1.6. They were new and sold to me 10 years ago, as 2.05 heads and I didn't have a use for them until recently, when I tore them down and found the 2.02's in them.
Most, if not all on this forum, know that 2.25 x 1.74 valves, are not to much for a 455 CI engine, reving in the 7K or less range.
For at least 60 years, the trend in top level racing (NASCAR, Indy Car and F1), is larger bore, shorter stroke. Maybe Yates should lesson to you and go back to a 4 x 3.5 bore stoke. But, I really don't think you believe what you trying to say. I really believe, it is because frnkeore, presented the 427/428 comparison and your job, on this forum, is to disprove, any thing posted by "that guy".
Your turn Stang :)
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Ok, two points, and then I'm done.
First point:
You are absolutely enamored with making everything as big as it can be. Huge cam duration, huge flow numbers, huge valve sizes. No, 2.25 x 1.74 valves are not too big for a 427 bore engine, but *that doesn't mean that they are the best*. That's what I'm trying to get you to understand. Why is it that 2.25 x 1.74 valves are not too much for a 455 (4.250 x 3.98) revving in the 7k range, but a 465 (4.310 x 3.98) will do that with MUCH smaller valves?
Second point:
I don't always run or preach for small bore, big stroke engines. There are times when it's more prudent to run a big bore, short stroke engine. I'm building a 449ci road race FE right now that's a 4.350" x 3.780". I'm doing that because I want him to have some displacement but a short stroke at 7000-7500 rpm is easier on skirts, piston rings, and bearings. He's a novice at road racing and I wanted to keep maintenance and freshen-ups at a minimum for him.
A shorter stroke can also work better with a smaller duration camshaft. When racing NASCAR, etc., smaller is always better, because it means that you will get more durability and longevity. NASCAR has a cubic inch limit and there's only so many ways of getting to 358 cubic inches. They usually run a 4.185" bore and a 3.250" stroke. The short stroke increases longevity due to the piston speed. When you're turning 8500-9000 rpm for hundreds of miles at a time, you want to make things last. Shorter .050" durations here mean shorter advertised durations, which can mean a lot less wear on the valvetrain components. NASCAR runs a lot less valve spring pressure on their solid roller cams than most of us do on our hydraulic rollers.
Third point (I changed my mind on the number):
My 352 is a big old huge mess right now. The crank grinder screwed up the crank that I was going to use. It was going to cost me about $1500-1600 to have a 361 crank ground, so I'm just going with a stock 352 cast crank with FE rod journals and different rods/pistons. It was cheaper for me to go that route than to shell out the money for the 361 crank. With that being said, the new rods/pistons are going to eat into my 352 play money, so my plan to get the heads ported is gone.
If you must know, the intakes are 2.185" because I was going to have the heads ported. Now that I'm done, I'm not spending any more money to make it correct, so they're gonna get what they're gonna get. It's not right and it will probably make less power because the port/throat/bowl are not set up for that big of a valve. To be honest, yeah, a 2.03-2.05" would probably be best.
Fourth point:
I'm not sidestepping this question, nor any other question posed by you. If you go back and read, it wasn't even your question to begin with, this thread that you have totally whopper-jawed belongs to another poster who posted the question. I answered him and gave some data and you came back with your rebuttals.
I'm absolutely done with discussing anything with your name in the thread, Frank. I'm assuming "Stang" hasn't come back because he's done arguing with this kind of logic as well. I think you completely ignored the data that he showed because it didn't fit your narrative.
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Ugh Frank,
I am in a completely different place than you think I am, and if you didn't bring up my name I was going to leave it alone. I really hate this kind of arguing on the forum and always have
I did the sims because I was reaching out with an olive branch so you didn't think I was attacking every time. The only reason I used my own valve sizes is because the exhaust valve would hit in your combo with the lift we run nowadays. I didn't expect it to be a thing based on the original question. I really thought by putting up the data that I was helping out. I am no savior, I also realized that sims are just educated guessers so I put two up and explained what I did for interpretation.
That beign said, by chance only at this immediate time, I am likely the only guy with 2 457s on the stands right now, one 4.25 stroke, one 3.98 stroke. Unfortunately, one owner won't dyno, and the other is built with all modern parts and will make significantly more power. So even if we did talk the side oiler owner into a dyno, the small bore would win and taint the data
What I can do though, is whatever combo you want, even if the valves would hit, I can run through a better sim that I have corrected for a 461 inch stroker with iron heads that I dyno'd last year. It is nearly identical to the actual dyno run. I did so by adjusting CSA, port length, and careful parts choices in the sim. By doing so, it should be as close as we can get and see what that sim only does. I can't do that until Saturday AM, but if you want, I'll do it, assuming you agree that we'll just see what it does with only a bore and stroke change.
If I could build two engines like you want, I would, but using your example for valve sizes, I couldn't cut the side of a cylinder wall to clear the exhaust and I don't have two guys wanting the exact same engine, especially with the lift range for a big exhaust valve on a 4.14-4.16 bore. BUT give me what you want run again, bore, stroke, valve sizes, and I will jam it in the better sim with no prejudice.
However, I do want to bring some things up. In the old days we ran 3/8 valves, often they weren't undercut stems, port CSA and taper wasn't great or even not considered. We used large chambers with big domes to get compression with big quench distances, and only the select few the Ramchargers talked intake port math and guys like Dama Elgin talked 5th cycle and primary tube effects.
That stuff is accepted now and changes things, it's different. If I can help it, I (and I think Brent, Blair, and Barry) don't build a serious iron headed FE with anything bigger than 11/32 stems, Brent is using 5/16 stems on his 352, we try to go smaller chamber and flat top or dish, with more efficient ports and use the primary tube for the RPM we run. On top of all that, we can run lift and cam timing we couldn't run before. I have to tell you, it's going to seem like I am fighting you, but I just look at the valve diameter as being sized for the port alone, like the right sized trashcan lid, I don't care how big it is, it just has to match the throat of the port that's right for the engine. A bigger lid works, but isn't better
FYI - The two 457s, the 427 based one has heavy Venolia domes, nearly a POUND more bobweight for each throw, mid 500 lift, med riser heads with 2.19 / 1.73 3/8 valves and a SFT with a tight snotty LSA and will be a TON of fun in a light car.
The other, 428 based, has CnC ported CJ heads, 2.15/1.67 valves, 11/32 undercut stems, a modern throat and port design, .600 lift, 112 LSA, 5 degrees less cam duration @ .050 and a dished piston for the same 10.5:1 the 427 block has. It's going to spank the other one if both were on the dyno. and yes, the CnC ported heads are about 10 cfm better, but they are better with the smaller valve and the port design does not get better with a bigger one
Regardless, even if I throw all those same parts, heads and all onto the 427 block, I don't expect it to make any more power than the 428 block. Actually that's not exactly true, maybe 5-7 HP at the peaks, but as I said, I believe it will lose somewhere else equally. Drag car, maybe that proves your point, street/strip, depends where you pay for it
Finally, I am not playing some sort of peaceful beatnik, I come to Jay's forum because it's very technical and friendly, we had the BS on the old forum, and even worse on the very old FE forum on Network 54. I put our last argument behind us because it took away from that culture....I have no intention to fight, this one round was only to offer the sim and tell you what I am doing.
If you take it any other way, as Brent said, I am out of this topic too. I have three FE strokers to get finsihed and/or to the dyno in a couple weeks and no desire to prove anything to anyone other than the owners of the engines. (Ironically, the third engine, as crazy as it sounds, has the smallest port in CSA and volume, the smallest cam and lowest compression one will likely make the most power by a wide margin, I will hang them on the dyno section as they are done)
Your call, post it up here and I will run it on the more involved sim, if not, we can let it die
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I spent way too much time trying to find the article but failed, but either HotRod or Car Craft did exactly what's being posed here years ago, they built two big block chevies with big bore/short stroke and small bore/long stroke and compared them, all else being equal. I recall them being surprisingly similar. Sorry, it's from vague memory but I recall being very surprised how close they were. I do recall the peak RPMs shifted around, as you'd expect, but the numbers were similar.
I do NOT recall if they optimized the big bore setup to use bigger valves, which is central to the debate.
I think the issue is when guys start using extreme examples to prove their point. When anyone starts using a 7:1 3500rpm max smog motor or a $75k 9500rpm NASCAR motor as arguments, that can skew the information being argued. I believe the bore/stroke debate is within the realm of OEM block and head architecture and what most would call feasible costs and operating ranges, where compromises have to be made. Bringing something like a F1 or NASCAR engine into the debate isn't really relevant as they operate in a way that basically has no bearing on a 6500rpm max street motor.
Race motors are big bore, while modern engines like the LS/new Hemi/Coyote have strokes that are as long or longer than strokes in similar displacement older engines....why is that? 5.7L LS which was built solely for performance applications is 3.622" stroke, where old 350 sbc is 3.48".
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Chilly that was Reher and Morrison that did that comparison , when everything is the same equal power through out the power band between the two as long as valve shrouding is not a problem , big bore can take advantage of bigger less shrouded valves and then its game over for a racing mill
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Chilly that was Reher and Morrison that did that comparison , when everything is the same equal power through out the power band between the two as long as valve shrouding is not a problem , big bore can take advantage of bigger less shrouded valves and then its game over for a racing mill
And then in some situations, you can add even more stroke and make more power. That's basically where they are with the Mountain Motor stuff. Increase the bore as big as the block will allow, throw as much head to it as you can, then add copious amounts of stroke and rpm. They're ending up with 1000ci engines, 2500 hp naturally aspirated, and 8000 rpm.
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Port shape, combustion chamber design, runner length, and exhaust port shape are more important than valve size increases to gain flow. Most of the really good heads available today have a very small exhaust valve compared to a few years ago, and the intake valves do not need to be gigantic to flow huge volume. SBF heads today can flow over 400 cfm with 2.135" intake, and 270-300 cfm with a 1.600" exhaust valve. Many are going to even smaller exhaust valves on the order of 1.540", 1.550" and still flowing in the 270 cfm range. Those heads generally go on the modern blocks with a minimum bore of 4.125", but some work on the 358 cubic inch oval track engines. I personally know of a FE that lost 60 cfm airflow going from a 2.090" intake valve to 2.190" intake valve and 6 tenths in the quarter mile. There will only be a few horsepower difference in the 427 and 428 if everything is the same except the block and crankshaft stroke. JMO, but arguing without actual builds to compare is just that, arguing, and counterproductive to good statistics. Joe-JDC
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First, I was a real racer in my day and still am and because of that, I am ONLY concerned with the last 2000 rpm of a power band. Look at my avatar, I owned that car and raced it. In the top 4 gears, of the 5 speed, my biggest rpm break was ~2000 rpm. 4 to 5th was about 1000 rpm. 2-3 shift was 2075 break and 4-5, 970 rpm. I looked it up.
The question posed was not about anything but power, at least as I read it. For sure, I didn't take it as a daily driver, street car question. There was nothing mentioned in the OP about any power band restrictions, was there? And as you saw I was relating it to the SBF and FE and my mind thinks in common race rpm's unless stipulated. For me, that's 8K for SBF and 7K for the FE. Yes, you can spin them faster but, usually at the price of reliably. Again, for my type of racing, I think in in minutes not seconds. A 1/2 hour race, rather than 8-11 seconds.
For the drag racers, to relate to bore & stoke, think of it as a 10k rpm Pro Stock engine. What are they doing with bore/stroke ratio's and valve size. I think all manufactures have gone to 4 valve engines for there higher output engine and even in most cases, their standard output ones also. What a 4 valve head gets, is a higher valve curtain area, in a smaller bore, that and a VVT extends their rpm band, as well.
Ross, I appreciate your input. Sims can come close, but close only only counts in horse shoes and handgrenades, right? I have 2 sims, Pipe Max and Dyno Sim 6. Both good programs and can do "about" but, I try to use them to get a direction by increasing and decreasing variables. But, I would never use them as fact. If I may ask, what are the sims that you have and is there a way to use valve shrouding in the input?
Since the 70's I have been a proponent of small valve stems. When first came on this forum, one of my first post was about the stem sizes, still being used with the FE. I had imagined that because of the FE's longer and by that, heavier valves, that 7mm & 5/16 valves would be, by now common.
There many trade offs in a cylinder head, bigger valves and wider cyl call for larger (width) combustion chambers, larger combustion chambers mean lower CR. Compression is power and we all try to get as much as we can use. While I had popups in my LR (1968 TRW's), they are not a good thing to increase CR but, at that time I just went with what was popular. I only consider FT's now and the 8.206 deck, SBF struggles with CR because of that, but you can get it with a 351W, FE's, with strokers cranks.
High velocity, high flowing valves are what can pack a cyl, after BDC so, all other things equal, a larger valve can and will flow more cfm. Other wise we'd still be using the 1 1/2" flathead size valve or at least the 1.72 283 SBC Power Pack intake valves.
My guess on NASCAR, valve sizes, is that they found valve shrouding a issue and went with the best compromise and highest velocity port but, the bore to valve size ratio is larger than the 427's with 2.25 valves. 4.26 ÷ 2.25 is 1.893, 4.185 ÷ 2.15 is 1.947.
"I personally know of a FE that lost 60 cfm airflow going from a 2.090" intake valve to 2.190" intake valve"
Joe, if you had ported those heads, would the it have had the same results?
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Well, the guy stated his car info was a '66 Galaxie convertible with a Gear Vendors overdrive, so my inference was that it's a typical street car. I realize this will probably just continue this hamster wheel of debate, which is really going nowhere. I don't think anyone argues that larger bore and resulting valves have the potential to make more power given a proper port shape and RPM to utilize them in a race application.
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There is also this in the OP:
I realize one is a short stroke screamer and one is a long stroke torque monster
I’m just looking to gather info as I have a few locals that ask “why didn’t you build this”
Screamer, is generally thought of as higher rpm.
You make torque, the thing that propels you, at higher rpm, with gear reduction. Not good for gas mileage or noise, on the street but, it gets the job done.
I don't know, I guess I just still have a young mind at 75 but, even so, I seem to think differently than the younger street racers of today.
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I spent way too much time trying to find the article but failed, but either HotRod or Car Craft did exactly what's being posed here years ago, they built two big block chevies with big bore/short stroke and small bore/long stroke and compared them, all else being equal. I recall them being surprisingly similar. Sorry, it's from vague memory but I recall being very surprised how close they were. I do recall the peak RPMs shifted around, as you'd expect, but the numbers were similar.
I do NOT recall if they optimized the big bore setup to use bigger valves, which is central to the debate.
I am pretty sure I can find that article in my magazine collection. It was a Freiburger deal and pretty good as I remember. Of course it can be picked apart like anything. I'll look for it this weekend.
paulie
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Frank, I use an old version of EA Pro, which I can adjust a lot but nothing specifically for shrouding. I have been able to back into some accuracy after real dyno runs, and in that case, I would only change bore and stroke from a known accurate run. Although I could likely reduce some flow at lift numbers, or increase them for a 427 bore, I am not sure how I would estimate that accurately
Take a look at this picture though. This is a 4.05 bore, 2.15 Ferrea valve. I don't see as much of an issue with intake shrouding. We would add .110 of bore (.055 radius) for a .030 over 428 then consider the mass of the air charge and it's direction toward the spark plug hole. It doesn't seem like we need much more room or valve that 2.15 combo can easily be a 300+ cfm head
Of course shifting to a medium riser spacing and shifting the valve over changes things,and needless to say, the 1.67 exhaust valve is pretty tight in that 4.05 bore, but the intake seems to be pretty roomy.
(https://i.postimg.cc/yY24WVyq/1.jpg)
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The exhaust valve is usually the offender. FWIW, I mocked up a TFS head on a 4.040" 352 bore and I didn't have any contact until about .900" lift. Those are 2.190"/1.625" valves.
(https://live.staticflickr.com/65535/49746932928_7a1e946b0b_c.jpg)
(https://live.staticflickr.com/65535/49673700438_b299664fc0_c.jpg)
I also mocked up a BBM head with a standard 352 bore and only had about .800" before the exhaust valve hit. That was with 2.100"/1.600" valves. If I remember right, that BBM head flowed around 330 cfm with the smaller valves and a raised floor (smaller CSA).
I did a 351C once that used standard 4V CC heads. Those heads moved about 310 cfm and used standard valve sizes, 2.190"/1.730". I used a 1.8 rocker on the intake but had to stay with standard ratio on the exhaust because the valve hit the cylinder at lift. That was a 4.010" bore.
Goes to show you what the aftermarket has provided because you can buy a CHI 3V head with a 2.070"/1.600" valve package that flows 330 cfm with about a 25cc smaller port volume and it will fit on any bore size.
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I’m sorry guys
I’m a new guy here and only was asking a theoretical question
I didn’t want to cause any grief
I’m sorry if I upset anyone
Dave
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I’m sorry guys
I’m a new guy here and only was asking a theoretical question
I didn’t want to cause any grief
I’m sorry if I upset anyone
Dave
You absolutely didn't upset one person. Thanks for joining.....
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I spent way too much time trying to find the article but failed, but either HotRod or Car Craft did exactly what's being posed here years ago, they built two big block chevies with big bore/short stroke and small bore/long stroke and compared them, all else being equal. I recall them being surprisingly similar. Sorry, it's from vague memory but I recall being very surprised how close they were. I do recall the peak RPMs shifted around, as you'd expect, but the numbers were similar.
I do NOT recall if they optimized the big bore setup to use bigger valves, which is central to the debate.
I am pretty sure I can find that article in my magazine collection. It was a Freiburger deal and pretty good as I remember. Of course it can be picked apart like anything. I'll look for it this weekend.
I found the article. Hot Rod June 2005. Same exact heads on both combinations as far as I can tell. AFR 335's on both. So that question is not answered. I think they did that on purpose. It seems the the idea was to test bore/stroke and rod/stroke ratio exclusively. Maybe they could have a different head on the big bore combo to take advantage of that extra real estate. Of course there are thousands of different ways to run a test. This is how they did it and I think it is pretty good. Better than I could do for sure.
The small bore combo was 4.28"x4.25" with a 6.535" rod. The big bore combo was 4.56"x3.766" with a 6.135" rod. The rod lengths seem counterintuitive, but they were trying to keep the rod/stroke ratio similar.
They also ran two cams on either combo with different compression ratios. The small cam was a 218/224, .510"/510", 110LSA hydraulic roller. The big cam was a 253/260, .734"/.732", 111 LSA solid roller cam.
The compression ratios were 9.039:1 (small bore) and 9.076:1 (big bore) on the small cam combo. The compression ratios were 10.83:1 (small bore) and 10.87:1 (big bore) on the big cam combo. They used a 0.125" thick head gasket on the small cam combo and a 0.040" thick head gasket on the big cam combo.
So there are 4 total combinations here:
1) Small cam small bore/long stroke
547hp peak@5300 rpm/ (455hp avg) / 592lb/ft peak@3500-3600 rpm/ (551 lb/ft avg)
2) Small cam big bore/short stroke
549hp peak @5400-5500 rpm/ (455hp avg)/ 589lb/ft peak@3600-4000 rpm)@ (550 lb/ft avg)
3) Big cam small bore/long stroke
717hp peak@6600 rpm/ (578hp avg) / 643lb/ft peak@4600 and 5500 rpm/ (612 lb/ft avg)
4) Big cam big bore/short stroke
727hp peak @6300 rpm/ (576hp avg)/ 636lb/ft peak@5400-5500 rpm (609 lb/ft avg)
paulie
Oh yeah, the small cam combo used an Edelbrock RPM intake and the big cam combo used a Weiand Team G intake, both with a 975 cfm Race Demon carb. 2" headers and 18" extensions on both. Small cam combo used Flowmaster mufflers. Big cam combo used no mufflers as far as I can tell.
edit: oops. corrected the rod lengths.
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Thanks, that’s the one I recalled, didn’t remember it had two cam comparisons. So basically follows what many here said, little difference between the two, big bore helps a wee bit either from the unshrouding or the reduced friction with a short stroke.
Imagine the reputation of 427 vs 428 had much less to do with bore/stroke and everything to do with solid cams in 427s, and people comparing that to sluggish passenger car 428s
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Ok
So again guys from what I’m reading on this thread
The engine dosent “know” anything about bore and stroke it’s the heads feeding the gulps of air it’s drawing in
Clearly that longer stroke engines will have advantages where shorter stroke engines will have others but output of each should be comparable
This question may be suited for another topic all together but I’m going to ask it here
Do Different camshafts perform “better” with Different strokes?
For instance a comp 270S fits a 331-427 and every thing in between but will it act differently with large bores and short strokes or smaller bores and long strokes
I’m just trying to understand as much as I can
Too often I’m explained things by people that should be listening
Thanks guys
Dave
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Ok
So again guys from what I’m reading on this thread
The engine dosent “know” anything about bore and stroke it’s the heads feeding the gulps of air it’s drawing in
Clearly that longer stroke engines will have advantages where shorter stroke engines will have others but output of each should be comparable
This question may be suited for another topic all together but I’m going to ask it here
Do Different camshafts perform “better” with Different strokes?
For instance a comp 270S fits a 331-427 and every thing in between but will it act differently with large bores and short strokes or smaller bores and long strokes
I’m just trying to understand as much as I can
Too often I’m explained things by people that should be listening
Thanks guys
Dave
You're correct.
A Comp 270S will physically fit into any FE block, but a camshaft has to be chosen to work with the specific displacement you have. To dumb it down, the job of the cam is to fill the cylinders. If you increase the displacement, the cam can't do its job anymore because the cylinders have more volume.
The cam that's needed depends on a lot of variables. I know that most cam catalogs will say "331-428, 2500-5500 powerband, choppy idle" or similar, but the truth is that a cam company can't list how that particular camshaft would work in every single combination of displacement/cylinder head/intake/etc. out there.
For instance, if you stuck that 270S cam in a 352, it would sound pretty thumpy and would make horsepower higher in the rpm range than if you put it in a 428. In the 428, it would sound a lot milder and the peak hp rpm would be much lower.
Coincidentally, how well the heads work plays a big role in it as well. If you have a poor flowing head, it makes it harder for the cam to do its job. A well flowing head makes it much easier, and you will see peak hp rpms go up, as well as peak hp when you keep the same cam and add a good head.
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I spent way too much time trying to find the article but failed, but either HotRod or Car Craft did exactly what's being posed here years ago, they built two big block chevies with big bore/short stroke and small bore/long stroke and compared them, all else being equal. I recall them being surprisingly similar. Sorry, it's from vague memory but I recall being very surprised how close they were. I do recall the peak RPMs shifted around, as you'd expect, but the numbers were similar.
I do NOT recall if they optimized the big bore setup to use bigger valves, which is central to the debate.
I am pretty sure I can find that article in my magazine collection. It was a Freiburger deal and pretty good as I remember. Of course it can be picked apart like anything. I'll look for it this weekend.
I found the article. Hot Rod June 2005. Same exact heads on both combinations as far as I can tell. AFR 335's on both. So that question is not answered. I think they did that on purpose. It seems the the idea was to test bore/stroke and rod/stroke ratio exclusively. Maybe they could have a different head on the big bore combo to take advantage of that extra real estate. Of course there are thousands of different ways to run a test. This is how they did it and I think it is pretty good. Better than I could do for sure.
The small bore combo was 4.28"x4.25" with a 6.535" rod. The big bore combo was 4.56"x3.766" with a 6.135" rod. The rod lengths seem counterintuitive, but they were trying to keep the rod/stroke ratio similar.
They also ran two cams on either combo with different compression ratios. The small cam was a 218/224, .510"/510", 110LSA hydraulic roller. The big cam was a 253/260, .734"/.732", 111 LSA solid roller cam.
The compression ratios were 9.039:1 (small bore) and 9.076:1 (big bore) on the small cam combo. The compression ratios were 10.83:1 (small bore) and 10.87:1 (big bore) on the big cam combo. They used a 0.125" thick head gasket on the small cam combo and a 0.040" thick head gasket on the big cam combo.
So there are 4 total combinations here:
1) Small cam small bore/long stroke
547hp peak@5300 rpm/ (455hp avg) / 592lb/ft peak@3500-3600 rpm/ (551 lb/ft avg)
2) Small cam big bore/short stroke
549hp peak @5400-5500 rpm/ (455hp avg)/ 589lb/ft peak@3600-4000 rpm)@ (550 lb/ft avg)
3) Big cam small bore/long stroke
717hp peak@6600 rpm/ (578hp avg) / 643lb/ft peak@4600 and 5500 rpm/ (612 lb/ft avg)
4) Big cam big bore/short stroke
727hp peak @6300 rpm/ (576hp avg)/ 636lb/ft peak@5400-5500 rpm (609 lb/ft avg)
paulie
Oh yeah, the small cam combo used an Edelbrock RPM intake and the big cam combo used a Weiand Team G intake, both with a 975 cfm Race Demon carb. 2" headers and 18" extensions on both. Small cam combo used Flowmaster mufflers. Big cam combo used no mufflers as far as I can tell.
edit: oops. corrected the rod lengths.
Pretty neat test and a lot of work.
EDITED....didn't realize you meant the intakes were different per cam, not per engine. My bad.
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Imagine the reputation of 427 vs 428 had much less to do with bore/stroke and everything to do with solid cams in 427s, and people comparing that to sluggish passenger car 428s
That's my guess.
The 4.125 x 4 combo in a SBF and SBC is a very potent combination. Why would it be any different for an FE? Obviously the rotating assembly is a lot heavier in an FE than a SBF, but the combo still works. There were 428's in Super Stock that were zinging up over 8000 on a regular basis.
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I spent way too much time trying to find the article but failed, but either HotRod or Car Craft did exactly what's being posed here years ago, they built two big block chevies with big bore/short stroke and small bore/long stroke and compared them, all else being equal. I recall them being surprisingly similar. Sorry, it's from vague memory but I recall being very surprised how close they were. I do recall the peak RPMs shifted around, as you'd expect, but the numbers were similar.
I do NOT recall if they optimized the big bore setup to use bigger valves, which is central to the debate.
I am pretty sure I can find that article in my magazine collection. It was a Freiburger deal and pretty good as I remember. Of course it can be picked apart like anything. I'll look for it this weekend.
I found the article. Hot Rod June 2005. Same exact heads on both combinations as far as I can tell. AFR 335's on both. So that question is not answered. I think they did that on purpose. It seems the the idea was to test bore/stroke and rod/stroke ratio exclusively. Maybe they could have a different head on the big bore combo to take advantage of that extra real estate. Of course there are thousands of different ways to run a test. This is how they did it and I think it is pretty good. Better than I could do for sure.
The small bore combo was 4.28"x4.25" with a 6.535" rod. The big bore combo was 4.56"x3.766" with a 6.135" rod. The rod lengths seem counterintuitive, but they were trying to keep the rod/stroke ratio similar.
They also ran two cams on either combo with different compression ratios. The small cam was a 218/224, .510"/510", 110LSA hydraulic roller. The big cam was a 253/260, .734"/.732", 111 LSA solid roller cam.
The compression ratios were 9.039:1 (small bore) and 9.076:1 (big bore) on the small cam combo. The compression ratios were 10.83:1 (small bore) and 10.87:1 (big bore) on the big cam combo. They used a 0.125" thick head gasket on the small cam combo and a 0.040" thick head gasket on the big cam combo.
So there are 4 total combinations here:
1) Small cam small bore/long stroke
547hp peak@5300 rpm/ (455hp avg) / 592lb/ft peak@3500-3600 rpm/ (551 lb/ft avg)
2) Small cam big bore/short stroke
549hp peak @5400-5500 rpm/ (455hp avg)/ 589lb/ft peak@3600-4000 rpm)@ (550 lb/ft avg)
3) Big cam small bore/long stroke
717hp peak@6600 rpm/ (578hp avg) / 643lb/ft peak@4600 and 5500 rpm/ (612 lb/ft avg)
4) Big cam big bore/short stroke
727hp peak @6300 rpm/ (576hp avg)/ 636lb/ft peak@5400-5500 rpm (609 lb/ft avg)
paulie
Oh yeah, the small cam combo used an Edelbrock RPM intake and the big cam combo used a Weiand Team G intake, both with a 975 cfm Race Demon carb. 2" headers and 18" extensions on both. Small cam combo used Flowmaster mufflers. Big cam combo used no mufflers as far as I can tell.
edit: oops. corrected the rod lengths.
Pretty neat test and a lot of work. I don't understand why they would go to the trouble of keeping everything the same, then do goofy stuff like use two completely different intakes and two grossly different head gasket thicknesses LOL
It makes sense if you think of it as two separate tests. One test with the small cam and one test with the big cam. They kept the intake and head gasket the same for each of the two tests. I could've posted either just the small or the big cam combo and you would have never known. I do think the big cam combo is probably more illustrative of what they were trying to do. But even then the small cam combo is good info, too. I'll grant you a 0.125" head gasket is always a bit goofy.
edit: just saw your edit. I was typing while you were posting.
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The engine dosent “know” anything about bore and stroke it’s the heads feeding the gulps of air it’s drawing in
Clearly that longer stroke engines will have advantages where shorter stroke engines will have others but output of each should be comparable
I agree. An engine doesn't know it's bore and stroke. Those things can have an effect. However the old wisdom that a long stroke engine NECESSARILY makes more torque, likes low rpm, and revs slowly, while a big bore engine NECESSARILY makes more hp, likes high rpm, and revs quick, is wrong.
As has been said before in this thread, there are a lot more differences between a 425hp dual quad solid lifter 427 and a 345 hp passenger car 428 than just bore and stroke. Cams, intake manifolds and carburetion, exhaust manifolds, cylinder heads, compression ratio, etc. are all different and more important in this case. Also, put the 428 in a heavy well optioned car with an stock automatic and the 3.25 gears and compare it to a (427 powered) lower optioned car with a 4 speed and 4.11 gears. Add all that up and yes, that big bore short stroke 427 will rev a lot faster and make more top end hp than that small bore long stroke 428.
paulie
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Do Different camshafts perform “better” with Different strokes?
Another thing they did in the Hot Rod article was vary the valve lash on the big cam combination, since it was a solid cam. They found the big bore combo liked 0.012"/0.026" lash on the intake and exhaust. The small bore combo liked 0.018"/0.024" lash.
The tighter intake lash equates to about 3 degrees more duration @0.050" according to the article. It equates to about 4-1/2 degrees @ 0.020", 5 degrees @ 0.015", and 6 degrees @0.006".
I would have thought the small bore combo might like more duration and/or overlap because of the overlap period in the cylinder. If the small bore is slightly shrouding the valves, especially at the intake opening, I would have thought it might want to open a little sooner? But this says no.
paulie
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Many 427 cobra actually came with a 428. Believe it was Shelby who said you could not tell the difference until you got over 80 mph.
Most 68 Cougar GTE came with a 427 rated at 390 hp. Later it was replaced with a 428 CJ. CJ had same heads, bigger carb, better exh. Manifolds, and intake. Rated at 335 hp. Really was faster than the 427. Ford was going to go with the 427, but the 428cj won out as it was cheaper.
427 was the basis of Fords race program. 428 just a hopped up street engine. Today all you need is a 390 stroked to 445ci tfs heads and a hydraulic roller easy reliable 500 hp. Street engine.
And I am building a 427... Because it is a 427 even knowing all need is a 390 stroker. So short answer to original question Ford answered that in 1968 when it ditched the 427 for the 428cj. It all comes down to application.
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Regarding the BBC testing, it really can't be directly compared to any in line valve engine. the canted valve mitigate the shrouding issue.
For example, the first Boss 302's and Boss 351's, had 2.25 intakes and I think 1.73 exhaust. You can't physically put that valve combo in a 4" bore, with inline valves. That totals 3.98, only leaving less that .007 between any surface and no tolerance for error and heavy shrouding. But, those heads flowed a LOT of air, with there canted valves. TO much and were scaled back to 2.19, the next year. Even that was to much, but for high rpm, in that size CI. But, that's beside the point.
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Regarding the BBC testing, it really can't be directly compared to any in line valve engine. the canted valve mitigate the shrouding issue.
For example, the first Boss 302's and Boss 351's, had 2.25 intakes and I think 1.73 exhaust. You can't physically put that valve combo in a 4" bore, with inline valves. That totals 3.98, only leaving less that .007 between any surface and no tolerance for error and heavy shrouding. But, those heads flowed a LOT of air, with there canted valves. TO much and were scaled back to 2.19, the next year. Even that was to much, but for high rpm, in that size CI. But, that's beside the point.
Actually canted valves get shrouded, too. I remember seeing a flow test with the same BBC head on 396 size bore and a 427/454 size bore and it was significant.
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Regarding the BBC testing, it really can't be directly compared to any in line valve engine. the canted valve mitigate the shrouding issue.
For example, the first Boss 302's and Boss 351's, had 2.25 intakes and I think 1.73 exhaust. You can't physically put that valve combo in a 4" bore, with inline valves. That totals 3.98, only leaving less that .007 between any surface and no tolerance for error and heavy shrouding. But, those heads flowed a LOT of air, with there canted valves. TO much and were scaled back to 2.19, the next year. Even that was to much, but for high rpm, in that size CI. But, that's beside the point.
Actually canted valves get shrouded, too. I remember seeing a flow test with the same BBC head on 396 size bore and a 427/454 size bore and it was significant.
That is correct. It works the same for canted valve heads as it does for inline.
The data you posted was on point. Nice to see those average horsepower and torque figures within 3 numbers of each other. Reasonably within any tolerance of dyno repeatability.
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Actually '69 Boss 302 had 2.230" intake valve and 1.711" exhaust valves, and were too large, went to 2.190" in '70, and the Cleveland used the same 2.190" intake valve size. Joe-JDC
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Many 427 cobra actually came with a 428. Believe it was Shelby who said you could not tell the difference until you got over 80 mph.
Most 68 Cougar GTE came with a 427 rated at 390 hp. Later it was replaced with a 428 CJ. CJ had same heads, bigger carb, better exh. Manifolds, and intake. Rated at 335 hp. Really was faster than the 427. Ford was going to go with the 427, but the 428cj won out as it was cheaper.
427 was the basis of Fords race program. 428 just a hopped up street engine. Today all you need is a 390 stroked to 445ci tfs heads and a hydraulic roller easy reliable 500 hp. Street engine.
And I am building a 427... Because it is a 427 even knowing all need is a 390 stroker. So short answer to original question Ford answered that in 1968 when it ditched the 427 for the 428cj. It all comes down to application.
Agreed. While I can't back up what Shelby may or may not have said the 427 platform was not as cost effective. It could have been overall molding yield or perhaps the post cast milling operations that I've read about. Either way the GTE 427 Cougar is rare. I couldn't afford one if they dredged it out of a river bed.
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Actually '69 Boss 302 had 2.230" intake valve and 1.711" exhaust valves, and were too large, went to 2.190" in '70, and the Cleveland used the same 2.190" intake valve size. Joe-JDC
Ford must’ve gotten a deal and needed to use up a batch of 2.19s, all purpose 302 Boss to 460PI universal valves :)
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First, thank you, Joe, for the correct valve info. I was siting from long ago memory.
Let me show you some pictures and info, on the canted valves, to show that the shrouding, is less on a canted, than inline engine and they can't be compared equally.
You can see, looking down the filled intake port, that when the valve opens, it's moving away from the cyl wall and the higher the lift, the less cyl wall to valve shrouding there is. If the lift was high enough and the cyl wall. long enough, the valve would hit the opposite cyl wall. The exhaust is set up the same way and at some point, if the lift and over lap is extended, they would run into each other. That is why canted valve engines got the nick name of Simi-Hemi.
A inline valve engine, with inclined valves, the valve, will remain near the cyl wall and get closer to the radius of that cyl wall as lift increases.
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First, thank you, Joe, for the correct valve info. I was siting from long ago memory.
Let me show you some pictures and info, on the canted valves, to show that the shrouding, is less on a canted, than inline engine and they can't be compared equally.
You can see, looking down the filled intake port, that when the valve opens, it's moving away from the cyl wall and the higher the lift, the less cyl wall to valve shrouding there is. If the lift was high enough and the cyl wall. long enough, the valve would hit the opposite cyl wall. The exhaust is set up the same way and at some point, if the lift and over lap is extended, they would run into each other. That is why canted valve engines got the nick name of Simi-Hemi.
A inline valve engine, with inclined valves, the valve, will remain near the cyl wall and get closer to the radius of that cyl wall as lift increases.
The exhaust valve on a 4V Cleveland will hit the cylinder wall down in the cylinder at .720" lift (using 1.73 rocker ratio) with a 1.71" exhaust valve and a 4.015" bore. Dropping back to a 1.6 gives .660" lift and gets it away from the cylinder. But it's still shrouded.
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I don't want to be a wet blanket, but is there any answerable question here?
Just to be clear why I am saying this. The first round, many of us looked at the question as being "If you built the two engines with the same parts, what would the difference be?" In essence, an oversquare vs undersquare cid question. I think it's pretty clear that within a small variance, HP per cid stays about the same
If we now shift to the same question but add the largest logical valve we can for each bore, the rest of the build would change dramatically to still be optimized for engine, which then requires additional changes and cost (not talking only money, but cost on the curve too), depending on intent (same rpm range?, peak power only? peak torque in a certain RPM range?) Even Frank as a racer, would design a car for a specific RPM range and of course people on the forum often are building for an existing configuration of the rest of the car
Some thoughts of what would change that make comparable builds difficult to compare
- Intake port change - highly probable to keep port shape correct and take advantage of a valve size change
- Cam change - likely if we are going to keep in the same RPM range, but then you run into "big port small cam" or "small port big cam" comparison. This could be significant, think of TP vs CJ head, or think of high riser vs CJ head. The cam design is wholly different for those heads and a given cid
- Intake manifold - maybe change too, but depends on the head and what the new build was
- Chamber shape and size - likely with a bigger valve, to include valve spacing, which could actually hobble the big bore a little, especially if it can't make compression without a dome
- Compression change - likely with cam change (and could actually have to be lower for the big bore if trying to stay in the same RPM range)
There is no doubt there is some good thinking going on, but I don't know how you could compare those engines. A valve size change without any change to anything else doesn't change much if anything. Remember, the valve itself just gets out of the way, what you are trying to do when discussing shrouding is make room for a bigger seat and throat as that valve gets out of the way. Of course at low lift the valve is part of the equation, but if you don't optimize the rest of the port, as I said in an earlier post, you are just putting bigger lid on a trash can. It covers it, but the trash can (throat) is still the same size.
I post this only because I started playing in the sim and realized either the builds departed so far from each other, or to stay in the same RPM range, I had to pick cams and compression we wouldn't run in two comparable engines.
This discussion then turns into the old "stone soup" story, and the changes add up to a different build all together. If just going for peak power regardless of RPM range, then it's simple, big bore, big head, cam to peak, compression for cam and fuel, and the one with the best cylinder fill wins.
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about the 91000 dollar engine with the large bore spacing.anyone ever thought about designing a fe based ,large bore spacing 1000 ci engine or is the fe design not a good candidate for big ci,big power?