FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: NIsaacs on November 26, 2014, 11:12:38 AM
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I have read a lot about this, that it is "easy" to get this number. I have also read a lot, that it is "easy" to get 2hp per CFM of head intake flow. However they don't seem to both add up the same. Since my 428/440 FE is on the mild side or in the "easy" category, I should have 440 hp. Or using the 2 hp head flow numbers, my ED's advertised at 270....I have read that in real life this number might be closer to 250..... so using the term "easy" I should have 500hp.
So....using my seat of the pants meter and a chassis dyno for power numbers, I would guess my 440 is more in the 400hp range. I have posted a dyno sheet that I have of this engine, before the Edelbrock top end kit and was :-[ when a stock '08 Toyota Tundra beat my numbers, Lol. Any thoughts?(http://i1381.photobucket.com/albums/ah211/NIsaacs1/scan0027_zps1b8cbc0d.jpg)
Nick
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Well, let's see...... the prep work along with the assembly is very very important. So zero deck, file fit rings and paying attention. Yes, you could get 1.5HP per CI. also if you have Ed heads. I would do some bowl work to them and have the seats / valves redone. You could find power in that.
You also need the right combo of parts to get what you need out of it..... So there is more to it then just slapping together an engine and expecting it to perform. Also we need more information than what your posting.
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It's not that tough to get 1 horsepower per cube these days. It is much more difficult to get 2 HP per intake cfm; you need a really good cam and intake combination to get there. Also, these horsepower numbers refer to horsepower at the flywheel. The chassis dyno gives you horsepower at the rear wheels, which is usually around 20% lower than horsepower at the flywheel due to drivetrain losses. Chassis dynos are also notorious for underreporting power, especially if you have an automatic transmission.
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It's not that tough to get 1 horsepower per cube these days. It is much more difficult to get 2 HP per intake cfm; you need a really good cam and intake combination to get there.
x2. The hp per cube goal is fairly easy. The hp per cfm is not. In addition to what Jay said, any engine that gets 2 hp per cfm is likely to be a high compression deal. Possible on high octane pump gas? Yeah, possible, but not at all easy in my opinion. Getting 2 hp per cfm requires everything to be optimized and sacrifices to be made, such as driveability. We are of course talking about naturally aspirated engines.
JMO,
paulie
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What's your full engine combo?
paulie
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That is about what I am shooting for with my 445, 1.5 per cube sounds like a reasonable number.
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That is about what I am shooting for with my 445, 1.5 per cube sounds like a reasonable number.
1.5 x 445 = 667.5 hp. I'd like to hear the plan for that. Not impossible, but that won't be a simple or easy deal.
JMO,
paulie
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I have read a lot about this, that it is "easy" to get this number. I have also read a lot, that it is "easy" to get 2hp per CFM of head intake flow. However they don't seem to both add up the same. Since my 428/440 FE is on the mild side or in the "easy" category, I should have 440 hp. Or using the 2 hp head flow numbers, my ED's advertised at 270....I have read that in real life this number might be closer to 250..... so using the term "easy" I should have 500hp.
So....using my seat of the pants meter and a chassis dyno for power numbers, I would guess my 440 is more in the 400hp range. I have posted a dyno sheet that I have of this engine, before the Edelbrock top end kit and was :-[ when a stock '08 Toyota Tundra beat my numbers, Lol. Any thoughts?(http://i1381.photobucket.com/albums/ah211/NIsaacs1/scan0027_zps1b8cbc0d.jpg)
Nick
2x head flow is a WAG if everything is optimized, parts choices AND tuning, some can get to 2.2-ish x head flow if real good. So it's not that you "should" have 500 hp, it's only that your heads "should be able to support" 500 if all else is right
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Everyone OVERLOOKS the most obvious issue with cfm/hp comparison which is the average airflow at average lift of camshaft. Yes max airflow is important, but what is the average cfm? Take that number and multiply it by 2 and you would be closer to the actual hp of a given cubic inch engine. A head that can flow 270cfm at .700" such as a tweaked RPM, will not flow that cfm using a .525" lift camshaft. Now the flow of that head at .250" lift will probably only be 165cfm, and at .300"lift maybe 190cfm, and at .400" 215cfm, etc. up to .700". If you take flow rates at each .050" lift on a flow bench, then average that number for average flow through the port, then you can realize the net probably horsepower of a regular street engine. It will not be the max flow possible giving the max horsepower possible. Potential is different from actual, and very few engines reach maximum potential for a given head flow.
Another issue that the cubic inches will draw on a head differently due to different cubic inch sizes, and that is another study within itself. That same RPM head that flows 270cfm at .700" lift and 28" hg will continue to flow more air at 30"hg, or even 40"hg, reaching maybe 350cfm due to the increased "draw" on the port. As long as the port doesn't go turbulent and reduce flow, it will continue to work at higher cubic inches, and at higher rpms, even though the camshaft only had .525" lift. Joe-JDC.
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It's not that tough to get 1 horsepower per cube these days. It is much more difficult to get 2 HP per intake cfm; you need a really good cam and intake combination to get there.
x2. The hp per cube goal is fairly easy. The hp per cfm is not. In addition to what Jay said, any engine that gets 2 hp per cfm is likely to be a high compression deal. Possible on high octane pump gas? Yeah, possible, but not at all easy in my opinion. Getting 2 hp per cfm requires everything to be optimized and sacrifices to be made, such as driveability. We are of course talking about naturally aspirated engines.
JMO,
paulie
Okay, that makes more sense, I could not understand the numbers I was coming up with. 1 hp per cube is not hard but 2hp per cfm is a work of art.... I go to a lot of chassis dynos on dyno days here and it always seems the gassers are on the low side and the diesels are high. I have never seen an engine dyno so I am not sure what goes on there. I have asked the operator what the loss differential is, but he says there are a lot of variables, so it's hard to compute. Using 20%, my 243hp would only be about 292hp at the flywheel then, kinda sick, huh? This next spring I will put my pickup on the dyno again and get a comparison with the new top end. The old combo had stock D2 heads, performer intake, 280h comp cam, and 750 edelbrock carb. I don't have the exact compression ratio, just guessing about 10.5.
Nick
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I don't think the "max cfm x2 = hp" deal was ever meant to be more than a rule of thumb for maximum hp potential. Air Flow Research (AFR) cylinder heads has posted the following "formula" and that may be the origin of it.
cfm x .25714 x no. of cylinders = hp
Take that .25714 times 8 cylinders and you come up with 2.057 x cfm = hp. While this is in formula form it is no way an actual usable formula. I mean that to say it does not calculate actual horsepower. Just an estimation of potential hp in a maxed out(race?) type engine.
Joe has a good point about taking the average cfm the port sees throughout the lift curve. That's more realistic as more data is used, but even that would be a huge oversimplification as there are many other factors affecting power. Duration at each lift point, compression, charge temperatures, combustion efficiency, exhaust efficiency, overlap, etc, etc. and on and on...... That is why I say it (2xcfm=hp) is just a rule of thumb for max hp given a max flow rate, and nothing more.
JMO,
paulie
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I don't think the "max cfm x2 = hp" deal was ever meant to be more than a rule of thumb for maximum hp potential. Air Flow Research (AFR) cylinder heads has posted the following "formula" and that may be the origin of it.
cfm x .25714 x no. of cylinders = hp
Take that .25714 times 8 cylinders and you come up with 2.057 x cfm = hp. While this is in formula form it is no way an actual usable formula. I mean that to say it does not calculate actual horsepower. Just an estimation of potential hp in a maxed out(race?) type engine.
Joe has a good point about taking the average cfm the port sees throughout the lift curve. That's more realistic as more data is used, but even that would be a huge oversimplification as there are many other factors affecting power. Duration at each lift point, compression, charge temperatures, combustion efficiency, exhaust efficiency, overlap, etc, etc. and on and on...... That is why I say it (2xcfm=hp) is just a rule of thumb for max hp given a max flow rate, and nothing more.
JMO,
paulie
Of course its a rule of thumb, what else could it be?
Blairs "twins" for example
High 260's on the CJ head - 517 hp (1.988x intake flow, but probably could have went higher if not pump gas)
High 290s on the BBM head - 572 hp (1.93x intake flow, same as above)
However I am truly missing the average calculation you guys like.
From the Edelbrock site
88 153 195 233 265 270 = Intake flow for a stock Edelbrock head
Average = 200.......I hope we can make more than 200 hp! If 2x average flow is what you want to use for a wag to adjust, fine I could see that, but I still say it's still low balling at 400, an Edelbrock head can support more than that out of the box
Read my post again, 2x head flow is good if everything is optimized for peak hp, that mean parts match each other and match desired RPM peak. You can't say "If you have a .525 lift cam" of course it isn't going to make the numbers, it's not built to take advantage of the head.
I personally build for rpm range, more than the hero numbers, but 2x peak intake flow is relatively conservative estimate for what a head can support and a decent wedge can do 2.2 with a good guy behind it. Some good heads will lean higher, crappy heads lean lower, but it's a very old and proven WAG
Like you said though, and what I tried to tell him was it has zero do do with what someone's motor WILL make.
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Using 20%, my 243hp would only be about 292hp at the flywheel then, kinda sick, huh? This next spring I will put my pickup on the dyno again and get a comparison with the new top end. The old combo had stock D2 heads, performer intake, 280h comp cam, and 750 edelbrock carb. I don't have the exact compression ratio, just guessing about 10.5.
Nick
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Chassis dyno's have a lot of variation between them. Plus there are more variables involved so it's harder to calclulate your true hp. Transmssion type (and converter) if auto), tire pressure, accessories on the engine, etc. affect the results. They're just not as reliable a measuring device as an engine dyno. And even engine dynos can have a fair amount of variation between them. If you have a C6 auto in your truck for instance, your hp loss will likely be quite a bit more than 20%. I'd guess closer to 30%. A big fixed blade fan with no fan clutch will also eat up a lot of power between the engine and wheels.
As for you combination, what exhaust do you have? Headers? Pipe diameter? Mufflers?
With the Edelbrock heads, a 280H cam, good exhaust, 10+:1 compression, a 750-850 cfm Holley, a good intake manifold, and good tuning, I think you could top 400 hp at the flywheel.
With the D2 heads, a Performer intake (not RPM), and an Edelbrock carb, it will be a lot less. What combination was on there when you got the 243 hp?
JMO,
paulie
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I don't think the "max cfm x2 = hp" deal was ever meant to be more than a rule of thumb for maximum hp potential. Air Flow Research (AFR) cylinder heads has posted the following "formula" and that may be the origin of it.
cfm x .25714 x no. of cylinders = hp
Take that .25714 times 8 cylinders and you come up with 2.057 x cfm = hp. While this is in formula form it is no way an actual usable formula. I mean that to say it does not calculate actual horsepower. Just an estimation of potential hp in a maxed out(race?) type engine.
Joe has a good point about taking the average cfm the port sees throughout the lift curve. That's more realistic as more data is used, but even that would be a huge oversimplification as there are many other factors affecting power. Duration at each lift point, compression, charge temperatures, combustion efficiency, exhaust efficiency, overlap, etc, etc. and on and on...... That is why I say it (2xcfm=hp) is just a rule of thumb for max hp given a max flow rate, and nothing more.
JMO,
paulie
Of course its a rule of thumb, what else could it be?
Blairs "twins" for example
High 260's on the CJ head - 517 hp (1.988x intake flow, but probably could have went higher if not pump gas)
High 290s on the BBM head - 572 hp (1.93x intake flow, same as above)
However I am truly missing the average calculation you guys like.
From the Edelbrock site
88 153 195 233 265 270 = Intake flow for a stock Edelbrock head
Average = 200.......I hope we can make more than 200 hp! If 2x average flow is what you want to use for a wag to adjust, fine I could see that, but I still say it's still low balling at 400, an Edelbrock head can support more than that out of the box
Read my post again, 2x head flow is good if everything is optimized for peak hp, that mean parts match each other and match desired RPM peak. You can't say "If you have a .525 lift cam" of course it isn't going to make the numbers, it's not built to take advantage of the head.
I personally build for rpm range, more than the hero numbers, but 2x peak intake flow is relatively conservative estimate for what a head can support and a decent wedge can do 2.2 with a good guy behind it. Some good heads will lean higher, crappy heads lean lower, but it's a very old and proven WAG
Like you said though, and what I tried to tell him was it has zero do do with what someone's motor WILL make.
I agree with all of that. I was (and am) just trying to drive home the same point you are. I read your post correctly the first time and I still agree with it. I don't use average flow numbers to calculate anything. It would have to be tweaked with more info like duration at each lift point, just for starters. I was trying to point out that even THAT extra information won't change the fact that we're still just dealing with a rule of thumb that estimates something given some ideal situation.
I'm not knocking the old 2 x max cfm deal. But you can see why the original poster saw the discrepancy between that and his results.
JMO,
paulie
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OK, we agree, sorry, you are still as cool as I thought you were before 8)
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I have used the .257 x 8 x cfm for lots of years, and it always comes close when you figure the average cfm vs max cfm. I have seen several dyno tests where an increase of 30cfm from a set of heads, and 30 cfm increase in the intake manifold only gave a 30hp increase, not 60 as most would suspect. When I started figuring what was wrong, I finally realized that the 30 cfm increase only brought up the average cfm by about 15cfm, thus the 30hp increase, which would hold true if you considered the average vs the maximum flow potential. JMO, but I have witnessed this many times through the years on dyno testing. Joe-JDC
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Easy is in the eye of the beholder - or writer/internet forum poster. The 1HP/cube level should be a fairly easy target.
I have had several wedge headed engines get beyond that 1.5/cube level - but none of them have been remotely close to anything you'd consider easy. It takes a pretty well refined package to get there. Getting the 1HP/cube is a lot easier with street style parts, but still requires good attention - or a frisky cam & intake choice.
The 2 HP per cfm is as noted - a guidance number at best. As JDC noted - it can be pretty close or far off depending on the combination wrapped around those heads. On the flow benches around here a bone stock Edelbrock head will blow around 252-254 at .600 lift. Theoretically it should thus support up to +/- 500HP. We struggle to hit that number with street oriented 445 cid combinations and usually come in 450-475ish at best. Slipping one of my castings into the combination will gain about 30-40 cfm and gets us over the 500 bubble pretty cleanly, but still short of the 2 per. Take that same head and stick it onto a 482 and the similar behaving combo will go past 600HP regularly - exceeding that same rule of thumb. That's 100 horsepower with the exact same heads - combination, combination, combination...
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It's not that tough to get 1 horsepower per cube these days. It is much more difficult to get 2 HP per intake cfm; you need a really good cam and intake combination to get there.
x2. The hp per cube goal is fairly easy. The hp per cfm is not. In addition to what Jay said, any engine that gets 2 hp per cfm is likely to be a high compression deal. Possible on high octane pump gas? Yeah, possible, but not at all easy in my opinion. Getting 2 hp per cfm requires everything to be optimized and sacrifices to be made, such as driveability. We are of course talking about naturally aspirated engines.
JMO,
paulie
The old combo had stock D2 heads, performer intake, 280h comp cam, and 750 edelbrock carb. I don't have the exact compression ratio, just guessing about 10.5.
Nick
This was the combo for the dyno sheet. This is with the c-6 and 3k stahl, open headers, 1.750 primaries.
Nick
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So, with the same short block as the above dyno sheet, will this engine make the 1hp per cube? I don't have the deck height, but the pistons are the Speed Pro 4.190 bore with a 10.30 cc dish with 4 valve reliefs, 4.40 bore, .038 compressed gasket and 72 cc Edelbrock heads. Complete Ed. top end kit. Heads, rpm manifold, rpm cam, 850 Ed. carb, Pertronics dist. set at 21 initial, 37 total, 1.750 primary piped open headers.
There is a guy that pulls in the Super Stock class with a 393 de-stroked 400 Chevy that pulls with the big dogs (500+ engines) He says the de-stroked rod/piston combo is better than a stroked 350. I love to watch his truck scream down the track. He is currently building a 496 big block Chevy that he says will be 2.1 hp per cube. If his little 393 is an indicator of him and his engine builder, this new engine will trash the Super Stock class, if the chassis will handle that kind of power.
Nick
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OK, we agree, sorry, you are still as cool as I thought you were before 8)
Thanks man......... I think. :)
paulie
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I have used the .257 x 8 x cfm for lots of years, and it always comes close when you figure the average cfm vs max cfm. I have seen several dyno tests where an increase of 30cfm from a set of heads, and 30 cfm increase in the intake manifold only gave a 30hp increase, not 60 as most would suspect. When I started figuring what was wrong, I finally realized that the 30 cfm increase only brought up the average cfm by about 15cfm, thus the 30hp increase, which would hold true if you considered the average vs the maximum flow potential. JMO, but I have witnessed this many times through the years on dyno testing. Joe-JDC
I wasn't trying to discount average flow, Joe. I do believe the average or I would rather say, the sum, is what counts in the end. How much power an engine makes is essentially the sum of the flow at all points when the intake valve is open. Your point about peak flow and it's affects, vs. average flow, are well taken.
JMO,
paulie
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The old combo had stock D2 heads, performer intake, 280h comp cam, and 750 edelbrock carb. I don't have the exact compression ratio, just guessing about 10.5.
Nick
This was the combo for the dyno sheet. This is with the c-6 and 3k stahl, open headers, 1.750 primaries.
Nick
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I think 243 RWHP sounds reasonable with D2 heads and a Performer intake, especially with a C6 and a 3000 rpm stall converter. You might have been making 340 flywheel hp at that point. Add Edelbrock heads, an RPM intake, and a bigger Holley carb and I could see gaining 50-60 flywheel hp.
JMO,
paulie
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So, with the same short block as the above dyno sheet, will this engine make the 1hp per cube? I don't have the deck height, but the pistons are the Speed Pro 4.190 bore with a 10.30 cc dish with 4 valve reliefs, 4.40 bore, .038 compressed gasket and 72 cc Edelbrock heads. Complete Ed. top end kit. Heads, rpm manifold, rpm cam, 850 Ed. carb, Pertronics dist. set at 21 initial, 37 total, 1.750 primary piped open headers.
There is a guy that pulls in the Super Stock class with a 393 de-stroked 400 Chevy that pulls with the big dogs (500+ engines) He says the de-stroked rod/piston combo is better than a stroked 350. I love to watch his truck scream down the track. He is currently building a 496 big block Chevy that he says will be 2.1 hp per cube. If his little 393 is an indicator of him and his engine builder, this new engine will trash the Super Stock class, if the chassis will handle that kind of power.
Nick
It could make 1 hp per cube with your short block. You may need more cam, or a different cam to push you over the 1 hp per cube mark. The 280H cam is a fine cam but it's not cutting edge and it's not overly big for a 440 inch engine. I'd go bigger if you have enough gearing and compression to support it. The Edelbrock RPM cam is a bit bigger, but not I what I'd pick. Go with a solid flat tappet cam in the 242-248 degree @ 0.050" range with net lift in the 0.560-0.590" range and you're there, in my opinion.
Also, I think you should verify the volume of the combustion chambers in your Edelbrock heads. I also have the "72 cc" versions, but mine have 79 cc chambers. Mine are very early heads and that is likely why. Yours are probably close, but it's so easy to check that you might as well. On an old engine build a long time ago I had TRW 2245 pistons in my 428 and I thought I had around 10:1 compression. I actually had around 9.3:1 compression. A pretty big difference. I think you probably want the true compression ratio to be in the 10.0:1 to 10.5:1 range
paulie
edit: added solid flat tappet recommendation.
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There is a guy that pulls in the Super Stock class with a 393 de-stroked 400 Chevy that pulls with the big dogs (500+ engines) He says the de-stroked rod/piston combo is better than a stroked 350. I love to watch his truck scream down the track. He is currently building a 496 big block Chevy that he says will be 2.1 hp per cube. If his little 393 is an indicator of him and his engine builder, this new engine will trash the Super Stock class, if the chassis will handle that kind of power.
Nick
I would think that a big bore short stroke SBC would out-power and out-pull a small bore long stroke SBC any day. It'd have to be geared correctly and run at whatever rpm the induction can support, but it WOULD do it.
JMO,
paulie
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Bare with me for a minute with all the info I am learning. But, if the rpm hydraulic cam is 236 @50 and .572 lift, is that not about the same as a solid 242-248 @ 50 and .560-.590 lift, when you factor in the valve lash? My English teacher always told me not to start a sentence with "but" but some times ya gotta ;D
Nick
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Bare with me for a minute with all the info I am learning. But, if the rpm hydraulic cam is 236 @50 and .572 lift, is that not about the same as a solid 242-248 @ 50 and .560-.590 lift, when you factor in the valve lash? My English teacher always told me not to start a sentence with "but" but some times ya gotta ;D
Nick
Short answer is no, but your thought process is valid. You are correct that when you subtract lash from the solid cam you will lose lift and duration at the valve. However, it is typically not that much of a duration change and more importantly, the hydraulic lifters will eventually get more difficult to control at higher rpm, taking power away that the solid cam will provide.
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Bare with me for a minute with all the info I am learning. But, if the rpm hydraulic cam is 236 @50 and .572 lift, is that not about the same as a solid 242-248 @ 50 and .560-.590 lift, when you factor in the valve lash? My English teacher always told me not to start a sentence with "but" but some times ya gotta ;D
Nick
Yeah, you're right. A 236 duration hydraulic is about the same equivalent duration as the solid range I mentioned. A good rule of thumb is to add 8-10 degrees for an equivalent solid cam.
I think a solid would make more overall power though. That Edelbrock RPM cam can work. I don't think most engine builders would pick it compared to something else. It's an old school design with pretty slow ramps and I've read it's not that great. Barry's about to tell me cams can't read and he's right of course. :) I've never run the RPM cam.
Do you have adjustable rocker arms?
paulie
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Nick, what RPM range do you run during the event? I think the most important thing is to not look at the HP goal alone but be sure the engine matches the track and truck not the dyno...
There are a lot of moving parts on this post that need to be addressed, but I think where you want it to make power is the most important
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I have been accumulating Holley Street Dominator intake manifolds, and Edelbrock Streetmaster intakes to try to prove a theory about increased airflow and the correlation to hp increases. I have 3 of each, and I plan to port them so that there is a 30cfm difference between each of them, and then port a set of either Edelbrock RPM heads, and BBM heads so that they have a 30cfm difference and then do extensive dyno tests of the different combinations along with a RPM intake, and Victor, BT8V, TW, etc.. I had hoped to have a couple of shortblocks available for this, also, one +.030 CJ, and a 4.390" x 4.250 stroke BBM block. I already have all the parts here, it is just coming up with the time to get everything ported, machined, and assembled. Should be an interesting test, with some of the heads flowing over 350cfm. I have a set of Survival heads that can be thrown in the mix, also. Just need a dyno that is available for that much testing, and is from a reputable shop. I have a couple available locally, but unless there is a known test comparison, it will always be suspect. One has had a EMC engine to compare with, so I trust it. We shall see. Would travel to any shop on the forum if this was a possibility for them to verify. Joe-JDC.
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Nick, what RPM range do you run during the event? I think the most important thing is to not look at the HP goal alone but be sure the engine matches the track and truck not the dyno...
There are a lot of moving parts on this post that need to be addressed, but I think where you want it to make power is the most important
I agree, I have had numerous conversations about a dyno test v/s real world testing on the diesel forum that I frequent. That a 10 second dyno run in a controlled environment, is not the same as towing up a 6% grade for 5 miles in 100 degree heat, foot to the floor, and towing 26k GCW.
I run 3k to wot, about 5800 rpm max, that's all it will pull. I have no problem launching the sled, so low end power is not an issue.
I am running the oem, non-adjustable rockers. I think because the rpm cam is old school with slow ramps, valve train control is not a big of issue as the quick ones. Power wise I am sure there are some way better, but the way it runs and revs, I am liking it :)https://www.youtube.com/watch?v=Mg8CWzqq2kw (https://www.youtube.com/watch?v=Mg8CWzqq2kw)
Nick
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Nick, what RPM range do you run during the event? I think the most important thing is to not look at the HP goal alone but be sure the engine matches the track and truck not the dyno...
There are a lot of moving parts on this post that need to be addressed, but I think where you want it to make power is the most important
I agree, I have had numerous conversations about a dyno test v/s real world testing on the diesel forum that I frequent. That a 10 second dyno run in a controlled environment, is not the same as towing up a 6% grade for 5 miles in 100 degree heat, foot to the floor, and towing 26k GCW.
I run 3k to wot, about 5800 rpm max, that's all it will pull. I have no problem launching the sled, so low end power is not an issue.
I am running the oem, non-adjustable rockers. I think because the rpm cam is old school with slow ramps, valve train control is not a big of issue as the quick ones. Power wise I am sure there are some way better, but the way it runs and revs, I am liking it :)https://www.youtube.com/watch?v=Mg8CWzqq2kw
Nick
2 follow on questions
1 - Are we trying to fix something or just BSing?
2 - What is tire size and gear ratio?
3 - What gear are you in and which tranny in the truck?
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I am actually really happy with the way it runs and pulls. If I can stay in the top 3 I will be satisfied. Like I posted before in another thread, I am done working on this engine, other than fine tuning. I was just curious if it was making the 1 hp per cube thing.
I am running the c-6 with the low gear kit, 2.72:1, 2:1 NP203 t-case, 4.88 gears and 31" tires. I never shift out of 1st unless it is a real small sled. With a big sled like in the video, it is 1st all the way.
Nick
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Bare with me for a minute with all the info I am learning. But, if the rpm hydraulic cam is 236 @50 and .572 lift, is that not about the same as a solid 242-248 @ 50 and .560-.590 lift, when you factor in the valve lash? My English teacher always told me not to start a sentence with "but" but some times ya gotta ;D
Nick
I usually don't post pictures from my book online, but I will make an exception here to point out that the hydraulic lifters and the Edelbrock spring setup will give up on your engine around 5300 RPM. That cam should pull a lot higher, and quite a while back I swapped a set of solid lifters onto the RPM hydraulic cam to see what the difference was. Here is the graph from page 228 of my book:
(http://fepower.net/Photos/Posts/solvshyd.jpg)
Bottom line is that you are leaving a good 30 HP on the table at the top end, running that hydraulic cam. I don't like hydraulic cams (flat tappet or roller), and this graph is a perfect example why. There are steps you can take to extend the RPM range, like running more seat pressure and a little higher open pressure,and probably get the cam/lifter/spring setup to work to 6000 RPM, but as that setup is delivered from Edelbrock, this is what you will get.
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I have been accumulating Holley Street Dominator intake manifolds, and Edelbrock Streetmaster intakes to try to prove a theory about increased airflow and the correlation to hp increases. I have 3 of each, and I plan to port them so that there is a 30cfm difference between each of them, and then port a set of either Edelbrock RPM heads, and BBM heads so that they have a 30cfm difference and then do extensive dyno tests of the different combinations along with a RPM intake, and Victor, BT8V, TW, etc.. I had hoped to have a couple of shortblocks available for this, also, one +.030 CJ, and a 4.390" x 4.250 stroke BBM block. I already have all the parts here, it is just coming up with the time to get everything ported, machined, and assembled. Should be an interesting test, with some of the heads flowing over 350cfm. I have a set of Survival heads that can be thrown in the mix, also. Just need a dyno that is available for that much testing, and is from a reputable shop. I have a couple available locally, but unless there is a known test comparison, it will always be suspect. One has had a EMC engine to compare with, so I trust it. We shall see. Would travel to any shop on the forum if this was a possibility for them to verify. Joe-JDC.
Geez Joe, all you had to do was ask LOL! I'd be happy to have you at my place if you don't mind the travel, and can work with my schedule (which, admittedly, is a little tight these days...) - Jay
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Nick
To answer your question... I don't think you have enough cam and or compression to make the one horsepower per cube... It's probably close but I'm guessing your in the 400-420 hp range... My 10.5 compression 390 with ported iron heads that flow just a little better than stock edelbrock heads and a cam that is 10-15 degrees longer duration and exhales through a 2 inch primary 3.5 collector headers made 1.16 hp per cube but i wouldn't exactly call it easy... The engine isn't anything spectacular or special but it was put together at home and I tried to pay attention to the details... Tight quench/ degree the cam... File fit rings... Low tension oil rings... Good valve job on the heads, blending the intake runners and a customized 800dp holley carb... Again I believe the devil is in the details... I searched a long time to get the power where it is with this engine... Other people have probably done better with the same parts I've used but I wouldn't call my build average either... Keep trying things on your combo until your either winning or satisfied with the results... Happy thanksgiving!
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Thanks, Jay, I will get back to you for a chat. I am visiting my son in FL, and it will be a while before I get everything finished. It would be an interesting write for a book if things go as I suspect. Joe
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It is funny how advertisers throw out numbers like 25 HP gains out of the box. How do they know what you are bolting it on, so if I bolt their part on my weed trimmer I get 25 more HP out or it LOL.
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It is funny how advertisers throw out numbers like 25 HP gains out of the box. How do they know what you are bolting it on, so if I bolt their part on my weed trimmer I get 25 more HP out or it LOL.
Exactly! I think I am a perfect example of believing what I read from those guys, the dyno graph Edelbrock shows with a stock 390 and their complete rpm top end kit is at 418hp/440tq, the graph stops at 6k and shows the 418hp at the top or 1.07hp per cube so......life goes on Lol!
Nick
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Exactly! I think I am a perfect example of believing what I read from those guys, the dyno graph Edelbrock shows with a stock 390 and their complete rpm top end kit is at 418hp/440tq, the graph stops at 6k and shows the 418hp at the top or 1.07hp per cube so......life goes on Lol!
Nick
But it does make that kind of power. Or pretty close.
Barry R did one up a while back and the old 390 made very similar hoof marks as Edelbrock.
I'd say my 396 ci makes similar power also.
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Exactly! I think I am a perfect example of believing what I read from those guys, the dyno graph Edelbrock shows with a stock 390 and their complete rpm top end kit is at 418hp/440tq, the graph stops at 6k and shows the 418hp at the top or 1.07hp per cube so......life goes on Lol!
Nick
But it does make that kind of power. Or pretty close.
Barry R did one up a while back and the old 390 made very similar hoof marks as Edelbrock.
I'd say my 396 ci makes similar power also.
I guess that's why I asked the original question. If Edelbrock can make that kind of power with their top end kit, why can't I? Their graft shows the rpm cam making power to 6000 rpm (418hp). Yet some say it is junk after 5300. I know for a fact it pulls to 5800 without a whimper, watch and listen to the video. Is it past it's peak power? Maybe, but it sure as heck is not making the valve train go crazy, or if it is, you can't hear or feel it. If I pull the small sled, the rpm's go scary high and again without any feel or noise that I can hear.
Nick
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You might have one advantage with the valvetrain stability that Jay brown didn't well maybe two... Your using stock non adjustable rockers which I believe are a bunch lighter than the rockers Jay had on his dyno mule... Other thing is maybe your lifters are of a tighter tolerance or quality than the set Jay used... I think I remember Jay saying he never felt the engine nose over in the car like the dyno graph would lead you to believe it would feel like it is.... Anyway hopefully you can find some more ground speed and power somewhere... I wish I could put nicer parts on the Fe pulling truck but rules keep me from getting more carried away... Also its usually harder to make the same hp per cube with a bigger cubic inch engine than a smaller one using the same top end parts... Happy pulling!
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Chassis dynos are never good for vehicles with automatics. The torque convertor goofs up the rate of acceleration and also never really locks-up.
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You might have one advantage with the valvetrain stability that Jay brown didn't well maybe two... Your using stock non adjustable rockers which I believe are a bunch lighter than the rockers Jay had on his dyno mule... Other thing is maybe your lifters are of a tighter tolerance or quality than the set Jay used... I think I remember Jay saying he never felt the engine nose over in the car like the dyno graph would lead you to believe it would feel like it is....
Both good points, Cody. Blair has discussed his theories about the lighter rocker arms also. I'd also add that a chassis and/or engine dynos put full loads on an engine like you would have in 4th gear. When you're running through the gears, it spends a much shorter time in 1st, 2nd and 3rd. The longer duration in 4th gives the lifters time to change to pressure fluctuations. I've seen this several times and even in valve float from spring pressure situations. There's more time spent going through the harmonic stages.
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... Happy pulling!
Thanks Cody, I am a happy camper puller! Win or loose, the rush is great, each run! A picture of your puller or video would be great....hint hint :D
Nick
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The whole rocker thing is what made me decide on the T&D race rockers, they seem like one of the lighter and more durable options out there. I had seen others at the time that were Cromo steel or cast steel and thought that would just increase float on my already heavy hydraulic roller valve train. I did go to a good spring to help some but I think 6800 is going to be about it for what I have cam wise.
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Thanks, Jay, I will get back to you for a chat. I am visiting my son in FL, and it will be a while before I get everything finished. It would be an interesting write for a book if things go as I suspect. Joe
I'd buy that book, Joe.
paulie
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I'd also buy that book Joe. Later, Travis.
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I would buy it as well :D
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Cody, since you sled pull ;D here is a video pulling the small sled in the 5500 stock gas class, note the rpm's ;)....this was with the stock D2 heads, rpm cam, rpm intake, 750 ED carb and oem dist. This was a test pull to "set" the sled. https://www.youtube.com/watch?v=iNKqyXlq8IY (https://www.youtube.com/watch?v=iNKqyXlq8IY)
Nick
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Nice, sounds strong. Even though it was a test to set the sled it looks and sounds like you could have pulled it downtown if you wanted to :)
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I have had many work/service trucks and vans with FE engines, they are very strong pullers when put under load. My work trucks were heavily loaded with parts, tools and cylinders and the engines always performed well under heavy loads. It was almost like a diesel engine in the way the engine performs better under load than empty LOL. My only complaint would be gas mileage but the injected 351 was actually worse mileage wise.
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That is about what I am shooting for with my 445, 1.5 per cube sounds like a reasonable number.
I have been reading until I am cross eyed, getting info for my current 440, but mostly for my next engine build, for the Super Stock class, they have a 500 cid limit. I was leaning towards 482+ but maybe the 454 size I have access to, is enough. I will need a minimum of 600hp.
Two sets of very similar engine builds come to mind. They were built by 2 very experienced FE builders, so build quality/attention to detail is a given. This is all about hard parts. Yet, the 396 out powered the 446 by a large margin. The mild 396 produced 1.3 hp per cube, the hot one 1.44 hp per. The 446 mild one, was at 1.13 with the strip version at 1.23 hp per. Where the heck did the difference come from? Dyno's? From what I can see, the hard parts were almost identical.
The 446's were built for Car Craft and the 396's are on BBM's site. I am sure you guys are familiar with these articles. If I can get 1.44 hp per cube on a 454 with good modern top end goodies, that's 653 hp....woo hoo....!!
Thoughts??
Thanks, Nick
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Dynos can account for a lot of difference in results....
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I have read a lot about this, that it is "easy" to get this number. I have also read a lot, that it is "easy" to get 2hp per CFM of head intake flow. However they don't seem to both add up the same. Since my 428/440 FE is on the mild side or in the "easy" category, I should have 440 hp. Or using the 2 hp head flow numbers, my ED's advertised at 270....I have read that in real life this number might be closer to 250..... so using the term "easy" I should have 500hp.
So....using my seat of the pants meter and a chassis dyno for power numbers, I would guess my 440 is more in the 400hp range. I have posted a dyno sheet that I have of this engine, before the Edelbrock top end kit and was :-[ when a stock '08 Toyota Tundra beat my numbers, Lol. Any thoughts?(http://i1381.photobucket.com/albums/ah211/NIsaacs1/scan0027_zps1b8cbc0d.jpg)
Nick
Good replies already, I feel also that the "2 hp per intake CFM" is a very rough rule of thumb, meant to apply to GROSS HP, ie open exhaust on the dyno, no fan, 29.92 60F dry air, etc. In a typical street car NET hp is a lot lower than GROSS hp, and REAR WHEEL is a lot lower than both.
Example I pulled from Gonkulator files -
63 Galaxie 427/410hp, bone stock
412 GROSS hp
316 NET hp
283 REAR WHEEL hp
58 Merc 430/400hp, bone stock
370 GROSS hp
283 NET hp
212 REAR WHEEL hp
..... a long way from the 400hp rating! The big Lincoln LX trans ate a lot of power.
All this stuff has to "jive" with the trap speed the car actually put out so that's where things come together.
The new cars/trucks are made with special lightweight exotic materials (ie stuff you cant fix or weld like our old iron & low carbon steel).
This makes the new rigs much heavier (yup) than the old cars.
I've started naming the new trucks after Tanks, like the Sherman, Panther, Tiger.
An old longbed truck used to weigh 4000 lb give or take, today they are well over 5000lb.
That's more than an iron FE with a c6 & starter & generator attached!
Therefore, your old light truck might still outrun that fat new iron, the heavy new rigs all need more power just to get them moving.
My favorite is the new Dodge Challenger Hellcat, at 4500 curb, heavier than my big-block Galaxie WAGON.
How do they make em so heavy today?
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"How do they make em so heavy today?"
Electric ass heaters with touch screen control. For a start.
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"How do they make em so heavy today?"
Electric ass heaters with touch screen control. For a start.
That and the big power, requires heavy duty power trains.
Werby, that's interesting on the hp comparison, with about a 35% (average) loss on the chassis dyno, that brings my old Ford up to about 330 hp, sounds about right.
Nick
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Here is a video of my truck with the exact same power as the dyno sheet, note how slow it was v/s todays power. The Edelbrock top end kit was a huge improvement, plus the addition of the low first gear. The axle ratio and tire size was the same in both videos.
https://www.youtube.com/watch?v=cUUdnDaCJ9o (https://www.youtube.com/watch?v=cUUdnDaCJ9o)
Nick
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Update: Here is a new dyno sheet from yesterday. With the Edelbrock complete top end kit I gained 51 hp and 32 trq, seems like a lot of time and money for the gain but it pulls the sled way better :)
(http://i1381.photobucket.com/albums/ah211/NIsaacs1/scan0001_zpsrapulapv.jpg)
Nick
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Copy of the old dyno sheet.
(http://i1381.photobucket.com/albums/ah211/NIsaacs1/scan0027_zpsu1ucchcw.jpg)
Nick
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As somebody mentioned. I have run the Edelbrock "package" on the dyno and it performed almost exactly as advertised. With chassis numbers often being 20% or more lower and notoriously inaccurate I would say you are right on the proverbial "mark".
As for torque per cubic inch on an FE for street use - once you get past 1.1-1.2 lbs per cube you are really doing very well on a traditional street build. Going beyond 1.3 per cube is a very solid combination. Hitting 1.4-1.5 pounds on torque per cube is reaching Engine Masters Challenge territory and does not happen with a "bolt together" package.
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It's not that tough to get 1 horsepower per cube these days. It is much more difficult to get 2 HP per intake cfm; you need a really good cam and intake combination to get there.
x2. The hp per cube goal is fairly easy. The hp per cfm is not. In addition to what Jay said, any engine that gets 2 hp per cfm is likely to be a high compression deal. Possible on high octane pump gas? Yeah, possible, but not at all easy in my opinion. Getting 2 hp per cfm requires everything to be optimized and sacrifices to be made, such as driveability. We are of course talking about naturally aspirated engines.
JMO,
paulie
Okay, that makes more sense, I could not understand the numbers I was coming up with. 1 hp per cube is not hard but 2hp per cfm is a work of art.... I go to a lot of chassis dynos on dyno days here and it always seems the gassers are on the low side and the diesels are high. I have never seen an engine dyno so I am not sure what goes on there. I have asked the operator what the loss differential is, but he says there are a lot of variables, so it's hard to compute. Using 20%, my 243hp would only be about 292hp at the flywheel then, kinda sick, huh? This next spring I will put my pickup on the dyno again and get a comparison with the new top end. The old combo had stock D2 heads, performer intake, 280h comp cam, and 750 edelbrock carb. I don't have the exact compression ratio, just guessing about 10.5.
Nick
I read thru thread and did not see anyone mention this:
When you say 243 to 292 hp you are adding to the small number. A 20% loss would be actually 305hp - 20% loss to get the 243
Your current would be 294.8 or a 368 hp - 20% would give you the 294. With a c-6 trans you will lose an additional 25hp from my testing years back.
That would bring you up to 393HP but I think you are really making a honest 400 flywheel HP. Large tires eating it up for one.