FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Agar426 on November 16, 2013, 11:27:53 AM
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I understand the basic concept of the roller cam vs a flat tappet cam. However, I don't know much about what it takes to install one, and what all of the caveats are. I remember when I was a kid, a friend of mine had a '73 Challenger which their family used as a street/strip car. After an engine failure at the track, they were actually excited, because they could now "rollerize" their engine.....talking about it like it was some magic pill. They also made it sound like it wasn't a trivial thing to convert an engine to a roller cam.
So....here are my questions:
1) I realize that the roller aspect allows you to be a little more aggressive with cam selection....but if the cams were similar, what kind of difference does the roller make? Basically, is the performance advantage worth the expense?
2) What exactly does it take to convert an FE, and what is the net cost difference...i.e., to go roller on an FE, it will cost me $X more?
3) While googling the subject, I found very little information. There some old hits from the early 2000s talking about how the Crane stuff would fail above 5,000 rpm.
4) What are the proven "kits" out there? IN my case, for a strong street engine? Or....for a street engine, is a roller's advantage not realized?
Thank you!
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The basic advantage of a roller cam is that it gives you more area under the lift curve. Let's say, for example, that you are comparing a solid flat tappet cam and a solid roller cam that have exactly the same advertised lift and duration numbers. On the roller cam, the ramps can be steeper on the flanks of the cam lobe, and so the valve opens more quickly and can stay at the higher lift levels for longer periods of time. This gives better cylinder filling on the intake side, and better exhaust scavenging on the exhaust side. The roller cam has this advantage because roller lifters can follow a more aggressive cam profile. So generally a switch from a solid cam to a roller cam with equivalent specifications will make a significant performance improvement.
In terms of installing a roller cam, you just have to make sure you have the right components. You need the roller cam, the roller lifters, and better springs than you would use for an equivalent flat tappet cam, because the higher opening and closing rates will need more spring pressure to keep the valvetrain under control. You also might need better pushrods, depending on the springs, and titanium spring retainers are also a good idea. Finally, most roller cams are machined out of steel rather than cast iron, and will quickly destroy a factory cast iron distributor gear. So replacing the distributor gear with a steel or brass gear is also going to be required. Other than that, there isn't really anything special you need to do. Just make sure you get good components that are matched up well with each other.
To answer your questions more specifically, probably figure an additional $600 on the cam and lifters for a roller over a solid, $80 for a steel distributor gear, and maybe another $300-$600 on springs and retainers, depending on the cam requirements. Whether that is worth the additional torque and HP is up to you, but on an engine like yours it wouldn't surprise me to see an increase of 30 HP and 30 lb-ft of torque with a change to an equivalent roller cam. Regarding engine speed, the hydraulic roller stuff can be made to go to 6000 RPM if you have all the right equipment, but often it will only get to 5500 or so before valve float sets in; this was the problem with the Crane hydraulic roller setups you mentioned. Solid rollers, of course, will go higher.
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The basic advantage of a roller cam is that it gives you more area under the lift curve. Let's say, for example, that you are comparing a solid flat tappet cam and a solid roller cam that have exactly the same advertised lift and duration numbers. On the roller cam, the ramps can be steeper on the flanks of the cam lobe, and so the valve opens more quickly and can stay at the higher lift levels for longer periods of time. This gives better cylinder filling on the intake side, and better exhaust scavenging on the exhaust side. The roller cam has this advantage because roller lifters can follow a more aggressive cam profile. So generally a switch from a solid cam to a roller cam with equivalent specifications will make a significant performance improvement.
In terms of installing a roller cam, you just have to make sure you have the right components. You need the roller cam, the roller lifters, and better springs than you would use for an equivalent flat tappet cam, because the higher opening and closing rates will need more spring pressure to keep the valvetrain under control. You also might need better pushrods, depending on the springs, and titanium spring retainers are also a good idea. Finally, most roller cams are machined out of steel rather than cast iron, and will quickly destroy a factory cast iron distributor gear. So replacing the distributor gear with a steel or brass gear is also going to be required. Other than that, there isn't really anything special you need to do. Just make sure you get good components that are matched up well with each other.
To answer your questions more specifically, probably figure an additional $600 on the cam and lifters for a roller over a solid, $80 for a steel distributor gear, and maybe another $300-$600 on springs and retainers, depending on the cam requirements. Whether that is worth the additional torque and HP is up to you, but on an engine like yours it wouldn't surprise me to see an increase of 30 HP and 30 lb-ft of torque with a change to an equivalent roller cam. Regarding engine speed, the hydraulic roller stuff can be made to go to 6000 RPM if you have all the right equipment, but often it will only get to 5500 or so before valve float sets in; this was the problem with the Crane hydraulic roller setups you mentioned. Solid rollers, of course, will go higher.
Thank you for a very for the response! Very informative.....
So, it looks like it will cost me at least a grand to move to a roller cam. If the gains are at peak, I think I would pass. If the gains are throughout the curve, then....it sounds like a winner.
To prevent an idiot like myself from mis-matching the parts, are they available as a package?
Thanks again!
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One of the good things about a roller is that you get to skip the flat tappet break-in dance....hahaha
If you're starting from scratch on a build, the price difference isn't all that bad. Even if you went flat tappet, you can count on spending about $200 for a cam/lifter set, new springs/retainers, possibly new pushrods, etc. When you compare that to a hydraulic roller setup, you're really not too far off in the overall scheme of things. Being able to just turn the key and skip the cam break-in is a blessing in itself.
I get about 6000-6100 before I see valve float on the dyno with a hydraulic roller. I use Comp Cams hydraulic roller grinds that are very mild. That seems to help. I also use Morel lifters. That particular combo is actually cheaper than a Crane setup. About $350 for the cam (billet steel core), $385 for the lifters. Valve springs and retainers don't need to be too exotic, usually around the same price as the equivilent new valve springs/retainers for a nice flat tappet build. As Jay mentioned, you will need a steel distributor gear. Crane sells them for about $70. Mallory also has them for quite a bit less.
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We do about a bazillion hydraulic roller FEs these days - for all the reasons mentioned. The real key to success is to keep the cam profile mild, and target the RPM range where hydraulic rollers are happy - I try to get the peak somewhere between 5700 and 6000 if possible. I have made hydraulic rollers rev far higher - but its neither easy nor cheap to do so, and defeats their purpose. The early Crane lobes were derived from SBC or SBF profiles and had short duration with lots of lift due to the FE high rocker ratio. That made them very hard to get control of the valvetrain, and we saw them get into pretty bad float. Crane does not sell those anymore for good reason.
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So, it looks like it will cost me at least a grand to move to a roller cam. If the gains are at peak, I think I would pass. If the gains are throughout the curve, then....it sounds like a winner.
To prevent an idiot like myself from mis-matching the parts, are they available as a package?
Thanks again!
You will see gains throughout the entire power curve with a roller cam. All the cam manufacturers will offer recommended spring packages for their cams, but my experience has been that they are usually on the light side. Pick the cam you want first, then post that info here and you will get some recommendations on springs, lifters, etc.
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Maybe this will illustrate.
First cam is a 282S solid flat tappet - 236 degrees at .050 and .571 gross lift
Second cam is a custom hydraulic roller 234/240@.050 and .594/.598 gross lift
Obviously the roller is a bit larger - -but close enough for comparison
(http://i38.photobucket.com/albums/e135/Barry_R/4452x4dynochart282SvsHydRollerironheads.jpg)
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Maybe this will illustrate.
First cam is a 282S solid flat tappet - 236 degrees at .050 and .571 gross lift
Second cam is a custom hydraulic roller 234/240@.050 and .594/.598 gross lift
Obviously the roller is a bit larger - -but close enough for comparison
(http://i38.photobucket.com/albums/e135/Barry_R/4452x4dynochart282SvsHydRollerironheads.jpg)
Excellent! Thank you for posting that. I love how the curves are smooth and that torque curve....lots of area underneath, making torque early and holding on to it throughout the range. This comparison was against a solid flat tappet cam, so I can only imagine the difference between the Hyd roller and hyd flat tappet cam is even greater.
Thanks again....
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I'm going to play devils advocate here.
If you look closely at the graphs, there is no discernible difference up to the 4000-4500 range. Above that, there is a difference....which can partly be attributed to the custom grind, such as (slightly) more exhaust duration and a fairly significant increase in lift. But it is still only showing a 20-25hp and 20-25ft lb increase above 4500rpm. That is barely enough to be noticeable while driving. Maybe worth a tenth at the dragstrip?
So, how often are you going to be needing that power above 4500rpm? Are you looking for every last bit of power you can find, or just wanting a good stout street engine? And how much is it worth it to you in terms of cash? How about durability? I know they get high mileage out of roller engines in newer cars, but FEs are not new engines, and expecting that sort of return in dependability in a roller equipped FE is not a reasonable expectation. Especially since it works the valvetrain harder. In fact, that's the whole purpose of a roller cam equipped performance engine, to work the valvetrain harder. Whereas in OEM applications I think it was mostly done for friction purposes.
Once broken in, a flat tappet cam (specifically a solid, maybe not so much a hydraulic) can be expected to run the life of the engine without any problems whatsoever. Whether its 10,000 miles or 200,000 miles. Despite the advancements in roller designs, they still fail. Rollers can come apart....and they almost certainly will cause some sort of major damage in the process, if they don't destroy the engine entirely. Yes, flat tappets can fail during break-in, but the percentage is still low if done properly. And once broken in, the chance of a later failure drops to near zero. Most builders and strip guys will readily admit that rollers should be replaced at certain intervals for safeties sake because failures are more likely to happen after so many runs/years of service. That's just the nature of roller bearings.
I am not saying rollers are not worth their use. And I'm not saying they are junk. Just that there are two sides to every story. And for every plus, there can be a minus. In other words, that old saying..."you don't get something for nothing" still holds true.
Just something to consider.
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I would not have any qualms about hydraulic roller lifters at all. Lifter failures are attributed to solid roller applications, with lash and high spring pressures. The only difference between an fe hydraulic roller lifter and your typical oem 5.0 ford lifter that goes 200k miles is a link bar.
20-25 hp may not sound much to you, but it's the difference between a 575 hp engine and a 600 hp engine.
Other than the price, I see no drawbacks. When you're starting from scratch and neec evetything, that price differential is even less.
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On the other hand, how many miles do people put on their high performance Fe engines without a teardown? Since Isky told me their good bushed solid roller should go 30K miles no problem before a rebuild with street roller type springs, it would last me pretty much for years. There is no way I would go that long without checking things out on a 600+ horsepower FE anyway. But that's just me. With good solid needle bearing roller lifters like Crane Ultra Pros, I changed them out after about 2K miles.
If I had a FE mild performance daily driver, I would just go hydraulic roller since I don't don't like taking a chance of a lifter going flat and having to pull the motor and cleaning the iron particles out of everything, even the rocker shafts. Don't want to mess with having to replace the outer spring after break in either if everything goes OK. Nothing wrong with flat tappets if you like them though. To each his own.
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Wow....a lot of good discussion here. As the OP, my questions were simply to get educated on the subject. However, in case anyone was wondering, I don't plan on racing the car, either on the track or on the strip. I plan on using the car for everything else, from going to work in 35mph traffic, to extended road trips, and everything in between. I would like to push the car on occasion, and I do like accelerating with a purpose. I don't need a 700hp beast, but I would like something that will put a big smile on my face, and push my butt back in the seat. If you read my other thread, the plan is for this to be in a 445 stroker, with output in the neighborhood of ~450=500hp, roughly 1 hp/ci, if not a little more, with a manual tranny.
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Wow....a lot of good discussion here. As the OP, my questions were simply to get educated on the subject. However, in case anyone was wondering, I don't plan on racing the car, either on the track or on the strip. I plan on using the car for everything else, from going to work in 35mph traffic, to extended road trips, and everything in between. I would like to push the car on occasion, and I do like accelerating with a purpose. I don't need a 700hp beast, but I would like something that will put a big smile on my face, and push my butt back in the seat. If you read my other thread, the plan is for this to be in a 445 stroker, with output in the neighborhood of ~450=500hp, roughly 1 hp/ci, if not a little more, with a manual tranny.
Looks like you're heading in pretty much the same direction as I am. In my case it's a daily driver with plenty of capacity to generate grins and tire smoke on demand. I'm also going with the hydraulic roller which seems especially well suited to these relatively low stress, big inch stroker setups. I read and studied up on the setup for a while and decided on my own that it was probably worth the added expense, but what really clinched it for me was the fact that our prominent FE engine builders seem to heavily favor hydraulic rollers for hot street setups. Since those are the guys whose paychecks depend on making good choices, I figured it would be wise to follow suit.
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20-25 hp may not sound much to you, but it's the difference between a 575 hp engine and a 600 hp engine.
Brent, I do realize that it's the difference between a 575 hp engine and a 600 hp engine. I believe it's also the difference between a 400 hp engine and a 425 hp engine, but I could be mistaken...lol I was merely saying that it would barely be noticeable while driving on the street. I believe it would be equally difficult to "feel" the difference between a 575 and a 600 hp engine.
You're right about the solids being more prone to failure after time, due to the lash and ensuing "hammering" of the roller. Not so much an issue with hydraulics, but I have still seen failures....even on mild engines.
I certainly wasn't trying to convince him that they were evil, or that you guys were all wrong. I was just trying to give him some of the possible downsides to rollers so he can make an informed decision. Hence the opening line.....devils advocate.
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Yep, and I wasn't trying to be a smarty pants, but you don't know how many of us would kill for an extra 20 hp on the dyno. It helps us to learn and it makes customers happy.
I have personally never had a hydraulic roller lifter failure. I had one lifter out of a set that refused to pump up, but that's pretty benign. I don't think I've ever heard of a hydraulic roller lifter failing, and with the sheer ginormous amounts of hydraulic roller lifters out in the OEM world, that's a pretty big task. Think of all the 5.0 Mustangs with hydraulic roller lifters....all LS engines, all LS6-LS7 engines that turn 7000 with hydraulic rollers. A lifter failure doesn't even cross my mind with these.
To me, the only downside with a hydraulic roller is the initial investment. You can play that a couple different ways....if you're upgrading or starting from scratch. If you have a mild build where you can use mild springs and factory non-adjustables, or if you're trying to do a little more with the build....etc, etc. But if you factor in the cost of a botched break-in, it's pretty much a non-issue.
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Brent is on to something here , hydraulic roller s have been around for years and think about your build . A 445 with a brand new crank , brand new rods , forged pistons and lets say even edelbrock heads then do a hyd roller and a t @ d rocker kit .. Sounds like a very reliable , and long lasting engine . A ton of fun to drive and enjoy and never a worry about having used 40 year old rods , and other already stressed parts .. Bud
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Yep, and I wasn't trying to be a smarty pants, but you don't know how many of us would kill for an extra 20 hp on the dyno. It helps us to learn and it makes customers happy.
I certainly understand that! For the money, it IS pretty cheap horsepower, comparatively. And horsepower, anywhere you can find it, is certainly worth considering.
I think they have finally reached a level of dependability in the aftermarket that I would even feel comfortable to consider using one....if all my blocks weren't solid lifter blocks. I always preferred solids because of their dependability, but now that kinda negates me using a roller in my engines because they're all street driven. That may just change on my next build :)
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2X to hydraulic lifters going on forever w/o failure. Modern roller lifter engine designs as mentioned have hundreds of millions of miles (if not a few billion, no exaggeration if one does the math) of hydro roller success.
And yes, starting out anew makes the cost less, even though nobody every said rollers were cheap! And while I do agree a well-broken in flat tappet lifter will last darn near forever, there have been way too many cam/lifter failures as noted on all of the American engine related websites (BBC, SBC, Dodge, etc.) just like this one. Today, many elect to go roller simply because, even doing everything right, they don't want to be one of those with a worn down cam lobe in a brand new rebuild.
I do have one beef about hydro roller lifters: added valve train weight does limit rpm potential. Jay has mentioned here a number of times the real-world limits of an FE's rpm levels merely due to this added weight. It's true for other engine makes as well. But, adding beehive springs or titanium retainers or smaller diameter stemmed valves or, most pricey of all, titanium valves is beyond the pocketbook or need for most weekend warriors.
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I'm hoping you guys are all right.
That's how I designed my new truck engine.
Hydraulic roller with roller rockers and light beehives.
Did I spend more than I needed to? Yes, but that's not the idea for me.
I want a low rpm, low cr engine with good power that will last forever.
To offset the cost I collected parts for a couple years.
Heading to dyno tomorrow with fingers crossed.
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A set of aluminum roller rockers might not be the best way to go for an engine you plan to run for a very long time without having to change things out unless you are running pretty weak valve springs like the original ones. Regular non roller rockers like the steel Graham rockers might end up being more trouble free for an engine like that.
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A set of aluminum roller rockers might not be the best way to go for an engine you plan to run for a very long time without having to change things out unless you are running pretty weak valve springs like the original ones. Regular non roller rockers like the steel Graham rockers might end up being more trouble free for an engine like that.
Yeah, this is where I get into the experimental/bias arguments (because of asian made stuff).
I figured that (only after reading all you gentlemen's experiences for a couple years) I wanted steel rockers.
Could I have gone with OEM rockers yes, but in the spirit of the build I wanted everything roller.
I bought a set of PRW (I know) steel rockers and changed out the adjusters to Mantons along with Manton push rods.
In this way hoping to fix any hardness problems with the PRW spec adjusters.
Cross fingers.
BTW, will be on the QMP dyno tomorrow if you're in the neighborhood.
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Hydraulic roller with roller rockers and light beehives.
Did I spend more than I needed to? Yes, but that's not the idea for me.
I want a low rpm, low cr engine with good power that will last forever.
To offset the cost I collected parts for a couple years.
Heading to dyno tomorrow with fingers crossed.
I did the same. My dyno session was last week, and with a very mild cam we quit at 5500 RPM because the power curve had flattened out (not because it dropped/floated or "whatever"). I think it would have gone 6000. Using Harland Sharp roller rockers. I don't know why they wouldn't be good for regular cruise night duty. I don't plan to drive it like a long haul truck ;)
Those hydraulic rollers are a big heavy piece though, aren't they?
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Those hydraulic rollers are a big heavy piece though, aren't they?
Just like me ;)
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Devil's advocate part deux. :P
One other thing about roller vs. flat tappet. If you are going to use a mild cam with say, 230 degrees or less duration @ 0.050, you will likely see little or no power gain with a roller. Some people even say there is little gain even up to 240+ degrees, compared to modern flat tappet cams.
Flat tappet cams can actually accelerate off the cam's base circle faster than a roller, but they are limited in their "max speed". Roller cams can't accelerate as fast, but they are basically speed unlimited. That means a roller has to catch up to an aggressive flat tappet cam, at first, but then it blows by it and keeps increasing it's lead. As long as the valvetrain can handle all this action, that is. So with a small duration cam a roller doesn't have the time/distance to make much difference. I would argue that with a very small cam a flat tappet might actually outpower a similar roller. Maybe.
Anyway the advantage of the roller gets bigger as the duration gets bigger. Sounds to me, that with a 445 cubes and a desire for ~450 hp you are on kind of on the border where it will make a difference power wise. Other considerations may be more important for you. Like as mentioned above, cost and break-in risk.
JMO,
paulie
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Don t forget about how much you will actually drive the vehicle , most of us have collector car/ truck insurance with mileage limitations . At best i would drive my car maybe 5000 miles a year , so a 100,000 motor would take 20 years ..
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Don t forget about how much you will actually drive the vehicle , most of us have collector car/ truck insurance with mileage limitations . At best i would drive my car maybe 5000 miles a year , so a 100,000 motor would take 20 years ..
I definitely plan on using the car as much possible. I am fortunate enough to live in a town that is relatively mellow and free of crime, so I can drive it to work, grocery store, etc. I definitely would like for it to be reliable enough to take it on extended road trips. It's more important to me that it be reliable and have a reasonable amount of drivability, then it being able to run a 10 second quarter mile, or be a beast on a road course. That being said, I still want it to be a muscle car......I want it to be able to live up to the rep that muscle cars had, even if the stories were exaggerated.
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TORQUE is what makes them fun to drive , the 5 speed makes a big difference in your ability to drive the car any where .. Bud
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TORQUE is what makes them fun to drive , the 5 speed makes a big difference in your ability to drive the car any where .. Bud
That's the reason I want to go with the 445 stroker....free torque! While I'm no mechanic or engineer, I've always liked the idea of displacement over pushing an engine harder. I figure with today's technology and parts, getting 1 hp/ci should be a reasonable expectation and still maintain a level of civility. Honestly, I think with today's heads, cams, and efi...I hope that I can squeeze out even a little more than that! ;)
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I think you should be able to get your target fairly easy , 1.08- 1.10 per c i on a mild street motor and remember with aluminum heads , intake , water pump and header s it should about the same weight as a small block that s all iron .. Bud