What is the performance gain from a roller lifter setup? Im having an engine built and have the choice between two blocks; a hydrolic flat tappet and a solid roller. Its a weekend warrior that won't see much track use and I am looking for 400 or so hp at the crank. All else being equal, what setup should I go for?

Thanks in advance

 

roller hands down, more power, less wear, dont have to break in cam. Down side is it is prob a little more expensive

 

how much more power we talkin' about?

 

Roller is definitely better. You won't pick up any MAJOR horsepower from it. But the engine (specifically the valvetrain) will last longer and run smoother. To me it's worth the investment.

 

ive always heard that you get more power from them... maybe im wrong

 

Its no extra investment. The block I have now is a solid roller but its a racing only engine (CR too high for pump gas.) I can tear this one apart and rebuild it for the street or I can build a hydrolic flat tappet with parts that I already have with a seprate block that is just lying around. Either way the car is only driven about 20 miles a week so this engine may never see 35,000 miles.

 

Actually you're absolutely right. Roller lifters create less friction. And less friction in the valvetrain creates more power. How much power all depends on the specific engine combo.

 

Double post...

 

With a 400 horse 355 would the horsepower gain be substantial? 10...20 maybe?

 

The major benefits to a roller cam come from the more aggressive lobe profiles that can be used compared to a flat tappet, not from the reduction in friction.

 

Roller cams help free up horsepower but the gain is not as great as you would imagine from just the reduction of friction. I believe the main advantage of roller cams is they run quieter and require less maintenance. The other advantage is it allows builders to create profiles that offer more lift without increasing duration.

 

Other way around. Increased duration with the same lift.

The gains from the reduction in friction are minimal. The gains from the steeper ramps can be huge.

 

So for an average joe with minimal mechanic skills that just wants a super fast car to play with on the weekend and doesn't want to have to tinker under the hood every time he goes on a joyride, should he go with the solid roller setup?

 

Average Joe would go with a flat tappet hydraulic cam, if he has an older block. Flat because it's cheaper, and hydraulic because you don't have to constantly be setting the valve lash.

If Average Joe has a roller block, he'd use a hydraulic roller.

 

Thanks, thats what I was looking for. I have a very experienced engine builder to built it for me, but who wants someone hanging around the shop every weekend with rookie questions about valvelash? I would hate to become a bother to anyone (not in person anyway )

 

I got the more lift without increasing duration tidbit from the summitracing site. In any case its the main thing that attracts me to converting to a roller setup.

Thump Sticks--The Basics On Choosing the Right Street Cam - SummitRacing.com

 

thanks for the link. It was very helpful. If the cam is a solid roller, I could change it to a hydraulic roller easily right?

 

You could easily change the cam and lifters to a hydraulic roller setup as easily as anything else. Roller lifters are expensive, though.

 

If its a solid lifter I can use the same lifters that are in there now right? They only have 8 passes on them.

 

Notice how nobody will say that, "Engine X with a roller setup made this much more power than the same engine built with a flat tappet cam". Some history may shed some light on why. Back in the olden-days (70's, long before the first factory roller cam engine) all-out racers used roller setups with extremely high lift cams because the base circle was so small and the lobe so steep that the contact loading surface was too small on a flat tappet that it dug into the side of a tall lobe.
Fast forward to the late 80's. The emphasis is on performance + mileage.
The rolling torque required to turn a cam is pretty constant at a certain rpm regardless of power output. The roller setup turned easier than a flat tappet at cruise speed by a lot. When the engine is putting out 25 HP at cruise the 2 HP less that a roller takes is significant. This is why the factory went to it. Miles per gallon.
When the engine is at max power, the difference between 245 and 247 horsepower is trivial.
So the answer is that a stock roller setup will make more difference in MPG at cruise than in max horsepower produced. When you get into high RPM operation and adding a "Rev Kit" to keep the heavy roller lifters from floating the advantage is negated. So from a "strip" horsepower standpoint it's pretty much a wash. If it's a street application where MPG is a consideration it's the roller setup. If it's all-out racing with lifts over .600 it's also the roller setup too.
Are ya confused yet?

 

No, I'm with you man. These are questions that I've always had but they are hard for one person to answer totally correct. Thats what I love about this site. I ask a question and less than two hours later I have half a dozen opinions.

I can use the solid roller lifters for hydraulic roller setup right?

 

Wait, what? Why would you want more duration with equal lift? Usually roller cams have steeper profiles, so you get more lift at X duration due to fast ramp. Thats why just about every roller cam you see, compare it to a flat tappet with comparable duration @.050", and you have more lift on the roller cam. Also the advertised duration is less on the roller cam 'cuz it snaps the valves open and shut faster.

Well, if you used solid roller lifters, it wouldn't be a hydraulic roller setup anymore Solid, whether it be on a flat tappet cam, or roller cam, need constant adjustment. Not constant as in "every stop light", but constant like "every oil change". So when you do an oil change, and grease the chassis, you throw in valve lash. Not a big deal. It also gives more high RPM stability, and that neato "tickety tickety tickety" idle sound that only race cars have I'd do a solid roller. Just keep the duration low enough that it's remotely street friendly. The smallest solid roller cam is probably what you want.

 

so the lifter makes it solid or hydraulic. Ok. I am pretty handy, I just never had anyone in my family that liked to mess with cars. If I was shown the correct way to set valvelash, I should be able to get it, right? I mean, it ain't rocket science.... just an internal combustion engine!!

 

I'm not talking about opening and closing events, I'm talking about the actual time the valve spends open at a given lift.

 

For each cam with identical numbers, a hydraulic cam is different than a solid lifter cam. The opening and closing ramps are different to take the slack out of a solid lifter valve train as opposed to a hydraulic setup which, if adjusted correctly has no lash.

 

oh, gotcha Ape, now I know what you're talking about. So technically we're both right.

That's right systalis, once you do the valve lash once or twice, you'll have it down. I'd go for it if I were in your shoes And yes, definately the roller over the flat tappet.

There's a handful of people on this forum with daily driver solid cams (ok, so I can only think of one off the top of my head, mwnova), but you can always ask more detailed questions to that/those guy(s). Like, "how often", easiest way, etc etc.

 

Like I said before, the car sees only about 20 miles a week. That should put me adjusting them no more than once every month or two right? From what I hear, my 400 hp goal would be easier to reach with a roller cam selection. Ultimately if I can get the car to break into the 11's at the track I'ld be happy. It would rarely go to the track though.

 

Is this a carb or EFI? Knock sensors don't play well with solid lifters.

 

it's real easy to make the duration longer while keeping the same amount of lift just make the ramp less steep which would put less stress on the valve train anyway.

it's a lot harder to make for more lift in the same amount of durationas the ramp would need to be a lot steeper and can laed to some issues with the lifter digging into the cam.


the other advantage is keep the same lift and same duration but instead up the ramp steepness and make the lobe a little more squarish so your in peak lift a little longer

 

Like I said to Sonix, I'm not talking about opening and closing events. I'm talking about duration at lift.

 

my misunderstanding. I was reading it as same PEAK lift not longer duration at the same lift at that specific point. my mistake

 

BTW guys, the car will be carbed. No knock sensors.

 

GM gained +5 fwhp when they switched from flat tappet to rollers on the Vette L98 engine (circa 1987). IIRC there were no other changes and the cam specs were similar.

To put that in the proper perspective, that's +5 fwhp at approx 4500 rpm (the rpm where a stock L98 peaked power) using stock valve springs. The valvetrain friction can be expected to increase with both rpm and spring compression load (if you added stiffer valve springs to handle the higher rpm and/or added a bigger cam).

If you wound the engine to 6000 rpm, you'd be running 33% more engine speed so the difference between flat tappet and roller lifters (using GM numbers as a benchmark) could be expected to increase to around +7 fwhp gain with no change in valvespring preload (for the sake of argument), and to +10 fwhp if you increased the spring load by 50% over stock.

So the gain isn't huge in terms of fwhp, stock or modified based on the above.

In terms of heat, there is a big difference. Every fwhp is 745 Watts at the flywheel (mechanical power). So a +10 fwhp gain at 6000 rpm (flat to roller tappet swap, an assumed 50% increase in spring preload) is 7.45 kW worth of heat your cooling system (water, oil) doesn't have to deal with. You would have to do a thermal load analysis to see what the impact would be.... but running to 6000 rpm would have much more of an effect with either flat or roller lifters, so the lifter choice isn't thermally important as compared to the rpm increase.

Is this worth doing? Using new parts, I say no. The gain in power and reduction in thermal load isn't worth the cost of new parts. A good used roller setup sourced from a junkyard is another story.

Similar arguments (to the above) can be made for double roller rockers, IMO, even though they seem to be wildly popular. Most of the power gains are from the increased valve lift (yielding more airflow) when jumping from 1.5 to 1.6, rather than from gaining power from friction reduction. Steel double rollers make sense with large lift cams and heavy springs loads, but then the reason for using them is durability and less for friction reduction. GM even abandoned double roller rockers (fulcrum, tip) in the LS1-series Gen 3 engines by returning to roller-fulcrum-only design. And the roller bearing fulcrum is more to avoid excessive metal wear than for friction reduction. Oil-fed sliding friction, even with moderate contact normal stresses, does a surprisingly good job.

FWIW roller rockers & lifters were used by marine diesel engines prior to WWII -- automotive applications didn't begin to use them until the late 50s and 60s in a few race applications, and not for production until around 10 years ago. The loads/speeds/wear didn't really demand them until then. HTH.

 

On a typical street motor at about 400hp you have to look at the cost benefit ratio. if you don't have good heads a roller will not make up for it. Invest in good cylinder heads first.
Lot more bang for the buck. it's very easy to make 400-425hp or even 450hp with a flat tappet cam.
retro fit hyd roller lifters are expensive. Typical solid roller lifters do not have pressurized oiling and tend to wear if idled a lot. The better premimum solid rollers with the pressurized oiling cost more.
For the typical 12sec 400hp+/- 350 a roller setup is not nessessary. (investing in good cylinder heads will return more performance) Once you get to about 460+ hp level it starts to pay off in increased valvetrain life/$cost.

 

WOW! Thanks. Knowing all that information isn't half as impressive as being able to recall it all at once.