Roller lifters/cams VS. flat tappets

This seem to come up every few years in the drag racing circle also.*bdh*
 
No sir....

seeker1056 said:
You get more power from a mushroom flat tappet vs a roller cam because the diameter of the lifter limits the maximum speed of the ramp possible with a roller cam, whereas a mushroom tappet allows a much faster more aggressive profile, therefore giving more area under the curve. The nascar boys have this science down to an art, and even if they were allowed to run rollers would not change over in any research posted online

Now if you are discussin the standard flat tappet lifter vs a roller lifter of the same diameter, the roller wins every time for more power production, and not because of the reduced friction elements

This has been discussed to death here several times.
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Nascar/cup cars do not run mushroom lifters FYI. As for ramp speed, here is the specs on our fuel bike cam, base circle .940 inch, lobe lift .462 1.6 roller rocker, .74x valve lift, 340 degrees at .020, valve stays wide open for 35 crank degrees before starting to close. Theres a high duration cam for ya. Standard diameter roller lifter, .946 I think. Ramps dont get much faster than that and we would never run a mushroom lifter. The lifespan would shorten dramatically IF you could control the valve. We run OVER 400lb. seat pressure and over 1100lbs. on the nose in order to follow the cam profile.
 
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We are a band of brothers (to quote Shakespeare) and there are a few things that will impact how you are viewed on here, and by extension how much help you will get.
We don't take to kindly to people telling us how great and smart they are. Especially when it is all their accomplishments in other motorsports. Good for you for having done xxxxx in xxxxx. This ain't that.


There is so many differences between the bike cams you are talking about, the fuel type, rpm, head flow, rocker ratio, base circle, and race only 1/4 mile at a time vs. a cam that will go 100,000 miles, that no true comparison can be made.




Zach
 
Some of you should read this book.

Cam design handbook - Google Books

You guys are stuck on mushroom lifters. If that is your only option, then, yes it is better than a standard lifter. It still isnt nearly as good as a roller lifter. The man who wrote this book has done more with cam design than everyone on this forum combined I would venture to guess. Guess what, he recommends mushroom lifters about NEVER. Actually, he says they are good in LOW lift cams with low spring pressures in industrial engines that need to run a million hrs. and such. Its old technology. He also says the only good time to use them is when roller lifters are illegal. Hamilton was talking about a direct comparison between a roller setup and a flat tappet setup. The man who wrote this has dyno sheets where the ONLY thing changed was cam/lifters and springs, and the cam has the identical specs. The roller made 30 plus horsepower more and 70 plus ft. lbs tq more on average. He also tested short and long duration cams with the same outcome. If you want the most performance I cant see why a roller setup in these trucks wouldnt be the way to go. As for comparing different sports, math is math, physics is physics and friction is friction. I provided our cam spec to show how much acceleration is possible with a roller. You cant run that cam with a flat tappet of any design. Think about this once, If mushroom lifters were so great wouldnt the large cam companies still make them? Guess what. They dont make them any longer except for some custom orders such as a class where rollers arent allowed. If someone makes a roller lifter/cam for a 24V I will buy and install them in my truck and dyno it. You can then tell me what cam and lifter you want me to compare it to and I will dyno it with that. Then whoever is wrong can buy the drinks. I am not trying to argue, but I just dont see how a flat tappet can win this. It defies logic. I have searched and searched on the net and have yet to find a performance engine builder who recommends a flat tappet over a roller setup of any sort. Also, this is COMPETITION DIESEL and we are talking about the best performance. Why would I care about 100k miles?
 
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In our case....

If you are looking for all out performance you dont care about 100k miles, and even then a roller is better. Here is some more. Here is where they are going away from mushroom lifters in favor of rollers in yet another engine design. http://www.aerosportpower.com/docs/007E22338B483021.pdf If it didnt work and wont last would they put it in aircraft engines?
 
matty169 said:
I understand that you were told this, but if someone tells you it doesnt hurt to shoot yourself in the foot are you gonna try it? Here is what you have. Nobody is mass marketing a roller set-up for the Cummins, YET. FYI, they ARE out there, and it may surprise you to see who has them.:poke::evil. In almost all forms of racing valve train is the limiting factor. Just because it works at lower RPM doesnt mean its the best option. It may be your only option so far. There MIGHT even be a couple guys reading this and saying, SHUSH, dont let the cat out of the bag!!!! Have any of you guys changed a engine over to rollers from flat tappets and changed nothing else? Guess what! Upon starting the engine it is quite common to have to adjust the idle DOWN using the exact same carb you had before. Why? Less friction which frees up power. I honestly dont understand how anyone cam claim a flat tappet is better. It defies all logic AND physics.
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If the roller set ups are out there, why don't you try one and tell us about it, if they are the answer to friction, would you say they should last a lot of miles, show us your dyno results and time slips, it defies logic you don't have one in your truck
 
I guess.....

Tate said:
I'd venture to guess that not many guys on here would buy a cam that would only last a couple thousand miles.
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Kinda depends what you are trying to do? This was started looking for the best performance possible, but rollers are better for longevity also. Lycoming piston engines in air planes have traditionally used mushroom lifters and they have now switched to rollers also. Guess if it wouldnt last they wouldnt put it in a aircraft engine. http://www.aerosportpower.com/docs/007E22338B483021.pdf
 
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matty169 said:
Kinda depends what you are trying to do? This was started looking for the best performance possible, but rollers are better for longevity also. Lycoming piston engines in air planes have traditionally used mushroom lifters and they have now switched to rollers also. Guess if it wouldnt last they wouldnt put it in a aircraft engine. Here is something a little more relevant since it is diesel. Cat 3208 engines can be bought from 215 hp. to over 300 hp. Anything over 225 hp. has a roller cam and roller lifters, pretty much everything else is the same. Pilot Engines Product List | Pilot Engines
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QSL/ISL engines are roller lifter engines also.
Here is a diesel engine article. Sorry...
 
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A roller lifter engine will always outrun a flat tappet engine and do it longer all else being equal.

It's just common sence.
 
matty169 said:
If someone makes a roller lifter/cam for a 24V I will buy and install them in my truck and dyno it. You can then tell me what cam and lifter you want me to compare it to and I will dyno it with that. Then whoever is wrong can buy the drinks.
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They do exist.

We'll be expecting your results.
 
matty169, you keep posting research that is not diesel related. This is not that. Find a street roller cam that has@.050" numbers either 188/220 .310"/ .320" or 200/225 .340"/.360". There are two ways to compare. One is valve motion vs. crank angle. Second is horsepower production.



I will even go so far as to build a long block to stick on the dyno. You build the same long block with a roller cam and I will install your engine, and then mine. Waco, Texas has a good dyno and I will cover the dyno time. We can install the engines on the dyno.Same rocker ratio, same lash, same head, same charger, same injectors, same truck, same programming. I will buy the drinks regardless, and the BBQ. Same rocker ratio, same lash, same head, same charger, same injectors, same truck, same programming.


I am not doing this for a pissing match, but I would jump at the chance to show you what I am talking about.
 
pwrstrokenstang said:
my motor came w/ rollers:poke:LOL
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I'm sure it makes good power and I bet it is not a street cam with short duration and high lift. I have a few vehicles with roller cams myself, and they are not street driven diesels with performance grinds.

We have ten different people talking pullers, bikes, gas, diesel, street, race only gas, street diesel, BBC, 4,000 rpm, 9,000 rpm, 12,000rpm etc.

I am begining to think that in this forum on this subject it is not possible to have an intelligent discussion.

I apologize for mucking up the thread.......
 
The benefit to a large mushroom lifter is the mushroom on the lifter. It will add around 2-3 degrees of duration to the camshaft(depending on dia.). You cam run a more aggressive lobe on a large mushroom lifter like the cr lifter, it's 1.5" in dia. If you run too steep of ramp angle on a roller cam, you are gonna have lifters outside your block!
 
2 are diesel related.

Hamilton Cams said:
matty169, you keep posting research that is not diesel related. This is not that. Find a street roller cam that has@.050" numbers either 188/220 .310"/ .320" or 200/225 .340"/.360". There are two ways to compare. One is valve motion vs. crank angle. Second is horsepower production.

I will even go so far as to build a long block to stick on the dyno. You build the same long block with a roller cam and I will install your engine, and then mine. Waco, Texas has a good dyno and I will cover the dyno time. We can install the engines on the dyno.Same rocker ratio, same lash, same head, same charger, same injectors, same truck, same programming. I will buy the drinks regardless, and the BBQ. Same rocker ratio, same lash, same head, same charger, same injectors, same truck, same programming.


I am not doing this for a pissing match, but I would jump at the chance to show you what I am talking about.
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I posted that ISL engines use rollers and a link to CAT 3208 engines available that start at 215 H.P and go over 300H.P.. They switch to roller lifter and cam at 225 H.P. and up. Just a coincidence? These are diesel right? This whole thread is about performance and power, and how to make the most of it.
I have done a search for cummins roller stuff and havent found anything other than big dollar pullers and drag guys using roller lifters in the Cummins, but the fact that they are using them should tell you they make more power. If they didnt, they wouldnt use them.
 
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