Roller lifters/cams VS. flat tappets

[matty169]

#43- Trouble with Flat Tappets Reher-Morrison Official Blog (http://www.rehermorrison.com/blog/?p=192)

Now these guys build some of the most powerful engines in ANY form of racing. I believe the last ADRL race in the mountain motor nitrous cars they took 4 of the top 5 positions. You WILL NOT find cams with more aggressive lift numbers than those cars. FYI, some of these engines EXCEED 1 inch lift.

[zstroken]

#43- Trouble with Flat Tappets Reher-Morrison Official Blog (http://www.rehermorrison.com/blog/?p=192)

Now these guys build some of the most powerful engines in ANY form of racing. I believe the last ADRL race in the mountain motor nitrous cars they took 4 of the top 5 positions. You WILL NOT find cams with more aggressive lift numbers than those cars. FYI, some of these engines EXCEED 1 inch lift.


One thing to remember is an engine that runs 9000 rpm needs a little more spring pressure than an engine that turns 4500 or so.

[shortbusdriver]

I am in the process of building two pulling motors right now that will be spinning over 5000 rpm's. I am wondering what would be a good setup to run on these motors with this high of rpm's. My pump is going to be set up to turn around 5200 rpm while the other pump will have an ag gov assembly put on.

Would it be benificial to run a roller cam in these motors? One will be running a 2.6 class and the other a 2.8 or possibly a 3.0 class. Would there be a difference between the two? Just want to get some ideas on this.

[j-rod]

I am in the process of building two pulling motors right now that will be spinning over 5000 rpm's. I am wondering what would be a good setup to run on these motors with this high of rpm's. My pump is going to be set up to turn around 5200 rpm while the other pump will have an ag gov assembly put on.

Would it be benificial to run a roller cam in these motors? One will be running a 2.6 class and the other a 2.8 or possibly a 3.0 class. Would there be a difference between the two? Just want to get some ideas on this.

FWIW I have been told by a few people that if you aren't turning over 6k, the flat tappet will out perform the roller.

Any idea on lift?

[shortbusdriver]

We have not decided on any specific cam, lifter, pushrod, or valve springs yet. We are just doing pump work and gathering parts for the bottom end so far.

[Diehard Ram]

[QUOTE=j-rod;1345247]FWIW I have been told by a few people that if you aren't turning over 6k, the flat tappet will out perform the roller.

Yes ,you are correct. You just have to watch for the wear on the flat tappet cams, more so than on a roller. And now that we have this crappy oil out there it's even more of an issue.

[matty169]

One thing to remember is an engine that runs 9000 rpm needs a little more spring pressure than an engine that turns 4500 or so.
Weight of the valve and retainer being much higher in a dodge evens out the spring pressure actually. How much spring pressure do you think we run in a SBC with steel valves, flat tappets, steel retainers? .643 and .672 lift cam. FAST ramps and long duration. 1.7 roller rockers. Roller bearing cam and 9300 RPM. Rules forbid roller lifters and any Ti parts.

[matty169]

FWIW I have been told by a few people that if you aren't turning over 6k, the flat tappet will out perform the roller.

Any idea on lift?

Back to back on a dyno. How much you wanna lose?:Cheer:

Taking the exact same engine, the area under the curve will be higher in a roller VS. non roller every time. Friction is friction, whether it be at 5k rpm or 9k rpm. You lessen friction, YOU WILL GAIN H.P.
Tell me why you think a flat tappet is going to gain on a roller set-up?

[zstroken]

Weight of the valve and retainer being much higher in a dodge evens out the spring pressure actually. How much spring pressure do you think we run in a SBC with steel valves, flat tappets, steel retainers? .643 and .672 lift cam. FAST ramps and long duration. 1.7 roller rockers. Roller bearing cam and 9300 RPM. Rules forbid roller lifters and any Ti parts.


Does the weight even it out? Isn't velocity^2 used?

[Chris Tobin]

I am in the process of building two pulling motors right now that will be spinning over 5000 rpm's. I am wondering what would be a good setup to run on these motors with this high of rpm's. My pump is going to be set up to turn around 5200 rpm while the other pump will have an ag gov assembly put on.

Would it be benificial to run a roller cam in these motors? One will be running a 2.6 class and the other a 2.8 or possibly a 3.0 class. Would there be a difference between the two? Just want to get some ideas on this.

FWIW I have been told by a few people that if you aren't turning over 6k, the flat tappet will out perform the roller.

Any idea on lift?

[QUOTE=j-rod;1345247]FWIW I have been told by a few people that if you aren't turning over 6k, the flat tappet will out perform the roller.

Yes ,you are correct. You just have to watch for the wear on the flat tappet cams, more so than on a roller. And now that we have this crappy oil out there it's even more of an issue.

If you are using the EXACT same grind the flat tappet may somehow be better but I just cant see a flat tappet being better than a roller cam with optimized ramp angles, lift and duration... The roller cam should always win in those situations because the cam can be set up to open and close the valve faster and allow for more open time because of that...

Now I am not sure if anyone builds optimized cams and roller lifters for our diesel applications but I would think they would definately allow for better performance...$.02

[matty169]

Does the weight even it out? Isn't velocity^2 used?
Sort of, but there is alot more to it than that. You have to take into consideration valve weight, retainer weight, angles, rocker arm ratio and weight over the valve, etc. How quickly are you trying to open the valve, and more important, close the valve in a controlled manner so it gets out of the way of the piston, but doesnt bounce off the seat. We use a 2.08 intake valve and 1.7 exhaust valve(moved) and have under 125lbs. of seat pressure.
As for the other person wondering about specific cam profiles, well, I cant think of a profile that a flat tappet would be preferred. Fast ramp, slow ramp, long or short duration, I WANT A ROLLER every time. Did you guys read that link and actually think about what is going on in that engine? Most of these things are answered in there.

[zstroken]

Sort of, but there is alot more to it than that. You have to take into consideration valve weight, retainer weight, angles, rocker arm ratio and weight over the valve, etc. How quickly are you trying to open the valve, and more important, close the valve in a controlled manner so it gets out of the way of the piston, but doesnt bounce off the seat. We use a 2.08 intake valve and 1.7 exhaust valve(moved) and have under 125lbs. of seat pressure.
As for the other person wondering about specific cam profiles, well, I cant think of a profile that a flat tappet would be preferred. Fast ramp, slow ramp, long or short duration, I WANT A ROLLER every time. Did you guys read that link and actually think about what is going on in that engine? Most of these things are answered in there.


I understand that there are many things to consider, my point was just because the cummins stuff may weigh 2 times as much but travels at half the speed, doesn't mean it needs the same spring rates.

[j-rod]

Back to back on a dyno. How much you wanna lose?:Cheer:


Reread my post. I have been researching this topic for quite some time. I am not making these claims...it is what I have been told by Cummins engine builders. Period.



If you are using the EXACT same grind the flat tappet may somehow be better but I just cant see a flat tappet being better than a roller cam with optimized ramp angles, lift and duration... The roller cam should always win in those situations because the cam can be set up to open and close the valve faster and allow for more open time because of that...


I don't know why you would use the same grind on a flat tappet that you would a roller. That makes absolutely no sense. Again, you guys want to quote what I said, you should reread what I posted.

[matty169]

Reread my post. I have been researching this topic for quite some time. I am not making these claims...it is what I have been told by Cummins engine builders. Period.



I don't know why you would use the same grind on a flat tappet that you would a roller. That makes absolutely no sense. Again, you guys want to quote what I said, you should reread what I posted.

What I am telling you is this. Friction is friction. It doesnt matter if it is in a sewing machine, Cummins, Chevy, or the space shuttle. You reduce friction in order to reduce heat, gain power(EVERY TIME), etc. etc. Show me one instance where you can gain power with a flat tappet over a roller. JUST ONE. Roller cams allow MUCH more aggressive profiles to be used and controlled, but even if you run street cams, rollers WILL reduce friction, rev quicker, and run cooler. You can also restrict oil to the top end gaining a little more. You can run your big azz heavy flat tappet or a lite weight smaller diameter roller, even with the same cam profile, the roller wins. As long as you are running heavy valve train parts you will be severely limited in RPM potential. Your heavy flat tappet has to change direction very quickly, right? In order to control that you need heavy springs, heavy pushrods, etc. Try this... tie a tennis ball to a string and tie it to your pecker and drop it. NOW try that with a bowling ball. Feel the difference???? You need to stop that weight and reverse the direction. Lite weight wins.

[matty169]

I understand that there are many things to consider, my point was just because the cummins stuff may weigh 2 times as much but travels at half the speed, doesn't mean it needs the same spring rates.

Might want to check your math on that. Parts with twice the weight may just take MORE than double the spring rate, depending on several factors, such as ramp rate and lift numbers, etc.

[zstroken]

Might want to check your math on that. Parts with twice the weight may just take MORE than double the spring rate, depending on several factors, such as ramp rate and lift numbers, etc.


kE=(m*v^2)/2

Holding the ramp rates and lift numbers constant.
400lb seat pressure on a small block is not uncommon and the cummins can get away with much less? I am running under 150 on the seat on mine, motor can run 5000+.

[Chris Tobin]

Reread my post. I have been researching this topic for quite some time. I am not making these claims...it is what I have been told by Cummins engine builders. Period.



I don't know why you would use the same grind on a flat tappet that you would a roller. That makes absolutely no sense. Again, you guys want to quote what I said, you should reread what I posted.

Matty already made the point I was trying to make... Roller will be better than flat tappet every time. I do not see any case where you can show that a flat tappet would make more power than a roller cam... It just doesn't make sense!!! Maybe you are confusing hydraulic vs mechanical lifters... in those cases the non hydraulic will make more power but there is also more maintenance and for street engines most builders recommend staying with hydraulic lifters, with roller hydraulic being the best for street engines...

[matty169]

kE=(m*v^2)/2

Holding the ramp rates and lift numbers constant.
400lb seat pressure on a small block is not uncommon and the cummins can get away with much less? I am running under 150 on the seat on mine, motor can run 5000+.

400 lbs SEAT pressure DOES NOT AND CAN NOT happen on a flat tappet!!! EVER!!!! Thats even too much for a roller set-up. Pressure on the nose, well, thats different. Also, if you think your valve is controlled at 5000 rpm with those springs you are wrong. Guarantee you that it is lofted over the nose if the ramps are even REMOTELY fast. We even tried ceramic lifters with a flat tappet. Guess what, as soon as you loft it over the nose and the lifter comes back to earth shiiit goes WAY bad way fast. And ceramic going through the engine destroys EVERYTHING, EVERYTIME. $30-50K paper weight. Remember several years ago at the beginning of the Nascar season? 2 big engine builders were lucky to have 1 engine survive the race out of about 10. Needless to say, ceramic lifters didnt last long. LOL

[j-rod]

Matty already made the point I was trying to make... Roller will be better than flat tappet every time. I do not see any case where you can show that a flat tappet would make more power than a roller cam... It just doesn't make sense!!! Maybe you are confusing hydraulic vs mechanical lifters... in those cases the non hydraulic will make more power but there is also more maintenance and for street engines most builders recommend staying with hydraulic lifters, with roller hydraulic being the best for street engines...

Again, I invite you to reread what I posted. I am not making these claims. Perhaps you guys should talk to a few Cummins engine and/or tractor engine builders since you seem to be "shooting the messenger" here.

And no, I am not confusing hydraulic and mechanical lifters. LOL

[KILLER 'B']

:pop:

[matty169]

Again, I invite you to reread what I posted. I am not making these claims. Perhaps you guys should talk to a few Cummins engine and/or tractor engine builders since you seem to be "shooting the messenger" here.

And no, I am not confusing hydraulic and mechanical lifters. LOL

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.

[zstroken]

400 lbs SEAT pressure DOES NOT AND CAN NOT happen on a flat tappet!!! EVER!!!! Thats even too much for a roller set-up. Pressure on the nose, well, thats different. Also, if you think your valve is controlled at 5000 rpm with those springs you are wrong. Guarantee you that it is lofted over the nose if the ramps are even REMOTELY fast. We even tried ceramic lifters with a flat tappet. Guess what, as soon as you loft it over the nose and the lifter comes back to earth shiiit goes WAY bad way fast. And ceramic going through the engine destroys EVERYTHING, EVERYTIME. $30-50K paper weight. Remember several years ago at the beginning of the Nascar season? 2 big engine builders were lucky to have 1 engine survive the race out of about 10. Needless to say, ceramic lifters didnt last long. LOL

Those numbers are on an extreme engine, turning 10K, and who said it was a flat tappet?


I am still curious about the equation for kinetic energy.
You do know what the m and the v stand for right?

[matty169]

Those numbers are on an extreme engine, turning 10K, and who said it was a flat tappet?
Thats the whole point. You can run higher pressures with a roller cam so you CAN control the valve closing and opening, instead of lofting it over the nose.

I am still curious about the equation for kinetic energy.
You do know what the m and the v stand for right?

Mass, velocity.

[j-rod]

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.

Did I say I believe it or am not going to consider running a roller camshaft? You guys read way too much into things.

Yes, I am aware of shops producing and installing roller cams for the Cummins, as I have talked to them already.

[zstroken]

Mass, velocity.


You do see that it is velocity^2 right?

back to the discussion of the mass and velocity aren't directly proportional. Something spinning 2 times the speed has 4 times the energy.

[matty169]

You do see that it is velocity^2 right?

back to the discussion of the mass and velocity aren't directly proportional. Something spinning 2 times the speed has 4 times the energy.

That is only if MASS is constant. Your heavy Cummins parts take more spring pressure to control. That was your question, correct? How much do stock style tappets weigh? Valves? Rockers?

If you cut down weight you can run more radical cam profiles with less seat pressure.

[M_Thomas07]

:pop:

Yupp :pop:

[zstroken]

One thing to remember is an engine that runs 9000 rpm needs a little more spring pressure than an engine that turns 4500 or so.

I understand that there are many things to consider, my point was just because the cummins stuff may weigh 2 times as much but travels at half the speed, doesn't mean it needs the same spring rates.

That is only if MASS is constant. Your heavy Cummins parts take more spring pressure to control. That was your question, correct? How much do stock style tappets weigh? Valves? Rockers?

If you cut down weight you can run more radical cam profiles with less seat pressure.


I never said mass was held constant, the first line I quoted is what I said.

[Scooter's Roofing]

Matty already made the point I was trying to make... Roller will be better than flat tappet every time. I do not see any case where you can show that a flat tappet would make more power than a roller cam... It just doesn't make sense!!! Maybe you are confusing hydraulic vs mechanical lifters... in those cases the non hydraulic will make more power but there is also more maintenance and for street engines most builders recommend staying with hydraulic lifters, with roller hydraulic being the best for street engines...

most automotive flat tappet applications don't have a large mushroom headed lifter... makes a huge difference at the valve

[NickTF]

most automotive flat tappet applications don't have a large mushroom headed lifter... makes a huge difference at the valve

BINGO!!!!! Now, if you're comparing same diameter flat tappet to same diameter roller I like the roller every time! Mushroom lifters don't have an equivalent diameter roller generally speaking save for maybe something like top fuel and even then I still think mushroom lifters have more surface area.

[KILLER 'B']

Did anyone ever consider utilizing and/or fabricating a side-loading, bolt in cam follower style like a nt or k series cummins?


ediT: ....just sayin'......

[12vlb7]

Did anyone ever consider utilizing and/or fabricating a side-loading, bolt in cam follower style like a nt or k series cummins?


ediT: ....just sayin'......

You dont have access to the cam through the tapper cover. But cool idea.

[KILLER 'B']

You dont have access to the cam through the tapper cover. But cool idea.

No chit....

[XLR8R]

Nothing a dremel tool won't fix. :)

[KILLER 'B']

Nothing a dremel tool won't fix. :)

LOL

[12vlb7]

just sayin....

[not enoughsmoke]

ok i have yet to see a roller lifter for a cummins what are yall using and can they be streetable?

[The Pooler]

One would think that a roller cam would make more power (less friction, More aggressive cam profiles, etc) But when I spoke to Van Haisley last year he told me they can actually make more power with a flat tappet cam. He didn't elaborate. So I cant tell you why.

[seeker1056]

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.

[XLR8R]

This has been discussed to death many times.

X2 - this stuff is old news.

[renopker]

This seem to come up every few years in the drag racing circle also.*bdh*

[matty169]

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.

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.

[matty169]

Roller lifter diameter is actually .842.

[matty169]

Cam design handbook - Google Books (http://books.google.com/books?id=m6keIkWZ75UC&pg=RA2-PA531&lpg=RA2-PA531&dq=engine+camshaft+design&source=bl&ots=idJvo-L-jp&sig=Iwla96XK2itebyotPFchPXkpWlc&hl=en&ei=34D_SpC-HKCStAPFvPjFDA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CBwQ6AEwAjgK#v=onepage&q=engine%20camshaft%20design&f=false)

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?

[Tate]

Why would I care about 100k miles?

I'd venture to guess that not many guys on here would buy a cam that would only last a couple thousand miles.

[matty169]

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?

[Charger]

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.

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

[matty169]

I'd venture to guess that not many guys on here would buy a cam that would only last a couple thousand miles.
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

[matty169]

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 (http://www.pilotengines.com/servlet/the-ALL/searchpath/11736/start/41/total/668/Categories)
QSL/ISL engines are roller lifter engines also.
Here is a diesel engine article. Sorry... (http://www.enginebuildermag.com/Article/81065/diesel_performance_camshafts_lifters_and_valvetrai n.aspx)

[DIESEL_POWER]

A roller lifter engine will always outrun a flat tappet engine and do it longer all else being equal.

It's just common sence.

[Smokem]

It's just common sence.

You should quit saying this, unless you spell sense correctly.

[j-rod]

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.

They do exist.

We'll be expecting your results.

[DIESEL_POWER]

You should quit saying this, unless you spell sense correctly.

Common sense, not very common any more..

[pwrstrokenstang]

my motor came w/ rollers:poke:LOL

[GRotman]

my motor came w/ rollers:poke:LOL

Maybe that's why fords don't make power. LOL

[07dodge]

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!

[matty169]

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.

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.

[Scooter's Roofing]

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.

what's the OD of the lifter bodies?

[matty169]

what's the OD of the lifter bodies?
I have no idea. I just found it and thought it was interesting. Here is an article from Crane Cams.

One proven way to increase power is by decreasing the amount of valvetrain friction. The biggest friction hot spots in any valvetrain are those where the lifter comes in contact with the cam lobe, where the rocker fulcrum rides on the shaft or stud, and where the tip of the rocker comes in contact with the valve stem. In basic, simplified terms, the more energy your engine exerts by overcoming these high-friction contact points, the less torque is exerted to the rear wheels. Replace the rubbing metal-to-metal contact with a bearing of some type, and the engine is going to spend less energy doing the same work. Hence, the creation of roller lifters and roller-tipped rockers.

With roller cams, two benefits are noted: (1) the friction reduction of a roller lifter and (2) the radical cam profiles the roller allows. Even if total lift is the same, the higher velocities are possible with a roller tappet lifter as opposed to a flat tappet lifter. The roller lifter’s higher velo-city is the key to achieving higher lifts sooner in the lift curve. While acceleration is quicker with a flat tappet, the velocity of the flat tappet lifter is limited by the lifter’s diameter.

While most will assume that the only benefit of roller rockers is reduction in friction, the other benefits of aftermarket roller rockers include true, blueprinted, at-the-valve ratios and precision motion.

By placing a roller on the tip of the rocker where it comes in contact with the valve stem, the rocker is able to roll across the valve as it travels through its cycle, instead of sliding back and forth across the valve stem. Beside the obvious friction created here by non-roller tips, serious side loads are placed on the valve stem as the tip drags across the top of it while the valve travels up and down in the valve guide, contributing to worn guides (Fig. 1).

I understand that in this application(Cummins) a mushroom lifter is easiest and works well and the 1.5" mushroom helps with velocity, but if you can make a roller lifter fit it will perform better, and you DONT need a lifter body as large as a mushroom lifter either.

As for 07dodge and this comment, "If you run too steep of ramp angle on a roller cam, you are gonna have lifters outside your block!" Go back and read some cam specs I posted earlier. Yes, it is a fuel bike cam. No it is not diesel. It doesnt matter. Its a matter of mechanical properties and what will or wont work. If anyone on here can read cam specs, draw a picture of that cam profile and then try to tell me your steep ramp angle theory and the results of running one holds up. That cam has ramps faster than ANYTHING you have ever seen. The lobe at peak lift is nearly wider than the base circle. It holds the valve at peak lift for a full 35 degrees of crank rotation before starting to close the valve. It wouldnt be possible with ANY flat tappet lifter.

Who sells a roller cam set-up for a 24V? Thanks

[matty169]

Flat Tappet Cams vs. Roller Cams - Lunati Power
(http://www.lunatipower.com/Tech/Cams/FlatTappetOrRoller.aspx)

See where it says "inverted"? Do some of you know what that means? Can you do it with a flat tappet?

[matty169]

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.

FLAT VS ROLLER TAPPET TEST
We know someone is going to ask for it, so now we'll explain why this really doesn't make any sense. We're talking about a dyno test between a flat-tappet cam and a roller cam with the same specs. The reason it wouldn't work is because even if the numbers @ 0.050 were equal; the cams can never actually be the same. Roller lobes are designed to open the valves with much more "area under the curve". That means that as the valve approaches max lift, a roller tappet can hold it open longer than a flat tappet. A roller vs. flat tappet test could never be equal no matter how the cams were ground. If we were to cut a roller lobe that EXACTLY matches the profile of a flat-tappet lobe, or even if we put a roller tappet on a flat tappet cam, the test results would still show the roller ahead, albeit slightly, simply as a result of less friction. But, there'd never be a reason for that type of lobe, or test, because it'd not be taking advantage of everything a roller tappet has to offer. However, we've done a few tests that closely mimic this idea and found interesting results. Certain flat tappet cams might be capable of more low-end power due to their slightly more aggressive initial opening rates. But their advantage quickly goes away as frictional losses start to take over compared to roller tappets and the top-end power increases of the roller tappets far outweigh the marginal low-end advantage.

This was a magazine article from a cam company. It also included this.

IT STARTS WITH THE CAM
There's actually way more to camshafts then we could ever explain in just a few pages, so we'll hit on the hard points of cam selection and offer up some data to support our theories. First of all, keep in mind that the cam's lobes are designed to do only one thing: push the lifter, (a.k.a. tappet), smoothly up to open the valve and let it follow the lobe back down to close the valve without bouncing it off the seat. It's much more difficult than you might think. Good-old flat tappet cams have never been the most efficient way to do this, but they were cheap. And their low cost has kept them popular. But now, flat tappets are becoming increasingly harder to find and their prices keep going up. There are a lot of reasons for this, not the least of which is that flat tappets actually cost horsepower. Another is that the OEM's haven't put a flat tappet cam in their engines for almost 20 years. So why should you? If it were still a good way to do things, the cost-conscious OEM's would've stuck with flat tappets forever. So where did the big push for rollers come from? That's easy to answer. It was all about reducing friction. Because friction costs power and since they're always looking to make the most reliable power for less dough, the OEMs choose to reduce friction inside the engine first. But notice that they've only advanced to hydraulic roller tappets yet.

[07dodge]

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.



The 3208 was the biggest pile of sh1t that cat ever made!!

[NickTF]

For all practical purposes it simply comes down to the following: For practical purposes compare a roller lifter which will fit a stock cummins lifter bore or typical sizes the cummins block lifter bores can be machine to without running into issues with the oil gallery or other possible issues to a typical cummins mushroom lifter. Plot acceleration of the valves by mapping lift vs. crank rotation (as Zach and possibly others have stated) for identical @ 0.050" duration cams, one roller an one flat tappet mushroom, and the discussion ends after comparisons are made. For the ultimate in determining the effects of mushroom vs. roller lifter all duration numbers as measured at the lobe (.006", .050", .100", .200", .300" etc.) should be kept the same but this neglects taking advantage of what each lifter platform offers.

Nearly all flat tappet vs. roller discussions are concerning normal non mushroom diameters between .842 an 1", the cummins doest not fall into this category when measuring the face of the mushroom lifter so far as my tiny brain understands.

The above test will not take into consideration any stability issues at rpm which may be present with each platform but it's a good start to end this debate atleast when discussiong lift profile transfered to the valve.

[matty169]

For all practical purposes it simply comes down to the following: For practical purposes compare a roller lifter which will fit a stock cummins lifter bore or typical sizes the cummins block lifter bores can be machine to without running into issues with the oil gallery or other possible issues to a typical cummins mushroom lifter. Plot acceleration of the valves by mapping lift vs. crank rotation (as Zach and possibly others have stated) for identical @ 0.050" duration cams, one roller an one flat tappet mushroom, and the discussion ends after comparisons are made. For the ultimate in determining the effects of mushroom vs. roller lifter all duration numbers as measured at the lobe (.006", .050", .100", .200", .300" etc.) should be kept the same but this neglects taking advantage of what each lifter platform offers.

Nearly all flat tappet vs. roller discussions are concerning normal non mushroom diameters between .842 an 1", the cummins doest not fall into this category when measuring the face of the mushroom lifter so far as my tiny brain understands.

The above test will not take into consideration any stability issues at rpm which may be present with each platform but it's a good start to end this debate atleast when discussiong lift profile transfered to the valve.

Thanks, and I understand all that. My point was that for MAX performance and quite possibly longevity(especially with max performance cam profiles) a roller lifter is a good idea for several reasons. I never said anything about using the stock size lifter bore, and to be honest, I dont know how big a bore is possible with machining or what the options are in a Cummins. I am looking at this from the standpoint that if you build an ALLOUT flat tappet engine and an ALLOUT roller engine, the roller wins. If you compare 2 engines that are similar builds(even street engines) a roller cam will ALMOST ALWAYS perform better(although packaging in a Cummins appears to be an issue). I never said anything bad about Hamiltons products to my knowledge. I had considered using his cam to replace my Helix 2 and compare them on the dyno. I had p.m.d him a couple months back about it actually and his recommendations for a cam for my truck. I am going to look into a roller set-up, but so far I havent found one for a 24V. Scheid does use them in his big pulling builds I guess, but they arent 24 Valves.

Something else Hamilton said that I wanted to address was the issue of side loading and higher oil temps with a roller cam because of the roller lifters. I dont know who told him that, but I havent seen that and we actually run some cams that have an inverted lobe. This profile would create the most side loading possible on the lifter and its bore. We have NEVER had a lifter failure and our lifters have absolutely NO oil going to them or the lifter bore.(yes this is a bike, doesnt matter) I decided I would check to see if I was missing something so I contacted Crane, Comp, Bullet/Ultradyne, and Howards cams along with DEI and Childress racing engines.(places we order from) They all told me I was confused, unless you were running WAY too much spring pressure for the application. Maybe its possible, who knows.

To those of you thinking maybe I dont know anything, heres an idea of what you can do if you think outside the box. We raced in a class where everyone else runs 160-180" billet engines. We ran Delkron(street bike) cases and a 124" engine. They run 13" slicks, we run 11". They ran high 5 second, low 6 second quarter miles, we ran low 6 seconds. They ran a 2 or 3 speed trans, we ran 1 speed. They break alot, we dont.

Just because its not what everyone else does doesnt mean it wont work. We do circle track, asphalt, dirt and off road engines. We are never lacking horse power, although its always nice to have more.

[NickTF]

Thanks, and I understand all that. My point was that for MAX performance and quite possibly longevity(especially with max performance cam profiles) a roller lifter is a good idea for several reasons. I never said anything about using the stock size lifter bore, and to be honest, I dont know how big a bore is possible with machining or what the options are in a Cummins. I am looking at this from the standpoint that if you build an ALLOUT flat tappet engine and an ALLOUT roller engine, the roller wins. If you compare 2 engines that are similar builds(even street engines) a roller cam will ALMOST ALWAYS perform better(although packaging in a Cummins appears to be an issue). I never said anything bad about Hamiltons products to my knowledge. I had considered using his cam to replace my Helix 2 and compare them on the dyno. I had p.m.d him a couple months back about it actually and his recommendations for a cam for my truck. I am going to look into a roller set-up, but so far I havent found one for a 24V. Scheid does use them in his big pulling builds I guess, but they arent 24 Valves.

Something else Hamilton said that I wanted to address was the issue of side loading and higher oil temps with a roller cam because of the roller lifters. I dont know who told him that, but I havent seen that and we actually run some cams that have an inverted lobe. This profile would create the most side loading possible on the lifter and its bore. We have NEVER had a lifter failure and our lifters have absolutely NO oil going to them or the lifter bore.(yes this is a bike, doesnt matter) I decided I would check to see if I was missing something so I contacted Crane, Comp, Bullet/Ultradyne, and Howards cams along with DEI and Childress racing engines.(places we order from) They all told me I was confused, unless you were running WAY too much spring pressure for the application. Maybe its possible, who knows.

To those of you thinking maybe I dont know anything, heres an idea of what you can do if you think outside the box. We raced in a class where everyone else runs 160-180" billet engines. We ran Delkron(street bike) cases and a 124" engine. They run 13" slicks, we run 11". They ran high 5 second, low 6 second quarter miles, we ran low 6 seconds. They ran a 2 or 3 speed trans, we ran 1 speed. They break alot, we dont.

Just because its not what everyone else does doesnt mean it wont work. We do circle track, asphalt, dirt and off road engines. We are never lacking horse power, although its always nice to have more.

I wasn't just addressing this reply only at you but the thread and this subject in entirety. As others have said this isn't the first time it's come up. Again, i'm not sure about the longevity comment either when comparing a mushroom lifter with a bigger face diameter to a roller lifter. If we were talking same diameter non-mushroom lifters however I would agree roller is likely to offer durability advantages but that huge face of the mushroom probably makes life pretty easy given the lifter edge does not dig into the lobe like in traditional ~.842ish sized flat tappet applications. Don't forget roller lifters (most) have a shaft and some form of retaining mechanism to fail vs. the big mushroom lifter being a solid piece.

Side loading may or may not be an issue depending on length of the lifter and the lifter bore. Do you know for certain that your bike example has the same length lifter body and bore as a cummins? Otherwise it's apples to oranges.

No one is questioning your credentials, that's not what this thread is about so no need for further examples of your accomplishments unless they are directly relevant to the discussion at hand, which is quite a good one.

[05_LLY]

kE=(m*v^2)/2

Holding the ramp rates and lift numbers constant.
400lb seat pressure on a small block is not uncommon and the cummins can get away with much less? I am running under 150 on the seat on mine, motor can run 5000+.

That is something i often wondered about but never asked even with the crazy boost some of us run, running 1/2 to 2/3 the amount of rpm as a gasser and run a 1/4 of the seat pressure the gasser guys run? My thoughs always beena (example)~ 60psi of boost, 110lbs spring on roughly 1"surface area" valve leaves about 50lb of pressure to get a rather heavy retainer, keeper, and valve closed befor the piston closes it for ya? Sorry if i make no sense.....ill sit back and listen now!! Thanx

[matty169]

I wasn't just addressing this reply only at you but the thread and this subject in entirety. As others have said this isn't the first time it's come up. Again, i'm not sure about the longevity comment either when comparing a mushroom lifter with a bigger face diameter to a roller lifter. If we were talking same diameter non-mushroom lifters however I would agree roller is likely to offer durability advantages but that huge face of the mushroom probably makes life pretty easy given the lifter edge does not dig into the lobe like in traditional ~.842ish sized flat tappet applications. Don't forget roller lifters (most) have a shaft and some form of retaining mechanism to fail vs. the big mushroom lifter being a solid piece.

Side loading may or may not be an issue depending on length of the lifter and the lifter bore. Do you know for certain that your bike example has the same length lifter body and bore as a cummins? Otherwise it's apples to oranges.

No one is questioning your credentials, that's not what this thread is about so no need for further examples of your accomplishments unless they are directly relevant to the discussion at hand, which is quite a good one.

Yes, most rollers have tie bars. Ours dont. We use a groove and a lifter with a pin that rides in that groove. It serves more than one purpose.

I dont know the diameter or length of Cummins lifters, or more importantly to me, what diameter is possible to machine the bore to. Diameter is .842 on ours I believe. Length is about the same as a small block chevy. FYI, the longer the lifter and shorter the pushrod stabilizes the valve train at higher r.p.m.s, but you have to watch all the related geometry/angles of valve stem, pushrods, rockers, etc. Thanks

[matty169]

The 3208 was the biggest pile of sh1t that cat ever made!!

I agree.