Question Roller VS. Flat tappet

[Amelio]

I have tried searching the forum on this question but I have not found what I am looking for. I am curious to know about the duration and lift on a roller vs a flat tappet. I have psoken to plenty of people and I have gotten a few different answers.

Question: Will a smaller roller proform better than a larger flat tappet, for instance some told me that a 210/210 roller would be comprable to a 220/220 flat tappet????is this accurate?

I am curious to know just because I like to undersatnd better and plus I am about to purchase a roller from FT I had a 223/223 flat tappet and I think I am going to go with the 210/215 roller from FT is the roller cam specs true to it being smaller but preforms better due to a faster ramp speedand less friction . either way I am a little confused.

Please help clear this up for me....

Thank you

 

["Turbo-T"]

I don't know if it will perform better, but what I have heard on roller cams is you can usually run less duration and more lift than you can with a flat tappet cam. More lift and less duration usually means a little more torque from what I have gathered.

 

[psycho6cyl]

Just call compcams 800-999-0853 and see what they recommend. Tell them you have this cam you want a roller.. Once they give you the info ask for the difference (or whatever question you have)..... Call Mike at Full Throttle see what he says...

 

[Pablo]

it all depends on the camshaft.

look at the camshaft lobe profile like a bell curve.

For two given camshafts of equal lift and duration, a roller should have more area under the curve than the flat tappet. To the extent that this is true depends greatly on the camshaft manufacturer. One quick way to tell is to look at duration@ .006 vs duration at .050 for a given cam. A lazy cam will have a wide spread between these two numbers, and generally a roller cam will have a narrower spread than a flat tappet cam.

This is why two cams of equal .050 duration may seem different when one is a roller and one is a flat tappet. The .006 duration on the flat tappet will usually be a good bit longer than the roller cam.

Compare cam cards and you'll see the difference

 

[Amelio]

This was also my train of thought, I do realize that a roller usually has a steeper and faster ramp which usually developes more Tq. So what you are saying is if you have two cams one flat and one roller with the same amount of duration then the ramp speed or "bell curve" will be different. Does this euate to more power or just a faster build of power. The reason I say this is because I did not agree with some one telling me that if you have a flat and a roller with the same numbers the roller is actually about twice the size as the flat. That did just not make too much sense to me

Either way I have pretty much decided to go with a 210/215 roller from Full Throttle and just before I m,ake the purchase I will talk to Mike about it. I just always like to learn and make sure I know what I am talking about

Thanks

 

[Pablo]

This was also my train of thought, I do realize that a roller usually has a steeper and faster ramp which usually developes more Tq. So what you are saying is if you have two cams one flat and one roller with the same amount of duration then the ramp speed or "bell curve" will be different. Does this euate to more power or just a faster build of power. The reason I say this is because I did not agree with some one telling me that if you have a flat and a roller with the same numbers the roller is actually about twice the size as the flat. That did just not make too much sense to me

Either way I have pretty much decided to go with a 210/215 roller from Full Throttle and just before I m,ake the purchase I will talk to Mike about it. I just always like to learn and make sure I know what I am talking about

Thanks

The ramp speed doesn't have that much to do with your power curve. Your power curve is dictated by overall duration, among other factors like heads, intake, exhaust.

A more aggressive ramp should give you more power all around if you keep overall duration the same at say .050. I can see how it would slightly act like a bigger cam with a roller. Im talking about low lift duration. There is increased effective duration when the cam has the valve open enough to make a difference in flow vs a flat tappet where the valve is open a lot less. But the actual lobe shape doesn't really have a whole lot to do with where your power band is. Cam timing, duration, lsa, etc play a bigger part in that

 

[Amelio]

I gotcha...thanks for the info

 

[DavzGN]

The second picture on this page Camshaft Tech: Flat Tappet vs. Roller | Title
shows a flat tappet and roller cam side by side. You cans see the difference in the steepness of the ramps on the two cams and as it says under the picture, "it allows the roller cam to have more time at max lift."

Of course this article Camshaft Lobe Seperation Angle
says a flat tappet gets from zero lift to .050 lift faster that a roller because of the wide surface area of the flat tappet, but the Roller can open the valve faster after the .050 lift point.

David

 

[BlackBandit]

says a flat tappet gets from zero lift to .050 lift faster
David

That's true and because of that it could be debated that flat tappets are better for our engines being that they're turbocharged and low revving. I would (and did) still use a roller in any LC2 to keep it from wiping a cam though.

 

[Pablo]

That's true and because of that it could be debated that flat tappets are better for our engines being that they're turbocharged and low revving. I would (and did) still use a roller in any LC2 to keep it from wiping a cam though.

Well that is news to me, learn something new every day.

I went and compared cam cards at summit, it's not quite cut and dry.
Many flat tappet cams did indeed have less adv. duration than their roller counterparts at .050, but, there were quite a few with more, and the same. So I think it really depends on the specific cam and manufacturer. The flat tappet can potentially have a more aggressive early ramp but its no guarantee that it will be ground in.


also, Ive never seen information that suggested that lobe steepness had a whole lot to do with rpm band.

I always thought that valve timing, lobe seperation, and duration in total had a much larger effect. Though I can see how a more aggressive ramp might act like a cam with more duration if you are talking about two cams with the same .006 duration but one is a roller and the other is flat tappet. In that case the flat tappet with longer duration at .050 will act like the bigger cam theoretically. If you look at it the other way, and compare two that are the same at .050, but the flat tappet is shorter at .006 then the roller theoretically acts like the bigger cam if you are assigning the .006-.050 airflow any importance. I dont think heads flow much at all at those lifts though so I think the effect on your powerband is negligible.

I think that dur at .050 is probably a pretty good indicator of powerband range more than .006

 

[jhanson1750]

When you get done thinking about the diffrence call Mike and talk to him in person. Great guy! I have the 210-215 roller in mine. I will FINALLY get mine running on Monday and I will post my opinion after that. I bought the kit and a new timing chain with adjustable button all at once. Jon Hanson

 

[Hot Air]

As an engineer, there are three huge advantages to roller cam:

First, rolling friction is a ton less than sliding friction. Less friction, more h.p.! Roller cam utilize rolling friction. Flat tappet cam utilize sliding friction.

Second, roller cams require NO break-in. The odds of wiping out a roller cam on first start-up are remote.

Third, you can remove one roller cam and slide another roller cam in it's place w/o changing lifters. Try that with a flat tappet cam!

Conrad

 

[Amelio]

When you get done thinking about the diffrence call Mike and talk to him in person. Great guy! I have the 210-215 roller in mine. I will FINALLY get mine running on Monday and I will post my opinion after that. I bought the kit and a new timing chain with adjustable button all at once. Jon Hanson

I would definitely like to hear your thoughts on that cam, the more I look at it I realize I need that cam over the 215/220 like I originally was going to get. Did you measure the pushrods that camein the kit or did you just assemble it out of the box? I hear a lot of roller users talk about a loud valve train and it may be due to inproper pushrod length.

Just would like to know how the assembly went, I plan on purchasing the roller kit in a few weeks.

Thanks

 

[Amelio]

As an engineer, there are three huge advantages to roller cam:

First, rolling friction is a ton less than sliding friction. Less friction, more h.p.! Roller cam utilize rolling friction. Flat tappet cam utilize sliding friction.

Second, roller cams require NO break-in. The odds of wiping out a roller cam on first start-up are remote.

Third, you can remove one roller cam and slide another roller cam in it's place w/o changing lifters. Try that with a flat tappet cam!

Conrad

I hear you on that!

The main reason I am going roller is because of lobe wear, I have been through 3 flat tappetts over the course of about 5 years and two complete engine builds Fortunately this time it did not wipe out the engine, I caught it going very early. However I did pull the egine and took it down to inspect everything, I found a few bearings that were qeustionable so I bought a new set of rods and mains.

At least now I can build this thing back and know for sure the bottom end is in good shape!

 

[Epitome]

Alot of flat tappet cams have been getting wiped because of the additives that are now removed from oil. Using Kirban's ZDDP every oil change adds those additives back and will protect a flat tappet cam. If you have heavier than normal valve springs and a flat tappet cam, the additives are a must or bye bye cam.

 

[Brer Rabbit]

Cam

I have run the 210/215 roller for 3 years now. It makes a ton of power more than enough to go at least 10.50 with a supporting streetable combination. The engine idles real smooth also. Best part about it is I dont need ZDDP .

 

[Blown&Injected]

Think of it like this: Heads flow more at higher lifts and if the valve is open the same duration, but one cam holds the valve at a higher lift for more of that same duration period, it is the cam that keeps the valve open higher for more time that lets more air fill the cylinder. Plus all the other "engineering benefits"