Roller vs. Flat-Tappet Cams! - Engine Masters Ep. 16 Motor Trend Channel

[blykins]

Oh my gosh, Brent.  We must be twins separated at birth.  I can say it's greenish-blue and you'll say "no, it's bluish-green".   I could say the sky is up, and then you'd stand on your hands and say, "no it isn't."   I'm sure I'm as bad as you are. 

The main reason I might use the solid roller lifters is to be able to swap cams.  I agree that a solid flat tappet or a hydraulic roller makes sense in most purely rational ways.  I just like driving down the road with solid tappet cam in my FE, ya big dork!  I'm gonna give you a wedgie when I see ya.   

I'm not trying to be argumentative or difficult.  But when I was in engineering school, there was a saying......"Theory doesn't always mesh up with reality." 

It's nice to sit and run Desktop Dyno sims and compare durations at .200" lift, but putting combos together and dyno'ing them is what truly builds up the database.   

I'm just trying to help, as is Ross with his statements about solid roller lifters.  Quality, pressure-fed lifters can make a tremendous difference, but they still fail.   And you don't know when it's going to happen.  If you're setting your car up with a high rearend gear so you can go cruising on long trips, a solid roller just isn't the best scenario.    You can pick a lazy lobe and you can pick low spring pressure, but lifter failure is inevitable, and if you have to wimp-out on the cam to make the lifters last longer, what good is that?

If you like the idea of a hot solid flat tappet, run a nitrided cam with some tool steel EDM valve springs.  I've popped the lifters in and broke in cams without even reducing the spring pressures.

Yeah, I didn't think you'd agree, Brent.      I am already doing the nitrided cam, EMD'd lifter thing.  My lifters aren't too steel, though.  I run somewhere between 400-405 lbs open pressure on my flat tappet and have for years and several thousand miles.  It seems like it's pushing it to me.

And yes, I do agree that real world experience trumps a desktop dyno.  I don't have one by the way, but I get the dig.    That's why I posted a couple of real examples. 

Post some of yours,

paulie

What kind of real examples do you want?   

I've got a 487 in a Cobra in California with a set of CNC Pond heads, 10.5:1 compression, with a ported Victor FE intake, and a custom Bullet solid roller.  It made 640 hp @ 6500.  Owner got tired of the cam and intake because it was soggy where he did most of his driving.   Since he had Isky bushed lifters and T&D race rockers, we switched to a custom Comp solid roller and a Blue Thunder MR 1x4 intake and he was much happier....picked up a ton of bottom end.   Went from 700 lb valve springs to 550 lb valve springs.     

Got a ton of 427's with custom solid flat tappets out there, EDM lifters.....

Got several 445's with hydraulic rollers and non-adjustable rockers that spun to 6500 on the dyno without losing control of the lifters.   

Got a 347 in a local drag car that runs a solid roller with 600 lb valve springs.   Comp "Endure-X" lifters with Harland Sharp roller rockers.  Refresh after 200+ passes, rocker arms had to go in for rebuild and a couple lifters had some draggy spots in the wheels. 

Pick your poison.


 

[blykins]

Oh my gosh, Brent.  We must be twins separated at birth.  I can say it's greenish-blue and you'll say "no, it's bluish-green".   I could say the sky is up, and then you'd stand on your hands and say, "no it isn't."   I'm sure I'm as bad as you are. 

The main reason I might use the solid roller lifters is to be able to swap cams.  I agree that a solid flat tappet or a hydraulic roller makes sense in most purely rational ways.  I just like driving down the road with solid tappet cam in my FE, ya big dork!  I'm gonna give you a wedgie when I see ya.   

I'm not trying to be argumentative or difficult.  But when I was in engineering school, there was a saying......"Theory doesn't always mesh up with reality." 

It's nice to sit and run Desktop Dyno sims and compare durations at .200" lift, but putting combos together and dyno'ing them is what truly builds up the database.   

I'm just trying to help, as is Ross with his statements about solid roller lifters.  Quality, pressure-fed lifters can make a tremendous difference, but they still fail.   And you don't know when it's going to happen.  If you're setting your car up with a high rearend gear so you can go cruising on long trips, a solid roller just isn't the best scenario.    You can pick a lazy lobe and you can pick low spring pressure, but lifter failure is inevitable, and if you have to wimp-out on the cam to make the lifters last longer, what good is that?

If you like the idea of a hot solid flat tappet, run a nitrided cam with some tool steel EDM valve springs.  I've popped the lifters in and broke in cams without even reducing the spring pressures.

Yeah, I didn't think you'd agree, Brent.      I am already doing the nitrided cam, EMD'd lifter thing.  My lifters aren't too steel, though.  I run somewhere between 400-405 lbs open pressure on my flat tappet and have for years and several thousand miles.  It seems like it's pushing it to me.

And yes, I do agree that real world experience trumps a desktop dyno.  I don't have one by the way, but I get the dig.    That's why I posted a couple of real examples. 

Post some of yours,

paulie

Why do you think it's pushing it?  Are you gaining lash?  Springs losing pressure?  If there is no wear or loss of integrity, I wouldn't have any negative feelings about it. 

[plovett]

What kind of real examples do you want?   

Pick your poison.

I'd like to see examples like the one in the Engine Masters video the thread started with.  They used a hydraulic flat tappet cam and a hydraulic roller cam both with the same duration @0.050"  I think the peak power was in the same rpm range, too. 

Now I know they used an old school flat tappet cam and a newer roller cam, so there's that.  I did say earlier that if they compared a modern solid flat tappet to the hydro roller the results would have been different.  I'm not sure if they would have made up the difference with a modern hydraulic flat tappet.  But, that is what the original question was about;  flat tappet vs roller. 

So if by chance you have had almost identical engine combinations, except one was a flat tappet and one was a roller, that would be good to hear about. 

thanks,

paulie

[plovett]

Why do you think it's pushing it?  Are you gaining lash?  Springs losing pressure?  If there is no wear or loss of integrity, I wouldn't have any negative feelings about it.

I have gained lash over the years.  Tiny bits at a time, but I see it. 

Maye when I get through the nitrided layer on the cam it will start to wear much faster?  Or maybe my lifters are too soft in comparison to the cam.  Tool steel might help there.  Or maybe nitriding is not a silver bullet.  My understanding is that nitriding hardens the surface, but weakens the interior.    Yes, you pick your poison.  Pluses and minuses to almost everything.

JMO,

paulie

[blykins]

I'll take a look.  Gotta go salt the driveway and knock the ice off the cars first....

It would most likely be solid vs solid as I don't do hardly any hydraulic flat tappet builds.  I'm getting ready to do a 428CJ with a hyd flat tappet that has almost identical engine and cam specs (as identical as you can make a flat vs. a roller), but I won't have it done for a bit.

[blykins]

Why do you think it's pushing it?  Are you gaining lash?  Springs losing pressure?  If there is no wear or loss of integrity, I wouldn't have any negative feelings about it.

I have gained lash over the years.  Tiny bits at a time, but I see it. 

Maye when I get through the nitrided layer on the cam it will start to wear much faster?  Or maybe my lifters are too soft in comparison to the cam.  Tool steel might help there.  Or maybe nitriding is not a silver bullet.  My understanding is that nitriding hardens the surface, but weakens the interior.    Yes, you pick your poison.  Pluses and minuses to almost everything.

JMO,

paulie

Gotta look at things relative to how many miles you plan to drive too.   If you're really planning on racking the miles up with this combo, then there are a lot of short-term situations out there. 

Seems like I remember you saying that you were trying to get a combination together to go on extended road trips, but I get you and Ballinger confused sometimes.....

[plovett]

Does that apply here?  Lifters are better, Rats load lifters differently, oil fed rollers didn't exist, so maybe not, but I am still unwilling to run a roller wheel with lash in an engine that periodically runs low RPM, and would never do it if I don't have an oiled pin...regardless of whatever good luck other guys have

Regarding rpm, I hear ya.  I set my idle high, even with my current flat tappet, for that reason.  If I had a street roller I would also set the idle high, maybe 1000-1200 rpm.  Going down the road I'm not worried about it even with high gears as the rpm's will likely be 2500+ at all times except for idle.

I'm still listening.

JMO,

paulie

[plovett]

Gotta look at things relative to how many miles you plan to drive too.   If you're really planning on racking the miles up with this combo, then there are a lot of short-term situations out there. 

Seems like I remember you saying that you were trying to get a combination together to go on extended road trips, but I get you and Ballinger confused sometimes.....

Maybe Bill and I are the same person???   Ever see the movie,  Sybil?   

Anyhoo, if a bushed solid roller can go 20-30K with the right selection of parts that is plenty for me and my extended road trips.    I also like solid flat tappets.  In fact I like them better in most respects.  I still would like to be able to swap cams at a moment's notice.   Hence, the indecision....

[plovett]

How much open and closed spring pressure do you all think this cam would need if running to say 6200 rpm on an FE with 11/32" 2.20/1.68" valves and Harland Sharp rockers?  I'd like to run steel retainers, but I'm not averse to titanium as I've been running them for years. 

http://lunatipower.com/Product.aspx?id=2284&gid=284

thanks,

paulie

I just looked at the recommended spring for this cam on the Lunati website.  If I'm doing the math right it ends up at 153 lbs closed with a 1.92" installed height and around 394 lbs open at a 0.600" net lift.  That ain't chump pressure for a flat tappet.

[blykins]

Whoops, then disregard my previous post about valve spring pressure for that cam.  I thought it was a solid roller.....

The manufacturers say 20-30k on a set of bushed lifters but I don’t have any customers with more than 6-7k on a set.

[scott foxwell]

Why do I feel like I'm trapped in the 60's when I read all this...

[blykins]

Ok, I have some combos that were *close* to each other, but I can't find anything identical and only difference was lifter type.   

I have found:

*A 428 with out-of-the-box Edelbrock heads, Tunnel Wedge, camshaft was solid roller 248/254 @ .050", 286/292, ~.680" lift, 110 LSA, 11:1 compression, 533 hp @ 6400, 472 lb-ft @ 5400.
*A 427 with 280 cfm LR heads, ported C3 2x4 intake, camshaft was solid flat tappet, 252/260 @ .050", .640" lift, 106 LSA, 510 hp @ 6100, 511 lb-ft @ 4200.

So basically I have nothing.... LOL  I use so many custom camshafts though, and I rarely use the same one twice. 

Something that I did find that was fun to note....the difference between cylinder heads.

First combo was a 430 cube combo, out of the box Edelbrock heads, Blue Thunder 1x4 intake, 10.7:1, 240/246 @ .050" solid flat tappet, 108 LSA, .620" lift, made 476 hp @ 5700, 489 lb-ft @ 4400. 

Second combo was a 433 cube combo, CNC Pond heads, Performer RPM intake, 10:1, 243/249 @ .050" solid flat tappet, 108 LSA, .620" lift, made 529 hp @ 5800, 552 lb-ft @ 4300. 

[blykins]

Why do I feel like I'm trapped in the 60's when I read all this...

Maybe I should ask for a clarification before I post....................

[plovett]

Ok, I have some combos that were *close* to each other, but I can't find anything identical and only difference was lifter type.   

I have found:

*A 428 with out-of-the-box Edelbrock heads, Tunnel Wedge, camshaft was solid roller 248/254 @ .050", 286/292, ~.680" lift, 110 LSA, 11:1 compression, 533 hp @ 6400, 472 lb-ft @ 5400.
*A 427 with 280 cfm LR heads, ported C3 2x4 intake, camshaft was solid flat tappet, 252/260 @ .050", .640" lift, 106 LSA, 510 hp @ 6100, 511 lb-ft @ 4200.

So basically I have nothing.... LOL  I use so many custom camshafts though, and I rarely use the same one twice. 

Something that I did find that was fun to note....the difference between cylinder heads.

First combo was a 430 cube combo, out of the box Edelbrock heads, Blue Thunder 1x4 intake, 10.7:1, 240/246 @ .050" solid flat tappet, 108 LSA, .620" lift, made 476 hp @ 5700, 489 lb-ft @ 4400. 

Second combo was a 433 cube combo, CNC Pond heads, Performer RPM intake, 10:1, 243/249 @ .050" solid flat tappet, 108 LSA, .620" lift, made 529 hp @ 5800, 552 lb-ft @ 4300.

It's not easy to find perfect data to prove a point unless you actually design a test like the Hot Rod guys.  Anyway, I'll add my old 433 here:

433 cid, ported Edelbrock heads, 1x4 Blue Thunder intake, 10.5:1, 240/246 solid flat tappet, 108 LSA, .580/.598" net lift.  517 hp at 6200 rpm, 521 lb-ft at 4200.

[blykins]

Fell right in there where I figured it would.   You have more cylinder head than the Edelbrock engine I posted and less cylinder head than the Pond headed motor I posted.

There's always a difference in dynos, difference in how the engines are loaded, etc., so if all the data is not from the same day on the same dyno, you just have to look for general trends.