MotorHead

I was using desktop dyno and I plugged in a Comp Cams 270 HR ( hydraulic roller ) for my engine and the numbers that came up where amazing. On my engine I am looking at a 50 HP gain and 45 ft/lbs of torque !

With my 1.6 :1 rockers I get pretty close to .500 lift with my 270 H ( hydraulic) cam and the 270HR is .500 lift too. Does this power increase sound correct ?

And if it is true why such a big increase ?

One more thing right now I am using stamped steel rockers, do I have to go to full rollers if I change the cam to a hydraulic roller with the same lift and using the same springs ?

MikeC

With desktop dyno, the manual says that mild hydraulic roller cams should be described as , if I'm not mistaken, solid flat tappet cams. For some reason the program greatly exagerats the effect of a roller cam on mild grinds.

I don't think you have to change to full rollers but I am not absolutely sure.

Matt Gruber

the dyno tests in the car mags show 20-25hp.

Taijutsu

I am using a similar cam, 218-224 @.050. W/1.6s I get .528-539 lift. There is no way you can get this kind of lift on Hyd w/o excessive duration. This cam makes power where I can use it! I wanted a SB that pulls like BB. I am very happy.

American Boy

Maybe the 50 hp gain is too much but there is definitaly an increase with the roller cam. The main thing about it is that the profil of the roller cam can be more agressive. The valve open faster therefore giving more mid lift duration. And with the same duration, you can have more lift than a flat tappet. Combine that with less friction in the engine and you sure have a great combo.

Hope it makes sense.

I remember seeing an article in Chevy Hi-performance about that with a nice draw explaining the difference. A picture worth a 1000 words. I'll try to find it to post.

Stephan

69 N.O.X. RATT

I would also check to see if the valve springs you have wil be ok. Rolllers always need heavier springs to counter their steep ramp angles and with a hydraulic roller the lifters are heavy also.

MotorHead

Thanks for the help, just went to a speed shop for a price, $499 for cam and $800 for lifters, ya I'll be buying that :lol:

I wonder if the idiots realize if they didn't try and fleece you so bad they would sell more pieces :mad

Fevre

I have seen roller cams going for 2 to 2.5 times a regular cam. What gives? :confused: Is it the core that is more expensive? Can't be the machining can it? :confused: I am looking at switching to the retro fit any suggestions for a mild manored 383 with 450 hp.

Thanks

American Boy

The price difference is about the kind of treatement that the metal of these cam have to get to support the roller of the lifter. The pressure that the roller put on the surface of the grind would be fatal to a regular cam.

Beside, a roller cam is suppose to be better so why not make the customer pay more... :D

Can't help you with the cam choice on a 383 but if you put info about your combo as the heads ,compression, gear, etc, maybe someone could help.

Stephan


[Modified by American Boy, 6:18 PM 7/20/2002]

Tom454

FYI... my 1987 Ford Crown Vic ... and two 1990 Rustangs have factory roller cams & stamped steel rockers. This is the "5.0" engine.

I know.... I know... Ford.

But hey, the roller cam/stamped rocker seems to work on that platform.
I just built a fresh 5.0 +.030 with the roller cam & MotorSport roller rockers. It looks great on the stand, so far. LOL

Fevre

Ah yes detail, details. OK here they are

383 ci
5.7 in rods
hyp pistons
@10/1 comp
1 5/8 headers
4 speed
3.7 rear gear
weiend stealth intake
600 4150 vac sec carb OR
750 dp (got both)
2.5 in exhaust
flowmaster 40's

I know the dp will give better hp numbers but I kinda like my little 600. :)

I tend to keep it below 5000 but if built right I might venture up to 6000. I like the roller cam idea because of steeper ramps which give more power in the lower end.

Thanks

Aaron-74

Roller cams don't have an angled ramp like standard hydrualic and solid cams. It's for lack of a better term a perfect "U" lobe. Instead of the valve slowly opening like on hyds("V" lobe), the roller cams go from pretty much close-WIDE OPEN-close. Not really much inbetween allowing more agressive cam files and better drivability with more agressive files compaired to hydraulic cams. Add that with less friction you can get more power. But, you pay the price for that added power. Mechanical roller setups also weigh less, allowing the valve train to be reved higher easily, but having the crank/rods/pistons balanced and rotated will help the revability greatly. It might not be as high of an RPM, but there's less inertia behind all of it allowing you to basicly rev faster.


[Modified by Aaron-74, 5:34 PM 7/20/2002]