Any HP gains by installing a set of roller rockers on my Z06? Would the non-adjustable type work over the adjustable ones?

 

The only real reason to go to roller tips is to allow the engine to run cooler. Sometimes extra power is seen, but it's usually from a higher rocker ratio, and even then it's much more effective to go with a bigger cam. There are lots of downsides. Currently Harland Sharps have been having failures, and I've heard Yella Terra's are even worse. You should expect to do some grinding to the heads and the valve covers to make any rocker kit fit, and the problem seems to get worse when you spend more $$. Lots of these rockers are nose heavy, which means more valve float unless you use a bigger double spring, which means even more valvetrain noise.

All that being said, I do have a set of HS rockers waiting to be installed pending more news about recent failures. I think it's Comp that has a kit that starts at 1.7, goes to 1.8 in mid-stroke, then ends up at 1.7 at top again. This means it shouldn't introduce valve-to-piston clearance problems, and it'd create fatter midlift airflow #'s. I can't recommend them until I hear more, but they sound promising.

Eugene

 

I have had the Comp Pro Magnum 1.85s in mine for almost three years now, got a 20rwhp (conservative) boost from them. No negative issues all good. Did have to do some clearence work on the valve covers (remove baffles, grind nubs). See picture on front page of my website in sig.

If you are going to be doing a cam anyway, its a bit redundant as you can get all the lift you need built into the cam. It was a nice pick up for me at the time, then last year I had a lifter fail and ended up doing a cam anyway. Went with a lower than usual lift cam so I could keep the roller rockers on anyway.

Hope that helps... Good Luck!

 

I've done alot of investigating on upgraded rockers (on this forum and a whole bunch of others). I also purchased a set of Comp/DRE shaft mounts. This is what I uncovered based on my investigations:
1) If you have the old style heads (perimeter cover bolts), there is no upgraded rocker system that you can install without doing some grinding.
2) On the new style LS1 heads, the only systems that will fit without head or valve cover modifications are the Crane gold race roller rockers, the Harland Sharpes, and the Yella Terras.
3) "All" of the shaft mount systems (Comp, T&D, Jesel) require valve cover spacers or valve cover modifications, as well as elongation of the pushrod gallery (due to a revised rocker arm geometry and the shaft height).
4) Shaft mount rockers do not provide any greater benefit over the upgraded full roller set-ups unless you are using them for extreme cams or racing.
5) Most of the full roller set-ups will give you a little more power over the stockers due to the decrease in friction, but mainly because they are designed to provide better rocker arm geometry, as well as providing a more ridgid structure (less rocker arm deflection).
6) A higher ratio rocker arm will give you more power by increasing the lift, and slightly increasing the duration (negligible). The average gains seem to be anywhere from 12 - 20 hp.
7) A higher ratio rocker arm also requires that you upgrade your springs (your effective lift is increased, and with this change it may also create a premature spring failure with used springs).
7) Lately there seems to be a number of failures (this forum and others)from the Harland Sharpes (they just don't seem to be strong enough with a big cam and stiff springs, but seem to be fine with mild set-ups).
I haven't come across any noted failures from the Cranes, Yella Terras, Comps, or Jesels yet.

If you are just looking for a quieter valvetrain, a little better reliability, with the added benefit of a little more horsepower, then go with a 1.8 ratio upgraded rocker system.
If you are looking for more power and lots of bang for your buck; skip the rockers and go with a cam.
Or if you have lots of money, get a cam, get better rockers, stiffer springs, and titanium retainers.
I hope this helps

 

Hightest,

Nice research! That pretty much hit everything I've ever heard of, except I know of one vendor that's had more problems with Yella Terra's despite selling many times more HS kits. Your advice to stick with stock rockers sounds good, although I'd get new OEM rockers or get them rebuilt by HS.

Eugene

 

Thanks for everyone's input. I will stick with my stock rockers when I do my cam install.

 

I think its the Cranes that have the "variable" ratio, not the Comps. You can read about that on the Vinci web site. The Crane Cams seem to have very very aggressive lobes though.