Quote:
Originally Posted by Aubrey N Bruneau
Once again, I'm going to be offering an opinion in an area that I shouldn't... but that's OK... as long as it makes people laugh.
Right now, isn't pretty much anybody running fast, running the absolute most duration in their cam that they can, due of course to piston-to-valve clearance ????? To me, the guidelines on pistons will ALWAYS set the limit there... and as long as NHRA keeps the piston monitored, more duration just isn't in the cards. That, I think, is good. Seperates us from Super Stock.
So.... roller rockers, in one way or another, brining about another 1000 RPM ?... even 500 ?
Can't see it.
Perhaps a couple hundred, but unlikely in the form of a completely altered torque curve.
For me, just providing reliability when buzzing that last 300-400 RPM over the shift point, when passing through the traps.
A LITTLE piece of mind at 120+ MPH !
Alan... as usual, a little over my head ! HEE HEE !
Though, I DO know exactly what you're talking about with the "variable ratio" rocker arm. INGENIOUS, if you ask me !
Money has always seperated the real players from people like me. I'm OK with that.
BTW... Have I ever mentioned that EVERY TIME I read this message board, I learn something ..... ? !
great place !
|
Actually Aubrey, we (read rectangle port big block Chevy racers) are not running all the duration that will fit in the engine, honestly, I don't think that many people are running every bit of duration that will fit. That's all I will say about that, but we can get more cam in the engine, so can many others.
Again if you accept the premise that you need "x" amount of spring pressure to turn "y" RPM, but you cannot run "x" valve spring with stock rockers, your rockers, for what ever reason, will only take "n" valvespring pressure, then yes, roller rocker arms will lead to a significant increase in RPM.
Also, let's just say that if you could go faster turning more RPM, but you need more valvespring pressure and a better rocker arm, you can change the lobe profile so that the valve opens just a bit slower just before TDC on the intake, and make the lobe faster elsewhere. With a really stout valvespring, you can slam the exhaust valve shut faster, only slowing it down slightly in the last 5-10 degrees before it seats.