usra/usmts allows 604 7000rpm

[brett4]

Is this a good or bad thing to be turning 604 7000rpm???

[Punisher88]

Better have some real good valve springs... I only turn my 525 7200, and iirc we only turned out 604 6700? It's been about 5 years but I know we didn't hit 7

[CCHIEF]

The intake valve in a 604 is heavy, for the amount of spring pressure "allowed" to control it. So turning one 7k is bad for/ hard on engine (valvetrain and seats/valves) but good for more pull than your competition, off the corner, on restarts and resuming speed from on track incidents. Keep a spare engine...or two.

[MLR19]

Agreed , 7000 rpm & stock valve springs on a 604 is a recipe for disaster. The CT 525 uses the same valve spring but has a much lighter rocker arm , when we ran those engines we ran 7300 occasionally with no issues. That being said and all else being equal, the guys that are wiling to turn the 604 to 7000 will have an advantage , for a while, how long is the question.

[50j]

Agreed x2, I wouldn't want to do it often with stock valve springs.