What could be the max safe rpm?

[IQ52]

The springs you have now, with a good short travel hydraulic lifter at zero preload, could allow you to wind the engine to 6500 rpm. But why do so?

You could raise the spring pressures to 400# on the seat and 800# open. That won't change the horsepower/torque curve.

Unless you change the heads and cam, you still make the same horsepower and it will peak long before 6000 RPM. If you must have high RPM, put in a solid cam, go 160/400 and wind it to 7000 RPM. But still, unported Stealth cylinder heads are all done making horsepower by 5000 RPM on a 512 ci engine.

Will it wind beyond 5000 RPM? Or 6000 RPM?

Sure!

So what?

 

[SwedCharger67]

IQ52, many thanks for your comments.

I understand what you are saying, and I understand that more revs is useless in my current engine. I was more thinking about learning for the next engine build, and I don't want more spring pressure than necessary for my planned revs.

My interest in higher revs is simply that I like the sound of higher revs in an efficient engine, but the engine will of course be built to work well at those revs.

 

[Challenger340]

Stealth Springs are more like 128# @ 1.875" on the seat and under 300# as installed @ .600" Lift(1.275")

IMO,
With that Lunati Cam, and UN-Ported Stealths on that big an Engine, I can't see more than about 5100-5200 for peak power, no point revving any higher, it will fall off very fast after that.
Also IMO,
Increasing Spring Pressure will do squat to extend that Cam's effective rpm range if the Stealths are UN-ported.

 

[SwedCharger67]

Yes, I think we all can agree on that, thanks.