How many RPM's?

[WeezyRT]

When building a motor, what's specifically done to handle more RPM's over stock? How do you know how much the motor can take without going too far?

[uwntsumrtII]

i would say the two primary things would be "balance" and "weight"

all my pistions are within a few hundreths of a gram of each other. crank has been balanced.

[uwntsumrtII]

shorter stroke results in less rotating mass. the cyntrifical force of a smaller rotating mass vs a larger rotating mass..... the smaller will spin faster much easier.

[bad360rt]

Valve train is also a key component, rev a stock engine too high and you'll float the valves. And there are still limits with a good valve train, I'm running T&D rockers (shaft mount), so now I'm limited by the hydraulic cam/springs, I'm told they probably wouldn't be able to handle over 7k rpms. Which is fine since my power falls off after 6500rpm anyway. I'd need a solid if I wanted to really wind it out, but it's got a pretty big stroke, so that's not what it's meant to do anyway.

And then of course, even if your setup can handle the rpm, does it need to rev that high? Gotta figure out where your peak power is, and then shift a lil bit above that. I'll probably be shifting at around 6600, my peak is at 63/6400 (565hp for both). That way after the shift you're not too far below your peak power. :biggthumpup:

[slvr03dakrt]

I plan on shifting my motor at 6000 to 6200rpm. Its going to have a full internal race balance so the limit is going to the valvetrain on mine but it should be good for 6500rpm.