97BlackStang

Simple, What determines a redline in an engine? I know it has something to do with the components, but i mean were do u know when to stop increasing it?

alexr

the factory probably destroys plenty of engines determining that.

97BlackStang

Hmmm. Then what about engines that are built custom?

alexr

its a simple equation. you take the engine displacement, multiply it by the diameter of (1) cylinder, all over (divide everything) the recipricol of Pi. that should give you an estimated max speed, take that number and multiply it by your gear ratio (3.73, 4.10, etc) and subtract 500rpms and that should give you a close estimate for the redline rpm.

alexr

by the way, that isnt true.

ShadowDrake

Double posts are for losers

Check with the manufacturer of your engine's internals, they probably have a rating. Keep in mind also your valve springs, if you spin the engine too fast the valves will float, and you'll run into a natural rev limiter. We have interference engines too, so floating valves could mean major trouble.

As RPM's increase, the load on the moving parts becomes much higher, it's not proportionate. There's a way to figure it out using math and knowing the most force the piston, rod, and crank can take... but that's where the money is . Get a cam that makes the most power around 5000 RPM and limit yourself at 6000-6500 RPM. Sure you can make more power up higher, but you run into diminishing returns.

97BlackStang

Im not building an engine or anything, i was just wondering how you dertermine that, cuase you cant just say OH about 9000K sounds good...lol

alexr

they pick numbers out of a hat

97BlackStang

You never know

alexr

they do, you dont believe me?