What Is the Max rpm you’d run on the stock crank, assuming all other components are upgraded, and the engine is kept na?

I’d like to run 8000 rpm, with a cut off at about 8,200.

 

I've rev'ed mine up to 8500 rpm quite often. No issues. But, as you stated, ALL other relevant components must be upgraded.

Also, be sure that there is a benefit from reving that high.

 

Why? The torque band peaks at 6400. The engine has nothing more to give after that...

 

Cams, big springs, lots of overlap and duration, lots of induction changes, gears. Typical NA tricks for a high revving technical course track build.

But for the street, there's absolutely zero reason to cam up that big and spinning that high. Miserable street performance. BTDT.... uggh. (I have the same argument for - actually against - light flywheels.)

So, OP, with that said, what're you building for?

 

I'd love to rev to 7-8k but I just don't think it's worth it. No variable lift equals bad manners, I'll be running a supercharger so there is no need, and also can't over spin. That being said i don't think the crank itself will have a limit.

 

sure ... you can do it ... once...

what year is your car? what mods do you have? what's the purpose for taking the engine this fast?

I dont know that the crank necessarily is the limiting factor...I think it's going to be the rods & pistons that will fail first.

Everything mentioned above and the stresses in the piston wrist pins and bolts in the big end of the rod (and bearings for that matter) are some of the most severely stressed components in the engine and the stress grow exponentially with RPMs.

call me a puss but I shift at 6k RPM because I'm well into the optimal torque region of my engine and the additional horsepower lost by short-shifting doesnt mean much to me.

 

Same, I hardly go above 6k. Typically the RPM limit of an engine is dictated by bore/stroke ratio, IIRC a square ratio is going to be better for high revs. The crank won't care how fast you spin it, the rods/pistons/cylinders will.