I have the ZZ4 crate motor that GM puts a 5500 rpm redline on. That seems a little low for a built up 4 bolt main motor.

I usually like to spin it up to 6000 and was wondering how high you can safely go with 4 bolt mains and a steel crank. What do you guys think? Is 5500 too low is there something I'm missing?

 

the mechanical limits of the block usually isn't the limiting factor. with proper preperation and set up more or less there would be no limits on the block or crank

 

I'm sure the block/rotating assembly can easily take upto 7K if balanced, but your cam is going dictate if it's necesarry to purposly shorten engine life by winging the snot out of it. If your cam all done by 5500, what's the point of spinning it to 6K other than slowing down some?

Somce guys like spinning engines to who laid the rail since it sounds so cool in NASCAR or other race bodies, but in reality for most of us, high rpms cause premature engine failure and lighter wallets.

FWIW, mine gets shifted at 6K all the time-does'nt pick up hardly anything past that point to justify beating on the engine.

 

Ok so it is more of how the engine was balanced that makes the difference. That makes sense.

The engine does pull up till about 6k from what I can tell. And if I shoot for that shift point there is a possiblity of hitting 7k, especially on the highway when your eyes have to be on the road instead of on the tach.

I guess this is where a rev limiter and a shift light would be nice.

 

You need to put your car on a dyno to see where the power curve is. You could actually be accelerating slower by shifting at 6000rpm. Dyno is the only way to tell unless you take it to the track. Allen

 

balancing is important but it still isn't the weakest link in the engine. bolts usually fail first or valve train parts