How many RPM's should the ZZ4 short block be good for before it blows up? I am putting one in a stock car and will gear the rear end to adjust the RPM's. I know it won't be the fastest but if I take care of it it should last???

 

i wouldn't take it past 5500, it should be ok to it, but its hp curve drops off after 5250(the crate motor specs i've read) so 5500's good

 

The ZZ4 is a good stout bottom end with forged parts and 4 bolt mains. It would be tough to blow up the bottom end. What will limit your RPM's will be hydraulic roller lifters. The weight and momemtum of the lifters will cause valve float probably a little north of 5,800 rpm's. That's what's going to cause your damage. In my opinion anyway. The best thing would to ask GM performance parts. They should be able to tell you.

 

The ZZ4 has hyper pistons and PM rods! The crank is really never the weak part, its almost always the rod bolts.

 

ok we a zz4 with a hot cam and fastburn heads that makes 430hp and 430tq...we've spun it to 7000rpm no problem. the thing is like a tank. the cam is good for about 6700rpm though. so the block is good.

 

Wow. That's amazing with hydraulic lifters. I would think you would have major valve float up there. Are you running the hydraulic roller lifters or did you put solids in?

 

runnin the lifter that came with it. just a hot cam and fastburn heads are the only thing different. with a 750edelbrock. its truely a beast. this is in our 77vette. at about 6600 it starts to flatten out. but it'll goto 7000rpm fast.

 

I regularly take my stock bottom end L98 to 6000 rpm going down the track. JerryWho has taken his to 6900rpm with the strock L98 bottom end. He is running the Holley Stealthram with a big cam and I'm running TPI with a ZZ9 cam. Allen