hopefully this is in the right forum if not someone move it for me please. would a cast crank, say in a 355-383 stay together with a 200 shot of nitrous? im getting eagle/scat rods and arp bolts regardless and good pistons. just wandering if i'd be asking for trouble using a cast crank. i'm on a budget here so i gotta do whats within my funds. i used to spray 150 on my stock bottom end but it wasnt reving nearly as high as the new motor will with maybe a LE3 cam. so what do ya'll think

 

One word.....................Forged

Consittering the power that cam will make and the revs it will turn to make it, I would probably run a forged crank even if I wasn't spraying the motor.

 

RPM's will be the demise of the cast crank. If it was limited to around 6000 and the setup was right, I wouldn't hesitate for a second.

 

If you're on a budget, use your existing crank and build a 355. I'm running 593 rwhp on the stock crank with no issues for the last 40K miles reving to 6200 rpm. The car doesn't see a lot of track time but does see spirited driving.

 

Im running the stock cast crank in my LE2 GM847 setup and it sees 7k rpm daily. It will see a 150 shot in a year. I would say as long as you have good rods and pistons you should be fine. I would also suggest ARP bolts.

The stock cast crank in these cars are tough, no need for forged IMO.

 

how many pounds of boost and how much nitrous you spraying? have any times yet?

 

as far as the high rpm's would having the block splayed reinforce it or that doesn't really have much to do with it?

 

There are different schools of thought on this issue. Mine is not splayed although it has billet caps, is filled part way and the machine work was done right.

 

what do you mean "filled" part way?

 

My take on this is....

Good block work is the foundation for making anything live. I'm a fan of a 4 bolt main to start with and from there you can do anything.

As for the crank material, the machining and assembly is more important to the life of the unit. After that it's piston speed, piston G's and the mass that's hung on the crank. The more stroke, RPM and heavier the parts the shorter the life of the crank. I'm not scared of turning a cast crank 355 to 7000rpm with the right parts and a good block under it. Hell it should be good for 500rwhp too.

Bret

 

What Bret said...

Filled half way up the water jackets with block filler to stabalize the bottom end.

 

Quote: "how many pounds of boost and how much nitrous you spraying? have any times yet?"

I'm running 10# of intercooled boost (Vortech S Trim, 7" crank pulley and Brad Brand solid intake tube). I've run a small (75) nitrous shot and ran 11.6 @ 120 mph with a lousy 1.7 60' time. The same combo has also trapped at 125 mph. I'm sure with a good track prep and better driving (M6) the times would be in the low 11's.

 

When evertying is setup right you shouldn't have any problems. Just search for "my stock crank exploded" and see how many results you get.

The pistons are the real weak link.. (and thats not to say they are weak).. Followed by the rods (which i've seen go to 550rwhp no problem for long periods of time)