high rpm ?

[rx191]

does anyone know if the cranks in the older 2.8-3.1 engines are cats steel or cast iron, i found a really nice cam for my engine build but it peaks at 7200 rpm so i figure 7500 redline. but will a stock crank take that kind of rpm, i would have the rods magnifluxed, shotpeened and polished but do you still think the crank would take it. also i found a set of flat top 2.8 pistons can they be used with a 3.1 crank and rods.

[sharkey]

2.8 pistons have a different pin height than a 3.1l. also flat top pistons are for a gen 1 ironhead motor. they have been used, you end up with 12.5:1 compression. not a very streetable setup.

the crank is iron. they are however very good cranks. many people have used them in high rpm motors (some up to 8000 pushing 300+hp, boosted of coarse). have the rods magged, beam polished, shot peened, use arp bolts and have them resized. that will give you a tough rod. in stock form, they are rated good for 7000rpm, but with some work, they are good for way more. i have never seen a rod fail in one of theese motors (unless it spun a bearing first).

[torq455]

turbo Z24 spins his between 7000 - 8100 RPM and uses the stock crank. proabably pushing 400+ HP. It's been a couple of years, but it's still going strong--maybe a little too strong.