I_Need_Land

iTrader: (12)

355 lt1, d1sc maxxed out at 6800 rpm, big cam, ported heads, intake, 58mm tb, longtubes, 4.30 gears.. heavy *** twin disc clutch... meth inj.

think i can safely take it to 6800 rpm?

hvyss

I am pushing my cast Eagle crank and SIR rods to 6700-6800 with a GM 847 and LE2 heads. Last year on a CC503 and 200 shot shifting at 6400. Rebuilt the motor this year reusing the crank and rods. Soon to add AI 200cc heads LS1 computer swap and nitrous.

96capricemgr

iTrader: (1)

Eagle's problem is NOT ability to handle power, it is quality control. You might be fine with them to 7200 or they could fail at 6200. Honestly I have heard a LOT more problems with their cranks than rods but still every machine shop I have spoken too wants to resize Eagle rods before installing them because they say they go out of round after a few torque cycles.

I_Need_Land

iTrader: (12)

good info, i was reading on some circle track racing websites that people are taking these rods to 8000+ rpm. im assuming that there is a trade off between the high rpm n/a and my car making more power with less rpm. i *REALLY* want to take my car to 6800rpm but i am so afraid to break it. i think im going to limit it to like 6500, build me another engine that i Know can handle the full 7000 and go from there.

96capricemgr

iTrader: (1)

Rods usually fail under tension so it is rpms that kill them more than power. They are under a LOT of tension when the piston is at TDC and the crank has to pull it back down usually against vacuum in the chamber. Just because you are running boost does not mean there is no vacuum in the chamber, just no vacuum in the manifold.

Piston weight plays a BIG part in the tension on the rod too which is why guys like to use lighter pistons.

A 4" piston has roughly 12.5 square inches it pulls that vacuum with so just a little vacuum ends up adding a lot of pounds of tension. Which is why revving an engine high in neutral is a bad bad thing.