/4 shortblock assembly + HP limits, case, crank and rods....how much abuse?? Options

[Mueller]

Let's say we take the stock heads and cylinders out of the picture and use heads/cylinders that are overkill and robust....

what is the next weak link in the motor?

are the rods going to fail once we start hitting the 200+hp mark?

will the stock crank turn to putty at 7000rpm?

what about the case??


at what HP range before it cannot hold everything together and gives up scatering it's internals all over???

[Brett W]

Guys horsepower does not kill parts. 120 hp will not kill the factory rods or bolts. If you use new rod nuts the stock rods (assuming properly balanced) will more than adequately handle that power level. RPM kills parts not HP.

If horsepower kills parts how can Winston Cup engines run zero wieght oil, at 10lbs of oil pressure per 100hp? The old rule has gone the way of the dinosaur. No more 10lbs per 1000rpm. These guys are turning 9600 rpms and making close to 800 hp. Alot of them run less than 60psi. Obviously this is not a perfect rule for the street, this just strengthens my argument that HP does not kill parts.

In anything over a sustained 6500-7000 rpm the stock rods are not strong enough. The rods in my engine which made 138 at the flywheel runs stock rods, polished, lightened by 60 grams, ARP bolts, and shotpeened. I watched my tach come back through 7000 after a missed shift at 80mph that was 10k miles ago. Never had a problem. I am running a piston that weighs 394 grams much lighter than the stock piston. Less reciprocating weight means less stress on the rods. Thus longer life for stock rods.