HEMI Tech- Crankshafts. Stock? Billet? Stroker?

I use a billet 92 crank in my 354. The mains are cut to a 354. .050 was added to the thrust. The rods were cut to 2.20. Thats bbc size for a much wider and cheaper bearing selection. I run alum rods. My car is a true dual purpose vehicle. I do drag week with it. If it can handle drag week it can handle anything.

 

My 354 crank is .20 under as it sits. If it cleans up at .20 will it be ok for a blower motor?

 

Yes

 

My 354 crank is 0.020"under on the mains, and has big-block Chevrolet size rod journals. Stock is 2.250". BBC is 2.200", so 0.050" under.

It sits under a 6-71.

No issues.

 

What would be considered a safe horsepower for a 20 under crank?

 

Is there any advantage to running BBC rods?

 

Anything Chevy compared to Hemi is going to be more readily available, have more selection, and cost less.

 

There's a lot of variables in trying to establish and answer to that question.

.020 under mains is the least of my concerns.

Things that are hard on the crankshaft:
Detonation
Heavy Pistons, pins, rods
High RPM
Lack of oiling
Overhung load on the snout from a large overdriven blower.
A junk 70-year-old harmonic balancer

Things that can help:
A safe tune
Main studs
A main stud girdle
Four bolt main conversion
Lightweight reciprocating assembly
A good damper


So depending on the circumstances I would guestimate that a safe horsepower level on a factory 354 crankshaft would be 500 to 750.

 

That makes a lot of sense!

 

Hemi, I wasn't planning on running a balancer. I don't know anything about running one except what I've read which is the belt will act as the damper. I'd love to hear opinions on this.

Again, I don't know anything on four bolt mains. I know on Flatheads a lot of people would say they can weaken the webs of the block. On my blown Flathead, my builder & I opted for the custom made billet cap straps.
I'm not familiar with the main stud girdle, but I'll look into it for sure.

 

I have done this many times. 392 crank in a 354 block. The crank thrust needs .050 added to it.
Rod choices are big chevy bb.
Small chevy bb.
354 or 426.
If 354 is used get the rods with the tang on the other side. Then pontiac bearings can be used. They are readily available. The 354 bearings sometimes can be hard to find. Hot heads has the rods in stock.
Used race billet cranks are the best. They need the adaptor to center the flywheel.
Hot heads offers the modified 340 balancer.

 

Thanks racer great info!