Hey HMT, I have a technical question about lightweight crankshafts in a turbo application.

I talked with Sean today ERL Performance and as we were discussing my upcoming engine build on a B18A and we got on the topic of crankshafts.

I know that the stock crank can handle almost anything that is thrown at it. With that being said:

Sean told me that using a light weight "Knife edged crankshaft from Eagle" wasnt a good idea in a High HP turbo motor being 400-550 HP.

this dis-comforted me, seeing in how i already bought the Stock stroke Crank from eagle (1,100$)

Sean said that the Eagle crank will flex to much under load.

So i think ill tell you guys how i would like my engine to perform:

Ive decided that ERL will assemble my shortblock Im having everything done to the block that can possiably be don, Assembly, berrings sleved, JE pistons etc.

But i really want my engine to rev lightning quick.. andi know a lighter crank will help in that area by reducing rotating mass.

Based on those facts from a Professional builder......

I just want to know what some of the engine builder on HT had to say about it. I would really like your opinions, tech info, and experience to show the pros and cons of the crank.

Thanks guys

 

I personally dont know much/anything about cranks other than the engineering behind them will make your head spin.

I dont think it is lightweight vs. stock weight.
The angles and size differences can drastically affect torque and hp.

 

i would rather get a lighter flywheel.
A Lighter then stock crank for boost isn't necessary, as is it will rev hella fast.
The guys at ERL know what they are doing, they've build a lot of good engines....

 

Yeah i want hella rev. Rpm gain is what im after, i want it to sound like a indy motor reving. Im just torn between using the crankshaft and not. because my engine builder in his opinion says no,

I dont understand why it would flex with 5 mainberrings and a 5main block girdle. not only that its made from the extremely strong 4340. they make there rods out of the same materail.

I men there are 1,500+ HP V8 domestic motors running the Eagle crankshafts. i have only heard great things about it. Then all of a sudden Stock is better in terms of durability? I know i may not be a top notch engine builder but that doesnt seem right to me.

The crankshaft is the same as stock in every way....except.... being knife cut on the counterweights.

anyone else have something sto say about it?

 

What kind of car/setup is this going to go into? I undersatnd a B18, but have you ever thought about traction?

Unless this is a full race car, I would stick with the stock crank and sell the Eagle.

 

traction isnt going to be that big of an issue i think, i have built a custom traction bar for my car, suspension has polyurethane busnigs al lthe way around, coilovers with higher tension springs, suspension tech swaybars, custom camber caster conversion front and back. and im waiting on the rotors i ordered from LSDmotorsports to get here to finish my brake upgrade.

how can i say the suspension is solid.

the motor is being swaped into a 1988 honda accord hatxh..

and as for yes its going to be a daily driver, with a roll cage. it might be something hard to drive in the rain, but it never snows in alabama, and only gets cold for like 2 months...lol

it seems that everyone thinks that the crank is totally a POS, or it wont handle up to the power of 400-500hp but there rated for 1000+ from the factory. or its not durable enough.

Anyone ever put a eagle crank into a turbo motor? or a knife edged crank? what are your thoughts about it? how did it perform?

Thanks

Nick

 

ull never sound like an indy no matter how u try
sell that crank shaft and go with the forged, proven to work, stock one

 

A light crankshaft will handle more revs without blowing up.
John Shepherd has a lightened stock crank in his 1300hp DSM, and he revs to 10500rpm and runs 56psi boost.

 

get a demeland start grinfing; take 1 inh off every journal.. max hp will be achieveed.

 

Nah, that ----'s hardened, gotta break out the air grinder.