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Author Topic:   Steel Cranks?
WILDphil
Dirt Full Roller

Total posts: 32
posted November 24, 2001 09:49 AM
I was wondering what kind of strength a school bus Steel crank would have compared to other aftermarket steel cranks?
See I know where I can get a school bus Steel crank(not cast iron) and the price is real reasonable I know that it is not crack and I know that it is 10/10 but I was thinking that I could buy this crank and save a lot of money.
The Car that I'm going to be putting it in will be a Limited Latemodel.

sdhnc29
Dirt Freak

Total posts: 467
posted November 25, 2001 11:57 PM
We have found that in a high compression alky or gas engine , the factory steel nitrited crank will go about 8-14 races before cracking , if you've got your car hooked up . A good 4340 chromolly crank will last you several years , in the stroke your talking about . You need to look at the journal radius on the crank your talking about ! If it was ground by a production grinder , the radius will be ground out , greatly reducing the strength of the crank .

WILDphil
Dirt Full Roller

Total posts: 32
posted December 03, 2001 07:11 AM
I'm Curious sdhnc29 What kind of horsepower were you guys running with that Crank (approx.)and what part of the country did you race at. See I betting that I won't be running as much horsepower as you guys wer thats why I'm asking. I'm only planning on running somewhere around 450 to 500 horse hopefully and 500 would be the max.
Thanks for all the info you have given so far.

Donnie Ross
Dirt Maniac

Total posts: 109
posted December 03, 2001 06:24 PM
a cast crank may be a better option, it is not quite as strong as steel but is far less brittle and less susecptible to cracks, it
should be plenty strong enough for your application ive used a stock 400 crank for 5 years with 12.5 to 1 compression, roller cam, good power no probs.

sdhnc29
Dirt Freak

Total posts: 467
posted December 03, 2001 11:55 PM
The high compression alky engines were run in California in the early 80's , the rules at the time required a stock crank . The HP level on those engines was right around 630hp. But now , here in North Carolina , I've seen factory cranks in high compression pure stock engines (13:1) go the same amount of time . But , these pure stocks are very heavy cars , they must weigh around 3,400lbs . These engines produce right around 425hp . I think there are several things that you must consider , compression ratio , car weight , traction capabilities , track size (shorter tracks being tougher on cranks), etc,etc , when deciding what crank to use . Donnie Ross was right in the sense that a cast crank will absorbe much of the impact loads much better than a factory steel crank . Most of the cast cranks that we've used , have out lived the steel one's by at least 10 races .

WPP
Dirt Freak

Total posts: 220
posted December 22, 2001 04:54 PM
What kind of cast cranks are best gm or scat

Donnie Ross
Dirt Maniac

Total posts: 109
posted December 22, 2001 08:55 PM
GM, a stock crank has to pass several inspections before it leaves the plant due to warranty considerations scats have to last long enough to sell compare the 2 side by side you will see the difference

6pack
Dirt Maniac

Total posts: 128
posted December 23, 2001 09:38 PM
Cast is lighter, also.

bbracer17
Dirt Freak

Total posts: 256
posted December 23, 2001 10:06 PM
Honestly I can't think of one person that has broke a 350 GM cast crank. I do know people that have broken steel cranks though. Untill I have crank problems I won't start spending high dollars on steel cranks.

bbracer17
Dirt Freak

Total posts: 256
posted December 23, 2001 10:07 PM
I need to add that I know a couple people that have broke 400 GM and Scat cast cranks.

Pit Bull
Dirt Full Roller

Total posts: 65
posted December 24, 2001 01:08 AM
I dont know if this will mean much, but we had a 350 chevy with a cast crank that we ran for 2 full seasons (11.5 to 1 compression; 6300 rpm) and we tore it apart after this season and it had a crack on one rod journal. I thought it held up really well - i was impressed.

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