Cast crank HP limits

[sbh126]

How much power can a 77 cast crank and rods handle?

 

[rumblefish360]

600

 

[demon seed]

How much power can a 77 cast crank and rods handle?

Is this a BB crank and how fast you plan on spinning it.

 

[sbh126]

I guess engine info would be a good thing to include lol. 77 440. I dont think I'll be anywhere near 600 hp so I should be good to go.

 

[Babyblue66]

I know they're tough. I ram mine 6,000 plus rpms for a few years. Only spun no 6 bearing once after a 140 mph run, the bearings only had 120,000 miles on them:toothy10:

 

[hemijoejr]

One of the biggest problems with a cast crank is the tortional stress limits. The crankshaft is twisted every time the engine fires and that amount changes with power that the engine makes. A cast crank with undercut fillets will only hold up to about 5 degrees of tortional stress before breaking where as a 4340 forged crank with wide radius fillets with hold up to around 20 degrees of tortional stress. As far as I am concerned a factory cast crank should never be used for more that 475hp and 6000rpm, a stock steel crank shouldn't be used past 575hp and from 6500-7000rpm. If you plan on making more than that just buy a new crank. Just keep in mind that I'm not saying you cant spin a cast crank engine past 7000rpm and make 650hp, I'm looking at safe levels and Murphy's law. Spend the money once, parts and machine work are expensive. For the extra $200 it could have been bullet proof!!!

 

[horsehead]

To add to all the above,a cast crank is balanced by the damper.This increases stress to the crank as a lot of the stress is going onto the end of the crank.

 

[72ScampTramp]

I played with this and tossed it back and forth in my head. Most everyone told me that the cast crank will be just fine for me. But in the back of my mind I always felt like it was going to be the weak point of my build. So for added peace of mind I got a forged crank and now feel like my short block will be very stout.

 

[RustyRatRod]

Forgerd cranks serve two purposes. They are fantastic insurance and they are great bench race fodder. Most fender lizzards talkin crap don't even need a forged crank. Josh, I think in your case, that was a WISE decision. Since you'll be runnin a tunnel ram, you'll see what I mean. that thing is gonna be able to rev outta sight and do it NOW. You'll be glad you did that. also, just as a reference, I'd like to add that cast cranks certailnly can be neutral balanced. I've had it done several times and will probably have it done with the engine I'm building. Internal balancing is just a better way to do it. It takes more mallory metal to get it done, but it can be done. It wouldn't bother me not one narry bit to stumble up on a good deal on a forged 440 crank, though.

 

[womanator]

A new steel 8 bolt 4.15 mopar crank with 400 mains in my race car.

In my Duster a cast crank running juice to get to 11.50's.

That being said I am waiting for it to fail along with the 8 1/4 rearend.
200 plus runs on the rearend and still waiting.

Take it for what it's worth.

 

[RustyRatRod]

A new steel 8 bolt 4.15 mopar crank with 400 mains in my race car.

In my Duster a cast crank running juice to get to 11.50's.

That being said I am waiting for it to fail along with the 8 1/4 rearend.
200 plus runs on the rearend and still waiting.

Take it for what it's worth.

I think it's worth a lot. Thanks.

 

[bremereric]

I like my big sharp 1973 factory forged crank...mains were turned down .010 and the rods were just polished...Pete my crank grinding guy told me to be careful when installing it...he said it was sharp and it was on the counter balances.....

 

[451Cuda]

Stock eliminator guys run cast cranks.

I've toyed with the idea of building a cast crank internally balanced motor with light rods and pistons, would rev like a small block :mrgreen:

 

[stroked 340]

If you don't plan on going anywhere near the 600 h.p. level i wouldn't worry about it, i ran a cast 4" in my 416 putting out 520+ h.p.with no issues,i'm currently running a "stock" cast in my 360 putting out about 400 h.p. been in the 11.70's n.a. of coarse..:-D:-D