How much HP can a cast crank handle?

[goose69]

The title says most of it but here's the deal.... My buddy has a 1970 Satellite that he built a 1977 (i believe) 440 for it with the cast crank. He wants to put a nitrous kit on it so......... I mentioned he might not want to exceed 100-125hp on it. Yes he has forged pistons too.
Any feedback? Have any of you pushed the limit of a cast crank? And if so what was the breaking point in HP for it (approx).
I've heard the claims in the magazines but would like the opinions of people who have done it before.
Thanks again.

 

[696pack]

Many see nitrous as cheap h.p. which it is for the dollars spent but the engine has to be prepared for it from the beginning in order for it to work and not damage your engine. If you are building an engine from scratch with nitrous in mind then it is not that much more expensive. However if you are slapping a system on an engine that is not prepared for it the results can be fatal.

From other sites with guys that have experimented with different power levels and what certain componants will take I beleive that anything over 500 h.p. is a risk for a casr crank. I don't think I would go that high if nitrous was involve as it is a sudden impact on the engine when you hit the button and that is much harder on the engine than smooth power. I don't think nitrous is a good idea in any combination with a cast crank. My guess would be if he has a cast crank that he probably does not have nitrous compatible rings either and is just asking for big trouble by using nitrous.

 

[wingcarenvy]

I have squeezed a cast crank 440 before. If the motor is well built with a good balance it will work. Obviously detonation will damage the motor in short order no matter how much prep goes into it. I would not exceed 600 hp (if it has stock rods) and definitely short shift it no more than 5500 rpm. The weight of the forged pistons can put more stress than the juice will. You can safely go 150 shot (.073 jet for a plate system) no worries. The stock rod is the weak link here. On another note, even if the motor is low compression I would run it on race gas for safety and back down the timing 2 degrees per 50 hp of nitrous. I would use Vp C12 (110 octane) at a minimum. Be very conservative with your tune up and it will live a long happy life with good results. This is just a general overview so more info would be needed for a more accurate answer.

 

[goose69]

Talking with him he doesn't plan on spinning it past 5200rpm. Good thing I think. He has a pretty mild cam, ported 516 heads with oversized valves, oh and claims his compression is about 9.7-1. I'm not trying to harp on him too much cause once something is in his head its stuck there & will take it to the point of blowing it up to prove a point. Hey, he might just do it with this motor too but if he's somewhat conservative it'll prob last a little while lol. We did do an experiment on a junkyard motor once for a friend. Took a 1968 383 out of a station wagon, freshened it up with brgs, file fit rings, MP 284/484 cam, valve grind, torker intake and 850 holley. Auto trans with 3500 stall in a '63 fury. Ran 13.20's but then stuck 150hp nitrous plate kit on it and it banged out 11.99's. Ran for a few seasons too..... suprisingly.

 

[goose69]

Thank you for your inputs by the way. Glad you guys could respond. And wingcarenvy, I was suprised when you said 600hp would b safe on factory rods. Wasn't aware they could handle that much, thanks
I'll pass this all on to my buddy.

 

[Cranky]

Mom's cast cranks are actually pretty good. GM is the one that gave cast cranks a bad name. Mom's cast cranks are probably just as good as GM's forge cranks were too! Also, a cast crank is lighter than a forged one and will spool up faster. Prep some stock rods, throw on some lighter pistons and go for it. Btw, buying an aftermarket rod is probably more cost effective than doing a total prep job on a set of stock rods unless you can do most of the work yourself but the LY rod will do the job if prepped for it. Heck, a 6 pack rod will too. A buddy and I ran a Super Street car back in 82-83 using TRW L2295's (very heavy) and spinning 6900 with a 4 speed using 6 pack rods!

 

[goose69]

Mom's cast cranks are actually pretty good. GM is the one that gave cast cranks a bad name. Mom's cast cranks are probably just as good as GM's forge cranks were too! Also, a cast crank is lighter than a forged one and will spool up faster. Prep some stock rods, throw on some lighter pistons and go for it. Btw, buying an aftermarket rod is probably more cost effective than doing a total prep job on a set of stock rods unless you can do most of the work yourself but the LY rod will do the job if prepped for it. Heck, a 6 pack rod will too. A buddy and I ran a Super Street car back in 82-83 using TRW L2295's (very heavy) and spinning 6900 with a 4 speed using 6 pack rods!

Holy moly Cranky, thats some serious R's for that 440! I love high winders tho. Good info to have. It sounds as if my buddy shouldn't have a problem here then.
Thanks again.

 

[Cranky]

Holy moly Cranky, thats some serious R's for that 440! I love high winders tho. Good info to have. It sounds as if my buddy shouldn't have a problem here then.
Thanks again.

Turned another 440 to 7300 using Hemi rods. Shifted it at 69 and crossed the stripe at 73 and ran 10.68. Had a 470 stroker (440 crank offset ground) and shifted at 7000, ran 9.95 and another buddy with a 499 turned 7400 went 9.30's. The 470 had aluminum rods and the 499 had steel H beams. I know a couple of others with prepped LY rod motors with light weight pistons that turn 7k tho. I have plans to build a stock stroke 400 using 440 length rods and the plan for that one should have it seeing 7500+ in a car that's right at 3000 lbs and hopefully less. I got the car down to 2950 from 3370 with a /6, auto and with the factory AC still on it. I plan on leaving the AC in it but it won't be factory....