crankshaft recommendations

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hemibee

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mopar performance cast crank any good compared to other chooses? forged cranks pricy, so can I run the mid length stroke crank they offer on a mild mechanical tappet cam Motor and have it last long time? yes, have heard of all cranks breaking eventually. They all can and do snap under lots of pressure. so it all interesting to me.
Thanks for your advice guys...
 
Maybe you could tell us what you're going to do? I would run a stock Chrysler cast crank before the MP cast steel unit.
 
ok, well street use. New .30 over je dished pistons. 340 /71 block. MP heavy cast looked good. I have the stock steel crank for the block. Needs to be checked out still. just wanted to go the mid length stroke on it. could go stock stroke if the steel crank is good. going in a dart or duster. 323 or 355 8 3/4 rear.
 
A stock Chrysler crankshaft is good to about 400-425 HP in a street application use your stock crank, put some good bolts in the stock rods and have them resized or go with after market rods if the pistons are full floating, new balancer. Have the rotating assembly balanced. If your using a automatic transmission it tends to be a little easier on the crank but the balancing will help a lot. Then using all the other info you have like compression, rear gear, vehicle weight, suspension, tire size. Decide on the heads, camshaft, intake, carb, exhaust, ignition system, converter if it's an automatic trans. After all that you should have a good running street car that is fun to drive and not have to worry about fuel, overheating and you can just ride.
 
That's wrong.,on the crankshaft big time.^^^^ A fair, conservative guess. (And safe,). A well machined one,and clearanced),will live all day long.Well assembled,thinking 480-500.Owned it.
 
I was thinking the same, Tim. Especially if you internally balance it. I think that would perhaps add even more to its power handling capability, don't you?

Oh.....and on that note, have you checked the Mallory metal prices lately? It's skyrocketed. My guy used to get like 300 to internally balance a 360. Now he says because of the metal cost, it would be about double that.
 
Excellent description, of real world Rob.No ,I did not know about ,Mallory exploding,thanks.Personally seen ,250 hits ,on these cranks. (scats) 600+.
 
sounds right on the hp numbers for a stock steel crank. a local machine shop by me, well he not trust scat, eagle products. He say not American made, Chinese made. junk he said. seen them come apart in his bosses race car. so he recommend forged Chrysler, or Crower, our any American company only. You guys hear Scat and eagle Chinese junk?
 
Hughes engines in socal has some awesome steel crank and rods for the small block mopars. Thinking they the best buy for the money. House crank is Molnar or K1. American made. Re read Scats specs. They are decent. That machine shop I talked to its being too hard on Scat. My use is for a street stroker. not interested in racing.
 
Eagle cast cranks have a bad reputation but SCAT? yes Chinese cast (think foundry work) but machined by SCAT in the USA.

K-1 is probably better but more expensive.........does K-1 even make a cast crank.

A longer stroke would be cool but if your stock steel 340 crank is good i would go with it.

If long turn plans are 550+ HP then maybe not. but i wouldn't go cast crank by any one if that was my goal. steel all the way!
 
If I already had a stock steel 340 shaft, to me that would MAKE my decision on which engine to build. Damn buying something else I didn't need. Especially for a street engine. It's just not needed.
 
I get the steel check out on Monday. stock steel is smart move if it is usable. only than would I spend too replace it. the cast eagle is junk, OK. scat better. but steel is the way. I see the truth and it has set me free.
 
I am running a MP cast crank in my engine. It it the 4" stroke unit. I had it internally balanced, have studded mains, Fluid Damper harmonic balancer. The engine cranked out 400 HP on the chassis dyno and I buzz the thing to 6500. Mostly a street car but I have been to the track a few times.

That is my $.02
 
85glht said:
I am running a MP cast crank in my engine. It it the 4" stroke unit. I had it internally balanced, have studded mains, Fluid Damper harmonic balancer. The engine cranked out 400 HP on the chassis dyno and I buzz the thing to 6500. Mostly a street car but I have been to the track a few times.

That is my $.02
Click to expand...

Those are the ones made by Eagle that break. Good luck.
 
Yes the MP cast crank comes in two versions. the heavy duty as they call it looks great for the price. Summit is $413/ 4 inch stroke. Stock is steel but not stroked. Oh well.
Some have said not to stroke the 340, makes for a less the ideal result. Something to do with bore to stroke ratio. That is a whole interesting area of discussion of course. The guys that have built and run strokers will have definite thoughts on this based on their real world results.
 
Oops, no I see MP is getting the cast from Eagle. OUCH..Crossed off the list. RustyRatRod, you right. If the stock steel is ok'd to build on, than it is a go. It is a street motor and there are a lot of other areas to spend money on when rebuilding the motor. Good rods and head and intake work. Etc....
 
Did MP start sourcing from eagle? They were always scat cranks unless something has changed.

Is this for a 4" crank? Stock stroke 3.58, you aren't gonna find a factory installed crank that's forged. 3.31 stroke, find a 318-340 factory crank.

Scat 9000 series cast cranks are pretty tough and usually no issue for anything that is a reasonable street duty build.
 
I build a 416 about 2000. I got it from Mopar Performance for a local dealer. It came in an Eagle box.
 
Someone may have pulled one over... was the MP number screened on the crank?

SCAT was the supplier for MP for a long time. You couldn't buy a scat 4" crank for a long time because of the exclusive they had with MP.

No idea who is supplying MP now.
 
Yes. The MP number was on it as well as EAGLE. I always thought it was Eagle and not Scat. Either way, it's chinkesium. I guess Scat is supposed to be better?
 
RustyRatRod said:
Those are the ones made by Eagle that break. Good luck.
Click to expand...

3 years and still going strong. I bought the crank in "03" I believe. Engine assembled and started in"10".

If it pops, it pops.
 
Not all of them do. And according to Rob, Scat makes them now. If that's the case, you're probably good.
 
Yea my HP estimate is low but unless you want to do it again in 2 years you need to be careful what you use in your engine. Everyone want high HP and low cost and good fuel mileage and still run power brakes A/C and power steering. If the crankshaft you have is 70-72 then the quality of the cranks is better than a 73 crank cast crank. I think you can make good HP with factory parts and sometimes the ping pong part may seem to be better but in real use they are junk. I have broken both Scat & Eagle parts but that was in a race application and not just in Mopars. I don't have all the answers but after owning a auto repair shop and machine shop for over 30 years I have seen a lot of parts break and I have done my share of damage to my own engines. I think you can have it all but if you set a goal your what you want and do the best you can to have it you will make out in the long run but if you want an engine to idle like stock and make 500-600 HP you will end up with neither and be unhappy. It have seen it time & time again that in a street engine less is more. A car that is good on the street is fun to drive & gets fuel mileage you can live with & doesn't overheat in traffic. my .02
 
the stock crank passed mag, needs turning now. last owner ran low on oil. had scarring on one or two main journals.
 
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