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At what point does a forged crank need to be considered essential. I am going to build a 393 or 408 stroker. I like the 393 but I only see forged pieces for the 408. Can the Scat 9000 crank hold up for an occasional 6300 rpm spin?
TIA
 

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289 and 289 Hipo cranks were of the cast variety and can turn 7k without failure. I don't really think RPM is the issue, it is more the load when your engine is making maximum torque and trying to accellerate your car.

I have never had an engine potent enough to have a crank fail, so others here will have more insite.
 

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A scat 9000 should hold up fine to 6300 rpm... Look at stock cleveland cranks... people spin them to mid 7000s.

Mathew
 

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I ran my 351W (Lightning block, rods, and crank) up to 6,800 RPM a few times, until I thought better of it. According to the Ford guys the two bolt block isn't strong enough without bottom end bracing; apparantly the crank is OK, but I wonder about the large diameter main bearing at sustained high rpm's.
 

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Well...high rpm's go hand in hand with higher compression engines....

The bigger the explosion the stronger your rotating assembly needed to be and the beating the assembly took is amplified in high rpms...

a well machined and well balanced rotating cast crank will spin into the 7000 rpms without a problem....

if you are gonna use the cast crank....use lightweight forged alum pistons and some light weight H beam rods or pauter rods

Get your damper, flexplate or flywheel and the rest of rotating assembly and pay to have it done right.....balancing seems like a waste but it isn't...it will help your motor last longer.

regards....

ps...forged bottom ends are essential for high compression, NOS, blower or turbo applications.

This is why Ford installed forged cranks in the BOss302s, 429's
CobraII.
 

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Good nodular iron cast cranks are plenty strong. Don't worry about it unless you plan a blower or serious nitrous (over 125 hp shot) use.

Don't worry about the two bolt mains - they'll do fine up to 600 hp. The large diameter mains are only an issue because of parastic drag (eats HP) and oil heating. Do the math - the surface speed isn't that much higher. You weren't planning to drive over 7K for longer than acceleration time anyway, were you ? In high gear you'd be doing, oh, 140 or so... Kind of gets the attention of your local P.D. big time..
 

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I know of a local racer that used a SCAT 9000 series crank. He made over 1600 passes in the mid 10 second range before the crank went south on him. I'm not sure what caused the failure. It may have been one too many shots of the juice.

I've pretty much decided to use the 9000 in my 331 buildup this winter. I think it would hold up fine for your application too. Attention to detail during engine assembly cannot be overstressed. Do that and the motor should last you a long time.
 
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My 466 has a stock crank, sees 7000 regularly & a 350 shot to boot. Haven't seen the necessity to put the 545 in. Scat makes a good part, one way or the other, you'll be happy with it.
 

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wether you are using Scat, Eagle, Lunati, Pauter or Carillo components.....

Attention to detail during engine assembly cannot be overstressed.

This is most crucial when building a high revving machine....detail and precision are most important.
 

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I have a 393W stroker crank (Scat) from Ford Motorsports, sees 6200 RPM often and has gone up to 6400.

This is a cast steel part...

There are cast iron, cast steel, forged steel, billet cranks... Price and strength go up from L to R...
 

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Discussion Starter #12
Thanks for all the valuable advice.
I want the nodular steel Scat crank, Thanks for the vote of confidence.
 

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Discussion Starter #13
Thanks for all the valuable advice.
I want the nodular steel Scat crank, Thanks for the vote of confidence.
 
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