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Scat crank, Twin turbo

dnewps

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So I picked up a boat with a 557ci twin turbo. Engine built in 1994 with excellent parts according to the build sheet...EXCEPT it lists a SCAT pro comp series 4.25” crank. Any chance SCAT was a good crank back then???
 

Racey

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Depends, How much boost you planning on runnin? 🤣
 

dnewps

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900hp 7lbs?? I guess what I’m asking is ...in 1994 did scat make a high quality american made forged crank? Seems weird that all of the other parts are matched with a scat
 

DRYHEAT

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I don’t know either I always thought they were made in China and machined over here.🤷‍♀️
 

Hammer

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So I picked up a boat with a 557ci twin turbo. Engine built in 1994 with excellent parts according to the build sheet...EXCEPT it lists a SCAT pro comp series 4.25” crank. Any chance SCAT was a good crank back then???
My old man Ran several scat cranks in blower motors in the 90’s. Never had one let go.
 

02HoWaRd26

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I know they were a big name in the 90’s and early 2000’s. Had a 383 with Scat crank and rods if i remember correctly (was for sure a scat crank), that gobbled the nitrous at 250hp at a time. Never a single issue with that engine rings and bearings every so often was it but that’s n02
 

bonesfab

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Well they are all forged over in Chinka now days. So unless you want to spend 3-6k for a billet from Bryant, Crower or Scat, there are not many other choices. Scat supposedly has been finishing the forgings over here.
 

ChrisV

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Get a new one from Bryant. Great cranks. Got a shop tour yesterday when picking my crank. Definitely cool procedure.

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Made here in Anaheim CA.
 

obnoxious001

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900hp 7lbs?? I guess what I’m asking is ...in 1994 did scat make a high quality american made forged crank? Seems weird that all of the other parts are matched with a scat
I would say at 7 psi you will be alright, and I would probably run it myself. Turbos are not as brutal as a roots supercharger. There was a time in the mid 90's when Kryptonite cranks were not available, or at least as fast as I needed one, so I ran a Lunati with good results.
 

oldschool

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I ran a Scat crank in a TT engine for a lot of years, 12-15 lbs of boost. I ended up detonating the thing and melting it down, but had nothing to do with the crank. I still have it, with the rod bearings welded to the journals and all.
 

cakemoto

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No idea on the cranks ...but I have worked on Tom leab personal cars.
 

BDOUCET

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The Scat Procomp's were cast cranks that sold for $200 back then. Scat does make some nice forged cranks but the procomp wasn't one. Hopefully the build sheet is wrong. Does it include a part number?
 

HBCraig

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So I picked up a boat with a 557ci twin turbo. Engine built in 1994 with excellent parts according to the build sheet...EXCEPT it lists a SCAT pro comp series 4.25” crank. Any chance SCAT was a good crank back then???
I ran one in a 383 in my Chevelle. Not one issue
 

Waterjunky

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Scat was a decent product back in the day. As also said, it lived there just fine for 26 years.

Don't screw with it.......
 

oldboatsrule

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I would say at 7 psi you will be alright, and I would probably run it myself. Turbos are not as brutal as a roots supercharger. There was a time in the mid 90's when Kryptonite cranks were not available, or at least as fast as I needed one, so I ran a Lunati with good results.


Lunati cranks about that time were made from forgings at Cola (Crankshafts of LA) in Rancho Dominguez . I was one of the crank grinders and also did alot of the knife edging. One of the funnest workplaces ever !


Sonny Bryant makes a great product. The ONLY cranks to run for big power
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bonesfab

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Lunati cranks about that time were made from forgings at Cola (Crankshafts of LA) in Rancho Dominguez . I was one of the crank grinders and also did alot of the knife edging. One of the funnest workplaces ever !


Sonny Bryant makes a great product. The ONLY cranks to run for big power View attachment 1069338

The mallory in that thing costs more than the crank. DAMN..
 

D19

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Run it til it breaks.
 

SixD9R

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Hey guys, my 2 cents is running a TT motor in a boat isn’t the same as running the very same engine in a car at the strip. The stress on the crank leaving the line with a tight suspension and a pair of slicks is higher than possible in a marine application.

Full disclosure- I’m not an engine builder but I did stay at a Holiday Inn express once or twice😁
 

Eliminator21vdrive

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Hey guys, my 2 cents is running a TT motor in a boat isn’t the same as running the very same engine in a car at the strip. The stress on the crank leaving the line with a tight suspension and a pair of slicks is higher than possible in a marine application.

Full disclosure- I’m not an engine builder but I did stay at a Holiday Inn express once or twice😁
But for just a blip in time=Marine is like going up the grapevine WOT all day!
 

oldschool

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Lunati cranks about that time were made from forgings at Cola (Crankshafts of LA) in Rancho Dominguez . I was one of the crank grinders and also did alot of the knife edging. One of the funnest workplaces ever !


Sonny Bryant makes a great product. The ONLY cranks to run for big power View attachment 1069338
I have a Cola crank that I ran in my turbo engine. Plan on using it in the blown engine I plan to build.
 

Racey

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Hey guys, my 2 cents is running a TT motor in a boat isn’t the same as running the very same engine in a car at the strip. The stress on the crank leaving the line with a tight suspension and a pair of slicks is higher than possible in a marine application.

Full disclosure- I’m not an engine builder but I did stay at a Holiday Inn express once or twice😁

Marine application is way harder, especially in something where the prop bites.

Not to mention you cant run a drag car at wot for several miles.
 

welldigger00

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I had my engine rebuilt this year, and the crank was cracked at #4 main journal. It was a Lunati, and I wasn’t running a ton of boost. Around 6 lbs, out of a roots blower. Strange deal, I was not happy none the less. We put in a Callies and that took four months to get. A simple refresh turned into a total rebuild. I had budgeted about 6k, ended up spending 25k! Thankfully I pulled the engine out before it broke, I’d have been totally screwed. I guess dart blocks are on major back order.
 

SixD9R

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Marine application is way harder, especially in something where the prop bites.

Not to mention you cant run a drag car at wot for several miles.
Yes I have heard that. I probably shouldn’t argue with the experts but I have a hard time equating the stress on a crank of launching a 3000# car off the line to a prop that has an inherent amount of slip. I totally agree that there are few applications where you can run an engine as hard and long as marine.
 

LargeOrangeFont

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Yes I have heard that. I probably shouldn’t argue with the experts but I have a hard time equating the stress on a crank of launching a 3000# car off the line to a prop that has an inherent amount of slip. I totally agree that there are few applications where you can run an engine as hard and long as marine.

In a car you are breaking nearly everything else before you break a crank.. axles, driveshafts, output shafts, input shafts etc.

Most big power cars have slip through the converter, or a slipper clutch anyway, not to mention slip at the tire.
 

Just Ducky

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Not to jack the thread but I have a chevy forged steel crank p/ n 3967416 that if checks out good with a machine shop would be worth what dollar wise?
 

hman442

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Interesting debate on whether a wheelie popping drag car launch or pushing a boat under constant load for hours is harder on a crank, etc., but I go back to "It's been in there for 27 years", probably going to be okay. This, assuming the previous owner(s) actually ran the boat.
 
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