WELCOME TO RIVER DAVES PLACE

Scat crank, Twin turbo

dnewps

Banned
Joined
Jul 27, 2012
Messages
1,339
Reaction score
2,019
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

Maxwell Smart-Ass
Joined
Sep 18, 2007
Messages
17,710
Reaction score
29,552
Depends, How much boost you planning on runnin? 🤣
 

dnewps

Banned
Joined
Jul 27, 2012
Messages
1,339
Reaction score
2,019
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

Well-Known Member
Joined
Sep 6, 2010
Messages
4,778
Reaction score
7,672
I don’t know either I always thought they were made in China and machined over here.🤷‍♀️
 

Hammer

Well-Known Member
Joined
Apr 17, 2010
Messages
20,761
Reaction score
9,253
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

Well-Known Member
Joined
Dec 19, 2007
Messages
8,711
Reaction score
18,384
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

Well-Known Member
Joined
Jun 20, 2008
Messages
2,289
Reaction score
7,198
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

Well-Known Member
Joined
Nov 30, 2020
Messages
325
Reaction score
720
Get a new one from Bryant. Great cranks. Got a shop tour yesterday when picking my crank. Definitely cool procedure.

IMG-2811.jpg
IMG-2812.jpg
IMG-2814.jpg
IMG-2816.jpg
Made here in Anaheim CA.
 

obnoxious001

Engine building character
Joined
Dec 28, 2007
Messages
5,802
Reaction score
2,442
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

Well-Known Member
Joined
Nov 1, 2007
Messages
8,164
Reaction score
9,290
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

Well-Known Member
Joined
Aug 12, 2009
Messages
1,728
Reaction score
1,206
No idea on the cranks ...but I have worked on Tom leab personal cars.
 

BDOUCET

Member
Joined
Nov 21, 2021
Messages
13
Reaction score
27
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

Well-Known Member
Joined
Jan 8, 2008
Messages
6,996
Reaction score
6,121
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

RDP Inmate #94
Joined
Sep 24, 2007
Messages
3,886
Reaction score
2,511
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

Well-Known Member
Joined
Oct 17, 2016
Messages
91
Reaction score
244
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
20211114_125359.jpg
 

bonesfab

Well-Known Member
Joined
Jun 20, 2008
Messages
2,289
Reaction score
7,198
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..
 

SixD9R

Well-Known Member
Joined
Mar 16, 2019
Messages
2,179
Reaction score
6,468
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

Well-Known Member
Joined
Jul 5, 2016
Messages
610
Reaction score
852
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

Well-Known Member
Joined
Nov 1, 2007
Messages
8,164
Reaction score
9,290
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

Maxwell Smart-Ass
Joined
Sep 18, 2007
Messages
17,710
Reaction score
29,552
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

Well-Known Member
Joined
Aug 18, 2010
Messages
2,808
Reaction score
4,370
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

Well-Known Member
Joined
Mar 16, 2019
Messages
2,179
Reaction score
6,468
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

We aren't happy until you aren't happy
Staff member
Joined
Sep 4, 2015
Messages
34,544
Reaction score
49,005
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

Well-Known Member
Joined
Sep 6, 2009
Messages
630
Reaction score
414
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

Well-Known Member
Joined
Mar 7, 2021
Messages
178
Reaction score
294
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.
 
Top