4.500 inch Scat Forged crank results
 

I know there have been some posts on here about how good or not how good the Scat Forged Cranks are and I have some positive results from them.
Last night I pulled the shortblock apart and the rod and main bearings (which are the same ones from last season) still look great. I am sure that running aluminum rods definitely help. I run some pretty high rpm also 8100 on the shift and trap 8500 and this crank has seen 8700 to 8800 rpms many many times. The BES oiling mod to the block and crank is one of the reasons this engine lives the way it does. Quality machine work is another reason why alot of people have had problems and that includes me. I would recommend using one of these cranks for anyone that is making up to 1500 horsepower. Hope this helps people that have been on the fence about using a 700.00 to 800.00 crank in an engine making decent horsepower. I purchased mine from Butler Performance and highly recommend them.

Great information Jeff.
I have a new SG 4.500 crank that came from AP but I’ve not heard a lot of feedback on them so I’m hesitant to use it. I do have a 4.250 SCAT crank so your post has been a plus.

I ran a 4.250 Scat that was turned down to 4.150 when I was running the 499 cubic inch deal and that was fine also

Nice info Jeff....... But you're on the 4.25 stroke max hit list now.

Thank you for that report and results from real on-track experience. This adds validity to my impressions after carefully looking those crankshafts over at PRI last year. Visually, to me the oiling circuits in the crankshaft are world's apart from the Eagle stuff and other off-shore offerings. I just hate the huge "winking eye" depressions Eagle uses to move oil from block to mains and then the rods. The Scat oiling looks similar to the way quality billet cranks carry oil. I will likely be buying a 3.25x4.25" Scat forging for my street car based on what I have seen and your experiences. Good info.

Good info....thanks

This must be fake news. I read on here that the ECM does not share information. :bounce:

LMAO^^^

Any pics of the BES oiling mod to the block and crank?
How about pics of the crank oil holes on mains and rods?


Is the rear seal area smooth or cross-hatched?


Thanks.

John,

IMO, I don't think that would be fair to BES to put that out there. They are in business to make money. It would be different if he came up with it himself and he wasn't going to market it. Jeffy might and that's his pejorative.

I think that should be prerogative?

:confused:

That's fine on BES thing.
It's probably well known anyway to most builders.
Goes along with Quality machine work


:)

He's trying to impress AQ :pound:

AQ for Prez!

Here is a pic of what Eagle main oiling looks like. Essentially, a rough, giant trough, carved into the crankshaft journal. No scoop or lead into the direction of crank rotation. So large, the depression takes valuable support area away from the crankshaft. Many of the cheap Chinese shafts utilize this low cost approach of feeding oil to the bearings. If your making a few hundred HP with a V-8, probably works OK. NONE of the quality crankshaft manufacturers use this cut rate approach to oiling. Crower, Moldex, Winberg, Bryant, and now apparently Scat, choose to oil the mains properly with carefully designed scoops and directional oil flow. Not the best place to cut corners IMO.

Here are a couple of pics of what a correct main oil feed should look like.

Better pics of Eagle stuff.

Thanks for the info, Jeff. I've had very good results with my 4.00" Scat crank I bought from BOP. Saved a ton of money and time compared to waiting on a billet crank.


Jim

Glad to hear it. Butler is almost thru with my 535 short block and that’s the crank we used with Oliver rods

LOL.. :D

Yea I will not post it for the reason above but anyone can send their stuff there to get it machined. I think it actually was talked about on py somewhere and people were saying that's not a good way to do it.

Yes sir.

No problem just trying to help out. Your info is very valuable as well. Billet cranks are pricey now adays.

I bet I can guess the players in that one Lol

Mike, that is pretty common even in the production side of engine remanufacturing. Like you, it doesn’t strike me as a precision machining operation.

Haha got me on that one! Damn phone! Lol

Got mine, tested steel batch. Thanks Tom V.
Will see how it does with billet steel rods.

That is what an engine shop told me in Connecticut earlier this year about the aftermarket forged steel crankshafts SCAT is OK. But avoid Eagle's because the cross drilling holes are poorly done.

As far as I know, SCAT is the only aftermarket forged steel crankshaft offering for a 3" main journal with 4" stroke for Pontiac, so that is what I purchased for my 1970 Trans Am "434" project. Am pleased to here read of people finding that SCAT makes some great alternatives to far more expensive billet cranks.

https://butlerperformance.com/i-2445...tegory:1234870

I see there is an aftermarket forged steel crankshaft with the 4" stroke for the 3.25" main journal Pontiac block. But not by SCAT, but another company "RPM"

https://butlerperformance.com/i-2445...tegory:1234872

How is the quality on that piece?

Such a size offering could be useful for a destroked 455HO or SD455.

Additionally, MOLNAR offers some options for the 3' main journal Pontiacs, with strokes of 4.25", 4.375", 4.5" and 4.65"

http://www.molnartechnologies.com/cr...m-pontiac.html

How is the quality on those compare with the comparable size SCAT 3" main journal crankshafts (4", 4.25" and 4.5" strokes)?

How do the SCAT ($799) and MOLNAR ($983) 3" main journal, 4.25' stroke offerings measure up, e.g respective weights?

And has anyone have any experience to share particularly about those more uncommon choices as the 4.375' and 4.65"

That's a start but from what I have learned, I wouldn't run my junk like that.

I have a scat crank with tons of work done to it Oliver billet rods no problems ,,

Looks like a brand new engine not sumn that has got that crap sprayed out of it and buzzed to 8500+

it show when you have good machine work done and a engine builder to knows his stuff.. We have a shop like that here in Canada many NHRA Wally line the walls and they put my motor together in 2012 check it last year still like brand new..

Great information!

Always interested in improving our durability. If you have any pics or tips to improve our oiling further and will share, I would be interested. Currently, a crankshaft that looks like that is working for us with additional bearing and system mods, but there is always room for improvement. We run higher load than your engine, but lower RPM. When things are working correctly, we don't see over 8500 RPM. If I remember right, you routinely run 8800-9000 RPM?

http://i67.tinypic.com/2drrpm8.jpg

Moldex version from several years ago

Pics of crank

Are you planing on running the same crank when you upgrade your heads ?

I was but just sold the rotating assembly and am getting a great deal on a crower billet.

Crower billet is a good piece... that's the crank we ran in the funnycar... 9200 rpm shifts and a lot of boost... never had an issue.
Ran .005 on the mains and .004 on the rods.. had some trick oiling mods done also...I forgot the % but it was over balanced... never hurt a bearing...not one.

Thanks for sharing your results Jeff, it means a lot to help other Pontiac racers.

From what I know I think you've done a great job without center counter weights. I think you're right on edge of knocking the center mains out without your RPM but block stiffness is a big deal. I moved to a fully counter weighted crank on my junk but I'm planning to run higher rpm.

Thank you again for sharing some real information.

There are times when it pays off being a Pontiac racer that wins and goes rounds. Manufacturers want to be associated. Goods deals or free stuff never hurt anyone.

Thank you for sharing.

I don't think BES owns the approach but I appreciate your candor.

Have been running my 4.5" stroke Scat crank for 12 years. Has seen I would guess at least 25,000 street miles and I get out to the strip a few times a year. Two different times I melted pistons back in 2006 and 2007. Been running at least a few 8 second passes each year since 2008. Short block has been together for the last 9 years, and it's a 1970 factory block, Eagle rods and Ross pistons. This is with a turbo.

How have your piston skirts looked and what length rod are you running? I had less than favorable results with a 4.75 crank and 6.7 rods in a street application with several thousand street miles.

6.7" rods, short block hasn't been apart in 9 years.

How many are running a 4.75 crank?

How about the MOLNAR 4.375" and 4.65" Stroke Crankshafts?
 

Anyone have any information on experience with the MOLNAR 4.375" and or 4.65" stroke 3" main journal crankshafts? For instance the cylinder wall wear?

We've been building 4.375 stroke Pontiac engines for decades (not with Molnar crankshaft) and it makes great combination . No issues whatsoever. Not much experience with the 4.65 stroke.

I destroked my motor from a 4.75 Ohio to a Molnar 4.375. Both used same 6.7 rod. Less side loading on the pistons and able to get the pin out of the ring land(no ring supports). Crank was spot on. Only about 2,000 street miles and 10 passes, but so far so good.

My SG 4.500 crank is going on 3 years of racing with no problems. Mild 700 HP build shifting at 6,800 RPM. Had it checked and mag'd by the machine shop when first purchased and it was good to go.