Eagle vs Scat cranks

Is a Eagle 4340 as strong as a Scat 4340? And after both cranks have been balanced w/rods and pistons and journals checked for assembly,is one as good as the other? If not equal ,then Why?

Usually the big difference is in the finish work. They might come from the exact same forging

I put a forged Eagle in a buddies engine last year. All the tolerances are on the big side. I had to use .001 oversize bearings and it barely had .002 thrust clearance at first.

BigDave65 wrote:I put a forged Eagle in a buddies engine last year. All the tolerances are on the big side. I had to use .001 oversize bearings and it barely had .002 thrust clearance at first.

I also had too do that w/my new Scat 4340 from Adney,so I think you will have that w/most cranks.

bbf-falcon wrote:Is a Eagle 4340 as strong as a Scat 4340? And after both cranks have been balanced w/rods and pistons and journals checked for assembly,is one as good as the other? If not equal ,then Why?

Besides the finishing, the Eagle crank has a larger lightening hole in the journals than a SCAT.
It may become a strength problem at higher loading but, is usually good enough.
Scat and Eagle cranks come from different factories in china and the raw forgings are different.

They could still come from the same foundry. The Chinese just copy what ever was sent to them, by whoever pays them and puts in a box. The kids pouring the molten metal wouldn't know one from another.

Eagle forging



Scat forging

I see what Randy is saying about the size of the Lightening hole sizes. But at what HP will that make a difference?

bbf-falcon wrote:I see what Randy is saying about the size of the Lightening hole sizes. But at what HP will that make a difference?

It's like everything else......we'll find out the hard way. Hopefully Blake will see this.....he did not have good luck will the Eagle unit in his 577" TFS street headed engine.
Speaking of Blake, he took the two pictures with his phone camera. Maybe he still has some additional shots.

I think Blake's was a "CAST" Eagle crank.

bbf-falcon wrote:I think Blake's was a "CAST" Eagle crank.

Could be...maybe he'll jump in here and shead some light on that build.

At any rate after the cranks were compared [this was side by side, same place and the same day] Blake, Jet Boat nor I had any "love" for the Eagle unit. There is no way the two forgings came from the same tooling.

Lem Evans wrote:

At any rate after the cranks were compared [this was side by side, same place and the same day] Blake, Jet Boat nor I had any "love" for the Eagle unit. There is no way the two forgings came from the same tooling.

I completely agree with that!

The reason i'm asking these ?'s is,I have a complete "balanced"4340 4.500 Eagle crank assembly that will be for sale or trade,and I want to make sure of all the details before I post anything. I appreciate all the input guy's.Thanks

It's been at least 3 years so hopefully Eagle has made running changes to improve the product.

Lem Evans wrote:It's been at least 3 years so hopefully Eagle has made running changes to improve the product.

Hopefully they have ... SCAT has their own forge plant and factory in China; Eagle, RPM, Star Galaxy and a lot of others, don't.
The base metal could be the same, though.

Curt wrote:They could still come from the same foundry. The Chinese just copy what ever was sent to them, by whoever pays them and puts in a box. The kids pouring the molten metal wouldn't know one from another.

If you saw them side by side you wouldn't say that.

They did not come from the same forging die I can say that with great certainty.

The Eagle crank we used in the 306 didn't look too bad, its been well over 8000 a bunch of times........but its only a 3" stroke lol. From what I have seen the Scat is a much better unit.

The crank I had problems with was a Cast Eagle............... It looked like on the dyno that somewhere around 700-750 hp it started going south. (flexing)

The Eagle 4340 forging equal to the one I had has not changed in three years, I have one at the shop.

All tho the lightning holes are smaller in the Scat unit the lightning holes in the 4340 Eagle are smaller than its cast counter part, and also angle steeper and faster towards the center of the rod journal than the cast unit.

How much power will it handle, I don't know, but it will handle a good bit more than the cast unit.

I talked to an engine builder that buys from the same distributor that I do and he sales both Scat and Eagle 4340 cranks and has several eagles running over 1100 hp. He said he has yet to have one break.

The Scat overall finish is way better than the Eagle, just looks better.

But as far as I know no one has found what hp level the Scat crank fails at, If it will carry 3000 hp and the Eagle 2000 hp, then there is no problem with the Eagle huh.

Jury is still out, I have hoped that some one would give us some feed back in the last 3 years , but it seems only a hand full of people actually share what the learn to help other ford people................

I am not selling them short yet because I think the Scat is way better than people think it is, and even tho the Eagle may not be as good as the Scat, it still may be all it is advertised to be. JMHO

Also I have talked to Eagle at length about there 4340 4.5 inch crank siting the differences between it and the Scat and they told me when they see one fail in the hp range it is sold for, they may look into it. So far they said they have yet to see one break.

richter69 wrote:The Eagle crank we used in the 306 didn't look too bad, its been well over 8000 a bunch of times........but its only a 3" stroke lol. From what I have seen the Scat is a much better unit.

I have sold several 4340 Eagle small block cranks that got run through the ringer and never a failure, one was in my friend Dons 414

(4 inch) small block windsor with C302b heads that ran low 6's at 3000 lb and never hurt it

They may not be the strongest but maybe they are strong enough...............

IDT-572 wrote:

If you saw them side by side you wouldn't say that.

They did not come from the same forging die I can say that with great certainty.

No doubt not from the same die. That doesn't mean they dont start at the same address. They Chinese copy the pattern sent, not the one that looks the best.

I really couldn't give 2 shits either way.

Thanks I was really worried if you did or not

Thanks Snake

bbf-falcon wrote:Thanks Snake

Your welcome

careful Snake, or he will get Nick to have himself added to your ignor list..................

richter69 wrote:careful Snake, or he will get Nick to have himself added to your ignor list..................

I handle my own list...............