FS: S38/M88 Scat 92mm Stroker Crank.

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Gents,

Up for offer is like New Scat M30/S38/M88 92mm stroker crankshaft with
knife edge counter weight design. Lighter weight than the OEM.

The crank is in excellent condition, rod and main are polished.
I also include the std 144mm rods including Moly coated bearings.

I am located in SoCal.

If you have any Technical question/s please sent PM. I can assist with
building an engine if needed.

Price $4500

Regards,
Anri

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Last edited:
Oldbmwcoupes said:
Just to veri/clarify, this is from an s38b38.
Click to expand...
Hi,

Thanks for your question.

No, this is not OEM BMW S38-B38 crank.

Back then around ~94' (my friend) Frank Fahey
and Steve Dinan ordered the first batch between them
from Scat crankshaft company (Brian).

This crank is 92mm stroke vs 90mm for S38-B38.

One of the main neat feature is that it uses
better rod bearing compared to S38-B38.

Depending on the bore one choses with this
92mm stroke the displacement turns into 3900cc.

This crank is also stronger than S38-B38 design.

It will work for either M30, S38, and M88/3.

In this kit one needs only pistons which I can design
and provide.

Regards,
Anri
 
Just to be clear, the crank is used, right?

The knifing looks nice, should help it rev faster.

Does this require any modification to the block webbing to clear like the other stroker cranks?

Is there a particular reason this one is 92mm vs other stroker cranks? (IE 95mm, VAC 98mm, for example) Since you seem to have some history with this, I figured you might have some insight into why that stroke was selected.
 
x_atlas0 said:
Just to be clear, the crank is used, right?

The knifing looks nice, should help it rev faster.

Does this require any modification to the block webbing to clear like the other stroker cranks?

Is there a particular reason this one is 92mm vs other stroker cranks? (IE 95mm, VAC 98mm, for example) Since you seem to have some history with this, I figured you might have some insight into why that stroke was selected.
Click to expand...

Hi,

Thanks for your question.

The crank is used with almost no miles on.
With 92mm no need to modify the block to clear.

I have seen 95mm iE crank and I must say it needs
additional machining to cover my standard..
When I sow one in person there were machining
chatter on the pin side... kind of made me think okay
I will fix that but what else I will find..

Going to 98mm stroke from VAC is not clever
from reliability stand point and longevity etc.

In general more stroke is good but there are other
factors from the puzzle one needs to deal with and
those are oil consumption, bearing loads, piston rocking,
all for longevity!

So there is balance in the package and the first one
is reliability.

Regards,
Anri
 
Anri, thanks for your response.

Crank machining requires extremely tight tolerances all right, about the only thing harder to machine are piston profiles. (in a normal ICE unit, anyway)

Along those lines, what peak RPM would you pair with this crank given the relatively large fore/aft main journal forces? I seem to recall BMW had issues with the S38B38 and S54 crank bearings for this reason.

Also, you mentioned this comes with OEM rods, how much would you want for a set of pistons to go with it for a complete stroker kit? Also, would your new bearing type require any block modifications? (overboring the crank journals for thicker bearing caps, for example)
 
mbmw said:
What RPM are you going to run this? You will get a very high piston speed.
Click to expand...

Hi,

Remember large displacement don't require
to rev them hi. They make the power early on
the revs.

Its all about power under the curve, not peak
power.

With this 92mm its not an issue to rev them to
7600-7900rpm piston speed is still great, it will
be 24 m/s, to name few proven examples, S54
GT3 991.2 are right there at 24 m/s. Some Honda
engines are in 25.5 m/s..not a problem.

At ~7800rpm this retains the S38 characteristics
of hi revving concept. Stock S38B38 revs to only
7250rpm.

Again, it's all about the "King-Torque". With the
proper aggressive bore this can turn into 4.0l engine.

Regards,
Anri
 
rblongboarder said:
Back in 2010 I owned a '88 M5 E28 which had been modified by Frank Fahey.. it was bored out from 3.5L to 4.0L.
(Fahey also federalized the '85 Euro M6 I once owned.)

Now I wonder if that M5 motor had this crank in it...
Click to expand...
Hi,

Yes that is the crank spec that Frank Fahey (my friend) had
back then when he was stroking those M88s and S38s.

Again Scat Crankshaft company made those for Frank
and Dinan back then.

If property build these S38s at 3.9L they become absolutely
no joke!

Regards
Anri
 
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