M50 Eaton M90 build (stock alt PS pump location)

[st.petebiodiesel]

Stock routing. About the same wrap on the crank alt and PS. If I develop a problem with charging/ steering I could always look into under drive pulleys.


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[wilholl]

Bro! Looks like proper fab work. That crank pulley may need more wrap to get to 7000rpm (not trying to be all douchebaggy).

???? Could it be that your looking at the power steering pump pulley???
Looks like the crank pulley has about as much wrap as it will take.
I am wondering about the alternator pulley wrap.

[Ether-D]

Bro! Looks like proper fab work. That crank pulley may need more wrap to get to 7000rpm (not trying to be all douchebaggy).

Also, I found a 10% overdrive pulley for my ford m90 from a place in Florida. I'll try to find it again and link it. I believe it's a 2.75".

[kalib0y]

this is a cool project!

[cleanasse30]

Looking good so far, keep it up! Interested to see how this comes together

[Lithium]

12306rpm sounds perfect for 7psi. Looking good.

[st.petebiodiesel]

Crank is 5.45" SC is 3.1" at 7000 rpm the SC will be spinning 12306 rpm. I'm hoping to keep it around 7 psi (engine is still stock). The nut is just loose on there now, I had to shim the pulley mount out a 1/4 of an inch on the shaft to get the correct alignment. I will use a low profile nylock nut to replace the stock one.


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[Lithium]

How many RPM will the blower be spinning @ redline?
The ratio looks awfully slow to me.
I am also concerned that nut does not look fully engaged.

[st.petebiodiesel]

Figured out the belt routing today. The extra pulleys are Dayco 89144 and the belt is a Bando 6pk1900. The duct on the alternator has to be hacked off to clear the supercharger.
The supercharger pulley has about as much belt wrap as possible so hopefully it won't slip.


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[Lithium]

Welcome to the world of pain.

[Streichholzschächtelchen]

Noice! I'm putting an m90 on an m30 and this is inspiring confidence.

[st.petebiodiesel]

The pulley is from Moddbox, they are the only company that I could find that sells a pulley for a Ford M90. The Ford M90 has a different input shaft diameter than a GM M90. There are a lot more aftermarket modular pulley options for the GM M90.

3.5" and 3.1" pulleys

I had to mount the pulley backwards on the mount with shims to get the correct alignment with the M50 crank pulley

I'm waiting on a mock up alternator and power steering pump to finish my pulley/belt routing.


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[st.petebiodiesel]

I'd like to share my M50 Eaton M90 build, it's not going in an E30 but all the technical data will still apply to M50 swaps. My goal was to keep the alternator and PS pump in the stock location. I see a lot of guys put the SC at the AC compressor location or move the alternator there. This being my first BMW with working AC I plan on keeping it.
I know they make centrifugal SC kits that achieve this, but they are way out of my price range. I'll be using the M90 from a Ford Thunderbird. They can be bought used for$200-$400.


Here is my mounting bracket. It picks up a hole on the oil filter housing and 2 unused m6 bolts on the block.

Stainless spacers

Cut M50 manifold. The stock manifold plenum interferes with the SC

3" plenum with runners from Ross machine

Perfect match for a silicone coupler.

Blower inlet

Blower outlet




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