Build thread - taking the road less traveled by

[ardaBMW]

This was the final phase on mine. Sorry to hijack the thread

[mechanicalzen]

No that's awesome. super clean looking engine bay.

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[mechanicalzen]

I just ordered myself an xmas present - a 2.5 inch pulley and a shorter belt.

I already have the puller tool. the numbers predict at least 14 psi and 360 whp.

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[ardaBMW]

I just ordered myself an xmas present - a 2.5 inch pulley and a shorter belt.

I already have the puller tool. the numbers predict at least 14 psi and 360 whp.

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Nice! I plan on doing the same thing down the road. Do you mind sharing the belts part #?


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[mechanicalzen]

Nice! I plan on doing the same thing down the road. Do you mind sharing the belts part #?


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K060815RPM - the fit is going to be .215" tighter than K060825 with a 3.0 pulley. Should be right where it needs to be. There are no intermediate belt sizes.

[Greenday694]

I run the 2.6 pulley with the Gates K060815RPM, = a little over 15 psi at 4600 RPMs, hitting 16 at 6800 rev limit.

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[Greenday694]

This was the final phase on mine. Sorry to hijack the thread

Really nice really clean.

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[mechanicalzen]

Update for posterity - I stretched out the 82.5 inch rpm belt due to slippage. Tried the 81.5 belt with the 3 inch pulley and saw 11 psi with no slip.

So now I'll need a shorter belt to go with the 2.5 pulley, going to try the 81.0 rpm belt. If it ever stops raining...

Also changed closed throttle detection to 0.5% and saw better response off idle.

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[mechanicalzen]

Nearly 2 years later - my aluminum power steering pulley has failed from fatigue/vibration. With the M50 pump, you can just buy a steel pulley from Dorman. Unfortunately, no one seems to make a steel pulley with the M3 style offset. So I will buy a spare, and change it out every two seasons.
PXL_20221015_175505930.jpg

I found that the M62 V8 throttle body has an appropriate 80ish mm diameter for this application and uses the same TPS sensor, so I picked one up.
PXL_20221015_175522309.jpg

The mounting flange is much larger, so the challenge will be to trim that back until it can fit next to the shock tower and then find a rotation that will allow the linkage to operate freely, and seal it up with a custom gasket. If I get it working, I'll post again.

[mechanicalzen]

After fixing the pulley, the belt had a few gouges in it, so might as well throw on my 2.5" pulley and shorter belt. I can't remember if this is going to make 12 or 14 psi, should be fun either way...

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[mechanicalzen]

13.5 psi, it turns out. Smallish "butt dyno" results between 10 and 13, but the blower whine is now extra nasty.

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