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Old 10-17-2012, 06:10 PM   #21
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Join Date: Feb 2008
Location: Fort Lauderdale
Posts: 1,827
My Ride: M3 HPF Stage 3
Originally Posted by MarcusLSB View Post
What do you plan on running for an ECU (have you got that far yet in planning?). If E85 is relatively available to you I personally would run the stock 10.5:1 compression ratio and tune the car to the lowest blend of ethanol you typically see in your area. Maybe thats 70%? Ethanol is a VERY capable fuel, and even on probably 40% ethanol you'd have no problem making 400-450rwhp on a turbo'd M52. You'd want to likely redo your fuel system from front to back, including uprated pumps to support the additional flow needed for E85. Some would say you're fine using existing lines and just installing an uprated pump.. which is probably true as well but that depends on your budget.
To OP: Exactly what Marcus says. Note the point I forgot to mention. Pump gas figures suffer a bit on a high compression build, but E85 will yield you untold bounty in so many ways.

Note also Larry from SP's post about how even stock compression on OEM BMW turbos is now 10.5.

At this point you should see some fairly compelling evidence for doing a high compression build. If you can commit to E85 in the manner that Marcus suggests (safe), you will have one of the better (best?) 330's around.

An optional but quite nice electronic item is a gauge that will simply read out your current ethanol content of what ever is in your tank. It is always good to know for sure.
Shop around for best pricing. An expensive, but handy option.

Also: "re do fuel system front to back" likely means needing larger injectors when switching to E-85 and FI.

You can start a "build" thread when you decide on a direction.

Good luck!

Last edited by Bdave; 10-17-2012 at 06:11 PM.
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