E46Fanatics - View Single Post - Throttle Body Size (post b30 manifold swap)
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Old 06-26-2012, 09:04 PM   #82
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Join Date: May 2008
Location: San Francisco, CA
Posts: 171
My Ride: 2000 323i
Ha! Its nice to hear somebody else bring up the same ideas I've had... its validating! Getting a bigger throttle body on the M52TU has been a multi-year obsession for me. I'm not sure what my fascination is, but I feel this overwhelming desire to remedy that poor engineering decision.

Anyway... I did research a few years ago on both the Dinan and Alpina throttle body options. The Dinan TB is a no-go. They only made a throttle body for the 325 and 330. Surprisingly, they offered two different sizes instead of just one. I was never able to confirm the size differences, but my best research attempts revealed that they were only 2 mm off from one-another in bore diameter.

As for the Alpina TB... that one felt like "the girl who got away". I've always felt that would have been a viable solution to our anemic throttle bodies, but I was never able to get any reliable information on it. Alpina did use a special throttle body -as well as a custom intake manifold. Also, from what little I've gathered, they removed the partial drive-by-wire throttle system in favor of a fully mechanical system. They also dissolved the DISA assembly in favor of a high flow intake manifold which has more in common with the M52 intake manifold off the e36. Its a very cool looking assembly, but I was never able to find either the intake manifold or the throttle body for sale online. Also, I have no idea how they controlled the traction control.

Side bar, I've been meaning to ask you something TerraPhantm:

Do you think its possible to integrate the MS43 into the 323 and 328s without swapping out the wiring harness? My thought is that if we could reduce the cost of an MS43 swap, that would solve our problems of a smaller throttle body. If someone can avoid buying a wiring harness from a 325 or 330, that would save a substantial cost. I'd love to map the differences between the two DMEs and figure out how similar/dissimilar the two really are...

Originally Posted by TerraPhantm View Post
Thanks for the explanation Alex. I meant to delete that "double the voltage" thought - one of the documents mentioned that the secondary potentiometer produces "exactly" half the voltage of the primary, but that doesn't actually seem to be the case based on other documents.

MS43 might be the way to go at those prices, though the 2.8L motors would need a custom tune since there's no 2.8L M54. I assume dinan never made an M52TU throttle body? I wonder if Alpina did (though even if they did, they'd never sell it).
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