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Throttle Body question


nbristow01
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I was planning on using the larger 325 tbody as an upgrade when I install my 318 EFI setup. I have higher compression, cam etc. I was told the TB off a700 series is bigger and better? Before I reinvent the wheel I was wondering if anyone has insight into this. I guess the 318 to 325 tbody setup is the same upgrade as a 32/36 to a 38/38. I want to upgrade to where my efi is an upgrade equal to say a 38/38 to dual 40s.

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Perhaps the Law of Diminishing Returns applies. I think (and I was told so) that 325is/E30 TB is the pretty much the optimal replacement for 318i manifold, anything bigger may deteriorate the performance. Of course, you have the MS, it may well be a good application since you can tune the computer easily.

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anything larger is waaay too big for even a built M10. I've got an M30 throttle body to go on my turbo project, I think its ~8mm larger in diameter than the M20.

Basically you'll turn your throttle pedal into an on/off switch with a really large throttle body because it will let in too much air. The guy I bought the motor from was running an M30 throttle body and switched back to the stock 318i throttle body so he could drive the car when it was wet...but he was making stupid high HP with that turbo motor.

I'll be switching back to the M30 throttle body because I don't intend the car to be driven on the streets often. I'll be using a 325i throttle body on my agave when I convert to to MSII.

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Guest Anonymous

As long as nobodies asking. 325is Tb = 62.5 mm 2002tii = 56 mm so my memory is about 10% off. But the Air Intake side of both throttle bodies IS the same. (So you can deduce that the tii tb tapers down, which it does before the throttle plate is encountered by the incoming air)

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As long as nobodies asking. 325is Tb = 62.5 mm 2002tii = 56 mm so my memory is about 10% off. But the Air Intake side of both throttle bodies IS the same. (So you can deduce that the tii tb tapers down, which it does before the throttle plate is encountered by the incoming air)

So is it safe to assume that the 325 Tbody at 62.5mm is as large as I should go?

9.5 comp, 284 cam, new motor and head. Will be run by Microsquirt. Or would larger allow for more HP?

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