Question re Fuel Injection conversion

[richk98]

I'm in the planning and parts gathering stage to convert my 02 to fuel injection and MS-II. I've read most of the FAQ posts and the great websites (Zenon, Finkbuilt, et al). I am likely to install a turbo once FI and MS are working. What I'm struggling with is finding data on the optimal throttle body to use with a 318i manifold. Fink used a 325is and 02again makes an CNC machined adapter plate for this specific application. While tempted to try to source a 325is TB to take advantage of the high quality parts made by Tom at 02again, I don't want to wind up with a TB that may improperly sized for a T3 turbo. If the 325is is in a reasonable range of acceptability, my "follow-up" question is whether a 325i, or other e30 models would provide similar flow and be compatible with the intake adapter.

Any experiences or advice?

Anyone have any parts they may want to sell?

[whatrudoing25]

a 325i throttle is the same as an 325is stay away from a 325e however as thats smaller

[richk98]

Thanks for the reply

[Harv]

That 325i TB is plenty big enough (56mm?). I think the only way to go bigger is with ITB's. Remember that if you go too big, your car will feel like you went full throttle when you have only asked for half. This can cause drivability problems.

Didn't someone on here get a 318i with stock TB to get big HP with a turbo?

John

[GrindGarage]

Something to consider is the 325i auto 89 up got a little bit bigger throttle body... check out the part numbers on the air boot.

Plus my auto TB has a idle screw!

I have a 325i turbo pretty easy to fit a m50 tps onto for megasquirt. Should be a fun project... been thinking about scrapping my e30 and dropping the turbo m20 into my 2002

-cliff

72 bmw 2002

89 325i turbo megasquirt

91 vanagon vw luv

82 honda nighthawlk 650sc

[PatAllen]

the one that is already on the intake works very good as well...

[JohnN]

Throttle tip-in is not a problem. Go as big as you wish on the TB

Cheers!

John N

[richk98]

I did notice the TB part number changed on the 325i as of 1/89 but wasn't able to determine that the later part was a different size. Thanks for your input.

[JohnC]

I've got a 325is on mine, I think it's 58mm. I'm going to take a guess and say that if you're going to install a turbo, it really doesn't matter because the boost will force as much air as your engine can take past a smaller throttle body.

There's no downside whatsoever of going with the 58mm TB, other than you need to buy or make an adapter. Tip-in is NOT a problem, and by designing your linkage carefully, you can make it so that the rate of TB opening is non-linear to your gas pedal. In other words, mine opens more slowly off idle, then opens more quickly as you push the pedal down. My design is based on fink-built's.

Here's a couple of pics. (pay no attention to the incomplete wiring!)