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10-13-2002, 03:56 AM
Hey guys, I have an Eaton M90 positive displacement supercharger off a Ford Thunderbird supercoupe that I am going to try and use with the m30 motor in my 535i with low boost (5-7psi). My question is, should I mount the throttle body upstream of the blower of can I mount it downstream?

The factory setup on the Thunderbird SC has the throttle body mounted upstream, connected directly to the blower inlet pipe. To mount the throttle body upstream on my 535i will take some more work, so I've been thinking of mounting it downstream in the stock location. Would it be OK to run the TB downstream, as long as I had a blowoff valve to relieve pressure? Any help/input is appreciated.

'85 535i (251k)

10-13-2002, 03:43 PM
and it works fine. Almost all turbos have the TB downstream.

'88 535is Dinan Turbo Final Edition

10-13-2002, 03:47 PM
since all turbo setups I have seen have the TB downstream in the stock location. But I read somewhere that with a roots type blower, that it is necessary to mount the TB upstream. Can anyone confirm/disprove this?

By the way, how is the KILR5ER doing?


John In Valdosta
10-13-2002, 04:34 PM
Most roots type superchargers go upstream, but I have seen centifugal SC's with the TB down stream. What did the Bird have, if the bird had a TB upstream like probably bolted to the SC the I would try to get one of those and fabricate linkage to make it work.

I found this on eBay, but even in the engine pic I cannot tell.

10-13-2002, 04:50 PM
I got the T-Bird throttle body along with the blower, but the throttle position sensors are different between the cars since the T-Bird had an MAF instead of an AFM. So if I need to mount the M30 TB upstream, I'll have to fab up a mounting plate to connect to the blower inlet pipe.


10-21-2002, 08:18 PM
Turbos only produce boost when under load, an eaton 90 would be pushing 90 cfm per revolution even at idle, (pushing alot of air not doing any usefull work) with the throttlebody downstream, (tried it with a jeep 4.0 with an eaton 62, rubber hose to throttle body looked like it was going to explode!) venting with a blow off valve would be wastefull constantly blowing alot of air, better to put throttle body in front. worked for me

10-22-2002, 03:27 AM
How much boost were you running? I would much rather try and mount an M62 on my M30, but I was thinking that to create 7psi on a larger 3.5L motor would overwork the blower. The M62, in MBZ SLK form, is a helluva lot smaller than the T-Bird M90 that I currently have and would be much easier to mount.


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