M30 throttle body flip R&D

Discussion pertaining to positive pressure E28s.
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iamcreepingdeath
Posts: 442
Joined: Dec 28, 2008 10:03 PM
Location: Mayer, MN

M30 throttle body flip R&D

Post by iamcreepingdeath »

Ladies and gents,

From my searching, it seems like it is a fairly common thing to flip the throttle body from the factory side of the M30 intake manifold to the other side of the manifold, especially in a forced induction application, to allow better intake piping routing for an intercooler. There seems to be several methods that I have seen people do, including welding the throttle body straight to the manifold, using a spacer plate that is welded to the manifold, etc. Also, E28goodies.com sells a plate kit (https://e28goodies.com/product/%d0%bc30 ... plate-kit/) that appears to be meant to be welded on to the manifold (plus a blanking plate to cover the factory opening), but I haven't found anyone with any experience with that kit.

So I am investigating different methods of doing this myself, with the possible plan to design a plate kit (or something) that can be made and sold in the US. So any input from anyone who has done this would be great.

So far, to make the fit clean and sexy, I slapped together a jig to hold the manifold level in the mill, and programed in a flat cut to set the TB on:
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Here it is with the flat and the TB air hole (pic taken before mounting bolt holes were drilled):
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So far the plan is to machine a spacer plate with thru holes, as the TB doesn't sit nicely in that milled section, as protrusions from the TB interfere with the rest of the casting of the intake manifold. I will see how it works to run bolts through the inside of the intake out thru the spacer and thru the TB and with nuts on the outside. Access to insert and hold the bolts should be easy through the factory TB opening. I plan to use lock nuts or jamb nuts, maybe with thread lock as well to prevent the nuts from backing off the bolts, but I figure the risk of a nut backing all the way off and a bolt falling into the throttle body is very small, especially with the nuts visible from the outside.
angry_ass_official
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Re: M30 throttle body flip R&D

Post by angry_ass_official »

On the right track for sure and the same solution we developed, let us know if you want to work together in some manner!

- Burro Grande
www.Angry-Ass.com
iamcreepingdeath
Posts: 442
Joined: Dec 28, 2008 10:03 PM
Location: Mayer, MN

Re: M30 throttle body flip R&D

Post by iamcreepingdeath »

So I ended up going a slightly different direction with this. After doing some test fitting, I decided (like others also have) that the stock M30 TB wasn't going to work because of the awkward throttle cable positioning. I was then inspired by another MyE28 member who used a GM LS throttle body, so I went that route. They are a dime a dozen, have a favorable throttle cable orientation, and have a built in idle control valve, so I can ditch the chunky external thing.

So I bought a spacer plate from Ebay and welded it on to my intake manifold, and so far it works out great! I haven't yet hooked up the throttle cable, I am going to have to fabricate a bracket for that.

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Painted:
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Here's how it sits in the engine bay now. Please excuse the wiring disaster. That will be a whole project on its own...
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tschultz
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Re: M30 throttle body flip R&D

Post by tschultz »

Looks great. How much bigger is the throttle body?

Any photos of the idle valve?
iamcreepingdeath
Posts: 442
Joined: Dec 28, 2008 10:03 PM
Location: Mayer, MN

Re: M30 throttle body flip R&D

Post by iamcreepingdeath »

tschultz wrote: May 16, 2023 5:37 PM Looks great. How much bigger is the throttle body?

Any photos of the idle valve?
The tb is significantly bigger than the M30 one, but not as big as the GM throttle body looks. If you google search GM LS throttle bodies (stock ones, not aftermarket), you'll see that both the throttle plate and the ICV are housed inside the throttle body.

This ebay listing for a used TB has some informative pics.
https://www.ebay.com/itm/304082513014

the idle valve is the small cylindrical thing with the 4 pin connector sticking out the side of the TB.
gadget73
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Location: New Jersey

Re: M30 throttle body flip R&D

Post by gadget73 »

another possible route, and I don't know if it would have any advantage, is Fox Mustang stuff. Those also have an idle control motor that bolts to the side of the throttle body but the mounting is just a round hole with 4 bolts around the flange. Could probably plunk one of those in the flattened space from the first pic.
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