M42 Intake question

[InNeedOfBoost]

I did a search already, got close to my answer..but not close enough.

Every time I see an intake kit, its from the MAF forward...still using the stock intake pipe between the TB and MAF.

Noticed the other day that tube is cracked..rather not replace it with another stock rubber pipe and just upgrade to hard piping. Is there a replacement for the tube? That odd shaped TB makes it difficult to find anything that fits.

[gearheadE30]

There's a company that makes a silicone boot that is a direct fit but I remember it being stupid expensive (like $180 or something) and I don't remember the company. You can also get a 90 degree elbow reducer from Siliconeintakes.com, and that will run about $40 iirc. The TB side is 3.5" diameter I believe, but since I don't have an AFM, I don't really know what that diameter is.

There's not really anything wrong with the rubber, though. A new one will last you another decade, and it will fit better. That boot certainly doesn't represent a flow restriction.

[Dj Buttchug]

its 3.5 to 2.5. Siliconintakes.com

[InNeedOfBoost]

Thanks for the info guys. If I have no luck with fitting something else, I'll just suck it up and buy another rubber one. Just don't want to buy used cause more then likely, the same thing will happen again.

Other question though, will it still work since the TB is an oval shape?

[AndrewBird]

Yes, it will work. It just flexes around the throttle body.

A new stock boot is only $25 though.

https://www.bmaparts.com/ShopByVehicle.epc?q=&makeid=bmw%40%40BMW&yearid=1991%40%401991&modelid=318is%40%40318is&pttypeid=fuel-injection-air-flow-meter-boot@@Fuel%20Injection%20Air%20Flow%20Meter%20Boot&mode=PA

[InNeedOfBoost]

Ah ok.

Thanks again

[InNeedOfBoost]

So I went ahead and got the silicone 90*. I forgot the stock intake has the fitting for the hose that goes to the IAC.

I tried putting a breather filter on a shortened piece of hose leading to the IAC but it wouldn't hold idle. The breather sounded like a massive vacuum leak.

Question, how do you use the silicon coupler without having that hose running to it?

[oldmann]

The hose running to it is required for idle control. It is a massive vac. leak not hooked into the boot.
Make yourself a hard fitting to fit into the silicone boot for the ICV to hook up to.