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My big ticket issue w/ 16T on 90+ manifold fitment (help)

89_740Turbo

New member
Joined
Apr 10, 2018
Location
Central New Jersey
My buddy and I are in the process of swapping a 16T onto my 740 using the 90+ manifold. This will be the last big performance upgrade to the car while I save up for a better transmission to swap in so I can run a fat a** turbo in the future.

This is our big ticket issue: The 16T will sit flat on the manifold, but one of the 4 which hold everything together hits the portion of the manifold where exhaust #4 bends upwards into the exhaust outlet housing. It wont allow a nut to fit between the bolt and the housing for us to tighten.

Here is picture so you can visually see what I am talking about where the figure in black is the manifold and the red is the bolt. The bolt cant squeeze in enough to be able to get a wrench or something around it to tighten. It cant fit in at all.

wut do

6hsl.png
 
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So you're saying the stud from the manifold is too long so it hits the turbo? Just cut it short then?
 
So you're saying the stud from the manifold is too long so it hits the turbo? Just cut it short then?

We already did that.

What I'm saying is the curvature of the manifold will not allow a bolt to line up so we can twist it to tighten it. That's our issue. We trimmed a small bit away from the manifold itself but that still doesn't give enough clearance and we don't want to cut any more
 
I don?t get it sorry. Are you using bolts to fix the turbo to the manifold? There should be studs in the manifold and you just use nuts to tighten the turbo..
 
I'm using the studs in the manifold but the studs, even when twisted all the way into the turbine housing, still sit so far down against the exhaust that I cant fit a bolt between the stud and exhaust housing to twist onto the stud.

I have to take pictures when I get out of work on Saturday.
 
This is an ugly 90+ manifold with factory studs and nuts sticking out (click for full size):


This is a 15G turbo. You need to remove the 2 studs and drill out the threaded holes slightly so that you can use all 4 studs on the manifold (and even then, you'll need to thread on the top-rear nut before seating the turbo)


Does this help explain your issue? Your original post is confusing because a bolt is not the same as a stud.
 
Pull the turbo back on the threads then start putting the nut on then push turbo forward and tighten
 
The manifold studs should just pass through the turbine housing holes and be secured with a nut. Not sure why you'd want to twist anything on.

The manifold studs do, and we drilled them out to make them larger. The issue is that that once everything is in place, there is no room to stick a nut underneath the manifold stud because the manifold's curve wont allow a nut to squeeze in.

The curvature of the housing prevents a nut from fitting between the manifold and the manifold stud. That's the issue we are having. How to fit a nut in there
 
The manifold studs do, and we drilled them out to make them larger. The issue is that that once everything is in place, there is no room to stick a nut underneath the manifold stud because the manifold's curve wont allow a nut to squeeze in.

The curvature of the housing prevents a nut from fitting between the manifold and the manifold stud. That's the issue we are having. How to fit a nut in there

Should not be a need for a nut behind the manifold. Maybe I'm confused.
 
Pull the turbo back on the threads then start putting the nut on then push turbo forward and tighten

Bingo

I may have used ever so slightly shorter studs on my manifold. If I can remember, I'll go out to the garage and photograph+measure the manifold outlet studs with 16T loosely attached for plumbing mockup purposes
 
I think OP drilled out the stud on the manifold and not the one on the turbine housing and is trying to fit a nut in the red circle:
IZT4gNoh.jpg


Well, thats what i'm getting from this, i may be wrong
 
If the stud hole in the manifold has been enlarged. You can use a stepped stud so the hole in the manifold can be 10mm thread and the other end of the stud will be 8mm to match up to the turbo.
 
I think OP drilled out the stud on the manifold and not the one on the turbine housing and is trying to fit a nut in the red circle:
IZT4gNoh.jpg


Well, thats what i'm getting from this, i may be wrong

The red circle is supposed to be the nut and shows where we are getting interference. The part where the red overlaps the exhaust
 
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