Attachment of turbo to ex manifold

[paul j]

What is the purpose of a stud and 3 bolts and not 4 bolts for attachment as shown in parts and assembly books? Also parts book '89-'92 says the bolts are 10 x 80 but mine are 9 x 80 was there a change somewhere along the line? What size are the popular turbos tapped for?

 

[JNR]

Been awhile since I looked at mine, but would say using 1 stud instead of a bolt at that location is probably for clearance (i.e. not able to get a bolt in there). An M9 bolt would be extremely rare, sure that is what you have?

 

[paul j]

For sure. I bought some M10 and they would not go through ex. man. Checked old ones and they were 9 x 1.25. I checked to see if a M10 would go in the original ex. man. and it was no go. I checked and all 3 of my turbos take 9mm so I decided not to enlarge ex. man holes and rethread the turbos.

 

[JNR]

For sure. I bought some M10 and they would not go through ex. man. Checked old ones and they were 9 x 1.25. I checked to see if a M10 would go in the original ex. man. and it was no go. I checked and all 3 of my turbos take 9mm so I decided not to enlarge ex. man holes and rethread the turbos.

How strange, least you know for sure though. Is this all stock stuff, like the manifold, etc.?

 

[paul j]

Yes all stock. I thought the one on the car when I bought it was original but when I started to refresh the engine I took the turbo to a diesel truck shop and they said it was no good. I bought a new Mits one they had which turned out to be a big 16g not the 14b. I discovered this through Justin Whitesell-on dstuner- by the numbers on the turbo. I sent the one off the car and another one I had bought some time earlier to Justin to rebuild. He said the one that had been on the car was a combo -small 16g- not a 14b. He said he could make a stock 14b and a small 16g with some parts and be like new. Those and the new 16g are all 9mm threaded. The manifold I have is an aftermarket original design like the old one. A M10 will not go through them. An M10 will go through a cast Forced Performance manifold.