Changed from TA49 .63 to PT6466 .85 4" S cover and having 3" THDP clearance issues

jasjamz

THS Racer
Sep 30, 2004
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I bet its due the the mount placing the engine around an inch higher than stock. Put a stock mount on the passenger side.

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Mike T

Well-Known Member
May 3, 2013
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If the DP is adjusted all the way down at the turbine housing you can loosening the two long motor mount bolts and roll the whole motor over a little bit.
 

Pronto

Chaos is a ladder.
Dec 9, 2002
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Have you tried loosening all the bolts on the downpipe and turbo mount? Sometimes you ca get a little clearance moving them around while loose.
 
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tminer

Not quite normal
The whole thing was a pain to put back together with the new turbo. I fudged it every way that I could just to get the downpipe bolts in. Exhaust hookup was part of the equation so I'm going back at it without exhaust and then do what I need to it to compensate.

But looks like my main question was answered in that the change of turbo should not be an issue. Wanted to get that out of the way first.

Thanks.
 

Pronto

Chaos is a ladder.
Dec 9, 2002
11,850
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Oh, don't get the rest of the exhaust involved until you get the downpipe situated. I ended up with a small flex pipe in the test pipe spot.
 

tminer

Not quite normal
Turns out that there was a small difference in the hole to hole distances. Also my new cap screws have a slightly larger diameter. I drilled out the 8.75mm holes to 10mm. Now getting .115 clearance and puck position is good. Think that's enough? Could get a little more if I remove header to turbo gasket or could put a piece of Helix insulation in there.
 

Ttype6

Well-Known Member
Aug 17, 2004
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Fini! Took out gasket and tightened up everything at most favorable position. Got it to point I can slide a piece of 1/4-20 all thread thru with slight budging. Good enough for who it's for!
I cured my fitment issue by drilling the downpipe mounting holes to the next sae size. A little bit of movement at the turbo adds up to a lot of movement at the hvac box.
 

Ttype6

Well-Known Member
Aug 17, 2004
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Yes. You just need to double check the puck alignment.
Since the turbo is new and the wastegate hole is un-ported,it should work out ok. I typically drive the car with the un-ported turbo then remove the downpipe to see the evidence mark from the puck.
 

RUQWKNF

KEEPER OF SECRETS
Staff member
May 26, 2001
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NEED TO KNOW BASIS
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One things for sure, going from a TA-49 to a PT6466 with a THDP, you have a lot of wastegate hole porting, contouring and blending ahead of you. Should be around the 1.15" mark. You won't have any boost control with the stock as cast hole size. It will creep and not stop so be ready to get out of it quick. Don't forget to smooth the transition on the inside of the housing where the hole starts. Give the exhaust a smooth transition into that hole, vs a sharp 90° turn.
Hope this helps.

-Patrick-
 
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Ttype6

Well-Known Member
Aug 17, 2004
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One things for sure, going from a TA-49 to a PT6466 with a THDP, you have a lot of wastegate hole porting, contouring and blending ahead of you.
I see many in this community who never ring out their current turbo and switch to a bigger one in search of more power. The bigger turbo now has to blow through the same restrictive engine as the smaller turbo did. Now the new problem is the inability to run lower boost numbers. Then modifications are done to allow lower boost. There is another way to fix the problem and that is to run more boost.
 
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