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Thread: T28/T25 Downpipe Question..

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2009-07-04 14:02:52
T28/T25 Downpipe Question..

I am still a little confused about the differences between a T25 downpipe and a T28 downpipe.

Is it true that the T25 downpipe is for the Avenir/Bluebird manifold and the T28 is for the GTiR?

So basically it doesn't matter what turbo you are using, only the manifold? You could be using a T28 turbo on a Bluebird/Avenir manifold and you'd want to get the T25 downpipe, right?

What are the differences between the two downpipes?

2009-07-04 14:29:58
I don't have any direct experience with this, but assuming the J-pipes for both turbos are identical in their routing, then the only difference is in the manifold and where it places the turbo, and thus, where the outlet of the J-pipe will be. So I'm going to agree with you, and say that it doesn't matter which T2 turbo you have, just which manifold you have.

Someone else will probably have a better answer for you soon.
2009-07-04 15:24:19
It's mainly matter what j-pipe (O2 housing) you are using. The 3 bolt flange is rotated in a different position from T25 to T28.
2009-07-04 15:59:38
usually the t28 and the t25 use the same downpipe. the 02 housing is the same on both turbos. unless you got some custome setup
2009-07-04 16:37:30
Originally Posted by jen36
the 02 housing is the same on both turbos.
That's not what I've heard. Also, it doesn't make sense that they are the same. The T25 and T28 5-bolt patterns are different (I think so a Nissan tech won't install a T25 turbo on a T28 car by accident/mistake). So that at least is different.
2009-07-04 16:46:10
GTIR 02 housing 3 bolt outlet is at a different angle over the T25 setup.

if you have a T28 j pipe get a T28 down pipe. if you have a T25 j pipe use a T25 downpipe.

manifold doesn't change much unless it's a VET manifold.
2009-07-04 16:51:31
What keo said. If you try using a t28 downpipe on a t25 o2 housing the downpipe will be facing out the pass side of the car rather than down the moddle.
2009-07-04 16:53:20
x2 what keo n II said. i learned it the hard way.
2009-07-04 17:56:08
on my first turbo set up i was using a t25 with a 3 inch dp then i got a t28 and i used the same 02 housing and DP and i didnt have any issues???
2009-07-04 18:22:56
yes becuse you retained the same o2 housing so technically nothing changed as far as the downpipe is concered.

Had you changed to a t28 o2 housing, or the opposite of what you have now the downpipe would have to be changed as well. Or at least cut off the flange turn it and re weld it.

I used my t25 o2 housing and 2.5" downpipe through out most of my builds, t25, t25/28, gt2871r. then i bought a t28 3" downpipe and realised it wouldnt work.
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