Thread: T28/T25 Downpipe Question..

i'm still trying to figure out the difference with the BB and avenir manifolds..

fwiu, the avenir manifold is curved like the GTiR and doesn't need grinding for a T28 to fit. Never seen it in person or in pics though, only what I've read.

Sorry, I had that mixed up. So the BB fits with grinding and the Avenir just fits?



Bluebird:








Avenir (big hump):

thanks swiss. the difference is quite obvious. but i thought it was the avenir with that hump that made it hard to fit the t28?

yeah my friend gave me his w11 manifold shield and it didnt fit the BB manifold and i thought it was odd because i thought they were the same, so is one manifold better then another because of design?

Like I said, the only benefit I have heard is that the Avenir manifold let's you fit a T28 without shaving the block.

Heres how it goes and what causes the fitment problems.

The GTi-R T28 turbine housing and the S13 Silvia T25 turbine housing have a slightly different casting with reguards to bolt pattern this is why the Gti-R and the S13 Silvia use the same turbine housing gaskets. This is also the reason the GTi-R o2 housing doesn't fit the Bluebird/Avenir turbine housings without modification.


Bluebird/Avenir/GTi-R, o2 hosuing interchangability - SR20 Forum

Some people swear that there interchangle but they really dont even know is they have a real GTi-R o2 housing, its very easy to tell the difference but some people cant still.

I have a disco potato on an avenir and I had to grind the block a little but. Nothing major.

T25 Avenir/Bluebird turbine housing


T25 S13 Silvia turbine housing, this is also the same exact bolt pattern as the GTi-R turbine housing granted the turbine housing is larger on a T28.

This picture is of a GTi-R o2 housing on a Avenir/Bluebird Turbine housing.

Notice the misalignment: