RB25DET GT3076R housing advice.....

[doyle4281]

Question:
Should I drill and tap T3 holes in my T4 manifold and use a GT3076R T3 Divided .78, .82 housing or......Keep the T4 flange and use GT3076R T4 Divided 1.06 housing?

Question:
How much loss in spool time do you think the T4 1.06 will actually cause?

Details:
I am in the process of upgrading the turbo on my RB25. Last year I purchased an HKS cast low mount manifold without knowing it had a T4 flange. I have been told it is possible to drill and tap for a T3 turbo, however I am hesitant to do so. I feel that the large T4 manifold outlet flange, will cause harmeful turbuelnce when exhaust is trying to enter to the smaller T3 turbo inlet. I may just be over estimating how sensitive the magic that is happening in the manifold. I am hesitant to order the T4 1.06 because I think spool times will be negatively affected.

Aside from a Greddy manifold, full exhaust, injectors, front mount, fuel pump, esc. The engine is stock.....

Any help would be appreciated.....

[doyle4281]

Any ideas.......

[eklips3]

i think you should buy a manifold that has a t3 flange. Just for the same reason that people port match intake manifolds and exhaust manifolds.

[doyle4281]

I was considering purchasing a top mount manifold, and use my HX35, however I can't seem to find a reasonably priced quality manifold. With all the chinese junk out there you never know what you are actually getting. The manifolds I have seen are either $200 or over $1000. If I could find a mid range T3 divided top mount manifold that I didn't have to hack apart to fit, I would go that route.

[mrflip69]

If you have room, they have T3/T4 adapters that taper.

[doyle4281]

There is absolutely no spare room.....

[fliprayzin240sx]

Personally, I'd just retap it to a T3. Then if you're worried about the flow, you can smooth down the turbine inlet to take out the sharp edge to lessen the turbulence.

[lazysk8er2]

Keep the T4 flange and use GT3076R T4 Divided 1.06 housing

it will be laggy but with a finely tuned head and a good ecu tune should bring down spool time and will have power all the way to redline.

[ross.cottrill]

dont retap it,just reflange it,that way you have no "step"to deal with.im not so sure id use that housing if it wasnt used on a twinscroll manifold.if i were you ,id give goeff a call at full-race,he will point you in the right direction as he has an abundance of knowledge in this field..goodluck sir..

[doyle4281]

How much more "laggy" do you think T4 1.06 will be as opposed to a T3 .86? The manifold is twin scroll. I was also considering retapping ad port matching the turbo to the T4 manifold. I have set Geoff at Full-race, I am awaiting a response.

Does anyone have any results with the T4 1.06 on any other car?