Rb25det Gt3076r Housing Advice.....

[DiscardTheWeak]

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.....

[scotty nm35]

The manifold would be prone to cracking if you drill and tap another set of holes, T4 would be a better option with similar lag to a .82 single entry im guessing and you wont need to match port the turbo then.

[PJ.]

Go 1.06 T4 divided, you will not regret it!

[tridentt150v]

You still haven't done that mod yet, hell you must take as much time as I do to do anything. Have to stop thinking too much about things and just get in and do it. A lot of the HKS cast low mount manifolds are tapped and drilled for both T4 and T3, mine is, no ill effects at all. It it still going OK, no cracks or such. And there is enough meat in the 0.82 to get into it with grinders and shape the exhaust housing throat to the same size as the manifold so that you have a smooth entry for airflow.

You should start a poll and see how many HKS cast low mounts are tapped for T3, T4, or both - you'd be surprised.

[JonnoHR31]

yep, myne has both. but i'm gonna buy a t4 1.06 TS housing anyway for more powaaaa

on the topic, anyone know where to get these housings from at a decent price?

[wolverine]

atpturbo.com might be the best bet.

[JonnoHR31]

yer they're the only place i've found on the net so far. gonna try a few local places on monday

[discopotato03]

I think you'll find that the two ports on the turbo side flange are sized for the twin inlet T3 flanged turbine housings - if they are std . Actually what people call twin scroll T3 flange I believe is actually named "Euro T4" even though it has the same bolt pattern as single entry T3 turbine housings .

The Big T4 flange size has much larger ports than the T3/Euro T4 , some call the big T4 size T4 International pattern .

If you ever get to see the RB26 version of the HKS single cast low mount manifold you instantly notice how big its two outlet ports are . It because it was designed to have a HKS spec TA45S turbo on it and they use the T4 International flange and port size .

I'm not even sure you could port the RB20 HKS manifold out far enough to match the twin ports in the larger T4 International size footprint .

As for those twin scroll turbine housings from ATP , have a look inside them if possible because some people reckon they're a bit dodgy looking . I've no idea who makes them and no ones said they have Garrett markings on them so anyone's guess .

A .

Edited July 17, 2010 by discopotato03

[JonnoHR31]

disco, do you have any diagrams showing the dimensions of all the different flange/entry types? i've measured myne before and the ports were close enough to what was called T4 on a diagram i found. But i'm not sure i trust it

[DiscardTheWeak]

You still haven't done that mod yet, hell you must take as much time as I do to do anything. Have to stop thinking too much about things and just get in and do it. A lot of the HKS cast low mount manifolds are tapped and drilled for both T4 and T3, mine is, no ill effects at all. It it still going OK, no cracks or such. And there is enough meat in the 0.82 to get into it with grinders and shape the exhaust housing throat to the same size as the manifold so that you have a smooth entry for airflow.

You should start a poll and see how many HKS cast low mounts are tapped for T3, T4, or both - you'd be surprised.

Yeah, I am still trying to figure this out. I pretty much dropped the HX35 idea, as I really do not think it will fit down there. I am now deciding between the GT3076R and the Bord Warner S200SX. If I knew that the T4 1.06 housing was not going to be too "laggy", I would purchase it, it would save me the trouble of drilling my manifold. My engine is stock, so I will not be exceeding 425-450 whp. The S200SX seems like an interesting option as well, it is offered with a .82 T4 divided housing and is claimed to offer more than the GT3076R, not to mention it is much cheaper.............

S200SX check it out.........

[DiscardTheWeak]

Go 1.06 T4 divided, you will not regret it!

With my stock engine, and 450 whp goal, do you think this housing will be too "laggy"?

[DiscardTheWeak]

yep, myne has both. but i'm gonna buy a t4 1.06 TS housing anyway for more powaaaa

on the topic, anyone know where to get these housings from at a decent price?

What are your power goals for the engine, and is your engine built? I am in the US, so I don't know the available elsewhere, but I was quoted $1345 shipped for the GT3076R T4 divided 3" v-band. I found just the housing for $392 at this website.....

T4 didvided housing

[PJ.]

With my stock engine, and 450 whp goal, do you think this housing will be too "laggy"?

US 450whp and Aussie 450whp are two different things!

I have seen one of these make 22psi @ 4400rpm on an SR, the extra 25% capacity of the RB25 will see that sort of boost around or 3500rpm or better, with positive boost pressure way before that.

Make sure that manifold is def T4 divided.

[XRATED]

Yeah, I am still trying to figure this out. I pretty much dropped the HX35 idea, as I really do not think it will fit down there. I am now deciding between the GT3076R and the Bord Warner S200SX. If I knew that the T4 1.06 housing was not going to be too "laggy", I would purchase it, it would save me the trouble of drilling my manifold. My engine is stock, so I will not be exceeding 425-450 whp. The S200SX seems like an interesting option as well, it is offered with a .82 T4 divided housing and is claimed to offer more than the GT3076R, not to mention it is much cheaper.............

S200SX check it out.........

Check out the new precision turbo, billet range... Go a 5557 with billet comp wheel, your choise of flange and size exh housings, ceramic duel bb core etc (no need for water cooling)... they're around 1200 USD.

I have one on a stock internals 25, soon to be tuned.

Don't bother with the website, just call them direct... great guys. Or Pm me and I can get you in contact with a dealer in Fl.

Cheers

Justin

[juggernaut1]

disco, do you have any diagrams showing the dimensions of all the different flange/entry types? i've measured myne before and the ports were close enough to what was called T4 on a diagram i found. But i'm not sure i trust it

Check out the Garrett catalogue....it has the flange sizes near the back of the catalogue.

[JonnoHR31]

What are your power goals for the engine, and is your engine built? I am in the US, so I don't know the available elsewhere, but I was quoted $1345 shipped for the GT3076R T4 divided 3" v-band. I found just the housing for $392 at this website.....

T4 didvided housing

Already have a .82 IW gt30 on a standard manifolded 25. building a 30det and going hks mani so was gonna get a bigger housing with a t4 flange to suit.

Check out the Garrett catalogue....it has the flange sizes near the back of the catalogue.

thanks for that. just compared them all and my manifold is closest to T4 Divided. looks like the only difference between that and T4I is the width of the flange itself and the width of the bolt holes. Now the hardest part is figuring out exactly which flange these housings for sale on various websites have.

[DiscardTheWeak]

Do you guys think the T4 1.06 divided turbine housing is going to be "laggy" on an RB25 with bolt ons?

[JonnoHR31]

depends what you call laggy, everyone has a different idea on what is and isnt laggy. but if its similar to a .82 single scroll on a stockish 25 you should make 18-20psi by 4000rpm under decent load (4th gear). of course theres lots of other variables too, such as boost control, exhaust, tune etc

[GTScotT]

Do you guys think the T4 1.06 divided turbine housing is going to be "laggy" on an RB25 with bolt ons?

With 'bolt-ons' I believe the simple answer would be, yes.

With head work, I think the T4TS would rain on everyone's parade.

[DiscardTheWeak]

My current modifications are:

Greddy Intake manifold

Walbro fuel pump

750cc injectors

Nistune

FMIC

HKS BOV

Eboost2 boost controller

Blitz exhaust

Blitz downpipe

HKS cast manifold

Koyo radiator

FAL fans

Spec clutch

Aside from this, the engine completely stock. Mind you this is in a S14 240sx. I could deal with full boost at 4000 rpm, although I have no data to support that estimation. With the engine being stock and wanting to keep the revs reasonable, I don't want to have a "laggy" turbo without the pay off at high rpm.

With the modifications I have listed above, do you guys think around 425-50 rwhp will be attainable with a GT3076R? And at what boost level?

I think I might snoop around on the STI forums, as I think a few have using the T4 1.06 GT3076R.