2G Need help deciding if I should go T3 or not.

[Highzenberg]

Hello everyone,,
So here is the deal. I'm running a GT35R with a .55 A/R BEP housing that was originally for a a T31 style turbine wheel. I had it machines to fit the 35R. I knows it's restriction to the turbo and it's killing my airflow. Now I'm having a hard time deciding if to:

1. Go full T3. T3 manifold, turbine housing, the whole works.

Or

2. Go with an FP35 style housing and FP manifold

Money wise it's more or less the same cost, so lets not talk about it. The motor is stock with the exception of cams basically 100001.onl/ 1921681254.mx/ acc.onl/hotmail. I will eventually build it.

My two cents is, I think option 2 should give me slightly better midrange power and powerband overall, and still make really good power when I build the motor and let it rip. just wondering if T3 is really worth it over an FP30 style setup.

Let me know guys, thanks in advance!

 

[92AWDHX40]

Depends on goals im doing a built engine, now I have a hx40 in a bep,, but will be getting a morrison t3 setup down the road. The bep can be restrictrive and I plan on having my turbo happy.

 

[Vegas Smith]

Hello everyone,,
So here is the deal. I'm running a GT35R with a .55 A/R BEP housing that was originally for a a T31 style turbine wheel. I had it machines to fit the 35R. I knows it's restriction to the turbo and it's killing my airflow. Now I'm having a hard time deciding if to:

1. Go full T3. T3 manifold, turbine housing, the whole works.

Or

2. Go with an FP35 style housing and FP manifold

Money wise it's more or less the same cost, so lets not talk about it. The motor is stock with the exception of cams basically. I will eventually build it.

My two cents is, I think option 2 should give me slightly better midrange power and powerband overall, and still make really good power when I build the motor and let it rip. just wondering if T3 is really worth it over an FP30 style setup.

Let me know guys, thanks in advance!

You're going to have a lot of trouble finding an fp35 housing. I have one and probably won't sell it but I know they're hard to find.

 

[1990TSIAWDTALON]

The T3 or T4 flange gives you options that are not specifically DSM flanged so you can pick and choose what size and type of turbo instead of having to use a DSM flanged unit. I think it allows more flexibility.

 

[RWD4G63]

Buy one of these:
https://www.atpturbo.com/mm5/mercha...e=ATP-HSG-391&Category_Code=GTHGT35-T3divided

and one of these:
http://morrisonfabrications.com/product/dsm-twin-scroll-t3/

And have the best of both worlds. Great spool and flow. It will probably respond faster than your current setup.

A general idea to remember is that the turbine itself is always the biggest restriction. Is the tiny .55 housing a restriction? Yes, but if you're not pushing the turbo to it's limit, it's not as big of a deal.

 

[1990TSIAWDTALON]

My son runs the twin scroll @MorrisonFab T3 with a Holset HX35 and it ran 11.5s right off the trailer. He credits that TS manifold for early spool and wonderful flow. That's our experience. He has the timeslip
He is running the factory Holset hot side too. 14cm I think but it might be different.

 

[MorrisonFab]

We also have a hard time deciding on setups, as many work well and just need to be matched to your personal goals

Here are some of our thoughts about each to hopefully help match your needs and wants out of it-

On a 4 cylinder, essentially any divided setup will have more midrange and better response, even when compared to a bolt on housing/setup with a small AR. For example, an hx35 in the factory 12cm^2 housing and proper divided T3 manifold with both out-spool AND outflow one in the .55 bolt on BEP housing. A win-win in that case, with more upfront cost.
Also, the way a divided setup picks up that extra spool through increasing VE and airflow at the same boost and rpm, it shouldn’t be as likely for compressor surge during low rpm spool up to be an unwanted side effect, as it is ingesting the airflow rather than necking down more at the turbine housing to gain spool with the small AR example.
We would, however, be a little hesitant with that .78 AR ATP divided T3 turbine housing listed. You usually want to size up the AR on a divided turbine housing as each exhaust pulse only sees half the AR at a time. The rule of thumb is something like it wanting/needing 30% more AR for a divided turbine housing vs a comparable open turbine housing. Many years ago a lot of folks had a bad impression of anything divided T3 and it seemed to stem from undersized AR options being all that were available at the time for GT35's especially. Divided T4 will likely open up your options considerably for AR sizing and any future turbo options (divided options T3 are slim). The larger flange footprint allows a higher flow potential (divided T3 is less tested/known for where it is comfortable power/flow wise) and each inlet is still well sized where spool/response will still be very comparable and is easy to merge into.

Even disregarding a divided setup, there is still plenty of merit in going with an open T3 setup vs the bolt on route. One is of course easy access to larger AR and other higher flowing/potential turbo options, but another overlooked one is a proper merge collector and a manifold with more overall design freedom (not constrained between the stock flanges). Cast manifolds can work well, and the FP does a really nice job in the collector area for what it has to work with, but they still tend to have the runners pointed more or less at each other than towards the turbine inlet- requiring sharp changes in direction to get where they need to go. Just part of the side effect to being so compact and the factory placement. The factory manifold is a glaring example with runners 1 and 4 pointed almost directly at each other. What this means is that scavenging is dismal and the exhaust can easily travel up another runner rather than into the turbo.

Most T3, T4, v-band, etc manifolds will be able to utilize better angles of entry and a proper merge collector which can greatly improve scavenging during overlap- with a much more measurable affect and over a much larger rpm range than we imagined after some recent testing. That increase in VE is also an increase in airflow, and it can have the same effect as increasing displacement when it comes to spool up and power per psi characteristics. So, even though most tubular manifolds have a larger volume for each pulse to expand into (vs cast) and a generally larger AR turbine housing attached to it, both of which tend to slow spool, being able to generate extra airflow sooner can often offset that AND make more power without needing as much boost to do so. All win-win… with more upfront cost. Runner size can often be played with to your advantage there as well.

 

[JusMX141]

My own personal rule of thumb...any realistic power goal above 500whp with modern turbo choices = go T3 or small v-band and never look back. With all the lightweight v-band turbine housings on the market from Xona/FP and Precision there are even more setup choices than old-school universal T3. The old FP30/31/35 housing series is basically the same a modern v-band housing that just happens to fit a DSM-flanged manifold. If you can find one, they're pretty nice...around .68 a/r and will be a major flow improvement over the .55 Bullseye housing but still not really as good as .82 T3 which is where the 35R series wants to be.

But for power goal above 500whp on a stock-fitment turbo, your new turbo choices are quite limited over what was available a decade or so ago unless it's a custom build using back-dated housings. Currently there's the FP Red and FP Black, and that's about it.