Gt42-76r

[Inhaler]

Thinking of putting this turbo on a 250ci 109.
What should I ask 4 as far as heads and flow #s
What size down pipe would I need.
TIA

[six slinger]

dont have any experience with this turbo,but think at least 3.5" downpipe. and definetly ported aftermarket heads gn1, t/a ,gn1r etc!!

[Ted A.]

Originally Posted by Inhaler

Thinking of putting this turbo on a 250ci 109.
What should I ask 4 as far as heads and flow #s
What size down pipe would I need.
TIA

4" out. You could transition it down to a 3.5 and I'm sure it would work just fine.

[Eticket]

The outlet on the turbo is about 3.25" if I can remember correctly.. a 3.5" dp is a natural size for that.. and that's the v-band coupler that you can buy from precision for this turbo.

I would say that this turbo is too big for 109 motor. The big compressor wheel would make it tougher to spool - not that it can't be done. A GT4294r (70mm version) would get the job done and you'd get the gains from the big exhaust housing still. It would make more power than the 70HPQ/GTQ variants, and it would come on sooner in the boost range.

Big negative about using this turbo or any of the GT64x's is all of the custom fab you have to do to get it to work and making the turbo inlet kind of sucks.

One that you might want to consider is the GT4094R.. maybe they can make that in a 70mm version. It's a 68mm turbo rate at 850hp.

[Red C5]

Where's John Wilde when you need him??

[John Wilde]

Originally Posted by Red C5

Where's John Wilde when you need him??

At home watching Blade Runner on Blue Ray with my wife.

[tom j]

I spool this turbo with 256cu, but with stock heads. 4 inch dp that tapers down to 3.5. I was surprised how well it spools for such a large turbo. You will have have to do some screwing around to get it to fit. The pic below is just mocking it up it's on now a little different than this pic

[Trbobuick]

Originally Posted by Inhaler

Thinking of putting this turbo on a 250ci 109.
What should I ask 4 as far as heads and flow #s
What size down pipe would I need.
TIA

Thats a LOT of turbo for a 109 block IMO.

[RUQWKNF]

With the right converter and motor combo, this turbo works excellent. A stroker 109 is just begging for this turbo. Cal Hartline did alot of testing with this turbo a few years ago with excellent results. It is available with 4 different turbine housings and with larger CI of a stroker motor, you can use the 1.28 A/R housing. The 1.44 A/R housing would be for 278+ CI motors. This would be for dual bb versions of this turbo only as the journal bearing version would be very laggy with any housing over the 1.01.
Here is the link to the base model used to make a GT4276R.

TurboByGarrett.com - Catalog

The comp map is not correct for the GT4276R, as PTE adds the 76mm compressor wheel to the GT4202R turbo to make it a GT4276R.
Hope this helps a little.


Patrick

[SGRIM]

Originally Posted by RUQWKNF

With the right converter and motor combo, this turbo works excellent. A stroker 109 is just begging for this turbo. Cal Hartline did alot of testing with this turbo a few years ago with excellent results. It is available with 4 different turbine housings and with larger CI of a stroker motor, you can use the 1.28 A/R housing. The 1.44 A/R housing would be for 278+ CI motors. This would be for dual bb versions of this turbo only as the journal bearing version would be very laggy with any housing over the 1.01.
Here is the link to the base model used to make a GT4276R.

TurboByGarrett.com - Catalog

The comp map is not correct for the GT4276R, as PTE adds the 76mm compressor wheel to the GT4202R turbo to make it a GT4276R.
Hope this helps a little.


Patrick

Man you are good!!!

[John Wilde]

Originally Posted by RUQWKNF

With the right converter and motor combo, this turbo works excellent. A stroker 109 is just begging for this turbo. Cal Hartline did alot of testing with this turbo a few years ago with excellent results. It is available with 4 different turbine housings and with larger CI of a stroker motor, you can use the 1.28 A/R housing. The 1.44 A/R housing would be for 278+ CI motors. This would be for dual bb versions of this turbo only as the journal bearing version would be very laggy with any housing over the 1.01.
Here is the link to the base model used to make a GT4276R.

TurboByGarrett.com - Catalog

The comp map is not correct for the GT4276R, as PTE adds the 76mm compressor wheel to the GT4202R turbo to make it a GT4276R.
Hope this helps a little.


Patrick

Patrick's answer = end of thread!

[Inhaler]

Thanks all.

Patrick what heads should I run with this turbo?
What CFM?

[Inhaler]

Eticket I meet you at donnys shop before.
Had the blue t-type.
Waiting until the divorce is over before I let Bill Duke Finish the car.

[RUQWKNF]

Aww shucks guys....
I just try to help when I can.


To answer your question Inhaler, at certain power levels, the GN-1 heads will suffice, but if it were me, and I was going to max that turbo out, I would be running a set of TA Performance race heads. That's just my oppinion tho. I ran converted 8-bolt to 14 bolt GN-1s on my 274 Stage II, into the 10.00 - 9.90 range with no issues. The cfm rating is going to vary, from engine builder to engine builder, so I'd recommend you talk to a reputable engine builder who knows about Buick V6 turbo combos. Give Dan at DLS Engine Development a call for the TA Performance heads. He's been perfecting these combos for the last 15 years. Here is the link to his site. Home

Hope this helps.

Patrick

[Inhaler]

Thanks. Will give him a call monday.

[Eticket]

Inhaler... don't remember your name or a blue car.. sorry man. Which time did we meet? Was Donnie and I working on my car? or just BSing?

How fast are you trying to go anyway?

I have to say, I'm a firm believer in using the biggest turbo "that you can use" on a combo... but I think this is still too big - and not worth the effort for a 109 motored car. Unless you are trying to set a record or split a block in 1/2. - you're committing to doing a bunch of fab work vs. a bolt on 70HPQ and about $1000 difference in the cost of a turbo alone. non bb vs gt42xxr.

Believer me, I've contemplated the GT4294r for a LONG time on my personal 109 motored car.. but I do remember the effort it was to change over to that big housing, I know it's tough to do. Maybe I'm real picky compared to most.

If you can do your own fab work, or can get it done cheap.. go for it. If not.. then plan on spending some $ and time to get it fitted to your car.