Garrett GTX3076R BB Turbo?

[911TT33]

Hi guys,

Anyone here tried one of the new generation GTX3076R ball bearing turbo's?

I'm told they flow as much power as a GT35R (~625HP) but the spool characteristics are similar to a GT30R.

Should make a very nice daily street turbo with great top end power too

Thinking of taking this path with a 3.4L 8.0:1 upgrade on my EFI'd setup.

Anyone?

[quattrorunner]

I have one. I like it but can't compare to anything as It's the first turbo I've had with this engine.
I have a 76 3.0turbo 930 engine. It spools, but not quite as fast as I expected. I have the euro heat exchangers and expect thats my issue but full boost of .8bar is realized by about 3200 rpm.
It does push very hard to 6000 rpm (sc cams).

[911TT33]

Originally Posted by quattrorunner

I have one. I like it but can't compare to anything as It's the first turbo I've had with this engine.
I have a 76 3.0turbo 930 engine. It spools, but not quite as fast as I expected. I have the euro heat exchangers and expect thats my issue but full boost of .8bar is realized by about 3200 rpm.
It does push very hard to 6000 rpm (sc cams).

Thanks for the feedback.

Yeah you would get better boost response with a good set of aftermarket headers and free flowing exhaust.

Perhaps a GTX3071R would have suited your motor better? It can supposedly still flow up around 525HP which is plenty for street.

Curious, who makes a good header system with a quality merge collector for a twin scroll housing turbo? Apparently a twin scroll inlet is suppose to be more responsive than an open inlet turbo.

Comments?

[TurboKraft]

This GT30R question comes up frequently.

Simply put, the turbine wheel is too small for a 3.3L engine, and a little big for most built up air-cooled 911 twin turbos. It is a good turbo for 3.0L Turbos, though.

If your power goals are very modest, and you have stock cams -- great. Your engine probably doesn't flow much anyway and you won't find the turbine side restrictive in the camshafts' limited rpm band.

If you have the usual 930 upgrades -- headers, muffler, intercooler, boost, cams -- then the turbine is a limiter. Ex: a 3.6 Turbo with EFI that should have done an easy 520whp on pump gas at 1bar was limited to 480hp, and had much less midrange torque, thanks to the existing GT30-based turbo the client didn't want to change.

Backpressure.
It is your enemy.

[911TT33]

Originally Posted by TurboKraft

This GT30R question comes up frequently.

Simply put, the turbine wheel is too small for a 3.3L engine, and a little big for most built up air-cooled 911 twin turbos. It is a good turbo for 3.0L Turbos, though.

If your power goals are very modest, and you have stock cams -- great. Your engine probably doesn't flow much anyway and you won't find the turbine side restrictive in the camshafts' limited rpm band.

If you have the usual 930 upgrades -- headers, muffler, intercooler, boost, cams -- then the turbine is a limiter. Ex: a 3.6 Turbo with EFI that should have done an easy 520whp on pump gas at 1bar was limited to 480hp, and had much less midrange torque, thanks to the existing GT30-based turbo the client didn't want to change.

Backpressure.
It is your enemy.

Thanks for tuning in, Chris. I tried to PM you privately on this exact topic but your inbox was full

Just out of curiosity, what would spool faster and feel more responsive on a 3.3L/3.4L EFI EVO CAM'd motor:

- A single GTX3076R / GT35R @ 0.82A/R vs
- A pair of twin GT28RS turbo's @ 0.63 A/R ?

[TurboKraft]

Yes, mailbox was full, but emptied now.

Spools faster or more responsive... it depends. There's just not enough information given.
3.3L or 3.4L?
Compression ratio?
Port sizes, and flow -- quality of the work?
Header sizes, primary & secondary? Twin scroll?
CIS or EFI?

You can pretty much rule out the GT30R-series turbos unless you want to power to flatten off at 5,000rpm.
The other 2 options -- GT35R and twin GT28R-series -- are dependent upon the above.
Yes, you can build a single turbo 930 engine with the response and broad torque band of a twin turbo.


But since your moniker is 911TT33, you are required to use the GT2860RS turbos. ;-)

[speeed racr]

turbokraft, which do you recommend about a pair of 3071r's or 3076r 0r gt35r on a 993 3.8 liter twin turbo, 7.5 cr with gt2 evo cams, headers and exhaust. thanks..

[TurboKraft]

speeed racr,

Both turbos are good, it just depends on what you're after.

Those engine specs are real similar to the black 1994 Turbo we built, the "TX UFO" (1994 Porsche Twin Turbo 3.8L | Marc, sorry about the broken thumbnails, we're working on it...)

That engine first did 560hp on an engine dyno as a 3.6TT with GT28R turbos. The turbos came on super fat but flat lined before 5,000rpm -- too small.

Then it got some larger custom-spec GT28R turbos and did over 700hp flywheel, eventually getting tuned to 645rwhp on 100-octane before it ran out of compressor flow. The midrange torque was the real killer, however -- from rolling starts, there were few cars on the road that could touch it. It ate up cars that ran 10.5 in the quarter.

It was later rebuilt as a 3.8L (got the very first set of Nickie 911 cylinders) and the subsequent owner wanted "more," even if it cost a little midrange torque. GT3071R turbos offered barely more top end, and robbed the midrange. GT30R turbos took it from 645rwhp to 752rwhp, but strong compressor surge was a problem despite having large external wastegates, 3" twin exhausts, and ported shroud compressor housings.

The best all-around for street? A set of our GT28R turbos. We used them on Avi's 3.8L 964 Biturbo, too -- engine dyno results here: Dynos.jpg Check out the torque at 3,000rpm. That car is crazy quick.

[quattrorunner]

Awesome!
As a side question, and sorry for a hijack but Chris, is it possible to give an opinion as to wether you like power from single or twin turbos better? Is it a simple enough question to ask or am I silly to have posed this question?
Looking at Toms car, with the simplicity of intake routing compared to twin, and his power levels achieved, what do you like better?

[TurboKraft]

If building the engine from the crank up, I'd do a strong single turbo. Pick the right combination of pieces, and you can end up with the midrange of a twin turbo, and the simplicity of a single turbo.

Probably the best all-around driveable single turbo we ever built: Yung's 1994 Turbo 3.6.
More torque at 3.000rpm than a 993 Turbo with ECU+exhaust+K16hybrids: Dyno results, before-and-after: Torque, Horsepower
Over 510ft.lb. and 520hp at the wheels on pump gas.

Who wouldn't be happy with that?!? :-)

[spence88mph]

The headers / exchangers on Yung's 1994 Turbo 3.6. look awesome, did you make them? Says "Installation of custom EFI-T camshafts, ceramic-coated stainless headers..."

[911TT33]

Originally Posted by TurboKraft

If building the engine from the crank up, I'd do a strong single turbo. Pick the right combination of pieces, and you can end up with the midrange of a twin turbo, and the simplicity of a single turbo.

Probably the best all-around driveable single turbo we ever built: Yung's 1994 Turbo 3.6.
More torque at 3.000rpm than a 993 Turbo with ECU+exhaust+K16hybrids: Dyno results, before-and-after: Torque, Horsepower
Over 510ft.lb. and 520hp at the wheels on pump gas.

Who wouldn't be happy with that?!? :-)

That's the reason for my original post. Would a GTX3076R turbo be suitabe for a "strong single turbo" for pure street? It has the flow of the GT35R with the spool characteristics of the GT30R. I assume that would be a great combination for a street turbo.

In terms of engine specs, I'm thinking something along the lines of a 3.4L Carrera base motor, running 8.0:1 C/R, Programmable EFI, GT2 EVO CAMs, FabSpeed Headers + Dual Out 3" Exhaust running 1.2bar of boost on pump gas.

[WERK I]

911tt33,
That turbo has too small a turbine. You're adding GT2 Evo cams in a turbo'd engine that will choke you with back pressure on the top end(not good). If you insist on the GTX30776R turbo, go with shorter duration cams.
I also think you may be undersizing your headers with the FabSpeed units. Anyone can chime in here, but with the size of those primaries, they may be too small for the 3.2 exhaust ports? I love the 3.2 engines. Those heads flow really well. Just think there may be issues with port mismatch to primaries.

[TurboKraft]

Originally Posted by spence88mph

The headers / exchangers on Yung's 1994 Turbo 3.6. look awesome, did you make them? Says "Installation of custom EFI-T camshafts, ceramic-coated stainless headers..."

Hi, those were built to spec by B&B, then ceramic coated by a little specialty shop that does outstanding work on exhaust coatings.

Say what you want about B&B exhaust -- real mixed results from their mufflers, yes -- but we've found their Turbo headers work better than other off-the-shelf Turbo headers.

[TurboKraft]

Originally Posted by WERK I

911tt33,
That turbo has too small a turbine. You're adding GT2 Evo cams in a turbo'd engine that will choke you with back pressure on the top end(not good). If you insist on the GTX30776R turbo, go with shorter duration cams.
I also think you may be undersizing your headers with the FabSpeed units. Anyone can chime in here, but with the size of those primaries, they may be too small for the 3.2 exhaust ports? I love the 3.2 engines. Those heads flow really well. Just think there may be issues with port mismatch to primaries.

Yeah, that's turning into a hodge podge of mis-matched parts.

Fabspeed headers are too small. They're fine for a really mild CIS engine with small cams; not right for a deep breathing engine with Carrera heads and GT2 cams.

Your choice of cams, heads, displacement and compression should be determining the header's size and turbine size. Those GT2 cams have decent lift and duration, with a narrow lobe angle (some overlap). They hate backpressure. If you want them to work and take advantage of the Carrera heads' 41mm exhaust ports, don't think so small. In this case, bigger is better.

[911TT33]

Ok, thanks for the tips guys. At least now I have some direction

So, I'm assuming you recommend sticking with headers that have 1 5/8" primaries to suit the Carrera heads ?

[JBurer]

That is a gorgeous torque curve, Chris!
I would honestly be scared to drive such a gnarly beast!

Originally Posted by TurboKraft

speeed racr,

Both turbos are good, it just depends on what you're after.

Those engine specs are real similar to the black 1994 Turbo we built, the "TX UFO" (1994 Porsche Twin Turbo 3.8L | Marc, sorry about the broken thumbnails, we're working on it...)

That engine first did 560hp on an engine dyno as a 3.6TT with GT28R turbos. The turbos came on super fat but flat lined before 5,000rpm -- too small.

Then it got some larger custom-spec GT28R turbos and did over 700hp flywheel, eventually getting tuned to 645rwhp on 100-octane before it ran out of compressor flow. The midrange torque was the real killer, however -- from rolling starts, there were few cars on the road that could touch it. It ate up cars that ran 10.5 in the quarter.

It was later rebuilt as a 3.8L (got the very first set of Nickie 911 cylinders) and the subsequent owner wanted "more," even if it cost a little midrange torque. GT3071R turbos offered barely more top end, and robbed the midrange. GT30R turbos took it from 645rwhp to 752rwhp, but strong compressor surge was a problem despite having large external wastegates, 3" twin exhausts, and ported shroud compressor housings.

The best all-around for street? A set of our GT28R turbos. We used them on Avi's 3.8L 964 Biturbo, too -- engine dyno results here: Dynos.jpg Check out the torque at 3,000rpm. That car is crazy quick.

[TurboKraft]

There's a video online somewhere called "Israel's Fastest" where a magazine hosed a shootout at a runway, tuned cars vs. a superbike (1100cc?)
Avi smoked them all -- WRXs, blown V8s, and a pair of tuned 996s from 9ff and TTP.

[TurboKraft]

Originally Posted by 911TT33

Ok, thanks for the tips guys. At least now I have some direction
So, I'm assuming you recommend sticking with headers that have 1 5/8" primaries to suit the Carrera heads ?

41mm exhaust port I.D. = 1.61" I.D.
Add tubing wall thickness, ex: 16ga to get O.D. = 2x 0.065" + 1.61" = 1.75" O.D.
So to port match to your heads and not add a flow restriction you would ideally use 1.75" primary headers.

Will 1-5/8" headers work? Yes...

[jimtweet]

i cant really speak much for being on a 930, but i had this turbo on my STi, and it ripped, i think i was making around 415hp....awesome spool and when it kicked, it kicked hard!

i ran it for about 7k miles before selling the car, no problems, great turbo IMO