Garrett GT 3071-63 turbo.
- PSU_Crash
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I run the GTX version with .63 A/R hotside on my non porsche 80s turbo beast. Dual ball bearing is the big gain there. Still makes 400WHP and spools up fast.
'86 Zermatt Silver 944 N/A 
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
Thanks for the reply. It's mainly the original standard GT3071 turbo I'm interested in. Is the main benefit the ball bearings, or is there more, that makes the extra fabrication work worthwhile.PSU_Crash wrote: Sun May 24, 2026 9:16 pm I run the GTX version with .63 A/R hotside on my non porsche 80s turbo beast. Dual ball bearing is the big gain there. Still makes 400WHP and spools up fast.
- PSU_Crash
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With the standard GT series I think the ball bearings is the biggest improvement. I'm sure the blade tech is also more efficient than 40 year old OEM. I haven't looked at a flow map side by side. That will really give the answers you seek.
Stock turbo loses effeciency around 17ish psi. The GT is efficient up to around 30psi. If power is the goal, the GT is the answer.
Stock turbo loses effeciency around 17ish psi. The GT is efficient up to around 30psi. If power is the goal, the GT is the answer.
'86 Zermatt Silver 944 N/A 
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
TBH driveability is what I'm interested in, without going to a smaller turbo than the K26-8. All of my fun 944 driving is on twisty roads now, so boost starting from under 3k would be more use than at 6.5k. Having said I don't want it to feel choked at 6k.
- PSU_Crash
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Hopefully someone chimes in that has run this setup. On my 2.6 mitsubishi 4 cylinder the GTX is at 18psi by 3k RPM. That's also a fully built engine, so it may not be apples to apples.
'86 Zermatt Silver 944 N/A 
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
- PSU_Crash
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I found this over on rennlist ...
https://rennlist.com/forums/944-turbo-a ... litre.html
https://rennlist.com/forums/944-turbo-a ... litre.html
'86 Zermatt Silver 944 N/A 
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
'86 Mitsubishi Starion - Purpose built SM class Autocross car
'87 Chrysler Conquest - Mid LS Swap
Thanks, as far as I know he still hasn't finished building that car 15 years later. It was in a 911 workshop around 10 miles from me until recently.PSU_Crash wrote: Wed May 27, 2026 4:00 am I found this over on rennlist ...
https://rennlist.com/forums/944-turbo-a ... litre.html
- Tom
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The 951 crowd has always leaned into vendors selling turbos as Stage this, Voodoo that, Raptor, SuperX, etc. Somebody posts good results with one, and others jump onboard. It makes getting feedback on off-the-shelf turbos like this harder than you'd think it should be... That's not to say there aren't plenty of pioneers out there, but we could use more. 
