Real World Testing - Garrett's G-XRace Series

Please note both runs were on the same day, same dyno, same tune (with the Haltech R5 trimming mixtures only) and the same wastegate duty cycle.

Firstly we would like to mention how amazed we still are at the power now available from only 73mm turbochargers from all manufacturers, technology has come along way since we started playing JZ’s over 20 years ago.

2 x Initial hub dyno runs were as we left it last time with the G45 turbo maxed out with 75% duty cycle in the wastegate and boost peaking at 37psi but dropping to 34psi in the top end. While we don’t have a turbo speed sensor or a back pressure sensor on this car we do know by the jumps needed in duty cycle vs the power and boost increases that we saw the turbo was pretty well done.

Now the G-XRace upgrade, this turbo is near identical in size to the G45 that we removed and even shares the same 1.15 T4 exhaust housing and the same turbine wheel, on the compressor side it has the new Garrett XBoost technology compressor wheel and is only 1mm larger then the G45 wheel.

2 x back to back ramps with the G-XRace netted a gain of 105hp at the hubs, with boost spiking at 40psi and dropping back to 37psi in the top end. With the same duty cycle and the same 3psi of drop in the top end we feel pretty confident that the turbo is also pretty well close to maxed like the previous G45 unit was.

Now the results, we are pleased and it’s about what we hoped it would be, and the turbo being capable of making more boost proves however you like that it’s more efficient and HP capable then the G45 turbo that came off (as expected). Air temps in the logs were also the same at 34psi with the G45 as they were at 37psi with the G-XRace.

What else did we notice, just about everytime you make more HP a sacrifice is made somewhere along the line even with new technology, and in this case even though it is minor a sacrifice was slightly noticeable to response (potentially just the 1mm larger compressor size). This you can look at 2 ways, if the G-XRace hadn’t come out and we wanted more power the next step up would have been a G45-1500 to make the extra 100hp, this turbo would have increased the lag more then what we saw today for the same 100hp+ gain, which in turn makes the G-XRace more responsive vs HP capable then a G series. Potentially you could upgrade a G45-1500 back to the smaller GXR45-73 and gain some response back without loosing HP.

In conclusion, we were not paid for this test and it’s something we have always jumped at to help customers when new products are released. We are happy to sell either the G series or G-XRace and makes no difference to us. So is the 11% increase Garrett claim correct ? Our results showed over a 9% increase and we also still run a full exhaust and only the 1.15 housing, so with a larger exhaust housing and no exhaust there could potentially be up to an 11% gain. We definitely would be happy to see more sizes in this range in the future.