opinions about new garrett g25-660 vs gen2 gtx3071r
 

I have been running a ptunning kit with a gen 1 garrett gtx3076r for many years now. Dynoed at 588whp at 20psi on e85. With all these new turbos coming out and there crazy high power ratings for small ass turbos i been thinking about geting rid of my gen 1 gtx3076r for something more responsive. I'll be more than happy with 550whp on the top end but i want as much bottom end and as fast of a spool up i can get. The new gen 2 gt garrett gtx3071 is ratted at a crazy 650hp at thats only a 54mm turbo. This turbo is 4mm smaller than my current gen 1 gtx3076r and is ratter for more power.

The new garrett g25-660 is a super tiny 54mm turbo with a tiny 49mm turbine wheel are is rated for a crazy high 660hp.

Is there any truth about these tiny turbos making such high hp numbers? back 10-12 years ago you would need a supper laggy 62mm+ turbo to make 600hp
If this is true i should be about to replace my gen 1 gtx3076r with the new g25-660 and making the same amount of power if not more with a huge increase in spool up and bottom end power.

https://www.atpturbo.com/mm5/merchant.mvc?Screen=PROD&Store_Code=tp&Product_Cod e=GRT-TBO-633&Category_Code=G25660

I went from a pte6062 to a BW257...Faster spool is def. where it's at. I have yet to go back on the dyno so take my advise with a grain of salt, but I would suggest using a turbine housing calculator. Don't take other peoples "advise" or odds are you'll be way off the mark. I had people telling me to go with over a 1.0 A/R. After figuring out my numbers I ended up at .83 a/r twinscroll and I love it. I come onto boost wayyy sooner. You''ll need to know some numbers to figure out what size exhaust housing you'll need but here is a calculator to get you to where you need to be.The compressor map will be of no use to you as this is BW specific but the turbine housing graph should put you in the ballpark

You can read more about them here:
Nerd-O-Scope: Honeywell Garrett’s G-Series Turbochargers

That G25 series turbine in the 0.92 A/R flows similar mass flow to the GT35 in the 0.63 A/R.

The GTX3071R Gen2 is the only easy upgrade in keeping your PTuning kit. If you want to go to the G-series, you'll need a whole new custom kit. I'm starting to work on my own setup, G25-660 with 0.72 A/R. Hope to have it done by the end of summer.

Or go for disco potato gtx28

Dude a gt28 = insta-spool on a 1.8 liter b series engine = fighting traction all the time. Unless you are looking for all low range and some midrange that's a seriously small turbo to match to a f22 / f20 (engines that revs to the moon and back). @riceball im also looking at the gen 2 gtx3076 (i emailed ATP and they said new CHRA + compressor housing = 1600 ish and i can reuse my tial exhaust housing).

Thay would be insane . G25-660 .spools same as gtx28 and make power like old gt3582. Off topic but how much does one of those Porsche variable geometry turning cost btw? Will Garret come out with one?

As i said in another post I have one and I'm fabbing it to put on a K24. Hope it's running in like a month. Hoping for 15psi from 2500 rpm to redline.
Ian https://cimg7.ibsrv.net/gimg/www.s2k...3951f5051f.jpg

2.4 should spool a little faster than ap1 and ap2. Aubbef for dyno numbers