G550 vs gtx2860 the G has a 2mm larger compressor inducer and larger compressor wheel diameter (58mm vs 65mm)
compressor housing A/R is also larger .60 vs .70 . G turbine exducer is +2mm , and + 8mm in diameter.

Also these turbos can handle higher temps.

Spdracerut would you mind filling in the blanks on that sheet?

 

Can you clarify what you mean by the larger compressor wheel diameter when the exducer is the same?

 

I'm as stumped as you are. No idea how that differs. just recorded what garret has. Could be the tapered tip of the exducer.

 

Correct, the G25-550 has larger trim compressor and turbine wheels than the Gen 2 GTX2860R. But that's not the only difference. The G-series compressor wheel creates slight more pressure ratio for the same shaft speed. The most impressive thing is the massive gain in peak efficiency of 80% vs. 73%! So even if you took the G2 GTX2860R and increased the trim to match the flow of the G25 compressor wheel, the efficiency would still be way below. The new aero of the G-series is very impressive.

Doing some quick math, even if you increased the trim of the GTX wheel from 58 to 65 to match the trim of the G-series compressor, it'd only increase the flow from ~42.5lbs/min to ~47.6lbs/min, still short of the G comp at almost 50lbs/min. That's just how much better the new G compressor aero is compared to the G2 GTX.

Here's a quick link on how to calculate trim:
https://www.garrettmotion.com/turboc...orks/advanced/

 

Thanks for that. according to garret the 67mm turbo is going to have a 30% increase in flow... the 2867 flows 550hp now, does that mean it'll be a 700hp turbo and the new 3076 will be a 1k hp turbo LOL?!

All I care about is faster spool and more top end. I've read that twin 660's made 270hp more than a 9180 with faster response on a R34 gtr time attack car as of late.

 

In theory, the G-series compressor wheel with 82mm exducer will do ~90lbs/min. Current G2 GTX 82mm exducer does ~84lbs/min. I extrapolated that from the 67mm exducer wheel flow. Of course, the further you extrapolate, the less accurate the prediction. PMC Race Engines made the engine with the twin G25-660s.

 

have you noticed a difference in spool time for the g series vs the GTX?

 

 

https://www.full-race.com/store/borg...v50-vtg-turbo/

these are the only place I know where to get VTG's at. Can't find any links to Borgwarner or garrett VNT / VTG / VTGERGGWERFIHERHF turbos anywhere.

 

The G-series 54mm turbine is has 74% efficiency and the GTX 54mm turbine has 69% efficiency...

 

I actually think the G-series pricing is quite reasonable. It's a within 10% of an EFR. Another way to look at, the G-series is roughly 1/2 to 1/3 the cost of a Garrett Motorsports turbo and it will do similar performance. The downside to the G-series vs. Garrett Motorsport is much higher weight. Also, the Motorsport turbos are customized to each customer with specific wheel trims, wheel designs, etc to best match the customer engine. Say a small displacement engine that runs really high pressure ratio gets a different compressor wheel design than a bigger engine running lower pressure ratio. So you pay for customization/optimization and lower weight with the Motorsports turbos. And rebuild services too which is much cheaper than replacing whole turbos.

Garrett has a couple gasoline VNT turbos on OEM applications. They say they can handle 1020degC exhaust too which is very impressive.
https://www.garrettmotion.com/turboc...r-gas-engines/

One is used on a VW 1.5L engine. I think one might be on a GM application too, but not sure.

 

 

EFR 7670 from Full Race is $1630 + $450 = $2,080 for least expensive hot side option (external gate also).
https://www.full-race.com/store/borg...-7670-turbo-2/

G25-660 from ATP, $2,088..
https://www.atpturbo.com/mm5/merchan...ry_Code=G25660

That's pretty close in price. And the Mar-M turbine won't be nearly as speed sensitive/failure prone.