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@s2kfinesse How much more room do you think you have on the g25 before you max it out? Also I picked up a G30 660 with a .82 AR, we share the same compressor side but my turbine is a bit larger.
@s2kfinesse How much more room do you think you have on the g25 before you max it out? Also I picked up a G30 660 with a .82 AR, we share the same compressor side but my turbine is a bit larger.
I'd guesstimate the G25-660 topping out around 550whp and the G30-660 around 600whp on E85.
Extremely happy with mine. 421&477 are ~15psi. 93/E85. Top mount recirculated dump
other two is a borg s256 at same psi on 93/100. Top mount open dump.
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What's your opinion between the two. Is the much higher of the cost of the g series worth it? how was the transient response vs the borg?
My opinion of the two is not in the same league. Granted you could buy 2 borgs for one g25 so I’d expect that. To me the engine felt bogged down due to the borg whereas now the g25 seems to pull the engine up the rpm range. I thought it was worth it but hard to say for someone else just do to not knowing what other stuff is at play.
I'd guesstimate the G25-660 topping out around 550whp and the G30-660 around 600whp on E85.
That seems a bit high, considering it's a 61 lbs/min turbo. But, some dyno's might show that and others not even close. With a gen2 GTX 3071R and ~14 PSI on ethanol, we got about the same power. This is a similarly sized turbo and I wouldn't expect to be able to hit the 600whp mark with it. I do have it running about 17 PSI on track, which is likely around 500whp, but it's on the downward slope of running out of steam.
Don't mind the label up top... I'm terrible at updating those. The lower graph was my car with an EFR.
That seems a bit high, considering it's a 61 lbs/min turbo. But, some dyno's might show that and others not even close.
Ah, yeah, I typically use 9whp per lb/min (everything optimum, turbo wheel sizing, exhaust, etc) on E85, so about 545whp on 61 lbs/min for the G30-660. Sorry, brain fart. So maybe 515whp-ish for the G25-660 due to the smaller turbine.
Ah, yeah, I typically use 9whp per lb/min (everything optimum, turbo wheel sizing, exhaust, etc) on E85, so about 545whp on 61 lbs/min for the G30-660. Sorry, brain fart. So maybe 515whp-ish for the G25-660 due to the smaller turbine.
Pointless bump, except to note that there’s more at play than the turbine impeller size; the G25-660 0.92 turbine outflows the G30-660 0.83 turbine up to about 3.0 Pr, at which point they equalize and are peaked out around 24.5 lb/min. However, the G25-660 0.92 hits that peak around 2.5 Pr with the G30-660 0.83 slightly less there and all the way back to 1.25 Pr. Since they both have the same identical compressor, I’m going to suggest that your assessment above is off some.
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I recently tuned an STi on a G25-660 and struggled with it. It would not spool like it should a would taper quickly, even after a 4-port, on an EWG. After taking it out on the road after the dyno, this happened shortly. This was a track car and really hoping to have had it competing in several events this month, but that did not work out.
I then learned that this was the second turbo the owner went through. The first would not spin as it was hitting the housing. With both old and new in hand, they were visually different (both purchased from major, authorized retailer). It was so bad that the piping no longer fit the turbo. The car did make a lazy 488whp, but clearly, something was amiss
