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That reminds me of the spool of a Gen1 GTX3071R Evo X bolt-on in the larger 0.94 A/R twin-scroll housing on stock displacement 2.0L 4B11. Using the smaller 0.73 A/R shifted 4th gear pull about 500rpms to the left.
That reminds me of the spool of a Gen1 GTX3071R Evo X bolt-on in the larger 0.94 A/R twin-scroll housing on stock displacement 2.0L 4B11. Using the smaller 0.73 A/R shifted 4th gear pull about 500rpms to the left.
I think the twin scroll reverse rotation exhaust housings will work well on the Evo platform.
G30-660 and G30-770 will be a good match for the FP Red/Black series turbo's
When I say compressor to turbine match, I'm referring to the resulting blade speed ratio. I apologize, I should have been more clear. Put the G35-900 in that same T4 1.06 twin scroll housing casting, and it'll spool as quickly as the G30-900 but probably free up about 50whp maxed out. It's very analogous to the GTX3076 vs GTX3576 comparison as they are the same mix of compressor/turbine wheel diameters, the same 76mm diameter exducer compressors put on GTX30/G30(60mm) and G35/GTX35(68mm). Putting the G35 turbine in the same housing as the G30 with both paired to the 76mm exducer compressor, the G35 will flow more resulting in less back pressure. But the G35-900 has better turbine efficiency because of better blade speed ratio due to better match of compressor and turbine diameters. So it can spool up the turbo as quickly, i.e. the same turbine power. Turbine power is a function of efficiency and pressure ratio. More of either and you get more turbine power. With the larger G35 turbine, you will have less pressure ratio to drive the turbine, but better turbine efficiency resulting in the same turbine power to spin up the compressor wheel. I would say the 1.06 A/R for a G30 size turbine is also a bit outside of ideal for turbine efficiency. Larger diameter turbines tend to have their peak efficiencies in larger A/R housings, and vice versa. 1.06 A/R size is better suited to the larger G35/GTX35 turbine diameter. If you look at the smaller OEM gas turbos (~GT15-GT17 size), like on the Ford V6 Ecoboost, they are 0.49 A/R. Look at the big GTX50 stuff, and they are around 1.2 A/R, approximately. If you're a cyclist, a mismatch of compressor to turbine wheel sizing is kinda like being caught in the wear gear pairing. The G30-900 will still be a lot of fun, just leaving some power on the table. Jackie Ding in his AMS Supra time attack car is doing pretty well with the G30-900.
In going with the G30-770, you'd probably gain about 300rpm of spool compared to the G30-900, but have about 50whp less maxed out. About 100whp less than the G35-900. But the G30-770 would be very snappy and responsive, having the lowest rotational inertia and good turbine efficiency.
When I say compressor to turbine match, I'm referring to the resulting blade speed ratio. I apologize, I should have been more clear. Put the G35-900 in that same T4 1.06 twin scroll housing casting, and it'll spool as quickly as the G30-900 but probably free up about 50whp maxed out. It's very analogous to the GTX3076 vs GTX3576 comparison as they are the same mix of compressor/turbine wheel diameters, the same 76mm diameter exducer compressors put on GTX30/G30(60mm) and G35/GTX35(68mm). Putting the G35 turbine in the same housing as the G30 with both paired to the 76mm exducer compressor, the G35 will flow more resulting in less back pressure. But the G35-900 has better turbine efficiency because of better blade speed ratio due to better match of compressor and turbine diameters. So it can spool up the turbo as quickly, i.e. the same turbine power. Turbine power is a function of efficiency and pressure ratio. More of either and you get more turbine power. With the larger G35 turbine, you will have less pressure ratio to drive the turbine, but better turbine efficiency resulting in the same turbine power to spin up the compressor wheel. I would say the 1.06 A/R for a G30 size turbine is also a bit outside of ideal for turbine efficiency. Larger diameter turbines tend to have their peak efficiencies in larger A/R housings, and vice versa. 1.06 A/R size is better suited to the larger G35/GTX35 turbine diameter. If you look at the smaller OEM gas turbos (~GT15-GT17 size), like on the Ford V6 Ecoboost, they are 0.49 A/R. Look at the big GTX50 stuff, and they are around 1.2 A/R, approximately. If you're a cyclist, a mismatch of compressor to turbine wheel sizing is kinda like being caught in the wear gear pairing. The G30-900 will still be a lot of fun, just leaving some power on the table. Jackie Ding in his AMS Supra time attack car is doing pretty well with the G30-900.
In going with the G30-770, you'd probably gain about 300rpm of spool compared to the G30-900, but have about 50whp less maxed out. About 100whp less than the G35-900. But the G30-770 would be very snappy and responsive, having the lowest rotational inertia and good turbine efficiency.
No matter what magic is used on the G30 turbine wheel, it can never escape the fact that it has to flow through a 55mm hole in the turbine housing. Below were my results going from the GTX3076r (yellow) to the GTX3576r (blue) on the same setup and both using a 1.06a/r T4 TwinScroll housing. These turbos use the exact same compressor wheel, but the 35r turbine wheel (62mm exducer) out spooled the 30r turbine wheel (55mm exducer) and increased horsepower.
I knew what you were saying as far as the match goes. What I'm still saying is that I don't expect to push the turbo to its absolute limits regardless, so I didn't feel the need to go up to the g35.
My car was out of injector already, and I'm not upgrading them because the car is just a fun street car already has traction issues. The g30-900 and G35-900 both will get to the power I'm looking for. If you're right, and I don't doubt that you are, I could have paid an extra ~300 bucks for the g35, spooled just as well, and made the same power up top because I do not want to go to the limits of either turbo. So $300 for less ex manifold pressure.
Anyway here are a few pics with the old precision 6262 and its 0.84 housing. The g30 is extremely compact, pretty impressive package. Interestingly, the exhaust housing is so fat that the chra vband only fits in the orientation in the last photo or about a 15 degree window around there
Could you liken that between the G25-660 and the G30-660?
The G30-660 seems like a much better match to me
Yes, the G30-660 is. Same as the old GTX2867 vs GTX3067. The GTX3067 made 25whp more in the same turbine housing casting with the same spool. In comparing the G25-660 vs G30-660, it's a little more complicated in that the G25 and G30 turbines do not share the same housings, but housings of the same flow. G25 0.92 A/R flows like G30 0.83. G25 0.72 A/R flows like G30 0.61 A/R. Until someone tries back to back, I'd guess the G30 in 0.83 will spool faster than the G25 in 0.92, and make about the same power. Or maybe a bit more power. Traditionally, The GT30/GT35 size turbines have peak efficiency in the 0.8-1.0 A/R area. Not the 0.6 A/R range. So in comparing the G25 in 0.72 A/R which is in more of its sweet spot for A/R compared to the G30 in 0.61 A/R outside of its sweet spot... hard to say. Only thing for sure is G25-660 has less rotational inertia. My guesstimates are based off of prior GT30/35 and GTX30/35 experience. So only a guess as to how the G-series behaves. It is a different wheel design in the G-series, so things may be a little different.
I knew what you were saying as far as the match goes. What I'm still saying is that I don't expect to push the turbo to its absolute limits regardless, so I didn't feel the need to go up to the g35.
My car was out of injector already, and I'm not upgrading them because the car is just a fun street car already has traction issues. The g30-900 and G35-900 both will get to the power I'm looking for. If you're right, and I don't doubt that you are, I could have paid an extra ~300 bucks for the g35, spooled just as well, and made the same power up top because I do not want to go to the limits of either turbo. So $300 for less ex manifold pressure.
Anyway here are a few pics with the old precision 6262 and its 0.84 housing. The g30 is extremely compact, pretty impressive package. Interestingly, the exhaust housing is so fat that the chra vband only fits in the orientation in the last photo or about a 15 degree window around there
Thanks for the pics. Garrett's new turbine housing supplier has really nice surface finish on the castings. That's worth a point or so of turbine efficiency compared to a typical sand cast housing. The G30 is really compact. Notice the Garrett housing has a proper diverging nozzle diffuser out of the turbine wheel whereas the Precision housing does not. That worth another point or so of turbine efficiency.
If only there was a simple Twin scroll Vband setup that would let me go smaller turbo for lapping track days vs bigger turbo drag/highway days.
You could do G30-770 as the small, and the G35-900 as the big being directly outline interchangeable. With a minor compressor outlet adjustment, you could go G35-1050. The only turbine housing option right now is the T4 1.06 A/R.
the Garrett housing has a proper diverging nozzle diffuser out of the turbine wheel whereas the Precision housing does not. That worth another point or so of turbine efficiency.
I'm not 100% sure that I'm with your terminology, but they're both divided all the way to the turbine inside. The Precision just had a spine down the middle, whereas the Garrett has asymmetrical volutes to shift the bulk of the housing forward toward the chra. Seems like they did some extra engineering to balance the flow just so that they had a more compact package overall. Not trying to argue, just geeking out.
Not enough of a difference, wish they did the XR10569 in TS
Originally Posted by spdracerut
You could do G30-770 as the small, and the G35-900 as the big being directly outline interchangeable. With a minor compressor outlet adjustment, you could go G35-1050. The only turbine housing option right now is the T4 1.06 A/R.
Not enough of a difference, wish they did the XR10569 in TS
If you give up exactly direct interchangeability, you could go down to the G30-660 (power like the old GTX3071) to the G42-1450 which comes with T4 twin-scroll in 3 different A/Rs. Though I think the G42-1450 is a mismatch and it really needs to be a G45 turbine which does not yet exist. So if you limit yourself to G42-1200, that's almost double the power capability of the G30-660. Though the connections for the compressor side will be significantly different. Oil feed and drain are probably different too.
I'm not 100% sure that I'm with your terminology, but they're both divided all the way to the turbine inside. The Precision just had a spine down the middle, whereas the Garrett has asymmetrical volutes to shift the bulk of the housing forward toward the chra. Seems like they did some extra engineering to balance the flow just so that they had a more compact package overall. Not trying to argue, just geeking out.
I was referring to how the flow exits the turbine wheel Rule of thumb for a narrow angle diffuser is to not exceed 14 degree included angle, 7 degree from centerline, to avoid flow separation as much as possible. The Garrett housing has a narrow angle diffuser, with the exact angle depending on which size turbine wheel is in it. The smaller G30 will have a bigger angle, larger G35 turbine wheel a more narrow diffuser angle. The Precision housing has more of a stepped flow outlet.
You can approximate the Garrett as the narrow angle 10 deg and the Precision as the 180 deg opening in the chart below. Of course, those are not the true values of the housings, but just to illustrate. The loss coefficient Ke is much smaller with the narrow 10degree angle compared to the stepped opening represented by the 180degree case. Approximately 1/5th to 1/7th the loss.
Last edited by spdracerut; May 24, 2021 at 07:41 PM.
May 22, 2021, 04:00 PM
Rule of thumb for a narrow angle diffuser is to not exceed 14 degree included angle, 7 degree from centerline, to avoid flow separation as much as possible. The Garrett housing has a narrow angle diffuser, with the exact angle depending on which size turbine wheel is in it. The smaller G30 will have a bigger angle, larger G35 turbine wheel a more narrow diffuser angle. The Precision housing has more of a stepped flow outlet.
