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To add to rx72c -
EFR9180, 6-7 years of drift use at 30-32psi, E85, 950-1050 deg C EGT's. Recently had a compressor wheel failure (suspect foreign object or excessive surge). Upon teardown the rest of the turbo looks fine - bearings/cartridge, seals etc. Visually you can tell it's been hot (and can smell it) but everything looks just fine. Good value for $! The turbine wheel/shaft will go into another core that lost all it's turbine blades when it swallowed an exhaust sleeve (also from a drift car with high EGT's)
The turbine wheel/shaft will go into another core that lost all it's turbine blades when it swallowed an exhaust sleeve (also from a drift car with high EGT's)
I've heard EFRs are not rebuildable so do you, or who has the skills to rebuild your 9180?
For the rotary, I'd HIGHLY recommend the G35-900 over the G30-900. The G35-900 will have much better turbine efficiency compared to the G30-900 which will result in less backpressure while maintaining similar spool-up. On a piston engine, should be good for about 50whp more with no sacrifice in spool-up.
Everything I’ve seen indicates that the G30 turbine lacks nothing against the EFR8374 turbine, but the G30-660/770 compressors are deficient enough that I’d just go with the G30-900.
it really just depends on your goals and needs. There will be trade-offs either way, but somebody else can hash over all of that if they want.
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I've heard EFRs are not rebuildable so do you, or who has the skills to rebuild your 9180?
They're real easy to work on - only slightly more complex than an SX or SX-E. The internal structure is really well thought out and as with all BWTS products the wheels are neutral balanced. There is no rebuild kit available as far as I'm aware but in this case none is required. It's only a matter of making one out of two. I'm fairly sure the comp wheel is available as a loose part, and possibly the compressor and turbine double seals. Comp nut torque setting is the same as S300. No special tools are required.
Everything I’ve seen indicates that the G30 turbine lacks nothing against the EFR8374 turbine, but the G30-660/770 compressors are deficient enough that I’d just go with the G30-900.
it really just depends on your goals and needs. There will be trade-offs either way, but somebody else can hash over all of that if they want.
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Putting the 900 compressor (76mm exducer) on the G30 turbine (60mm inducer) will result in lower turbine efficiency due to a poor blade speed ratio. Yes, the compressor can flow well, but it's paired with a turbine that is too small for optimum performance of the total package. So even though the G35 turbine flows more in the same A/R housing, it'll have much better efficiency resulting in similar spool-up with less back pressure. Note that BW does NOT do a similar size pairing. Similar EFR sizing, wheel diameters sizing at least, would be an EFR7663. BW knows this pairing would suck, so they stopped at the EFR7163 and the jump to the EFR7670, then EFR8374. In my perspective, BW doesn't make a EFR7663 because they know performance would not be good. Why does Garrett do it? In my perspective, back in the day before billet compressor wheels and significant money being put into their aftermarket business, Garrett made the old GT3076 which was very popular. They were limited to the wheel options they had from various OEM programs, and your average car tuner enthusiast was not as tech smart. Then the GTX series came out, so of course, they made a GTX3076 which sold like crazy because people were of the mind that the GT3076 was great, so the GTX3076 must be awesome too; because billet wheels add 1000hp! But Garrett also started making the GTX3576 because it is the better overall performing turbo. So why make the G30-900? All you have to do is look in instagram and the number of tags for GTX3076 compared to GTX3576. It's a 10 to 1 difference! If those posts numbers are even close to representing the same ratio in sales numbers, it's a no-brainer to keep on making that wheel size pairing of the 76mm compressor exducer with 60mm inducer turbine, even if it doesn't perform as well.
I've heard EFRs are not rebuildable so do you, or who has the skills to rebuild your 9180?
Ball bearing turbos (Garrett and BW at least) in general are not designed to be rebuilt; which is not to say that people are not rebuilding them. This is due to how they are assembled with the turbine shaft wheel assembly being pressed into the ball bearing. With this design, a final full assembly level balance needs to be done on a high speed balancer. Typical process is individual component balance of the compressor wheel and turbine shaft wheel assembly. Then the full assembly level balance. Say you take apart this turbo, reuse all the exact same components but the ball bearing is not in the exact same alignment, then the balance could be off a bit. Another thing, at least with the Garrett ball bearing turbos, is that the nut for the compressor is only designed to be torqued at most 2 times as it's basically a torque-to-yield joint which stretches the shaft. So, it'll be weaker if rebuilt.
I’m neither going to reply copy all of the G30-900 response or argue over it other than to say that what doesn’t seem to be registering imo is that the new G30-900 replaced the prior GT35 wrt to flow/performance. A GTX3076 compressor is only 65 lb/min, or between the G30-660 and G30-770.
Which when you compare those two against the G30-900 you see how they’re not the good match up you mentioned, and as I stated here and other forum threads. If you get hung up on the G-series impeller dimensions rather than the actual performance data then you’re not going to see either the trees or the forest.
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Which when you compare those two against the G30-900 you see how they’re not the good match up you mentioned, and as I stated here and other forum threads. If you get hung up on the G-series impeller dimensions rather than the actual performance data then you’re not going to see either the trees or the forest.
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What performance data are you referring to? Because one of the most critical pieces of information is turbine efficiency which is not shared. The compressor just cares about the shaft power it gets from the turbine. Turbine shaft power is a function of mass flow, pressure ratio, and efficiency. What the engine cares about, especially rotaries, is a low turbine pressure ratio. In order to have a given shaft power with given mass flow, in order to minimize pressure ratio, you must increase turbine efficiency. Turbine efficiency is a function of turbine housing A/R and blade speed ratio. Blade speed ratio is a function of the compressor to turbine wheel size match essentially.
A G25 with 0.92 A/R flows about the same as a G30 in 0.83 A/R which flows about the same as a G35 in 0.61 A/R. Do you believe a G25-900 would be a good pairing? That seems to be what you're implying based on looking strictly at turbine flow. I can tell you right now that a G25-900 pairing would result in a really poor blade speed ratio and therefore abysmal turbine efficiency making for a really poor performing turbo. So yes, the compressor and turbine wheel diameter matching does matter.
not exactly; according to Garrett’s data the G25 0.92 outflows the G30 0.83 until 3.0 Pr where they then approx. equalize
the turbine efficiency is a good point and I’m glad you brought it up because some assumptions are being made there. Garrett lists the peak turbine efficiency for the G30 and G35 at 74%, but that’s all they tell us. They don’t list it for the G25, but my expectation is that it’s at least the same based on the map, maybe a bit more.
No, I’m not just basing it on turbine flow. To say so is an exaggeration. There’s going to be a pretty big difference between a G25 and a G35 with regard to MOI/response. However, while they may eventually equalize at peak mass flow at a very high Pr as previously noted, your example again overlooks that the that the G25 0.92 outflows the the G35 0.61 up to that equalization point. Which that lower 2.0 - 2.5 Pr range just happens to be where a lowish-400 whp 13B would be operating at and needs that extra flow. You won’t be revving it out much past 7000 - 7500 rpm though
The actual application matters. For an 8500+ rpm track car, yeah I probably want a G35. Maybe for low octane fuel too, I can see that point, but it’s more of a just depends situation imo. For a 7500 - 8000 rpm, 450 - 520 whp street car on E85, I’d rather have the G30. That’s what I was referring to earlier about your comments lacking enough details to discern your intent. If I want to max out that 900 compressor to the far right rpm limit then I can certainly agree the G35 turbine is a better choice.
So I’m not outright rejecting your points on choosing the G35, but more trying to figure out where it is you’re really coming from. That turbine is not that far from a GTX40. To me that’s more of a competition/high hp choice then. Because for throttle tip-in on the street it is going to make a difference for a lower hp application, depending on what the actual application/desired result is.
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As a reference on the effect of blade speed ratio on turbine efficiency due to compressor to turbine wheel size matching, the GTX3576R has up to 10 points better turbine efficiency than the GTX3076R; I've personally seen the turbine maps with efficiency curves. Even though the GT35 turbine wheel flows more than the GT30 in the same turbine housing casting (cut to fit each wheel of course), the GTX3576R will spool up nearly identical to the GTX3076R. Back to the turbine shaft power equation, the GTX3576R is getting the same shaft power as the GTX3076R at a lower turbine pressure ratio and higher mass flow due to greater turbine efficiency. Higher turbine efficiency also offsets the higher moment of inertia of the higher mass bigger turbine wheel. Of course, with the lower turbine pressure ratio due to the higher turbine efficiency, that allows more power out of the engine. The same trend was seen between the GTX2867R and GTX3067R with the larger 3067 having similar spool but more power than the smaller 2867. Now that similar spool of the bigger vs smaller turbo was occurring when the turbine wheels were in the same exact turbine housing casting cut for the different size wheels. So this would be applicable with the G30 and G35 which use the same castings. The G25 uses different castings. I actually think a G30-660 in the 0.83 A/R could spool faster AND make more power than the G25-660 in the 0.92 A/R. I'm not a huge fan of the G25-660, the G25-550 is a better overall pairing.
in other words, you don’t really understand what the exhaust flow output of a 13B is?
because the G30 0.83 is going to be flow limited early in the powerband and the minor improvement it will provide below 3300 rpm or so is going to get hammered from 3500 rpm and up with negative emap coming in sooner and peaking higher.
again, compare the two from 1.5 - 2.5 Pr and you can see why that is, because a 13B can fully utilize the difference, whereas maybe a reciprocating engine may not. And that difference is well needed at the top of the powerband, which even the 0.92 starts coming up short despite flowing more than the 0.83. To then say the 0.83 will make more peak power raises my eyebrows.
Which you seem like an experienced, intelligent person, but are perhaps not quite on target here. Maybe that’s why you keep fussing on over the previous GTX numbers, but those are entirely different impeller designs and not so relative imo, and also larger with more mass influence. Have you even actually looked at the in/ex diameter differences between the those and the G-series relative to their flow output?
in other words, you don’t really understand what the exhaust flow output of a 13B is?
because the G30 0.83 is going to be flow limited early in the powerband and the minor improvement it will provide below 3300 rpm or so is going to get hammered from 3500 rpm and up with negative emap coming in sooner and peaking higher.
again, compare the two from 1.5 - 2.5 Pr and you can see why that is, because a 13B can fully utilize the difference, whereas maybe a reciprocating engine may not. And that difference is well needed at the top of the powerband, which even the 0.92 starts coming up short despite flowing more than the 0.83. To then say the 0.83 will make more peak power raises my eyebrows.
Which you seem like an experienced, intelligent person, but are perhaps not quite on target here. Maybe that’s why you keep fussing on over the previous GTX numbers, but those are entirely different impeller designs and not so relative imo, and also larger with more mass influence. Have you even actually looked at the in/ex diameter differences between the those and the G-series relative to their flow output?
It’s apples vs. oranges.
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The 13B is basically a 2.6L, but performs similarly in torque and power production to a 2.0L from the era, so like a SR20 or 4G63. I can't speak specifically to the G-series because I haven't seen the efficiency numbers on the turbine maps nor has anyone done a direct G30-900 vs G35-900 comparison. But the blade speed ratio principle and the resulting turbine efficiency effect remains the same.
Yes, I'll stand by my comments of a G30-660 in 0.83 A/R having faster spool and making more power than a G25-660 in 0.92 A/R even though the turbine flow of the G30 in 0.83 A/R is slightly less than the G25 in 0.92 A/R This is due to significantly higher turbine efficiency. I'll also stand by my comment that the G35-900 in 0.83 A/R will spool similar to the G30-900 in 0.83 A/R while making significantly more power. Again, due to greater turbine efficiency.
If you want to try an experiment, do a match in Matchbot with the EFR 76mm compressor wheel (7670). Then use the 64mm turbine and 70mm turbine (close enough to G30 and G35), both in the 0.92 A/R turbine housing. To make it simple, use 65% turbine efficiency across the board for the 64mm turbine and 75% for the 70mm turbine and get back to me on the turbine pressure ratios.
Ok, I wasn’t thinking too clearly in the previous post and won’t make excuses; the G-30 0.83 could possibly make more power on the top end because it’s closing in on the G25-0.92, but imo it will have to be quite a bit more efficient in the Pr range we’re discussing (1.25 - 2.50) to overcome the difference between them as indicated in the overlay below. What’s different here from your “go do Matchbot” example above is they aren’t the same A/R:
this is the comparison from earlier in the thread, though it wasn’t made directly, but again it likely depends on your current and future intentions. As you can see, the 770 compressor efficiency range is less, but at some point for the 900 the turbine efficiency too, at which point the G35-900 needs to be considered.
Originally Posted by TeamRX8
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Originally Posted by TeamRX8
There’s some overlap in the G-Series line; overall the G30-900.
If you’re shooting for 520 whp or less though, the smaller compressor on the G30-770 should in theory offer slightly better response. Not quite as efficient out at the far RH side as the 900. It would be better to state what your goal is imo.
The one caveat though is the 1.06 divided T4 is EWG only. There’s a 1.01 divided T4 IWG planned, but no word yet on when it will be released.
I think the 7670 would be a better comparison to the G30
it’s hard to say with full certainty without having detailed turbine efficiency maps, but after running many direct comparisons on Matchbot (for whatever that’s worth, not a huge believer in it projecting rotary engine results accurately) it aligns more closely to the 8374.
07-19-21, 07:37 PM
