Garrett G42 1450 - 20B application
 

Has anyone tried one yet? I'm thinking the G42 1450 with a 1.28 V band turbine would be a good choice for a responsive 900-1000hp at the treads (drift application). I'm just a little concerned turbine flow is going to be an issue.

The BW 76SX-E - 87/82mm turbine wheel with Tialsport 1.30 housing gets to 1.5:1 turbine back pressure real quick above 8k rpm (20B).

I know the Garrett turbine wheels flow more than the BW wheels for a given size, however I just can't see the G42's 82/75mm turbine wheel outflowing the larger 87/82 BW wheel?

I am a few weeks away from it being a 13b.. But using a 1.15 rear instead, and will be through a C4 built auto..

I am guessing you mean a S476SX-E? if so thats a 76mm wheel and is a 121lbs per min turbo?

The G42 1450 is a 79mm and is a 136lbs per min turbo.. and the rear is a 82mm which is almost a 1:1 turbo.. the response will be amazing on a tripple..

That setup will easily flow 1000hp.. even on the twin rotor it would be maxed around 900-950hp.

Also need to keep in mind new designed wheels as well.. .next gen tech

Compressor Specifications

• Compressor Wheel Exducer: 79mm
• Compressor Wheel Inducer: 98mm
• Compressor Wheel Trim: 65
• Compressor Wheel Material: Forged Billet Aluminum Alloy
• Compressor Housing A/R: 0.85 A/R
• Max Flow Rate: 136 lb/min
• Max Recommended Turbo Shaft Speed: 114,000 RPM

Turbine Specifications

• Turbine Wheel Exducer: 75mm
• Turbine Wheel Inducer: 82mm
• Turbine Wheel Trim: 84
• Turbine Wheel Material: Mar-M
• Turbine Wheel Max Temp: 1050C / 1922F

Correct - S476SX-E 121lb.

Comp flow doesn't worry me, it's turbine flow. The last drift 20B I setup uses the S476SX-E with 1.30 Tialsport however it's not as responsive as I'd hoped, and given the fact turbine back pressure passes 1:1 at 7500rpm I suspect it's the lack of turbine flow affecting response. Plus the 87/82 BW turbine wheel is actually a cut down 90mm wheel so it's never going to be real efficient anyway.

This time round I'm looking for better response from a unit capable of at least 120lb compressor flow. There doesn't actually seem to be much choice for a 20B - it's either a G42 or a S476SX-E. Xona Rotor doesn't appear produce anything large enough yet. If there was a 120lb+ EFR option I'd use it in a heartbeat, however the Gamma/Ti turbine wheel diam vs strength limitation rules that out from ever happening. It's just hard to imagine the G42 82/75 turbine wheel can flow enough for an E85 20B application. It could well do it, I just don't know yet.

Edit - I just discovered the G45 is due for release early next year - the G45 1350 with it's 89mm turbine wheel might be the ticket...

yeah ok, so you are worried it might choke in the higher rpm? - There is no question it will be more responsive than the SX-E but i don't have an answer for the rest. Surely it would come down to blade design in the wheel to allow it to flow?

Unfortunately because these things are same expensive there is no real data on them yet on either 13/20b at all..

The G45 looks promising but depends how much they increase turbine flow. Definitely one to watch out for. Have you also considered the S476SXE T6 96mm turbine? Pretty sure the 96mm wheel flows a little over 50lb/min.

Where are you getting the BW turbine flow data from? All I can find is the matchbot data, of which I'm unsure how to convert to lb/min.

I think the 96mm wheel might be a bit too heavy and adversely affect transient response. Drifting has to be the most difficult application when it comes to correct turbo selection.

The matchbot spits out a turbine flow number, I'm not sure how accurate that is but that's all I was able to find. :)

Why exactly do you need so much peak power at a high rpm for a drift application? Would it actually make you drift better? I'm just not understanding the goal here. When you say it's a drift application, does that mean all you do with it is drift and drive to drift events? Or like you're going to drift twice a year and then do some drag racing? Are you ever on the street? Or is this partly a show car -- pop the hood and see a shiny big turbo and 3 rotor?

Dedicated drift competition only. The piston guys are well over 1000hp these days. The higher the hp available the greater the rear end grip that can be dialled in. This equals higher drive and corner speeds which can be a huge advantage, particularly in a lead run.

The last car used a BW 76SX-E S400 frame and makes around 800hp. Another 100-200hp more and better transient response would be ideal this time around.

For a target of 1000hp you want the S480SXE T6 1.32 96mm. It will probably be slower to spool, you'd just have to put up with that if you really need the extra power.

It's possible that the G45-1550 could also get you there with quicker spool, but it's hard to say until Garrett release some more information.

saw Rob Dahm put a G42-1450 on a 20B semi-PP recently and then ran 172 mph for a standing 1/2-mile untested on 14 psi boost, basically just doing shakedown runs on a rough tune.

sounded like it’d be going on the dyno next, so maybe some defining results in the next week or two
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for 1000 at the wheel id be looking at the gtx5533 with the 88mm compressor wheel, control emap vs spool with Area Ratio on turbine housing
s480 will max out around ~800 and emap / compressor rpm speed will rise

Seems a tad oversized in relation to the comment on response with the S476SX-E 1.30 Tialsport

the one uncertainty factor on the G42-1450 is that Garrett only shows one undefined turbine map curve, yet there are three A/Rs listed (1.01, 1.15, 1.28)

in agreement with one of the earlier comments; imo the G-series is often not well understood still on how much better they flow despite what the wheel diameter sizes might suggest based on past experience. They’re really setting a whole new standard wrt size vs. flow. Based on swag-comparing some other G-series turbo sizes against the GTX-series I’ll pull one out of my tailpipe and reckon that one turbine curve is for the smallest 1.01 A/R and the 1.28 might be low-mid 50 lb/min.

The overall efficiency of the G-series also tends to be overlooked from what I’ve seen and the EMAP is likely to be lower than might be expected based on past turbo sizes as well. I was thinking it might be capable of 900.

those are just “sticking my fool-neck out” guesses though, which is why I’m anxiously waiting to see some actual numbers
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:spew: …


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Yeah if you want the nastiest 1k whp i would do the g42. A side note its really only safe to 950 but i made a mistake in that video and forgot that electric gates dont open up to back pressure. Which is why i was surprised it hit 1k.

Its beautifully responsive. in fact im over 800 whp in every gear at 6300 rpm and blow the tires off. Too much power haha

guy on the Subaru forum wasn’t happy that he had two G35-900 turbos fail back to back and Garrett rejected the warranty claim due to excessive over-speed. Somebody else posted up the compressor maps for the 900 and 1050 and told him the 900 speed limit was exceeded and the 1050 would be better for 3.75 Pr, and his response was “unfortunately I have no idea how to read that”. :lol:

Not making fun of the guy though as it was just amusing to read that, he had gone on about how one of the most respected tuners in Dubai had built and tuned it, etc. and it had to be the turbos fault. A link to an article on how to read a compressor map was posted for him, he came back later to revise the post to say it was his and the tuners fault for not having a speed sensor, etc. Classic intrawebz story.

So just pointing out that the G-series are speed limited to the far right, but the efficiencies are so high there that the turbo will charge right on past the speed limit still making good power rather than giving any indication of stalling out etc. A speed sensor and control strategy is strongly recommended.

Have also heard some people complain about the turbine housing weight, but on the Garrett website they go into how the new G-housings are designed for containment in the event that extreme overspeed occurs and the wheel catastrophically fails, along with pictures showing the internal carnage when they intentionally tested them to extreme failure speed.
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Please do bare with me for this stupid question (because frankly I am stupid) but why is it only safe to 950? What would happen if you pushed it further? This is coming from someone with absolutely ZERO knowledge about actual physical tinkering and engineering so sorry if it’s a really stupid question.

The compressors and turbine seem to maintain a reasonable level of efficiency beyond the max rated shaft speed. Depending on boost/porting/rpm you are probably skirting the maximum rated shaft speed at that power level.

the 114,000 rpm turbo speed line on the upper right side of the compressor map is a “do not exceed” maximum hard limit.

maybe reread the post I made just prior to your own, but you might get another 30 - 40 whp out of it riding the edge of eventual doom depending where specifically it’s operating at on it. The 950 whp recommendation is a safer bet unless you don’t mind the $3700 replacement price when the weasel goes pop. Assuming the motor doesn’t go with it since it’s usually the compressor wheel that comes apart or stretches outward into the housing scroll and potentially spits out shrapnel.


https://cimg8.ibsrv.net/gimg/www.rx7...a91c00e2e.jpeg

Ah I see! Very sorry about that, so if a >950 whp goal is wanted (without the turbo shaft joining the exhaust gases out the car) a larger turbo would be needed, a G45-1500 or something right? I assume now that rotaries usually can get less hp out of a turbo compared to a piston engine due to the reduced exhaust gases of the whole motor.

unfortunately not that simple, the G45-1500 is actually a worse choice. It’s aimed for high boost efficiency and once you compare the compressor map for it (below) against the G42-1450, it should be apparent that you not only won’t reach the required flow for the boost level, but it will also be less efficient there are as well


https://cimg8.ibsrv.net/gimg/www.rx7...a0dc1871e.jpeg

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