When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
as many know the EFR turbo is limited to 116,000 rpm. this is primarily due to the titanium-aluminide turbine wheel. BW has encouraged all who are running it hard to install a speed sensor. i believe the larger (80 mm) wheels are at highest risk due to larger forces at play from the diameter. i have seen the 116,000 number in print somewhere in BW literature.
no news here.
i attended the BW presentation at the Deals Gap deal a month ago. During the talk, Brian Rhinehart added another EFR limitation... 950 C EGT!
1742 F!
that sure was news to me. i asked him if this was something new. he said, no, it is in the 122 page Training document... which i have read numerous times. i just did a tour through it again prior to this post and didn't see anything. i am pretty sure it is somewhere, i just haven't found it.
i asked Brian the "why" question. he answered that titanium-aluminide "changes state" above that level.
a brief conversation w Geoff Raicer/Full Race Motorsports and a serious BW insider, generated a "don't worry about it" response.
of course there are tons of EFRs running around on rotaries, which typically generate about 300+ degrees more EGT than a piston engine and i don't see any stories.
Brian, however, clearly was sending a serious message.
There goes my idea of running one on an antilag equipped Duratec. I'd probably see EGT waaaaaay over 950c, even with modern air-recirculation antilag and not old school bang-bang type.
There are a lot of them in service on rotaries, there has been the odd failure from people running them to choke flow on the compressor.
kind of pushes you towards G series if you want widest possible power curve running near choke/rpm limit but they are even more expensive than EFR. Fortunately it looks like the Pulsar knockoffs are very high build quality, only $1150 AUD for a twin ceramic roller version of an s372 (with more efficient s472 compressor) or $1550 for G42 1200 compact clone (vs about $4700 from large dealer), noting they are inconel 713c turbines.
Edit: double checked the Garrett site again, seems the larger G42+ size stuff is inconel too, they say 950 deg C a quick search of the 713c Inconel listed on the pulsar site suggests 980 degC, noting the G35 and smaller have another alloy "Mar-m" they say is good for 1050C, so you could really lean on a garret g35 if you were aiming for traditional P trim/GT37 turbine flow levels. I think I will go for the Pulsar made G42 compact given it shouldn't be much different to a traditional P trim in response.
what was a GT35 wrt flow/performance is now in a much smaller G30 package. Actually better performance in every regard despite the much smaller comp/turb impeller sizes. Essentially a G-series has better performance in a 1 size smaller turbo than before. You can pretty much throw the impeller wheel size comparison approximation method out the window imo.
Once you have the correct equivalent G-series size, the Mar-M turbine appears to challenge and possibly exceed the BW ceramic turbine in spite of the heavier material due to it making equivalent or better flow with a wheel having a much smaller radius (MOI is radius-squared dependent). There’s no reason to think that BW’s Matchbot program doesn’t output the correct peak turbine lb/min flow rates for their own turbos.
So if you go generate those numbers and compare them to the G-series turbine flow maps, the results are a bit shocking when you note the impeller diameter differences. So imo the P-trim comment might be off; it should be exceeded in every regard; better flow, better spool, better emap, etc.
A G30-900 should in theory get close to 590 whp and the G35-1050 should be close to 730 whp maxxed out on a 2-rotor. As you noted, the efficiency at those peaks is fairly substantial compared to the other brand. That will translate directly to positive improvements. The speed sensor option is pretty much mandatory.
a big thumbs up on post 4. i found the 34 minute video very enlightening. clearly an unstable bearing assembly. what could go wrong? after absolutely eating your intercooler the "cheap" turbo looks like the expensive turbo.
when i made the switch to a single turbo i bought a Garrett GT4094r. at the time choices in the Garrett family were the GT35, not enough power for my needs, or the GT42, just toooo big a frame, or the hybrid GT4094r. it was awesome. 80 pounds per minute/600 rotary rwhp and between the two on size. then i started seeing the GTX comp maps... big flow from the smaller frame. pricey and for a while no divided T4. i really did/do like the small frame concept.
on the EFR/EGT subject i did get this from a friend ""BorgWarner did let us know the EGT limit for the Gamma-Ti wheel is 1,760 degrees." this was published on Forced Performance's website.
the Garrett G series uses MAR-M material for the turbine wheel which they state is good for 1050 C/1922 F.
No divided T4 for which turbo? They released several of them at the end of April.
Can you provide a link for this? I haven't been able to find them. Granted, I already have a few EFR's so I'm unlikely to get a garrett, it's just for curiosity.
"No divided T4 for which turbo? They released several of them at the end of April."
as i stated: "and for a while no divided T4"
the GTX35, with its zippy comp map, was introduced at SEMA in 2010. my 2016 Garrett catalog shows no divided hotside available including the GTX3584RS. that'd be 6 years later and still no divided T4 so probably that qualifies for a "while?"
the Aerospace Division of Honeywell bought Garrett in 2004. Dan Sussna was in the jet engine division of Honeywell and became Pres of Garrett. i had the pleasure of spending time with him at a number of PRIs and always lobbied him for the T4 divided. he indicated that they have to contract out housings and it is a difficult process. difficult as in 6+ years.oh well.
as pointed out, it is not a problem today.
i do think the outstanding flow V size on the Garrett wheels is directly related to the fact that Dan used HON's aerospace resources. he told me he has 2000 engineers that he can use if he wishes. Dan is no longer Pres of Garrett and Honeywell spun off Garrett in 2018.
Garrett now is Garrett In Motion, a public co HQ'd in Switzerland. Job one for all turbo manufacturers is to be ahead of the OE electric turbo curve. Mazda, true to it's aggressive engineering nature, is near the head of the pack. we will be seeing 48 volt elec systems which are needed to spool the turbo. but i digress.
FWIW, ATP Turbo has been my go to Garrett site for 15 years. generally if you want to know what's new at G take a visit.
i find it interesting that Garrett is making a big deal out of their ability to withstand higher EGTs... it is 4th of 11 bullet points for the G Series..
i find it curious that BW, sort of did an OBTW on the EGT limit during the presentation. i was very surprised and spoke w Brian about it. he was emphatic re 950C/1742 F.
EGTs are a big deal in turbo rotary land as we are often 300+ degrees hotter than piston engines.
so far, i am not aware of any melted or exploded EFR hotside wheels. i have often seen 1800 at the end of a run on gas.
the material's primary use is on the vanes of GE's monster bypass jet engines.
Last edited by Howard Coleman; 07-04-21 at 06:50 PM.
i find it interesting that Garrett is making a big deal out of their ability to withstand higher EGTs... it is 4th of 11 bullet points for the G Series..
I cannot find it right now, but in one of the Volvo press releases for their new (for 2004) S60R/V70R, they made a point of noting that the turbocharger was enhanced to be able to handle higher EGTs. I believe the actual number was 1050c.
The turbocharger is a KKK K24-7400, and KKK was folded into Garrett a while back.
The annoying thing, for a vintage-dork like me, is I have a ten valve Audi that I want to build up like a Group 4/early Group B rally engine, and those engines used K27 turbos. The K24-7400 outflows those old K27s, making more power with far less lag. The march of time is annoying. So I have a K24-7400 hanging off the side of that engine now, because why have lag measurable by number of upshifts before full boost with a dinner plate sized compressor wheel when you can make more power with a relatively cheap modern turbo?
Can you provide a link for this? I haven't been able to find them. Granted, I already have a few EFR's so I'm unlikely to get a garrett, it's just for curiosity.
Who has had an EFR fail on a rotary? Has anyone had a failure due to EGT? So far all I've seen is a lot of EFR kits being sold and used with very very few complaints. Considering the amount of EFR users here, it seems like we would hear if there were issues
So what is the Garrett G series turbo that provides similar output to lets say a EFR 8374?
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.
Who has had an EFR fail on a rotary? Has anyone had a failure due to EGT? So far all I've seen is a lot of EFR kits being sold and used with very very few complaints. Considering the amount of EFR users here, it seems like we would hear if there were issues
Biggest complaints seem to centre around B2 frame compressor casting quality, with post op machining, exposing that issue on a fair few. That cosmetic issue, that's ultimately hidden inside the intake, gnaws away inside a lot of people. Anecdotally, there's been 80mm failures down here in non street use, no info on mode available though.
Basically going on a stock port engine looking for quick spool and 450rwhp max without aux injection (is this possible?)
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.
.
Basically going on a stock port engine looking for quick spool and 450rwhp max without aux injection (is this possible?)
Depends how much boost you are willing to run and if the turbine and compressor are still somewhat efficient at your peak power flow. Not a lot of people are comfortable pushing pump fuel to make a genuine 450 at least on a DD or mainline on a stockport, if it's Freedom Shetlands on a US made dyno shouldn't be too hard if the turbo isn't screaming and you run high teens boost.
In all honesty, the EFR8374 is pretty much a perfect fit for that power range (60 lb/min) and may be the way to go for 450 whp on pump gas given how efficiently it is for where your engine will be operating. However, I think you’ll need to port it some to keep boost at the proper level for pump gas. There are a few threads in here if you search “stock port” (without the quotation marks).
I more or less concluded that the G30-660/770 are not really optimal and leave a gap in hp range. The 660 is really only a 600 (barely) and the 770 also comes up short if you adhere to their max rpm limit based on the 10 bhp per lb/min compressor flow theory for piston engines.
.
Most rotaries seem to do around 7.5rwhp/pound airflow and you need to be mindful of true pressure ratio with filter loss and intercooler pressure drop. Compressor inlet density relative to STD conditions will generally scale the flow map too.
In all honesty, the EFR8374 is pretty much a perfect fit for that power range (60 lb/min) and may be the way to go for 450 whp on pump gas given how efficiently it is for where your engine will be operating. However, I think you’ll need to port it some to keep boost at the proper level for pump gas. There are a few threads in here if you search “stock port” (without the quotation marks).
I more or less concluded that the G30-660/770 are not really optimal and leave a gap in hp range. The 660 is really only a 600 (barely) and the 770 also comes up short if you adhere to their max rpm limit based on the 10 bhp per lb/min compressor flow theory for piston engines.
.
Had some time on my hands and ran the numbers for 18 psi from 3500 - 8000 rpm between the Garrett 900 and EFR8374 compressors. When I posted that I was thinking the earlier efficiency of the EFR might favor pump gas. Not entirely sure if that’s a correct assessment though. Partly because BW skews their map on the horizontal axis and Garrett is skewed more on the vertical axis
The G30-900 with 1.06 T4 could be an option. I also received a G30 1.06 T4 housing from ATP Turbo the other day to for some fit up assessment. Fairly compact for what it is.
BW doesn't advertise the 950C temp limitation loudly because it is a performance limitation on track cars. On a street car that just does a pull here and there, it's not a big deal. But on a road course with sustained WOT, the EGTs will climb. Garrett uses MarM in high performance applications and MarM is also what Garrett's motorsports turbos have always used (well, last two decades) for their turbine wheels. They had to use MarM to survive WRC rally cars and their bang-bang anti-lag systems. The G-series is basically an off-the-shelf Garrett Motorsport turbo, using MarM turbine wheel, dual ceramic ball bearings, and stainless steel turbine housings just like the Motorsports turbos. All to handle sustained high EGTs in motorsports use. Two examples of street cars and how the different turbine wheel materials are selected, Ecoboost 2.3L and the BMW 4.4L V8. In the lower power Mustang, the turbo gets the inconel turbine wheel but the higher power Focus RS gets MarM. The pedestrian ~400hp V8 that goes into regular BMWs get inconel. The high power M5 gets MarM turbine wheels.
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.
when i made the switch to a single turbo i bought a Garrett GT4094r. at the time choices in the Garrett family were the GT35, not enough power for my needs, or the GT42, just toooo big a frame, or the hybrid GT4094r. it was awesome. 80 pounds per minute/600 rotary rwhp and between the two on size. then i started seeing the GTX comp maps... big flow from the smaller frame. pricey and for a while no divided T4. i really did/do like the small frame concept.
The GTX4088R came with the same turbine housings as the GT4094R. It came out around 2011? Not sure it'd be worth the effort to swap, but the GTX4088R would be more responsive and probably spool a little faster.
thank you spdracerUT... sounds like the real story.. i agree based on my experience that the EGT limit for an occasional blast is probably a non factor but if you are on track for a number of laps it might be smart to consider options other than the EFR if you are running gas as base fuel..
thank you spdracerUT... sounds like the real story.. i agree based on my experience that the EGT limit for an occasional blast is probably a non factor but if you are on track for a number of laps it might be smart to consider options other than the EFR if you are running gas as base fuel..
I look after the Mazda RX8 SP Which is turbo charged. Has an EFR8374 on it.
He races it weekly and it does full days of 1000 degrees celcius. (Usually 5 20 minute sessions a day)
Almost 18 months on the turbo and it is in perfect order. We had the engine out after the first 12 months for an inspection and new seals. We couldn't see anything to point to any issues. Exhaust wheel almost looked new bar the discolouring from fuel.
06-27-21, 08:51 AM
