Which is why I pointed out my engine operated at 1,000C egts at cruise...

40,000miles of lean burn 1,000c cruise 2001-2014 between the WOT pulls.

The "regular" Inconel Garrett P trim and BW TiAl exhaust wheels had absolutely no issues.

I believe the egt issue will be those elevated egt temps PLUS wide open throttle exhaust flow = exhaust manifold pressure.

As you point out a torture test scenario.

In a rotary that will cook your turbo exhaust wheel shortly AFTER you sack out apex seal springs, corner seal springs, seize your sideseals lengthwise against the corner seals.

1967-2002 rotary has an exhaust port that never closes.

If ones EGTs under high EMP cook your exhaust wheel, its usually cooking your rotors.

Been there, done that 3rd gear rolling burnout down the freeway- added a bunch of fuel to medium boost high rpm map after rebuilding the engine and seeing the damage.

Havent heard a single report of failed EFR on a rotary.

EFRs TiAl exhaust wheels seem to be up to Indycar and F1 reliability standards.

I am open to learning.

______________

I dont know of Im saving for another EFR or waiting for Garrett to give me a G series

 

Yeah, Garrett and BW have a fun little battle going on in the performance aftermarket. Though, BW hasn't shown anything new really since EFR which came out more than a decade ago. You do know Garrett is typically the largest OEM supplier right? Closely followed by BW. Then a big gap to the rest. Garrett has been averaging about 3.2 million turbos a quarter for the last 6 quarters. Link to their quarterly report for investors below. I think they can afford to give away a couple turbos as marketing costs. I'll assume Rob Dahm is getting his turbos for 'free' from Garrett. What does Garrett get for 'giving' a few thousand dollars worth of turbos? Rob's video's typically rack up 150k-200k views each and he has over 1 million subscribers. Plus, Rob is doing tons of testing. For the cost of 'giving' Rob a turbo, they've already gotten their investment returned in one dyno session from Rob. It would cost Garrett much more money to do dyno testing themselves after you rack up the labor to install, dyno time, tuning, etc. And of course, Garrett would need to purchase a car and all the modifications necessary to go with a turbo upgrade to start. Garrett is literally getting 50x return on investment by giving Rob a turbo in data and marketing. Gas stand data is one thing, real world on-engine data another.

https://investors.garrettmotion.com/...e-c9b16c50bc9d

Indycar is a cake walk compared to Le Mans or WRC. 24 hours straight at full throttle in Le Mans and full throttle or tons of anti-lag in WRC. And BW isn't in F1 as far as I know. Garrett supplies Ferrari. Mercedes makes their own turbos; Mercedes makes their own turbos for some of their commercial trucks. Not clear who supplies Red Bull or if they do in-house. Of course, F1 turbos are e-turbos.

Really, TiAl turbine wheel is best suited for street applications where you want quicker transient response at low engine speeds. That is less relevant in motorsports where you're always in the upper half of the engine speed range. Not to say irrelevant because any racer wants anti-lag for max response on a road race car, assuming no e-turbo. But with modern advanced engine control systems, they run different strategies these days which makes anti-lag and inertia less important. Audi DTM dominated by being clever in their engine management. Their control strategy was to maintain a target boost, not a target lambda. Essentially keeping the turbo always spooled up and not even using old school pop-bang WRC style anti-lag. This magazine has the tech article on the engine. Really fascinating stuff. Oh yeah, not to mention modern dual clutch and race transmissions where you're never off the throttle during an up-shift.

https://www.highpowermedia.com/Produ...logy-issue-136

The full back disk turbine wheel design is both for strength and efficiency. It's basically mandatory for VNT turbines as the vanes in a VNT create extra excitations in the blades, so the full back disk is required to strengthen up the blades of the turbine wheel to keep them from breaking apart. Of course that mass is at the largest radius which creates the most inertia, so it's a trade-off. Casting TiAl is tough and my theory for why BW has to use thicker blades. The stuff just doesn't poor easily. That wide flat surface at the inducer of the turbine blade can't be doing the flow and efficiency any favors.

@Howard Coleman I think you'll love the G40-1150. I think it's one of the best turbos in the G-series lineup. The others being the G25-550, G30-660/770, G35-900. Maybe the G42-1200 too.

One more note. The G-series helps make up the gap to EFR in inertia by flowing as much from smaller wheels. The G30-660 with 67mm/60mm comp/turbine flows almost as much as the EFR 7670 with 76mm/70mm wheels. Though, I've always thought the EFR 7670 was the low performer in the EFR series. The G30-660 is basically a match for the EFR 7163 in flow with a bit smaller wheels to gain back some of the inertia disadvantage of the MarM turbine wheel vs TiAl.

 

"In a rotary that will cook your turbo exhaust wheel shortly AFTER you sack out apex seal springs, corner seal springs, seize your sideseals lengthwise against the corner seals."

yes.

the rotary's blessing is also it's curse. blessing is it can FLOW so much charge air and therefore make loads of power. curse is it can flow so much charge air and make so much power.

combine the monster flow with delicate internals such as corner seal springs, apex seal springs and yes apex seals. (they WARP)... and you have a challenge. actually a number of challenges such as block integrity, a subject for another time.

while i won't be doing any of the OE torture tests i do think the Mile is as close as you can get to thermally challenging the motor ex laboratory. certainly other forms of motorsport also present challenges but often of a bit different nature. many running the quarter are in another zipcode from my 600. the Q is also different due to duration. 6 to 10 seconds. the mile is approximately 30 seconds. Indycars and F1 are limited as to power and stress and are exquisitely engineered and tuned. (me, not so much)

prior to running in 2013 we did a dyno run in 5th gear to 205 mph. for sure, it isn't the same as the real thing for obvious reasons but it was 22.2 seconds in 5th gear w the foot planted firmly on the floor. it was also after numerous runs so the intercooler no doubt was a bit toasty. the motor was perfectly happy after:




at the time i was running a T56. unfortunately it had a waay too long 6th gear (.5) so we had to stretch 5th gear out to get to 205 mph. 8604. while this might have been do-able, when you get to around 200 mph your acceleration is close to zero which means the poor old motor is almost static at 8600 and around 575/600 rwhp. that's where we were in 2013. fortunately i now have the new Tremec Magnum F with a wonderful 6th gear so now 200 is a much happier 7000.

my only point here is that on the dyno we were able to find the top of fifth and the motor was fine. on track may be different of course. this was w my wonderful GT4094R and 77% ethanol.

the primary reason i switched to the G40 was to help with IATs. in the above log air exiting my turbo before the IC was 377 at 8400. intake air was 165. 100% methanol at 165 psi was in the mix lowering the IAT by 30 F. corrected for the meth my IAT was 190. dyno ambient was 75.

377 minus 197 = 180
377 - 75 = 302

180/302 = 60%. IC efficiency was 60%. this is exactly as indicated by my Spearco IC core efficiency chart. yes, in the real world really good ICs can remove 50-65% of the temp increase above ambient. real world being logging your IATs with a thermocouple.




.
my focus is 80 pounds per minute and about 3 pressure ratios, 30 psi. efficiency about as good as you can get. we will soon generate some on the road numbers.

 

I'm curious if anyone has thought about C02 (cryo) injection into the intercooler?

I remember seeing a few kits long ago. Now with all the tuning tech, a can bus running cryo injection being triggered by IAT sensor could fog the intercooler sometime during the 30 second mile long blast.

 

Sure anything helps.

Remember cold C02 on a hot IC can cause cracks in the Aluminum.

Water works really well as its the endothermic reaction of phase change from liquid to vapor that takes most of the heat out of the IC.

In fact at the local hillclimb I found hot water cooled my IC down much faster than cold water because I was able to keep more water evaporating off the core over time with water closer to its vaporization point.

A real trip putting hot water on a hot IC and getting a cooler than ambient temp IC out of it, but that is science.

__________

For the 12hr Bathurst/Eastern Creek production car races the FD dominated 1992-95/cancellation Mazda filled the gas tank with liquid nitrogen chilled gas each pit stop.

 

It sounds like ditching the Greddy Vmount for an air to water set up with heat exchanger for the street with pump and rear tank is a better idea. The drag guys run A2W but I'm not sure if I've ever noticed a heat exchanger with their set ups.

 

i spent lots of time researching IC spray systems using both CO2 and nitrous.

while CO2 is much less expensive and easier to find (for me) the problem is it should not get anywhere near your air fiter/into your motor.

as to nitrous, it is just a question as to how much cooling can be delivered V the amount of heat passing thru the IC. i have seen some calculations where a whole bottle is pretty inconsequential.

as to water, if it doesn't evaporate off the core it acts as a great insulator keeping the heat in the core and keeping the core from contact with the passing airstream.

after testing 4 IC cores i took the best and then found some 360 F silver tape. i taped the duct to the core so it is literally airtight. i then added two Spal puller fans/just over 2000 CFM/ to the back side of the core... and called it a day.

i do think that generally the single turbo FD is very poorly served as to intercooler efficacy and that includes the current heartthrob the Greddy V mount. if FD owners measured their IATs with a thermocouple many would have heart attacks.

the net is no matter what we do it is all about IATs.

here's a recent log, around 550. end of the run (end of the road) about 7800. note the bottom section. air temp out of the turbo topped out at 416.3. IAT topped at 158.8. the third plot is my AI system pressure. about 1000 CC/min of 100% meth. 37% ethanol as base fuel. notice with the onset of meth the IAT stopped following the turbo output temps and pretty much went sideways. looking at the rising turbo output temps and the initial IAT plot where might IATs be with no meth? at 26 psi. how about at 9000 and 30 psi?

 

I gave up watching that guy’s videos a long time ago. He never provides a fair and balanced viewpoint when making this comparison; never.

Not sure if anyone caught this recently; 13B-REW semiPP with G35-1050 T4 div1.06; run 3 on bottom was just to see how fast they could get it to spool -

33 psig and 560 ft-lbs at 4300 rpm, had to back out of it because everything was maxed out and not able to support the output.





the two runs above it are @ 20 psig … semi-pp really needs the G40/G42
.

 

Are we talking about the same videos? Turbodirect S.A.?
He cuts the turbos in half, takes them apart, and weighs the parts on camera. He also sells both products. Not sure how you get less biased than that?

 

Whats not a fair and balanced viewpoint from Rob's Rotary C5 videos? He seems pretty fair to me.

 

Rob also says the Turbo itself was maxed out- he said it twice, he made 612 hp at 1.5 bar(20 lbs of boost).

As the video in this thread claimed and on the compressor map where the G35 1050 falls off, it's just past where rob made max power on the rotary corvette. Even if he had enough fuel for another bar of boost, I bet he'd pick up a max of 75- 80 hp.

Map 2.8 (1.8 actual)=100 lbs of air

The 33ps torque number would have most likely to equated to 700hp or maybe less since the turbo is falling off on the map at that boost level.

 

...not if the turbine is choked off due to the increased flow of the Semi-PP engine. So while the compressor mathematically can make 700hp, the exhaust gasses back up the turbo in the small turbine housing and prevent that power from being made.

 

And that's "if" the G351050 can actually move 100lbs of air as the compressor map claims. I doubt it can.

i Remember when it was said that the latest versions of EFR models with the larger compressors were miss matched vs the turbine and that they were inefficient. Not in this comparison.

At first glance, 600 hp at just 20 psi is appealing, that is until you need more and this $3500 turbo has already dropped its nuts.

 

When does any turbo make the peak number on a given compressor map?

You probably won't make 600whp at 20psi without a Semi Peripheral Port.

 

Of course the compressor flows what the map says. Garrett has calibrated gas stands for all their testing. Calibrated gas stand are required for doing simulation and matching for customers like Ford, BMW, Caterpillar, John Deere, etc. Without calibrated gas stands, you can't do accurate turbo matching for the OEM customers. If you can't do accurate simulation and matching, you end up wasting time and money on hardware iterations and testing on-engine. Like I said, I'm kinda meh on the G35-1050 as the turbine really isn't big enough for that compressor. I'd guesstimate the turbine pressure ratio is around 4.5, i.e, really high and bad. Doesn't mean the compressor isn't flowing 100lbs/min though. The G35-900 is the better overall efficiency turbo. And that's also why I say the G40-1150 is a better overall efficiency turbo than the G35-1050; the G40 has a proper size turbine to go with the compressor.

 

People fail to realise the filter loss most people trying to make big power will see on our motors, compounded by high i let temps if not ducted, easy to lose 10%+ inlet density and hence total flow capacity.

 

which G40-1150 a/r turbine housing better suits a semi-pp 13B-REW for a wide powerband and peak power of 600-700whp? T4 divided 0.95, 1.06 or 1.19?

 

[QUOTE]
which G40-1150 a/r turbine housing better suits a semi-pp 13B-REW for a wide powerband and peak power of 600-700whp? T4 divided 0.95, 1.06 or 1.19? [/QUOTE]

Since you did not specify "turbo response" as a requirement I believe the answer would be the largest exhaust housing.

A Semi peripheral port powerband is VERY wide flat torque band by nature 5,000rpm to 9,000rpm can be within 10% of peak torque at 800rwhp like in ErnieT's old set-up.

From what I have seen though, a stock based long runner intake manifold (example- XS LIM plus any UIM) will limit the semi peripheral ports broad powerband greatly.

An old school short runner 4150 or any newer Projay short runner intakes are typically needed to extend the flat torque plateau beyond 7,000rpm.

 

Well, turbo response is always desired, after all, it's still a street car.

I have a semipp modded Elite intake manifold on it which has slightly shorter runners with larger diameter. Everything was port matched to cosmo gaskets. FD throttle body bored by RC Engineering.

Right now I will be using a GTW3884R 67mm (6765) with 1.15 a/r divided. The G40-1150 would be a future upgrade.

 

This map, while it doesn't show the turbine efficiency curves, actually shows more detail than Garrett usually shows. The key thing being where the lines end. Every turbo shaft speed line on the compressor map has a matching speed line on the turbine map. Compressor power increases with mass flow and compressor pressure ratio. More compressor power means more turbine power required which equals more corrected gas turbine flow and pressure ratio. So the first speed line on the compressor map would be the very first portion of the turbine flow line; low compressor power requires low turbine power = low gas flow and low pressure ratio. The fastest/top speed line on the compressor map which requires the most power will be the end of the turbine flow line per A/R housing. Turbine power is a function of gas turbine flow x pressure ratio x turbine efficiency. On a real turbine map, you can see all the corresponding turbine flow lines that correspond to the compressor map speed lines. But Garret just blends all the turbine flow lines into one solid line for general consumption. The turbine efficiency drops so hard on the 1.19 A/R housing when the compressor is operating at max speed, that even with higher mass flow, the turbine pressure ratio has to be higher than the 0.95 A/R and 1.06 A/R to make up for the bad efficiency. Another sign the 1.19 A/R is too big is that the corrected gas flow actually starts to drop at the high pressure ratio.

So the sweet spot will be either the 0.95 A/R or the 1.06 A/R. If you're looking to max out the turbo running at the top 125k turbo speed, I'd just go 0.95 A/R. Might as well get the spool-up benefit. If you're looking for max efficiency at a more modest power level, the 1.06 A/R will allow you to make more power at the same boost compared to the 0.95 A/R in the mid-range. Say if you were only pushing 100k-110k turbo speed. Road race car, I'd probably lean towards the 1.06 A/R to lower the overall stress on the engine during sustained high-rpm use. Street car, I'd lean 0.95 A/R for the spool-up.

You'll notice the divided housings have a bit more flow resistance/higher turbine pressure ratio than the V-band due to the extra surface area of the divider wall. But the divided housing more than makes up for it on the engine by preventing the interference of exhaust pulses from the other rotor (or next firing cylinder on a 4-banger).

 

Guess you will know more of what you want once you have it running on the GTW3884R. That sounds hairy enough for me in a street car.

 

I felt the G40-1150 with 1.19 AR was too laggy for the street/track on a street ported engine. The Semi-PP will help but I'd recommend the 0.95 for your use.

 

you missed the ongoing thread context then; I was referring to the videos from the guy in South Africa. IMO he’s biased in his numerous presentations on BW EFR vs Garrett G-series. He’s very selective on which strengths and weaknesses are presented and how they’re presented.

As for Rob, not really sure where his head is at times. I addressed all that and this too in other past posts though.

Again, people keep discussing A/R, what they never discuss is turbine mass flow values. Likely because they still haven’t concluded what the range needs to be for a given whp on a rotary engine yet.

if you go to where they were dynoing at 20 psi it was stated that the fuel system was maxed out. They still were able to generate the superb tq output at 32 psig, but only at low rpm because of that. Obviously the turbo would be maxed out if they had the fuel system to support it for higher rpm/power, but the final output then has yet to be determined.

So my suggestion is this: go see what the peak flatline mass flow rate is for the G35 1.06 A/R div T4 turbine housing and start familiaring yourself with this information. Because as the turbine flow curve draws close to that flatline is when excessively increasing backpressure becomes manifest.
.

 

Im guessing the G40/G42 will have better emap?
Other than slightly better response on the G40, would it not make sense to just use the G42 1200 on a semi pp to make more power on lower boost with better emaps?
I've got a G35 -1050 and with only 14psi im hitting 100-200kph in the 7.6s range but I dont know if the G35 will be able to run a 5s 100-200kph. Its great to have dyno results but would be even better to see real world performance alongside the data as well.

 

There's a general bias in this single turbo forum to get big turbine housings, which makes sense because it's a high hp crowd. Of course smaller turbine housings are restrictive. It's the price you pay for making boost. If you put the car in 5th gear and floor it (obviously speed limited on the street), the boost you make at a given rpm is more affected by the turbine housing and porting than anything else. This is why the FD used sequential turbos (given the turbo technology of the era). It only had to spool a small turbine area when running on the primary turbo. You also get into weird scenarios where retarding spark (actual antilag or just in the spark maps) actually increases boost because it effectively adds mass flow to the turbine.

Remember the pressure ratio on a turbine map (p3/p4) is the turbine inlet pressure compared to the turbine outlet pressure. Higher pressure ratio = more backpressure, which drives the turbine. It's all very straightforward. Stock turbos on stock engines (your mom's Ecoboost Ford Escape) are practically choked on the turbine housing, but that's how they make boost at low rpm. That then allows the transmissions to stay in higher gears and lug more for fuel economy.

Selecting a turbine housing for boost at low rpm and low backpressure at high rpm is like a fundamental optimization exercise in any turbo selection. Nobody here has a full simulation model of their engine, or a test stand, or a huge array of turbo combinations to try in the real world. There's a certain amount of artful guessing involved, and more importantly -- clarifying the priorities is important.