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I like how he made an account to "school us" yet speculating just like the rest of us and has no a/b results just like the rest of us.
carry on
Well, there's three pages worth of speculation now, so criticizing the critic when we still don't have much data seems a bit on the nose.
And I'd say my pocking and prodding had the desired effect, exactly. I got a knowledgeable explanation behind one's opinions backed by true findings, which is far more constructive than many of the one-liner "EFR pwns all" responses that have been prevalent.
The theory is nice, sure. Scallops good, thin blades good, all good. The reality, however, is that T25 turbine wheels has had very similar scalloping for decades. Perhaps not identical from an airflow standpoint, but certainly close enough from a rotational inertia standpoint to call them identical. Fair point. Garret has been working with these much heavier turbine materials for decades and has built many tendencies in their designs, many of which depending on requirements from previous iterations.
Here's a GT2560R wheel for reference. Very similar scalloping. I did my best here to find what I believe is an OEM wheel, vs. a stock photo of a Chinese copy. I believe this is either an OEM Garrett Aftermarket or OEM Nissan GT2560R wheel.
And yet, empirically, the EFR responds substantially better to throttle inputs, despite being ~4mm larger in diameter. So I'll go out on a limb (pretty stout limb IMO) and call bullshit on scalloping making a substantial enough difference to overcome the difference in material weight. I'm not sure I ever tried to make the point that the scalloping and blade thickeness would overcome the material differnece, simply making the point that 2x material weight per volume != 2x the part weight. I'm saying some of the weight difference is made up by material design.
As far as blade thickness, they sure look similar enough to me, perhaps the EFR is a skosh thicker, but certainly not 2x except maybe at the leading edge, where it would have almost no impact on rotational inertia. It's also impossible to see the profile of the blade as it hits the shaft. And here I agree. We're bench racing at best, and I also concur that thickness/weight in the middle is nearly irrelevant which is why we also don't geek out about saving weight in the shaft.
It's also misleading at best to state in this context that "less dense materials are generally always designed thicker". We are not comparing steel and aluminum here, so your rocker example is completely out of place. A more apropos comparison would be Titanium. Titanium has roughly 60% the density of steel, but a piece of titanium with the exact same dimensions as a piece of steel will have 95% of the strength of that piece of steel. Add a few thou to make up the gap, and you have a part which has exactly the same strength at perhaps 2/3rds the weight, conservatively. I don't know if titanium rockers exist, but if they did, I'd bet they'd weigh a lot less than steel and cost an eye-watering amount of money as well. Oh, titanium rockers certainly do exist, for those who spend money on cars like most do on houses. And I agree the analogy isn't perfect, but I still find it fitting. Yes the gamma-ti in the BW is stronger than it's competitors, but it's also brittle (yes, less so at temp but still brittle by comparison standards) and has to be designed accordingly. We see the SAME design considerations when moving to Alu from steel, as most aluminium (you want to use anyone) are far less accepting of bending forces over steel. My point wasn't that "less dense materials are always designed thicker" but that when an engineer has a pallet of materials like an artist has colors, they made trade offs and design accordingly. The main "problem" with gamma-ti is cost, and BW openly admits this drawback. But the drawback they don't readily talk about is it's semi-ceramic nature (since it's not a ceramic or a metal) which leads to very different failure modes as well as rebuildability. I know if I had an EFR on my car (which I'm still considering actually) I'd not want to reuse the wheel if I ever suspected FOD damage, even if it looked visually okay, because of the potential for microfractures. Again, this is an aspect I'm sure BW knows about, and I'll be curious to see if these EFR wheels ever make it into an OEM where there's very different design and approval considerations.
Titanium Aluminide is in the same ballpark as Inconel when it comes to strength at temperature, so unless Mar-M is significantly better than either one (doubtful, and no info on Matweb yet), it's perfectly reasonable to infer weight from density, given that the two parts are designed to function in the same environment. The Mar-M part would have to be substantially smaller to achieve the same inertial performance as the EFR. Not "feathery", but like 2/3rds the overall size. I too, am looking forward to more material data on Mar-M, but suspect you're probably right. My suspicion is that it's basically a "lighter' weight inconel that allows slightly improved heat handling with a shave of the weight cut off. All of Garrett's talk about the new wheel is about temperature handling, not weight/spool, so we know they're not trying to suggest a revolution of design here.
One last tidbit on turbine blade thickness as it relates to flow. Yes, thick blades are in the way of the air. To combat that, all EFR turbines are larger in size than their Garrett counterparts. Like, a lot larger. A GTX2863R has a 53.9mm turbine and a 63mm compressor, an ER6258 has a 58mm turbine and a 62mm compressor. If you're well-versed in turbo sizing, and you seem like you might be, you'll know that 4mm on the turbine wheel is huge. The EFR can get away with that because of that low weight. Empirically, they seem to have absolutely no problem moving nigh-unbelievable amounts of air. I've lost count of how many B1-frame EFR Miatas have cracked the 400whp mark, and I know of at least 3 that have cracked the 450whp mark, all on that 58mm turbine wheel through a 0.64a/r housing. That does not indicate a restrictive turbine side in the slightest. Which actually goes back to my design versus weight discussion. If you're running a larger diameter turbine for the same flow application, that's also going to push the weight of the gamma-ti wheel up, along with inertia from the larger wheel. Now, this is likely more than made up for by weight reduction, thus the gamma-ti is still far ahead, but it's more and more proving my case that it's highly unlikely the Garrett wheels are TWICE the weight... Heavier? Probably. But that's not a reason to start generating blanket statements that lead to ignorance of others. Because if you want to go there, then we might as well start propagating myths that mustangs will now all be faster than miatas because they have irs and more powa...
Empirically, the EFRs outperform a similarly-sized Garrett GTX. They do so substantially when it comes to throttle lag and torque linearity. The T25-550 gives me absolutely no reason to believe they are substantially better than the outgoing GTX units in this respect. I might be proven wrong, but I don't think I will be. And I take up no argument about the EFR vs GTX. From most dynos I've seen and compared, the EFR spools faster and in most cases doesn't seem to run out of breath as easily. The main interest I have in the new G series is that not a single specification has carried over from previous models. It's the first clean slate design in DECADES and I'm extremely curious to see how it does. Also, the fact they're offering mirror variants at the same price has special interest for my packaging concerns.
Responses in bold. And I truly thank you for the time you took to give a knowledgable response instead of just name calling against brands or opinions.
But the drawback they don't readily talk about is it's semi-ceramic nature (since it's not a ceramic or a metal) which leads to very different failure modes as well as rebuildability. I know if I had an EFR on my car (which I'm still considering actually) I'd not want to reuse the wheel if I ever suspected FOD damage, even if it looked visually okay, because of the potential for microfractures. Again, this is an aspect I'm sure BW knows about, and I'll be curious to see if these EFR wheels ever make it into an OEM where there's very different design and approval considerations.
On rebuildability, BW won't do it because they just aren't set up for it, but a couple of members here have had chipped turbine wheels (chipped due to mechanical damage during housing removal) replaced by Mike Franke at Southeast Power Systems. They are AFAIK the only authorized EFR rebuilder in the country.
On OEM use, TiAL wheels are used in the current-gen Panamera Turbo S. Porsche has been an early-adopter of BW's pointy-end tech for a while, at least as far back as their use of Borg BV50s on the 997TT, which was AFAIK the first use of variable-vane turbo tech on a gas engine (someone will be along shortly to tell me that some obscure French car from the early 90s was actually first, I'm sure).
I agree that the EFR wheels likely aren't half the weight, but I bet they get closer to that number than you might expect. The anecdote I was told was that the 58mm turbine wheel weighs the same as the 62mm aluminum compressor wheel. I didn't mean to imply that the wheel was actually half the weight, although I can see how it would be taken that way. I meant to imply a drastic difference in weight as opposed to an exact figure.
Tell you what, though - if you (or anyone else) has a bare turbine wheel and shaft with a T25 Garrett turbine wheel attached, throw it on an accurate scale and weigh it. I happen to have a bare EFR wheel and shaft floating around the shop somewhere that I can dig up and weigh.
Originally Posted by Gollum
Responses in bold. And I truly thank you for the time you took to give a knowledgable response instead of just name calling against brands or opinions.
Seriously though: I believe we were all similarly skeptical of EFR when they just hit the scene and none of us really tried em. So there is hope for the garrett
I would have been skeptical too had I not driven Evan Witty's car at the end of 2011. He had one of the very earliest 6258s on a nigh-untuned stock '94 longblock, but it was still good enough to let me peek at the potential. I was hooked then. AFAIK Soviet bought that setup from Evan, swapped the early defective 6258 under warranty for a revised 6758, and did his 450whp+ setup.
Mar-M (246, or 247... probably the former) is a nickel based superalloy with the biggest material composition difference from Inco 713 being a big dose of cobalt (something like 10%!). There are other differences, but that's the biggie. Mar M is of insignificantly lower density than Inco. The move to Mar M is undoubtedly to double down on robustness to adverse thermal conditions.
Simply weighing the turbine shaft-wheel assemblies won't tell you much about inertia, which varies with the fourth power of diameter. Measuring inertia empirically is a bit more complex but is an established process (trifilar torsional pendulum). And again, inertia is only one part of the story when it comes to transient response (the rest being overall turbocharger efficiency which is an outgrowth of aero efficiency on turbine and compressor each, and the interplay, match-wise, of the two).
Titanium aluminide has existed on the fringes of the OEM turbo world for quite some time. As for VNT gasoline, Sav is right that some pedantic ******* will point out that the first one was the Shelby Lancer CSX in the '80s. It had a VNT25.
Has anyone run one of these on a Miata yet? I've seen some good results from the 0.72 a/r on VW engines, but nothing on a Miata or with the teeny 0.49 T25 housing.
I know it's not a BP, but I saw a dyno from a G25-550 on a Ford Sigma 1.6 GTDI engine. 1.9 bar of boost on 99 RON (93 US R+M/2) = 455bhp, 350tq and 200tq by 3450rpm. They did another run on 110 RON which made 503bhp but they didn't show the plot. They don't state the A/R, but it's a vband setup so likely the 0.72.
That would make for a serious engine in a miata despite only being a 1.6.
I can't see how to link it, but it's on the "EFI Parts" Facebook page from November 2019.
Still wondering if it's worth the cost to go w/ an EFR series. A 6258 would put me back roughly ~$1500 + a new Manifold/DP + adapting current exhaust ~$1100 for a total cost of ~$2600. A 25-550 is about ~2k which works with my existing setup. If the 6258 provides significantly more low end power, then I would say it's worth it for me. I (personally) care more about low end since my car is primarly a daily.
Still wondering if it's worth the cost to go w/ an EFR series. A 6258 would put me back roughly ~$1500 + a new Manifold/DP + adapting current exhaust ~$1100 for a total cost of ~$2600. A 25-550 is about ~2k which works with my existing setup. If the 6258 provides significantly more low end power, then I would say it's worth it for me. I (personally) care more about low end since my car is primarly a daily.
The EFR comes with the nice built in BOV, the 25-550 does not.
The cost is the big problem for me. When all is said and done it is close to $3k in cost to be comparable to the EFR.
I've seen reports that the built in bov leaks with the efr, so a common upgrade is the turbosmart kompact bov. If i do make the jump for efr, i'm hoping that isn't true. It's a small amount in terms of how much the turbo costs but prices start to stack.
I've seen reports that the built in bov leaks with the efr, so a common upgrade is the turbosmart kompact bov. If i do make the jump for efr, i'm hoping that isn't true. It's a small amount in terms of how much the turbo costs but prices start to stack.
I wouldn't say it leaks but it does stay open at certain low throttle situations which causes a very annoying whistle. Borg sells a heavier spring that cost me a ridiculous $35 after shipping. It does solve the problem though.
Still wondering if it's worth the cost to go w/ an EFR series. A 6258 would put me back roughly ~$1500 + a new Manifold/DP + adapting current exhaust ~$1100 for a total cost of ~$2600. A 25-550 is about ~2k which works with my existing setup. If the 6258 provides significantly more low end power, then I would say it's worth it for me. I (personally) care more about low end since my car is primarly a daily.
No EFR dyno I have seen demonstrates where the EFR shines; boost response and boost recovery.
For the few hundred in price difference, that is worth it's weight in gold and makes the car not only much more tractable, but overall a much easier car to drive fast.
Unless I can drive a G550 turbo on the same engine, I am sticking with the EFR for the forseable future. Garrett still hasn't caught up to the Gamma-Ti wheel on the EFR as of yet in terms of weight.
EFR sounds like garbage though? I know that sounds like a silly thing to add to the equation, but none of the video's I've seen have impressed me with their integrated BOV. It is less things to worry about when assembling a new kit, but don't think it's worth a swap now that we have better Garret options.
^^ An integrated CRSV is less things to worry about than an external BOV that now one will have to source, get welded to a pipe and have to fabricate the location as well as re circulation?? If you already have one sure, but if starting from scratch, that thought process does not compute
^^ An integrated CRSV is less things to worry about than an external BOV that now one will have to source, get welded to a pipe and have to fabricate the location as well as re circulation?? If you already have one sure, but if starting from scratch, that thought process does not compute
You lost me at "sounds like garbage"......
Yup if your starting from scratch I can see many advantages to EFR. On sounds, I'm talking about the whistle which does have a aftermarket fix.
04-16-2018, 11:09 AM
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