Lithium

I bet a cheeseburger that their packaging is not a spitting image of the RB26 configuration. A huge amount of my argument against low mount twins in a GTR when any kind of flow is needed has to do with the packaging.

Things have changed a lot but there are still PLENTY who say that kind of thing, surprisingly.

9180 would do for now Hows that build of yours going? Sick f**king work Piggy, looking forward to seeing the final result - but you're already smashing it. Can't wait for the data, and for you to finally be able to get out there and do awesome shit with it. I remember the OTP discussion we had back in 2013 where you were challenging me to think of any RB setup with response and power like your own, bet you wouldn't have expected your own car to end up with a single turbo on the exact same engine and as a result stand up harder earlier than it ever did before? f**king kudos to having the Insight involved to get a great thing even better. Honorary mention gotta go to the drunken conversations with the Wild the sphincter of the universe Rare Breed. * This post sponsored by the SAU language filter

There is one part of it I reckon has a fairly good chance to, look forward to seeing how it goes though

Yeah agreed GTSBoy, but it feels like there are mixed messages regarding avoiding failures and I am just trying to get the best info I can for the good of everyone. I don't want people to have failures, and neither do anyone who are selling them - but also I don't want people to be using them well below potential for fear of overspinning them when the failures could just be to do with people trying to push past their speed limit and everything going out of control. It is the turbine wheels which are failing, and there have been noises that the 9174 is good because the turbine can be spun faster - it clearly has the same compressor though, so maybe you can see why raise the question of if the compressor rpm limit may not necessarily be an overruling safe limit for that turbo? Not saying I think that's the case, but would love to know if I should be telling people "ACTUALLY, stay below 105,000rpm to be safe" or "so long as you keep under 116,000rpm you should be ok". Make sense? Either way, anecdotally (at least so long as the safe limit for turbine speed is safely past the compressor stonewall rpm) it seems any argument about worrying about overspeeding these turbos being a sign they are too fragile to push hard is completely invalid - if the overspeed failures are because of exceeding the choke flow then they really aren't making any more power because of that speed anyway... its just trying to beat a dead horse to death at the risk of causing a turbine failure.

Using 560/(comp.exducer / 1000 * pi)*60 I get the following numbers. I am using the truncated exducer sizes from the turbo names because lazy so that will add a bit of error, but overall should be close enough. EFR 6258 - 172,503 RPM EFR 6758 - 159,630 RPM EFR 7163 - 150,636 RPM EFR 7670 - 140,726 RPM EFR 8374 - 128,857 RPM EFR 9174 - 117,529 RPM EFR 9180 - 117,529 RPM Clearly the EFR6258 and EFR6758 are both the same turbine wheel, so this is nothing directly to do with the turbine's ability to handle those given rpm. Also worth noting, based on that data the Full-Race site is suggesting you can spin the 91mm compessor off the map with the EFR9174. I trust this explains my concern?

OK, I went through all of the wheels converting the 560m/s max to rpm and it seems that the numbers closely correlate compressor tip speed to the comp maps with rpm instead of tip speed. The trick here is that completely backs up what I had being saying that I suspect that the compressor maps don't give any information about the turbine wheel max speed. In fact, the full race site actually gives the 9174 a higher max rpm than the 9180 despite having the same size compressor. It's VERY easy to see what I mean here... please hold...

Is that at full throttle, or just cruising around? What fuel? Those are BIG timing numbers if it's on boost. If thats cruising then that sounds like some real messy mapping or the remote possibility of a boost leak if it's transitioning onto boost, perhaps knock control? Very hard to speculate with so little info but sounds a bit off.

That was exactly what I was asking Geoff... if they had picked a max line based off the suggested max turbine speed, or if it was just the stonewall for the compressor. I don't agree that the 116krpm mark is at 70+% efficiency at all. Look at this map and extrapolate what compressor efficiency you'd be at if you were running PR 3.1 (~31psi) and running at 90lb/min - it's going to be <60% compressor efficiency which is beyond what Garrett would normally show on their compressor maps at all.

Yeah, without getting so specific - this is what I was getting at earlier. The compressor maps from Borg Warner for all I can tell are very much based on rpm stonewall as you say - which has nothing to do with the turbine side, yet the rpm limits thrown around are painted to be max turbine speed. What worries me about this is there have be comments about the 9174 being "safer" to push hard than the 9180, and that the new EFR range will be lower rpm to save the turbines... this could make one hypothesize that the turbine speed on some of these turbos (ie, the 9180 particularly) should be kept below the rpm stonewall for the compressor, but there is nothing to give any confidence one way or the other. Does that make sense, or do you think I'm missing something?

As far as I know the 8374 can reach the max compressor flow without any worries of the turbine speed being exceeded - if you start overspinning it then part of the silliness is that the gains are going to not justify the risk. When you reach that point there is nothing a GTX3582R would be doing that the 8374 isn't - in fact you could probably run it with no gate and still fall short though I am not totally sure of that but you should get the idea. You sound like you don't know enough about turbos to bag them and rslg should be talking to someone who does before making expensive decisions - if you are out of compressor then trying to push harder is just being silly. You can't just keep trying to turn the boost up and hope some how you will make more power if you have the wrong sized turbo... You probably should have got a bigger EFR if you needed more power and were willing to spend that money

I don't agree at all, that is bizarre logic in itself "If it does fail due to exceeding the RPM limit" is ... uhhhh.... just read "Exceeding the RPM limit" and think about the meaning of that phrase. You've (and others) have bought a turbo which has a turbine wheel which is way lighter than the typical inconel offerings and that is why you have the epic response you'd not have with the equivalent Precision, the cost is that the fancy material is less tolerant to abuse... its nothing to be cheap or dodgy. Its about being a numpty and expecting a precision piece of equipment to hold together being push outside it's design specifications and somehow thinking its on the components fault if it doesn't cope. You are right, you can probably push a 6266 harder and make more power so if that extra response is not your cuppa then you know that - so it naturally makes sense to you if you are willing to accept the alternative situation where you could run the turbo within the advised limits and it could start smoking just because it feels like it, or get a Garrett and again ... not get quite the response but know it will be reliable and perform well. In all reality a lot of this is why I often recommend Garrett turbos as the GTX are the simplest most reliable solution even if they aren't the pinnicle. If you / the people you are working with know what you are doing and want the best and can afford it then the EFR is the best option but certainly not the only one.

Those are clearly pulled from the compressor maps - unless there is info which answers what I was asking (ie, that the compressor map factors in turbine speed) however if you look at the EFR6258 and EFR6758 ratings, those speeds are clearly not to do with turbine speeds given they run the exact same turbine. I'm talking about something actually official and definitive, from Borg Warner and stating that it is about the *turbine*.

Awesome, obviously I am missing something then - I've tried looking and so far can't find it, can you please point me at somewhere which either a) Specifies specifically that the turbine speed should not exceed 150,600rpm (which is coincidentally the last rpm line on the compressor map, which doesn't have to mean that it's at all linked to max turbine wheel speed b) Clarifies that the compressor map is constructed to sit within the confines of the maximum speed you should spin the turbine to. ? I research these things quite thoroughly and I've not seen anything beyond the Full-Race website's "125,000rpm" limit mentioned - that is the only time I've seen a limit mentioned, and it doesn't refer to any Borg Warner official specs I've seen, and I've certainly not seen that in any of the Borg Warner spec sheets I've looked at. If you are investing heaps of money and intend on pushing hard it really would be nice to have some more clearly communicated specs on this. I'm not saying that they aren't there, but I have no found anything which I consider clear and exact so admit that I may have missed it but I'm certainly not the only one who hasn't seen it specifically outlined for the whole range and would benefit from that being clarified, so pointing it out would be very appreciated!

This is kind of a good point which I've been meaning to ask @Full-Race Geoff... or anyone who has found anything, I've never seen any official Borg Warner documentation on the maximum recommended turbine speed for any of their EFR range - same goes the Garrett range?! They both have the rpm lines on compressor maps, but there is nothing stated to indicate that any of those imply a maximum rpm - which from all I can tell is treated like a single magic number. Is there any information available we can refer to? There has been much noise made about how risky it is to go past the max rpm of any of these turbochargers but without that max rpm I feel awkward sometimes bringing it up without any supplied information. One of the justifications given for the EFR9174 existing is that it allows for more rpm safely, which implies that the compressor wants to spin faster than the turbine can happily spin at - but that is a number which we are not given... obviously going off the compressor map will result in rpm skyrocketing to try and move any more air as compressor efficiency plummets but surely the intention of the 9174 isn't to encourage running the compressor into uncharted territory? Clarification would be awesome

I am not sure they are totally consistent, my general feeling is the order of "generous" to "heartbreaker" for your average example of each would be Dynapack=Dynojet, Mainline=Mustang, DynoPower (Popular NZ dyno), then Dyno Dynamics... but then there seem to be more generous and also harsher examples of all of those which throw the rules, rules of thumb for dyno comparisons can't ever be taken as gospel from my observations so far. Sound Performance use a Mustang dyno and they made ~770whp (over 550wkw) out of a 1.05a/r EFR8374 on kill with a hot 2JZ - if that was an absolute then comparing that with this result basically kills the "twins are better" argument for EFRs, which to be fair is a tricky one as there has not yet been transparent public result for twins which have justified their use over a single EFR that I've seen beyond where the twin kit covers what no single EFR can do (ie, twin EFR7163s flow MUCH more than any single EFR).

Oh that's interesting - that sounds a LOT more positive than I expected, what size cams and what headwork do you have again? Normally 758whp on a US dyno doesn't necessarily represent THAT fast a car.

Interesting - I would have expected more than that! Still, must be pretty solid even with that? That doesn't sound great

Sounds not too bad all things considered! So was there any reason why it's tuned conservatively or not pushed as hard as it initially sounded like you would? They should have HEAPS in reserve. Keen to see the dyno plots and the further updates you mentioned

You need to go in a "normal spec" GTR after your own sometime, and realise that maybe what you're trying to build isn't a GTR at all

Cheers for the updates - that is actually even laggier than I expected, but of the ilk. Glad you are at least not having issues building higher boost levels.... is the higher boost/E85 tune still being done today? 641+whp on 91 on a Mustang dyno isn't kidding around, that will be very interesting with E85 in it

What kind of dyno is this on? Good luck for the rest of the tune, keen to hear how it goes - if you are winding it up then this should be a drop in the bucket considering what twin 6758s should be capable of

So which are you going?

1.05a/r twin scroll setup. I know it sounds big, but trust me on that - it'd be the go. No matter what you'll be down for a bit of fabrication for that power level, what packaging limitations or preferences do you have? Are you preferring to stay single entry? In your position I'd personally be looking at a GTX3582R if single entry was the preferred choice, or EFR8374 if twin scroll was an option. Both are very potent turbos and ideal for that mid 400kw @ wheels range on E85