Lithium

I don't fully agree, sadly. And given I'm the one that started going on about these turbos ~12 years ago its hardly that I'm biased haha. There has been some pretty good conversation for, against and about from one side or another and it is still fairly frustrating that the conversation has been going for 12 years and there is still pretty f**k all data on them. I don't blame people for having doubts.

At THAT kind of level, yes EFRs have their place, as with Xona Rotors and Garretts.. The 6466 and 6870 are beasts as well, but I only really lean to them as being "the best" until you are looking at over 1000hp - realistically it seems that as much as you get people talking about EFRs being fragile, smoky Precisions seem more common than broken EFRs. Why not stick with your Garrett? They should have heaps more in it.

This! I was gutted when the trolling started in my original thread which ended up with it being locked, now there is near 12 years of quantity over quality to browse on the topic - I'd take an obscene bit of pride in starting the longest running technical handbag fight on the interwebs!

No worries. Based on what you've seen there, and if you've got the setup to hold it - I'd write off the G42-1200, the 7275 as well as the EFR. I personally would go the Precision 76mm over the Garrett 79mm as well, the Precisions are just so proven at this kind of level on this kind of setup... just such a known quantity for offering a good balance of compressor flow, response, and backpressure. If you haven't seen this then find some time to have a watch over it, it is very relevant to this discussion. The TRC R32 GT-R runs an RB32 with a Precision 7685 Gen2.... Out of interest there are people running Xona products in Oz, Cartel in Oz (https://www.cartel-aus.com/product-category/turbos/xona-rotor/) sell them and have a few people running them to good effect. They're also pretty proven in the US, but there are levels which different brands seem to have focussed on and the area you are looking (single turbo comfortably making >1000whp on a 2-4litre engine) is pretty well covered by Precision and I'd not suggest anything else. The Xonas are best at the "700-1000whp per turbo with epic response and not epic backpressure" kind of deal - to the level that cars running them often are matching or beating things with bigger peak power numbers.

Hi sir, this definitely feels like it could be wide open aside from the fact you seem to have stated the "1100hp GTR" thing as an absolute requirement. I'm going to do my normal annoying thing and respond to your question with more questions, and bring in some philosophical yarns about it - not to talk you down as that might not be needed, but just in case they are things you've not thought about. 1) What kind of dyno are you looking for "1100whp" on? Making that on a Dynojet in the US or a hub dyno anywhere vs making it on a Dyno Dynamics or even Mustang rolling road dyno are two quite different things. We're talking the possibility of needing to make 15%+ more power to measure "1100whp". 2) Given that dyno numbers are so all over the place, do you have an idea of how ACTUAL fast you want it to be? Have you experienced a car which would do sub tens, or driven a "BIG turbo car"? 3) What kind of transmission are you going to be running? If you are going to be running a clutched/h-pattern gearbox predominantly on the road I'd definitely be biasing the more punchy things versus hoping for a full 1100whp personally. I guess you are using a few cubes, but it can be pretty amazing how much boost you lose in shifts if you don't have no lift shifting or anything like that when using a large turbo.... there is probably a zone where if you are going to have some mechanical sympathy that a more responsive/lower powered turbo will be as quick or quicker EVEN on the 1/4mile. I'll leave those questions and be interested to see what you say, but to give a general feeling from what you've said so far - what I'd go for if I were in your position: 1) If the 1100whp target is important and you are using a sequential/auto and especially if you have the option of no lift shifting when you are in race mode - I would actually go Gen2 7675, or even 7685. The amount of lag you step up to when you try and aim for a legit 1100+hp starts blurring a bit, and if "crazy power" is important to you then you're going to want more anyway. People don't seem to sit with 7275 sized turbos for too long, once you go past the solid 68mm things people just end up unhappy until they've gone ~76 from what I've seen. If you really want 1100whp, just go straight here imho... don't f**k around. 2) Of the options you've provided, if the peak power isn't THAT important but you want it to be fast then if it were me and I wanted something that 90% of its life it was on 98 and road use and especially if you're using a more convention transmission etc then I'd use an EFR9280. I don't think it will make 1100whp on E85, it may fall pretty well short - but it will be very fast, and very usable. I'm not super blown away by what I've seen of these though, like I'm not certain that they are any better an option than the best 68mm turbos out there which makes me hesitant to suggest them given the price, intolerance to overspeed, and less than ideal packaging which brings me to: 3) If I'm answering #2, but casting a wider net to options you've not mentioned so that I'm just answering "this is what I would do in your shoes". If it were ME then I'd go with a Xona Rotor XR9569S. This is not because I have enough data to prove that its the best choice, or even that I am necessarily 100% sure that it is. It's more that I have a hard on for Xona Rotor right now, I feel like the best 68mm turbos (so the Precision 6870 deserves an honorable mention here) offer a real nice in between for being a fun street turbo but also the potential to be real world FAST... often nipping on the heals of things running the bigger frame units despite being down on peak power, especially where conventional gear shifting is involved. The Xonas are something different, very unique turbine wheel which have amazingly low EMAP for their size, very good transient response, have a TiAL v-band flange which is easier packaging and potential upgrade path wise I think, and you're not likely to make peak numbers any higher without going >70mm. The two quickest A90 Supras in the world right now (well, last I checked) are running high 8s at >155mph with these turbos on 3.2litre straight 6s without nitrous - peak numbers aside they can make for a proper fast car but something that would be still really fun and real world fast "just" running on pump gas, you'd not need to have E85 and be revving it to the moon to be making it seem worthwhile. In regards to the twins, imho you would have to REALLY want to go that way specifically. PMC's G25-660 RB28 does seem like an epic combo for the power to be fair - probably the most impressed I have been with a twin-turbo RB setup that I can think of but as you said yourself, a lot of expense and not a very flexible point to build on if you decide you want to change in future. Just my NZ2c

The trick is there seems to be a trend of this from the few black series EFRs I've seen results in, at least one tuner I've spoken to has decided it's a back pressure issue but this data doesn't suggest that to me. The trick is I don't know where to go with it beyond the possibility that the compressor map or something about the data is not accurate which I'm not going to leap to concluding. If you follow the compressor map the line where 116,000rpm sits hovers over 90lb/min until about PR3.2 which I would be surprised if it is reaching that high, but never know. Fwiw Gen2 GTX3582Rs fall fairly short of 90lb/min on the compressor maps and cars have made more power at the hubs than this on E85. Not hating at all, I would prefer an 8474 over a GTX3582 but there are things I still have some question marks about

Nice! Awesome to finally see some data on the EFR8474 looks really solid in terms of what the data is saying about it - I'd be happy with that EMAP at that power. What is odd though, and seems to be a bit of a trend... where your IMAP is, and where your turbine speed is lines up with 90lb/min of compressor flow. Do you reckon you're making the power you'd expect when your compressor speed and boost level suggest you are pushing at least 90lb/min of air? This is part of what I've been told from people who have tried black series EFRs, they aren't getting the numbers they were expecting before they run out of compressor speed but perhaps the expectations need to be adjusted? And yeah, the back pressure comment was about people looking at making use of the >100lb/min rated compressor flow of an EFR9280 - so closer to the 1000hp @ hubs territory, unfortunately I don't have first hand data so much as just going from people who I'm spoken to who have used them.

The power target would be helpful with this discussion Generally speaking, most people I know who have tried the EFR9280 have not been particularly blown away so far, exhaust back pressure seems to be a thing - especially on bigger engines... if you're going to do it then the 1.45a/r hotside is the only option I'd consider. The G42 1450 is definitely going to flow better but also most definitely comes at an impact to response, in fact one of the guys I know went to a G42 1200 from an EFR9280 and that delivers power in the higher rpm better but even that turbo added reasonable lag over the EFR.

Most Thursday nights I have a low key group of car mates who meet up and yarn in Lower Hutt, there are 2/3 Skylines as regulars but its really just across the board (@Looney_Head included) - welcome to pop down sometime if you want. PM me if you are interested and I can let you know details, watching the weather for tomorrow night as it looks borderline atm haha

So far the only "modern" twins setup that I've seen which has generated a result which gets one thinking is the PMC/Integrated Motorsport R34 GT-R which makes >1100hp @ crank on G25 660s. It's laggy as hell, but has a wide (like 6000-10000rpm?) power delivery so there is a bit of a swings and roundabouts thing going on there - you would NOT use that for what most are looking for with twins, not least because it's not stock location but instead some wild fabrication involved. I don't expect there to be any major development with stock location twins as turbo tech isn't really the primary hold up, it's mainly packaging limitations imho... which is a lot of why I'm so pro-single on an RB. BTW, this thread is hilarious to look back over.

I'm not so surprised about the G30, but I mentioned the G35 - which is what this discussion is about.

SOOOO much this. Fun detail if you are paying attention, at PR 3.5 the G35-900 has 0 compressor flow advantage over a Gen1 GTX3582R and it drops back rapidly from there. A Gen1 GTX3582R is probably capable of more power reliably and arguably with better response (for equivalent exhaust housing size) than a G35-900 on a 4cylinder.

Old comment, but never saw this and seeing as the thread has been pumped I feel compelled to address it haha. Running 3.5bar or so base fuel pressure is so far from flogging the ass out of pumps. It makes way more sense running 3.5-4 bar base pressure on sensible sized injectors than running CNG based or other nugget things that a lot of people do to try and get sensible fuel flow for E85. It's real common these days for factory cars even to run that range rail pressure, turbo Falcons all run 4bar base. Most of these "Bosch 1700" etc injectors don't even match the claimed flow rate at 3bar differential pressure, the likes of ID1700x at 3.5bar will flow an extraordinary amount of power and if everything is specced correctly there will be 0 issues at that fuel pressure.

Cheers for coming back, and glad you've found stuff. What did you change in the system? Are you still on the same turbo/cams? I'd say with the kind of things you have found it probably will be a different beast to drive using those same parts

Pretty sure it ran 7.6, and while I love the car and it should go VERY fast, but it's not an R35 - it should not be compared with the likes of SIN35 which is actually an R35 GTR... not a tube frame chassis. Will be interesting to see how it goes, though - but apples vs oranges.

What records is it going to break? Aside from creating "new" records I am pretty sure it can only really shoot for "pro mod" type times, or possibly an outright AWD record. I doubt very much any of the GTR record lists/holders will consider it a valid entry. In regards to the main question, I think the main points are covered - twins are more practical and logical on a V6 and a single is more logical on a straight 6. I got the impression the STHitec 4WD funny car went single partly as a point of difference as opposed to specifically for performance reasons.

Wow, no need to talk like I'm an idiot - I was kinda trying to set up to be complimentary if it was an RB25, it wasn't inconveivable that it would be an RB25 - but it was getting into the area of some RB30 results I've seen which is why I asked for confirmation. Definitely combo is working well, one of the best RB25 results I've seen and probably the best I've seen in terms of power delivery using an HX40... nice work.

Just found this, nice to see a Kiwi build - very solid power delivery. Couldn't find any detail of the engine, guessing its some kind of RB30/25 setup?

Makes sense, the drop in response and the stretch up in the rpm could be partly (or likely is partly) to do with the poncams - I remember a mate here with an SS2 ended up feeling doughier down low when he swapped to the poncams, but sounds like he didn't pick up the kind of flow up high that you have when going poncams and GTXG2 (as expected). Looking forward to seeing how the Plazmaman goes, there could be some real happy wakey uppy goodness to come yet

How do you find the GTX3576R to drive / tune compared to the old SS2?

Awesome work Johnny, and thanks for sharing everything - science ftw. Those IATs... yikes, there is some serious airdensity improvements to be had there. Look forward to seeing how it goes with that lot sorted.

Nice, missed the tag initially sorry! Hope you can iron out the boost control, holding it higher up high could deliver some solid numbers - not that it's shabby now So with Haltech, is that correction table basically added to the base table? So 7000rpm and 250kpaA it's running around 26deg timing on eth?

And there is the clincher - arguments about dynos and power figures aside, if you are talking a full weight R32 GTR which can run solidly in the 140mph range while still being pretty responsive then who cares if the dyno reads 400kw or 900hp, that is a fast street car!

This is why I don't really like to talk about dyno numbers anymore (or really a lot of technical stuff), unless I feel like the audience are capable of having a sensible conversation about. Dynos don't tend to lie either but it's all data and like any data - how useful it is doesn't just come down to how it's measured, its no use if people who are interpreting it aren't capable of taking context and you end up with comments like this. 620kw range, possibly even a bit more is about right for a 6466 pushed hard on a hubber on E85. Sure, it'll make less on a Dyno Dynamics dyno but these days you hope most people know that and don't need to act like someone is lying. Also, if you throw the donk from an S14 into a full weight R32 GTR with stock transmission you probably shouldn't hope to run the same trap speed.

That should be a very solid setup all around if it all cooperates and you aren't shy. I'll go with 452kw but more or less wouldn't shock me