Lithium

I'm not sure all the rationale or limits you are considering here, but just to pluck a random number out of the blue - what is the difference on the bottom end between making 500nm at 6500rpm with VCT on, or 500nm at 6500rpm with VCT off but running more boost?

The effect vcam has on power and torque is negligible compared to the boost targeting and ignition timing. It may make it easier to hit the high torque levels earlier, but you are not obliged to make use of that. There are MASSIVE amounts of setups running around which would be capable of doing this kind of thing with variable valve timing which are perfectly reliable. I feel like going to laggier/less streetable setup to avoid cracking blocks when all you have to do is exercise some restraint where it could be a risk is very very strange, though I could be missing something.

Snap, pretty much what I was getting at with my above post - just a bit confused about why you're blaming vcam instead of blaming the boost target/ignition timing which have far more direct influence on the kind of failure you're talking about

I'm bringing up a couple points not to be a dick, or even defend the fact I've suggested that this kind of combo is good - just like to investigate things which have either turned out well or not... it kinda helps both understand what is working and why to help all of us get better results. With the info you've presented so far I feel like blaming VCam is a mistake, especially if you have it and you're looking at spending money at moving away from it when its probably not the cause - at least all by itself. Peak cylinder pressures happen when the intake and exhaust valves are closed, some time after the spark event happens. There is absolutely zero influence that valve timing has on this all by itself. The cylinder pressures are going to be everything to do with the compression ratio, how much air/fuel combo has been forced into the cylinder, when the spark has been lit and how stable the combustion process is after that point. It is VERY possible with a given static cam head setup to exceed the cylinder pressures achieved using a variable cam head setup. Not doubt Vcam (and the turbo setup used) could be making it easier to create a situation where cylinder pressures get to a point the block can't hold it - but blaming vcam for a cracked block is a bit like blaming a Porsche GT3 for being too fast if you don't brake for a corner and throw one off the road. Things that improve torque naturally have the ability to put more stress on the parts which have to hold the associated forces, its up to the builder to ensure things are best setup to ensure the best chance of sustaining those forces and in this metaphor - the tuner/owner have to decide where to draw a line in terms of how far its pushed so they have less chance of overcooking the combination you have. By all means remove vcam if it makes you feel better, but it won't necessarily lose you the ability of cracking the block due to excessive cylinder pressures if you were pushing things hard enough to achieve that. There may be other reasons you are looking at changing as well, but realistically - if the only reason is due to cylinder pressures then perhaps it should be considered to hold back torque where you think it has caused a problem and keep the nice responsive drive that VCam provides while not compromising reliability. Modern ECUs/control systems make it not particularly hard to target the torque you want, so instead of building the car to be inherently laggier in all situations it is possible to have your cake and eat it too.

Ahh I see. And you think that the same cylinder pressures would not crack the block if there was a non-vcam head ?

What happened, and how is it related to vcam?

Rightly or wrongly, back when he had talked about that I was definitely pro VCam/6870 for what he said he wanted at the time.

Kinda want to know the story behind this, kinda understand why you maybe wouldn't want to tell it. Do you reckon the cylinder pressures associated with huge boost at those rpm become a general liability - or are you talking about the general power level? Something I've not seen talked about much, but kinda have discussed with mates on projects we've done (not specifically just for block strength, but usability etc etc) is that the whole "full boost by x..." I feel becomes increasingly meaningless as bigger power levels come along, start thinking more about "usable boost"... like how hard it is to get meaningful acceleration to happen. For quite a while I've been into the idea of tuning the target boost curve to suit the capability of the setup and what its going to be used for - like the MAX power delivery potential of a setup all the way may be less beneficial after a point, but what is cool is if the setup is capable of supporting useful power before 5000rpm while also being able to provide off its nut power >6000rpm is the dream imho. Not necessarily meaning that if you can hit 40psi by 4500rpm that you should.

You know, I read threads like this and wonder why more people don't use nitrous for the special occasions. Keep your 6466 as a good street turbo, shove a 150shot of nitrous down it's gizzard for roll races against cars which justify it. A 6466 is more than enough for street and track playing and 6466+150hp or so from nitrous oxide will arguably make the car at least as quick as it would be with a 6870.

It is possibly realistic depending on what boost number he is talking about and what size engine, how long it's loaded to achieve that or maybe how much nitrous. For what it's worth this dyno plot is of a RB32 with VCam running a 6870, it's going to be harder to make a 6870 come on quicker than this on a sensible ramp run on a dyno without nitrous. Definitely not with an RB28

I'd love to hear about any of them having failures if they're that common, as obviously they've caught my attention and so far looking at individuals experiences I've only seen Precision reliability issues (granted, that's probably partly tied to people just sending it with them) and people getting performance improvements going from Precision to Xona. I've not seen anyone have any Xona failures anywhere yet, though they also are not used as much so it's hard to get a failure rate but I definitely don't want to be suggesting something that has any problems. Like anything, any claims without proof or data should be taken with a huge grain of salt.

Interesting, yeah I personally wouldn't swap from a 6870 to a Xona (or vice versa for that matter) - they are both similar enough that it's not going to be worth the money. The reliability thing sounds odd, haven't heard much issue about them at all. Is it definitely the Oz agent, or someone who can get Xona rotors but sell precision? Lol

Oh yep have seen all the stuff there, the EFR7163s tend to make 800-900whp max depending on the dyno (which is consistent with the Xona result) - which is decent, but not any territory outside of what people have made with singles. Sky-Engineering are one of the outfits which use "BHP" so that 1000+hp number is not what it looks like, if you're assuming that's whp and just by reputation I won't really necessarily take results from there as gospel. The video blog didn't show any results, in terms of presentation if you like that then definitely have to weigh that up - but so far I've never seen a legit 1000whp all-turbo from an EFR7163 setup.... let alone on the likes of a Dyno Dynamics dyno. Nothing against them, just strongly suggesting that they aren't the best tool for your job by a long shot.

I guess results all vary, I'm not sure that I've seen a solid EFR twin result yet - like not bad, but nothing to sing out about yet... be interested if you have anything you can point me at though as I obviously like to keep aware of this kind of thing. The Xonas are worth a look for the right situations I think, again I don't think it's the right thing for your needs but they are great. Popularity does not necessarily have any reflection at all on how good or potent a product is. I remember mentioning Precision turbos to people in NZ/Oz for YEARS before they started being used and people basically responded the way people tend to respond to Xonas at the moment, more or less the way you did. Better the devil you know, I guess?

Between this, and me trolling this thread with Xona Rotor propaganda - I happened to have stumbled on a pretty relevant kind of post on Instagram today, dude turned out to have swapped from twin EFR7163s to a single Xona Rotor XR11569S on his RB28. I stand by the 7685 being probably the beast for your aims, but thought this would be interesting info as a point against the EFR7163s.... https://www.instagram.com/p/CKZ0greHgfj/

All sorts going on wrong with that, no least being that Garrett have been gradually adjusting how they provide power estimates for a given compressor flow. Back when I first started reading compressor maps they took the flow at the chokeline of the compressor at PR2.0 and multiplied it by 10 - which in most cases with modern engines/tuning actually resulted in pretty conservative engine hp estimates, ESPECIALLY when E85 was concerned. When the GTX series came out they seemed to stick with the "multiply by 10" strategy for lb/min to hp, but now they pulled the "peak" choke flow for the compressor instead of whatever it was at PR2.0. When the GTX Gen2 series came out they seemed to have changed their multiplier to 11, and they seem to have stuck to that with the G-series as well. That graph above looks like they probably forgot to use the same multiplier across the board, and somehow still let it get to market like that - which looks ridiculous. I can sortof see why they've changed the multiplier as the old one didn't really reflect what most were getting out of their turbos before, BUT where it starts feeling disingenuous is where they've left the previous generations rated using the same old system - which makes it seem like the difference between the old and new Garretts are much bigger than they really are. I guess an example would be if you rated a GT3582R using Garrett's estimate for GT, then for GTX, then GTXG2/G-series it would be respectively 600hp, 650hp, and 715hp. All for EXACTLY the same turbo. On the flipside, if you did the same thing for the GTX3584RS which Garrett rate as good for up to 1000hp - that comes out at around 750hp, 890hp and 980hp. Basically they are claiming it as capable of 250hp more than they would have pre 2010. Ah yeah, its been many a year since I've been around 2.6s with low mount twins and comparing with different things - it will be a beast by comparison, lol

This kind of thing is why I asked all kinds of questions trying to ascertain where you were wanting to go, as you didn't put that across with your original question. The fact you were asking at all, and the fact you highlighted that it would be on pump gas, used on the street and sitting at around 700whp most of the time suggested that you might be quite concerned about the "around town" part of the rev range. Realistically if you are concerned about the 8500rpm part of the rev range then you have to be willing to sacrifice some of that bottom end, which it sounds like you are now - hence we've moved on and a couple of us are telling you to go 76mm Precision Different people like different things, and this is why people are silly to make out like there is one size fits all - there will be people who will shake their head at the big cams and big turbo discussion for a street car that is going on. Hell, it is not the way I'd go personally BUT I understand that different strokes work for different folks. I've seen that Real Street video misses this kind of point entirely to me, in some ways it shows how the 68mm is way better for the street - or that the 72+mm is where you are transitioning into something which is more of a drag/hp hero car. It dulls the car down on the road, but is much faster if you're keeping it on the boil... IF you have the build to keep it on the boil like that. A 72mm+ turbo that does everything at the top end is not going to be the perfect thing for someone who might want to be able to accelerate hard without dropping 3 gears and / or using rolling antilag to make a quick burst of acceleration happen.

Phwooooar going to be pushing it, maybe on a hubber? No maybe what its going to be pretty damn saucy, in that size range I don't feel like there is a Precision turbo that response vs power is going to be a worth while change from what you have.

What is your power target? I feel like I've said a few times that the 3576 should be capable of more than some may expect, or do I not count as an SAU internet mechach00ner?

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