Lithium

Same. Do you have I2/I2 Pro? How familiar with the software are you?

Ah sorry, from some things you'd mentioned I assumed you were more comfortable with reading compressor maps. Nah, you're right against the edge. The red line I've drawn through the map is a rough estimate of where your engine may be operating in and it "stops" basically just at the max-rpm line on the right side of the compressor map. Touching that line doesn't mean instant fail by any means, but it does assume there are no outside factors meaning it has to spin harder and obviously I'm also just taking a punt so there is no guarantee that's accurate. Nice computer Maybe not necessarily quite a straightforward to work out the airflow the ECU reckons the engine/turbo are moving though it's definitely capable with I2 etc.

They've been out for a few years and actually a "joint" effort with (or FP say basically is a FP turbo that Mitsi liked so much they've sold as an OEM option) Forced Performance. They seem like excellent performers and are loosely FP Greenish from memory. They also happen to be "standard rotation" as they are an Evo X option

This is what I get when I have a quick go at Matchbot, let me know if it seems like I'm missing something. I'm "only" running it to about 7700rpm though as that's all your dyno plot goes to. Plausible that running it to 8500 could go further but it looks like your VE is going to start plummetting after 7700rpm so I'd not necessarily expect the compressor to need to do heaps more. What ECU are you running? You could look at logs to get a gauge of the estimated airflow. Here's my attempt at matchbot: https://www.borgwarner.com/go/N0YW5D

Ugh actually. Please hold, I'll just actually run the math properly and see where you're likely to actually be instead of guessing. Bbs

Ohh. I may have made a bad assumption with my previous post - I kinda glanced at the power and assumed your were running ethanol (which kinda assumes a certain airflow vs power conversion) which would make that power seem perfectly within the G30 770 capacity but actually, looking at the rpm and boost you're right... all things being "typical" your engine is likely to be breathing a heap more than that turbo would want to give at that boost. What fuel are you running on?

Argh also, I missed a point above - it seems that especially with the Pulsar turbos third party dealers seem to sometimes mess up orders. I've seen it (not directly experienced it, but definitely seen it happen to other people) where someone will order something like a GTX3584RS and end up with a GTX3582R, or a "G30-770" turns out to be a GTX3071R etc. If you had a GTX3071R or even GTX3076R or G30 660 and tried to run it like a G30 770 then there could easily be carnage. I've seen people run near 600hp @ hubs on the Pulsar G30 660 on ethanol so it can be done, but probably not super wise.

Seeing as it's a little ambiguous as to why you might be upgrading, I'll give some bullet point answers based off the two reasons you may be: Upgrading because you're assuming the failure is overspeeding: A G30 770, either Garrett or Pulsar version should not be overspeeding at this power level. It's leaning on them a little but should still be in a relatively safe place Any details on how the turbo looked/what broke and when? First time I've heard of a catastrophic failure with a Pulsar, can never rule out a manufacture issue with them (I know people who've had this with Garrett, Borg, Precision etc so Pulsar probably won't be immune) You can also overspeed the turbo without actually trying to make more power than it can support, if you have a restrictive intake or intercooler, or some kind of boost leak then there is the possibility that either the turbo is seeing a much higher pressure ratio than you'd guess based off when you see at the intake manifold - or alternately the turbo could be moving a heap more air than the engine is seeing, both causing it to overspeed while actually giving the engine less air than the turbo can provide if everything is working efficiently. Make sure there is no other issue with your setup that could possibly cause a premature failure, like oil feed blockage or something to that effect ^ Especially #3 and #4, make a seriously good effort in ruling out or identifying any possible cause there because you don't want to spend >2x the cost on a replacement turbo to end up with the exact same thing happening. Upgrading because you're levelling up: How much more power are you after? If you're happy with the power and response you had already, 590hp @ hubs isn't a heap short of what the compressor supports with those so going up an a/r may result in an underwhelming increase in power vs how much extra lag you get from it - imho the .83 seems like a good balance on the 770 even if it may hold it back a little at the top end of it's capabilities. Check out the 6466/G35 900 thread, someone has gone a 1.06a/r T4 Garrett G35 900 on their VCam RB28 and it's a lot laggier than this. There's no magic, if you have a bigger compressor, bigger exhaust wheel, big tubular manifold and larger exhaust housing then twin scroll is not going to offset the response at all.... but it will be capable of an extra 100kw @ wheels safely. If you are after an incremental increase maybe consider the 1.01 T3 G30 900, or if they have it a 1.06 T4 G30 900 - I'd wager that has a good chance of being a sensible in-between if you are concerned about response. It's unlikely that you'll be able to go up in power potential without some cost to response but that is one way that's likely to manage the impact somewhat. Just my thoughts.

PS part of why I did the above is so you can see your setup is likely reaching as high as PR 3.3

K, I've thrown some numbers loosely based off your dyno plot and what you've said into BW Matchbot. I've selected the EFR8474 compressor map because it happens to be an excellent match for what you're actually doing and also funnily enough Borg Warner doesn't have the Garrett data I used turbine flow data for the G35 900 with 1.01 hotside (as the 1.06 T4 isn't listen) to loosely match the turbine data. Very loose but should give a general idea of what EMAP and pressure ratio etc might be doing. https://www.borgwarner.com/go/3I1H4G

2.3PR is around 19psi boost at sea level if you have zero intake restriction - you sure you aren't missing a PR there?

Just to clarify, has yours failed or are you worrying about how risky you're playing it?

If you hate Precisions but like some of the "insane power vs turbo size" things maybe worth having a nosy at ApexTurbo, be super interesting to see something like one of their 64mm or so type units on an RB30. They seem to be getting results that seem impossible, even when you consider the latest Precision offerings... most significant Evo/Honda turbo records have already been picked up by things running ApexTurbos and one of the Honda guys "downgraded" from a bigger Precision turbo to a 62mm Apex to try and make it easier to get off the line and ended up making significantly more power at the same time, like they cracked 1000whp which is mad even on a US dyno without nitrous etc.

A Holset HX35 and a Mitsi TD06(/SL2) are *completely* different turbines - you absolutely cannot take what a Holset 10cm divided housing behaves like and try and use that to determine what a turbo with totally different housing and wheel geometry on both sides will do. May as well say they're both loosely based on circles so will behave similar. Hmmmm. I did write a post saying that the only ones I experienced were the bigger ones but decided to verify and there is every possibility I had actually been exposed to TD06SL2 20Gs when they had been referred to as simply "TD06 20G" so I'm actually going to have to not weigh in on that. The only thing I *can* add to the "maybe the SL2 doesn't add as much value as it's given credit for" is arguably the most famous TD06 aside from the TD06(something)-20G is the classic FP Green which was basically a 50-trim T4 compressor paired with a TD06H turbine, and had the reputation of outspooling and out flowing 20Gs of almost any combination... though this potentially brings the whole "compressor vs turbine matching magic" side of things into the discussion. Sometimes the result can't exceed or fall short of the sum of the parts. My memory also probably stretched here, but one of the best 20G setups in the entire RB kingdom was @Roy's RB20... I'm not sure that was an Sl2?

Good call on the altitude, I even thought briefly about that when I posted the comp map but so used to people living close to sea level that I didn't dwell on it... I guess there are a lot of areas people live that are high enough that the relatively "not high boost friendly" shape of the G35 900 map would mean it'd not be hard to over speed them when trying to make their rated power even at not a particularly high altitude. To add to that, there are a LOT of people likely running around out there with boost leaks. Like people think they've gone above and beyond if they've done a solid spanner check, or even smoke tested their pressure sides of turbo setups - before tuning where possible we'll try and pump 20+psi through the intercooler piping and the amount of times we've heard rushing air on a "nah it's definitely all sealed" setups is solid, potentially in the area of 50%+. I'd not be surprised if the reason a lot of the car's my little group have done that have ended up with "better than people expect" for the setups are if anything an indication of how many people are running around with undiagnosed issues. If you're one of the MANY people who are running around with a boost leak then yeah, turbine speed is the only way to be sure unless you pressure test it - I am certain some of the EFR horror stories come from boost leaks, they were basically booby trapped by having a selling point of coming with an internal BOV that just happened to often leak at high boost. Perfect. Re: Precision, yeah I've seen some data from people testing big Gen2 and NextGen Precisions and while the Precisions aren't the most "low inertia" turbos it becomes clear from the turbine speed stuff that some of the "magic" with them comes down to the fact they can actually tolerate a hell of a punishing. Like its not unheard of to have 76mm Precision turbos being run at speeds (as in turbine rpm, not tip speed....) that you should be starting to think about calling it a day with a G35 900 hahaha.

Ok, should have said that was your priority instead of response - a preference because you just like the idea etc is fine. So the TD06-20RX will basically make the power of a 25G but with the spool of a 20G. Turbine is the same so should have the same "Mitsi turbo" exhaust note you're probably looking for.

Are the Trust TD06-20RXs super super cheap? I'm not sure why you'd go a TD06 these days unless it costs almost nothing. From the perspective of someone who has been into RBs/turbos for over 2 decades now - I remember a time where TD06 20Gs were a wicked thing for an RB20/25. Like they cost less, were strong, and performed admirably (for a journal bearing turbo) against Garrett/HKS turbos which cost a lot more back in the day - a 20G would be a solid alternative to something like a Garrett GT3071R or HKS 2835 for sake of argument. That was around 20 years ago. In that time Garrett have since released a GTX3071R, then Gen2 GTX3071R, then the G25/G30 range of turbos - and there are budget equivalents semi-loosely based off all the previous things. This TD06 20RX from everything I can see is basically Trust finally upgrading the compressor wheel (but nothing else) to something comparable flow wise to the improvement Garrett did with the GTX3071R, a turbo that's been available for about 13 years now. If the year was 2010 and this turbo had just came out THEN (and at a sharp price point) then I'd understand threads like this coming up... but in 2023 I just don't have a clue why they'd be a thing anyone would consider. So yeah, short answer - it's something that will spool like a TD06 20G (a 400whp turbo from 1998) but is capable of around 10% more power. But a Pulsar GTX3071R (or the like) will probably cost less and do everything better.

I'm not aware of any "random" failures. I feel like I heard of people running into issues when going on a mismatch combo but it may be from this thread, or associated with the guys posting it - the general agreement at the time is that it due to overspeed which thanks to the more efficient G-series wheels etc it becomes a lot more likely than earlier Garretts so the idea would be to keep within the recommended "area" of these things. To get an idea of if 2bar-ish is a risk, the max wheel speed published for the G35 900 at PR3.0 lines up with around 79lb/min I'd not necessarily expect that line to be a "it asplode when you go past this point" level, but realistically the further you go from that line the risk climbs exponentially. Ironically the anti-Borg Warner silly people chuff at the idea of wheel speed sensors being a good idea as though they're the first turbos to be efficient enough to be able to blow themselves up if you let them keep pumping air, but this is why it's not a bad idea. It's worth noting at that map that it looks like compressor efficiency is actually QUITE solid still at the maxrpm which means it'll be super easy to overspeed one of these things, the common method of waiting until it stops making power easily is likely to get you way off the map if you're going for >2bar. The "next best" idea is estimating your airflow and picking where on the compressor map you land based off that and your intake manifold gauge pressure. My super bro-math way of estimating required airflow with a 2wd car on a hub dyno is relating lb/min to kw with a factor of 7.1.... so if you wanted to know what is a "safe max" point to push a G35 900 on E85 on a hub dyno at bar would be 79*7.1 = 561kw. If you pushed one to say 600kw you could also go 600/7.1 and find you're likely pushing in the territory of 85lb/min of air which is starting to get a bit up there but shouldn't be COMPLETELY insane. Ymmv as different dynos, different tuners etc will give different results A lot of modern ECUs support VE based fuel equations, and if the tuning is done competently (injector/fuel/charge temp etc settings all calibrated accurately) then the ECU will have a pretty good idea of the airmass getting into the engine as otherwise they'd not be able to command the correct injector flow to hit target AFR. If you have a Link ECU for example you can check a value call "airflow per cyl (estimated)" or something like that. If you get that value and throw it at an equation like "(percyl * 6 * rpm / 2) / 453.6" which takes the g/s airmass the ECU is assuming each cylinder it's getting and converts that to lbs of airflow consumed by the entire engine over a minute. I've found it to be relatively on point for cars I've tuned so far... this again should be <80lb/min at 200kpa MGP if you want to be safe.

Fairly sure I've already seen a bonkers NextGen 7275 result, trying to think of where. Could just be another Apex turbo result as those things are just mental

Thought I'd bump this thread as Precision have been superceding their Gen2 units with the "NextGen" range and the updated 6266 and 6466 have just been released, rated at 925 (more than the Gen2 6466) and 1000hp respectively so decent improvements and probably most relevant to people who would be reading this. The NextGen 6670 has also been released, kinda like a 6870 flow (quoted at 1100hp) but sitting between the 6466 and 6870 size wise.

PSA: seems FullRace have limited stock of one of the best turbos you could put on a car that also happens to be one of the hardest to get: https://www.full-race.com/borgwarner-efr-8474-turbo

Yeah, I've actually tuned a car using the S257SX-E "smaller brother" running a 1.15a/r divided hotside on a 2.3 4G63 and that made ~390kw @ hubs and was JUST hitting 1:1 exhaust vs intake manifold pressure at that point - definitely more in it but we called it there as it'd hit the target for the setup but the thing is an absolute beast, response etc is awesome. Here's a clip of it in action to give an idea:

That may well be partly to do with cam timing though I'd not rule out the possibility that it's the hotside. I've seen a good number of EFR7163 results with divided housings which seem to choke up a bit, and realistically that turbo is not necessarily ever going to be ideal for an engine that flows reasonably well compared to a more mild SR20DET (like an RB25) but as much of a divided housing fan I am, I'd be super concerned about a divided EFR7163 working well on an RB25. EMAP seems likely to get up a bit, and with internal gates that can turn into a super big pain in the a55. I feel the cost and expense of a twin scroll EFR on an RB25 aiming for "only" 300kw may not age well and would be more inclined to go with an open housing 7163 if that was the direction. There isn't a lot out there, I personally am not a super big fan of the EFR7670 relative to the rest of the EFR range. The only RB25 EFR7670 I've experienced was a T3 open one so not the best example - however I'd not recommend it for what it sounds like you're after, it was definitely lazier than I'd hoped or expected <4000rpm and I'd say a small G30 or the likes would actually be a lot more rewarding if you're only aiming for 300kw (hubs or wheels?). As I mentioned above, I feel like the healthier flowing 7163s I've seen are ones with open housings - here is a dyno plot from a car over here in NZ running BP98. This is a 4WD Primera running an SR20VE (someone can probably correct me but I get the impression the VEs drive turbos a little less at lower rpm but hold on WAY better at high rpm compared to their DE siblings?) and a vband open housing. Despite being the VE head I think this is a pretty decent spool for this kind of power on pump gas: Being able to support that kind of power on pump on low 20psi boost makes me suspect it would be very nice on an RB25 in terms of not being excessively small, but also can imagine it'd stand up NICE in the sub 4000rpm range. As has been mentioned elsewhere in here, the boost threshold on EFRs isn't necessarily where they really impress - it's how responsive they are to throttle when in their boost threshold area. This kind of setup has potential to be hilariously fun on a 25 you want to stand up well from low rpm. As an aside, despite being WAY off topic here and probably an unpopular viewpoint - I went for a drive in an EFR7670 car and also drove my old Skyline which now runs a Holset HX35 and the Holset setup made the EFR feel lazy as f**k. Granted, it was comparing a ~50lb/min turbo with a ~62lb/min turbo - but the Holset was making 320kw @ hubs which is a nice spot for a pump gas RB25 street car and it drove hands down better than any other RB25 I've driven. Full boost around 3200rpm/3300rpm from memory, insane transient response, and sounded awesome. Annoyingly that was my original choice for that car when I owned it but I went GT3076R to make things simpler and go stock manifold but that turned into a nightmare of trying to make boost control stable. At least I was a guinea pig for people doing the same thing in future But yeah, my old car makes more power than when I had it and spools almost like it has a stock turbo.... I suspect a huge amount of people over the years who have looked into RB25 turbo upgrades would actually choose that turbo in an instant if they experienced it - especially when you consider how cheap they are. On what kind of dyno? On a hubber I'd expect so, spool should be pretty respectable but it's obviously a journal bearing turbo - the Airwerks range are decent but not the most (or least...) responsive under foot so it kinda depends on what you're comparing to. Given the turbos aren't even in circulation yet it's hard to say how seriously they should be considered but if it helps, I'd not go for one if I was counting on it being all in under 4000rpm - but I'd also hope not too much later than that either.

Yeah. When I saw RB335's comment I had a "I'm SURE we've been through this before and I actually thought it was in this thread" moment. I'm also not talking sh1t when I say some of what I said above, I've actually effectively "put my money where my mouth is" (and convinced other people to make similar educated gambles off the back of it) and convinced people to upgrade compressors while using the same turbine after being told that the hotside is a restriction and suddenly EMAP has dropped and making more power has got a lot easier. What does my head in is that Borg seem to often have the Airwerks range of turbos "a step ahead" of the EFRs in terms of nice compressors - they may not necessarily flow heaps more for the size, if at all, but their maps often suit things like RBs and JZs a lot better than their EFR counterparts. Its like the EFRs are more aimed at 4cylinders, and SX are "for bigger engines". If a 68mm 9180 is not big enough for a RB32 your only choice is a 74mm EFR9280 which fixes the problem but definitely comes at cost in terms of spool *and* you really need to go the 1.45a/r hotside to make the most of it whereas the latest generation Airwerks compressor looks like a thing that would basically be what a lot of RB people who went for 9180s were looking for but didn't get because of their anaemic performance at lower boost levels (and not realising that looking at the compressor maps). Behold the S368SX-R compressor map, same inducer, smaller exducer, is able to flow similar to the bigger EFR9180 compressor at the same rpm so you don't actually have to spin it any faster despite the smaller size: So the red line is where an EFR9180 compressor starts being more useful as a hot air pump, and the orange line (more for interest sake) is where the turbine rpm speed reaches the maximum listed for an EFR9180 if you are at all nervous about the idea of spinning the 80mm turbine faster than the EFR9180 was mapped to. If Borg combined these two I can't see how you'd not end up with what the EFR9180 "should've been" for the bigger engine guys, it'd actually be more responsive than the 9180 and more likely to give the power levels you'd have expected if you spun it closer to that 116krpm zone (the S368SX-R is actually mapped out to 126,000rpm but I feel like it's wise to keep the 80mm turbine not being spun any faster than Borg ever advertised for it).

Nope, 116kRPM is the "beyond this we make no promises about how long the turbo will last here - good luck" point. The red line I've drawn is more the "the turbo is probably able to push a bit more air than this but it ain't gonna be pretty" marker, beyond that pre-intercooler IATs are going to skyrocket and exhaust manifold back pressure is also going to take off as the gate is going to have to shut to try and squeeze more out of the compressor. That funnily enough causes back pressure to go up a lot as the drive pressure isn't being diverted past the turbine. IMHO people have often underestimated how much hotsides on Borg turbos flow because of mismatched compressors hitting this kind of situation. Really its not more turbine that's needed, it's more (or a better) compressor. I've put a cute orange star roughly where @Predator1 sounds to be sitting