Lithium

Strictly speaking I'm not sure if you really should need closed loop - I guess I don't know how tricky your setup is, but I would have thought open loop should be sufficient with a good external gate setup to hold a pretty consistent boost level, unless it's actually just physically difficult to build that much boost in the lower gears with your setup and it's more a lag thing than a boost control one? Either way, I've never used it - even with internal wastegates if you don't have any tricky stuff you are trying to achieve the open loop setup is pretty good. I think (/thought?) the gear trim thing was more to reduce or increase boost for each gear as opposed to aid it in reaching the target boost. .3+bar sounds to me more than what I'd have thought was the intention behind closed loop boost control, I figured it as just being there to tidy up slight deviations from the target.... getting near half a bar is like a whole different target though I could be off point here.

So the guy you are recommending those cam settings has exactly the same bottom end, cams and initial degreeing came out identical?

Off the top of my head, loosely - some algebra (ignoring any extra trims) m = Master fuel (ms) p = Pressure (MGP in kPa) a = Target AFR t = Fuel table value i = Injector pulsewidth If Open Loop AFR is off... i = m x ((t/100) x ((p+100)/100)) If Open Loop AFR is on... i = m x ((t/100) x ((p+100)/100)) x (14.7/a) I think that's more or less right, just kinda brain spewed but should give the general idea.

Hi AH_HUH, I went hunting through the thread and can't find a dyno plot for the RB28/PT7175 combo - what was the most power it made, and how was lag with it... if you don't mind sharing? Do you reckon it needed much more than 5000rpm for full boost? Cheers

I <3 your trap speed.

Oops yep I am thinking of the Boostlab one, not the genuine Airwerks article

Very impressive What is your pb?

Guessing thats not the FMW S366 at that price, Bigmikespec? What spec motor is it going on? Keen to hear results from that

Awesome Cheers for the update, good to see it trucking on.

I'll put my 2c - these are opinions, not direct experience but I've been tracking these things for ages so have a couple of ideas... I'd like to think 1 - I'd say in the territory of 600awkw should be achievable, I've not seen many of these run all in so that is more theoretical than anything. I'd say >550awkw would definitely be doable. Word of caution, the 9180s sound like they don't like being oversped - think of the Gamma-Ti turbine wheel like an uber material version of the old Nissan ceramic turbine wheels Nissan used in the earlier Skylines etc.... people HAVE pushed them when leaning on these HARD so I'd personally not push one the way some people push the Precision/Garrett/FP alternatives. 2 - If I were a betting man I'd be saying to set expectations for near 5000rpm, I'd like to think under but that area. 3 - You'd have to talk to Full-Race or another dealer, I don't get the impression that there are any issues from anywhere 4 - I've seen nothing anywhere to consider the 9180 superior in flow to any of the other "typical" MFS 67mm turbos doing the rounds at the moment, I'd consider them to be flow wise comparable (give or take) to the GTX4088R/PT6766/FP3794 but more responsive. 5/6 - Sorry can't answer that, not sure. I'd guess that the amount of time with supply issues and reliability issues in the earlier days didn't do any favours for popularity at the start and now the Precision/FP etc turbos are so proven and so much cheaper, easier and prettier to get and use it became too little too late and most people don't really see the point when these aren't completely head and shoulders above everything else. I kindof see them as something that if you can justify the cost (either you have lots of money or just really need the absolute best response versus power level) then go for it, but it's not something you're silly to not buy if you're not ultra serious or rich. The alternatives are more than sufficient for most I reckon - which I think is a common conclusion and obviously one you are entertaining.

Reason I mentioned the 16G is I have driven two RB20 powered R32s back to back, one running an RB25 turbo and the other an EVO 16G and the 16G basically did everything as good as or better than the RB25 turbo. If that was anything to go by I suspect it would be basically like driving a stock turbo on am RB25, if not more impressive overall when you factor in the extra flow and ability to cope with a good dose of midrange boost.

Awesome, good data sir! Will check out the xlsx when I get to a computer but that gives a good idea. Very very similar to a GT3076R, solid looking power too I know VD had issues with MAP in he past, I assume it still does but still... seeing 3.6 bar on the pressure plot for a stock 25 makes my eyes water haha. Just confirming, is externally gated? Cheers for sharing

Yep that was clear... and sorry if my ramble came out wrong. If GTSboy has a ramble over the math I am sure no one will complain

This. I half wanted to weigh in here too, but I'm sticking to my "Try not to care too much about forum conversations" pledge and he has a habit of saying things I am thinking anyway so I get the enjoyment of it without the frustration of writing lots of stuff and finding a lot of it falls on deaf ears, or gets recycled and then regurgitated back to you as though you are being taught something so this works much better for me The whole way this started was comparing like setups anyway, its going kind of off topic anyway - we end up down a path of levels of extrapolation in the comparison getting bigger and bigger and it reaches a point where we may as well say "BLARH my Dad is bigger than yours". If no one else does I'll try and collect some useful data on the SS2 when I get into tuning it.... I kind of wish I still had GT3076R log data on hand, but either way its clear than the boost threshold difference is probably trivial which makes the SS2 a good thing, again because of how convenient it is price and bolt-on wise.

So do you guys use soft timing zones to try and induce better spool?

Yep, I'm probably the last person you need to tell that to I never ran 20psi deliberately so admittedly I can't quote exactly what I ran there but used to hit ~1.1bar around 3700rpm in 3rd quite happily so I doubt it is any worse. 4th was a different kettle of fish altogether (would hit 17psi before 3500rpm): Anyway - I (obviously) think the SS2 are a good thing, hopefully will have a better idea of how good soon... but I definitely like to keep it real, as well. Considering the price and convenience difference I think they deliver very very close to one of the most popular Garrett options.

Yeah that is definitely laggier than a GT3076R - not bad for the price, that they seem to make similar power and the fact that they are a journal bearing turbo... goes well when you add up the costs of buying and installing one I look forward to experiencing it in person though and seeing what they're all about!

Whats full boost? 4100rpm in 3rd sounds less responsive than a GT3076R if anything

I'll be tuning the internally gated one on BP98 with a Dynapack hub dyno, probably not as tough an audience as you guys are overall used to - though similar to some. Will probably go for around 18psi, but will see how knock limited it is and decide whether to go higher from there.

Crikey, nice - with that engine setup she'll do some pretty sharp times at the drags if you can get it all hooking

So I am helping someone make their RB25 Skyline go a bit quicker, so after much discussion the choice to go with an ATR43-SS2 was made - as soon as we nut out how to best pay across international borders we may have the first Hypergear turbo on NZ soil that I am aware of. Looking forward to checking one of these things out in person after all the discussion, and will be nice to have first hand experience of the SS2 If I'm allowed I'll post results after we are done with it - will be internally gated, stock manifolds all around, BP98 on a stock internal RB25.

Very nice, is that petrol or E85?

Orly? I mean, yes - correct... just testing

Kinugawa TD05-16G6, port the wastegate port, profit. Flows better than the stocker, stronger, no laggier, cheap as.

I find it interesting that people are going into so much detail into choosing/designing (!?) cams here yet the high lift UE 250 cams are being recommended as a blanket rule for 2.6, 2.8, 2.9 and 3litre engines - dynamically cylinder filling/trapping between all of those engines are going to be quite different. I've chatted about this with XKLABA and Piggaz before but it still seems to be being overlooked, not sure if I am missing something with the design here or if you guys have found that they are a magic bullet regardless of compression, turbo combination, piston versus valve location etc? The results are very good, and achieve what has been expected - but there are lots of really good results out there, I guess it's impractical to do a test but I'd love to see the 250s compared with other cam options on like spec motors and see if the results are all as expected. I like to think there is always a better way