Lithium

In NZ the laws are a lot looser than in Oz, we have people running around with GT45Rs on high mount manifolds and all sorts of crazy stuff - a high mount GT4088R replacing a high mount GT3582R isn't going to make that much of a huge difference I don't think Just to clarify, you haven't made any thumb sucks about how much power you think the GT4088R would make or any explanation if or why you are suggesting alternatives to going that way - do you think its a bad idea?? I know the 1.06a/r flows a fair bit better than the .82a/r GT35 turbine housing but I'm thinking we could be running the risk of running out of compressor as well which would dampen things a bit. The plan is in the next month to completely max out the GT35R and at that stage we'll have a bit more of an idea of what it can give, and that should indicate whether 1.06a/r would be a good idea though at this stage looking at maps etc it looks to me like the GT35R is starting to run out of motivation a bit already. The car isn't just for going fast, the guy would like the shock factor of seeing a large turbo sitting in there - and it would be particularly nice if there is a large looking turbo in there that makes big power and isn't aweful compared to the likes of a pair of GT2530s etc. The GT3582R is a lot nicer to drive on the road than GT2530s/GT2860-5s so the hope is a GT4088R might bring it up to the same as if not at worst a little laggier than the twins. I have heard comments (potentially unfounded, but) that the 1.06a/r GT3582R is hardly any better at spooling than a TS .9x GT4088R... any thoughts?

Cheers Disco, again - I understand the benefits to twin scroll and its one of the reasons I have been bandying the GT40R I am not new to quick GTRs and know the common combinations, part of the exercise here is to do it a different way but hopefully have it still done well but I just wanted to make sure the GT40R itself is really the way to go, and get an idea of the feel etc. To give you an idea, the motor is being built with the intention of sustaining well into the 8000rpm area - its previous engine build was running a .82a/r GT3582R which ran 372kw @ wheels at a bit over 7500rpm and in doing so has already matched power and out done in spool a few GT2530 GTRs on the same boost etc which we consider a successful "responsive 600hp on a single" type setup, As I mentioned earlier in the thread (to avoid dyno debates) the plan is to get a solid 10s street car. I also mentioned it would be nice to pass 450kw @ hubs on a Dynapack.

Have a look around for GT2871R results as well, or HKS GT-RS ones as they're pretty much what "2560-10s" are. Dirtgarage on this forum is one such chap running twin GT-RSs.

Cheers disco, all of that stuff I had heard or worked out over time - hence the fact that we are looking at a GT4088R, and will probably get a TS manifold from Fullrace. R14 uses a GT42R which is a completely different beast to the GT4088R, I'd be keen to hear if anyone has any experience or know of anyone with a GT4088R on an RB26 and any quantifiable results to suit. I know of one guy who put one on his RB26 in an S13 but then got rid of it before he really went anywhere near its potential which was frustrating, I had been watching that build for ages. I have theories and stuff written down on paper which suggest it COULD be a "on song by 5000rpm" mid/high 400wkw turbo on somewhere in the midish 20psi range on a built RB26 running suitable mods using a decent TS manifold and maybe even nicer to thrash than a T04Z equivalent despite everyone running for T04Zs as the big single of choice for a street car. Your thoughts would be appreciated.

Yeah certainly doesn't look anything like a GT4094R!

Thanks, I know about Geoff's ones but I don't like to ask people who could be trying to sell me stuff things if I can help it - though one of his twin scroll manifolds could easily end up being used anyway.

I am in the mood for some epic thread resurrection - no one has really answered or covered this. Has anyone tried this yet? On *any* RB engine? We are looking into using one for a street/drag/track R32 GTR running a built RB26DETT - it will probably be a pump gas setup, looking at running well into the 20psi range but not reaching 30. Obviously as much power as possible without being too laggy is the order of the day. A big single is definitely the preferred option, to break the mold as much as anything else. The ability to run in the 10s in full street trim is one of the requirements Cheers

Thats because as far as I know they don't exist. For some reason some people have developed a like for called GT2871Rs GT2860-10s.

I often wonder if tuners over there are a bit rough when hearing this kind of thing - or is this people running stock turbo and no tune? All pros aside from the conversion cost imho.

I would have thought under 21psi for 400wkw would be a bit hard to achieve unless you are running quite large cams and lots of revs?

AWHP EVO, not rwhp haha - and it put its power down extremely well, its an absolute monster on a race track. I don't mind big turbos, they have their place - I just hate it when people under or oversize their turbo for their setup. For example, that evo running 280degree cams and revving to >8000rpm on 29psi is running not overly short of the choke line of the compressor map at redline but it is a huge turbo on a small motor. On the other hand I reckon a lot of people on SAU using GT-RS are running them beyond their efficiency (both hot and cold side) and I'd hate to imagine what life would be in the exhaust manifold of those things. Anyway, sorry to thread jack Nytsky - I find it hard to avoid this thread as I am amping to see how your car goes, when do you expect it to hit the dyno? (edit after seeing Cube's response) Yes, you hurry up too I eagerly await both of your results and impression to help decide the fate of mine haha

I would call a T67 more in the GT3037 or bigger territory myself, much bigger than a GT-RS - even the smaller housing ones. A TD06-20G I'd compare with a HKS GT2835 or Garrett GT3071R. I have seen an internally gated T3 flanged TD06 once off a Skyline which was imported from Japan though it didn't come with any real details.

The GT3076R when I looked for and chose one looked like it'd be best used at around 22psi on a built RB25DET so there isn't a huge amount of use for it over that. Its a nice not overly laggy turbo on an RB25 so with 22psi there should be a huge fat power delivery, it'll be wicked for a road car that can do drag and track. Just because the engine CAN make 100hp/cyl doesn't mean you are obliged to - it just adds one part of the equation to get what you want out of it. Highest power pump gas/power per litre car I've been in was a still 2litre EVO 2 running a .82a/r GT3582R running ~2bar of boost putting down just under 500whp (125whp/cyl), way faster than any daily driveable 4cyl street car should be.

Haha well if whatever record they have made up for themselves to target makes them happy then thats good. For the rest of the world - you have one of the very very few 7s GTRs in the world

What about T518Z?

Doh my bad! In that case the closest I know of is a dude who had an R33 GTS25t running a Trust TD05-18G bolt on turbo for an R33, it looked a little laggier than a stock turbo but the car was making around 260rwkw. Seemed similar to a GT-RS, maybe a little less flowing.

LMAO. Apparently a GTR is only a GTR if it runs on a particular kind of fuel?? Bugger - you got ripped off.

For what its worth I'd prefer the Trust TZs over a pair of GT-RSs

The high turbine pressure versus intake pressure at this stage could possibly be largely due to the fact that the inlet pressure is disappearing after the intercooler?? Going by his pressure measurements as far as the turbo is concerned its running 2.4bar of boost - it just so happens the boost is not making it all the way into the engine. For it to have pumped itself up to 2.4bar it'd have to have developed sufficient turbine pressure for it to reach the shaft speeds necessary to do that, which would be why you are still running high exhaust manifold pressures. I would probably try and drop the boost level while trying to resolve where the boost is going so you don't blow a turbo trying, as whereever the pressure is going is not doing anything any good! Though how far did you drop the cam duration?? Does the car idle high or do you have any lean miss condition going on? I suppose if its still running an aggressive cam it would be hard to identify this kind of thing.

I hate boost leaks A tool which could pump "smoke" through the system post intercooler would be very handy at this stage to see if or where it came out. One then we did when I had a leak with mine was squirt compressed air at different points of the outside of the piping etc while the car was idling and at least in my case you could hear the engine react to the higher available airflow. I assume you have ruled out any chance of the blow off valve or a join in the piping leaking? Good luck with this, this sounds like it will end up completely insane when done - how far did you go with the twin GT30R setup?

Roy - I didn't mean outright VE, I meant maintaining a good VE up into the higher revs... the engines VE changes throughout the rev range, peak VE in my understanding should be where peak torque is and then it drops. If you want to have an engine which CAN rev to 9000rpm a large amount of the focus will have be be put on making sure the head is going to support the flow at those revs. Both RB20s and RB25s are dropping off hugely by then. And I understand what you mean by dribbling on, I am a big fan of it - its what keeps these forums going and conversations like this can end up in really interesting things happening. Or shitfights haha No worries Seeing as it sounds like you have perused the dyno threads, where are the RB20s falling over? I know people who have spun RB25s to over 8000rpm, even on hydraulic lifter heads - 8500rpm is the highest I know of but I'm not 100% sure on all the supporting mods done. I know a lot of it was pretty typical, forged pistons (lower than stock compression, ~8.6:1 but thats just for high boost friendliness), rods, balance all the bottom end stuff, get an oil pump which can handle the revs and generally make sure you are always going to have enough oil in the right places. Get it all balanced!! And you will have to run a decent exhaust and inlet manifold as well, a nice high mount manifold can actually help them wake up in the high end quite nicely once you've got some decent cams etc. I'd probably swing towards going a Neo solid lifter head if I were to try something like that myself, though I've been in RB25s running 8200rpm and I tell you - with a GT3582R bolted on the side and a decent set of cams they feel a LOT angrier than what you'd associate with the power delivery on an RB25 running a stock turbo or even a GT-RS. And that brings me to the next bit, how much boost/power are you aiming to run? I think GT-RSs are struggling to flow enough air efficiently at the high end of the rev range of a stock revving RB25DET, much less an RB of that displacement area which wants to rev to 8500rpm or so. You are going to need a turbo with a reasonable amount of compressor to not choke the engine on its mission up there, you can probably forget any GT28 or potentially even GT30 based turbo - and unfortunately as a result of that also forget any chance of making full boost under 3500rpm. This kind of stuff is why we rarely get to have the best of both worlds

OK you are talking about RB20 blocks - in the case of an RB20 block, it comes with a head which takes reasonable work just to match a stock RB25 head in terms of flow, but alas you can do work to the RB25 head to take that further too. As much as your bottom end is able to rev is no good if it doesn't have good VE up there. In terms of what the topic is about, the block thickness (which I am unaware of anyone not shooting near 1000hp having issues with anyway...) "issue" will apply to this guy anyway given he is using the RB25 block. Unless he is specifically on a mission to build a motor to rev as high as possible without any concern for performance etc then seriously man, 2mm of difference in stroke is not going to be noticeable on a decently built motor. Food for thought - Hondas F20C (S2000 motor) which has a stock rev cut of around 9200rpm and generally makes a RB20DE feel like a joke in terms of willingness to rev and has a almost RB30ish stroke of 84mm, go figure.

Its an interesting idea, and its always interesting to see something different but seeing as you are asking for an honest opinion I am going to be predictable and say I think its a ridiculous idea. I have no idea why people think that RB20s rev better because they need to rev - being torqueless doesn't mean they are better up high. Yes it has a SLIGHTLY shorter stroke, but the same as an RB25 has a slightly shorter stroke than an RB26 - no one complains about how they rev. To be honest, do the same work on a true RB25DET (people will just call it a destroked RB25 anyway) and get all the revs plus the bigger displacement - you get the best of both worlds. If you do the same work to an RB25DET and your hybrid, then drive two cars with the different setups - one will make more torque than the other... and a little more power. Thats all that will stand out. My opinion, save your money - its going to be an aweful lot of money with the only positive at the end being the ability to say you have something a little different.

The cam profile thing comes up again - a couple of us answered this on GTRUK forum and there was no answer, hard to feel motivated to add more if you don't know if the person is reading or considering the suggestions.