Lithium

As said / shown before - outright boost threshold the GT3071R seems to have nothing over the GT3076R. MAYBE (you'd have to go in both back to back) the GT3071R might have better part throttle behaviour, but I am serious when I say mine is really really nice to drive. You can tell its down on torque below 3000rpm but who drives hard there and expects to go fast aside from people with 5000rpm redlines? Got a vid on youtube of a run from the drags this weekend where I managed to badly bog a launch with the .82a/r GT3076R racing a fairly mild R32 GTSt, gives a reasonable impression of how it pulls from low revs in 1st I think:

Haha just because thats what we're both running is by far not because we "needed the .82 to make that". I don't have a boost controller, I am running completely off the actuator and was just loading up preload. If I went any higher it was going to start creeping - it made the 270rwkw REALLY easily. It would have made quite a bit more but we put more fuel in to make it run ~11.6:1 to keep the motor understressed relatively speaking. If/when I get a boost controller and following how easily the car gained power when we did things, I expect it to crack 300rwkw without too much stress- just a bit more boost. People have made over 300rwkw with the .63 BUT it'd be a yuck way of doing it.

The most powerful stock bottom end RB25 I have been in/come across is this one - has cams and thicker head gasket, stock from HG down. Made 450rwkw (~600whp) on a pretty high reading dyno though I reckon it'd run over 500whp on most sane reading dynos. Here's a video of it running a 10.6 with full interior, pump gas and a set of drag radials: Trap speed etc seems not the best, but they were being a bit gentle with the gearbox etc - remember, all stock bits.

Agreed. I did expect a better threshold (mine almost looks better) from the GT3071R but still on the road the 71R should feel better. Same with GT3076R vs GT3582R, the lag doesn't SEEM hugely different but GT35Rs start feeling quite weak on RB25s - you need to really give them some beans to get going.

LOL, if you are worried about that then you shouldn't be looking at up to and over 300kw @ wheel turbos On the road its really not as bad as it looks, if you think it looks bad. Remember RB25s are WAY under turbo'd stock. 12psi at 3600rpm is better than a stock turbo'd RB26DETT will do, and the RB25 comes in a much lighter car - makes it that much more streetable. With a "laggy" .82a/r GT3071R or GT3076R you'd out accelerate a stock turbo'd GTR from low revs, then it will catch up because your tires want to liquify.

The only stock standard GTR I went in was really really disappointing. Was running stock boost, stock exhaust, stock everything - I struggled to believe it.... I had a semi-wanked up NA Honda which was pretty comparable in acceleration (dodges flames). The new owner of the otherwise mint R32 GTR trucked on and did a full service, got it a very unrestrictive full exhaust system, pod filters and an electronic boost controller for it and ran 1bar of boost. He was pretty happy with it and told me I should come for a drive to see if I thought it was better - to be fair I didn't have overly high expectations after how horrid it felt before. Seriously, the thing lost traction when it hit full boost in first and had my whole hearted attention from that point forward. It felt like it was designed to be like that... like Nissan would have liked to have done it from factory but knew they shouldn't, so set it up so you really HAD TO.

This will probably be a useful reference, shows how the boost builds...

Interesting to see that it hardly seems to build boost any quicker than my .82a/r GT3076R on an RB25! This is from my dyno tune:

I believe that at the level I am currently at, my turbo has nothing over a .82a/r GT3071R - but a GT3071R would have a fair bit over mine in terms of streetability. If you are confident you aren't going to get bored with 250-260kw, then I think you are on the money. My car is perfectly streetable, and even at the "underutilised" level it is at the moment I think it would be really really good on a track. It has an exceptionally predictable power delivery, once the thing is past its boost threshold the thing leaps into life as soon as you get on the throttle. A GT3071R could only be better It is nice knowing I potentially have another 100hp @ wheels of flow without changing it if I want it without adding any lag or changing it though....

I'm all for seeing a decent medium sized single on an RB26. A mate of mine is actually first firing up his R32 GT-R running a built RB26 and a .82 GT3540R on it - probably bigger than a TD06 25G but the same kind of idea.

Yeah me too. For what its worth, you really can't feel any of it on the road. All passengers etc perceive it as just building up and having strong power all the way through, the only "weakness" is that the thing doesn't go straight to 15psi and hold it. If it did that it'd be so much more solid, nonetheless there are definitely gains to be had by removing that slight dip. The plan is next year to go to a built motor etc and then give it some boost and revs, this tune was just to get it safe and fun to drive - not to hunt every last hp For what its worth, I gave it a run on a rolling road dyno for fun and the dip wasn't anywhere near as extreme.

The fuelling on mine was nice and consistant, and the timing is all fairly sensible though we / he didn't play with the VCT point. The tuner is a very accomplished tuner, he tunes some NZ GTR who went over to Australia last year and turned a few heads.

On stock ECU and turbo etc my car had the same dip at the same revs.... are you running VCT?

The Mafia - sorry I got a bit up on my high horse, its hard not to when you spent a lot of time and effort researching something and someone swoops in and says that its funny seeing people imitate their setup and tell you who to thank for your research. Cheers man Yeah it'd be good to hear what Mafia feels about his on the road etc. I personally find it fine, of course its not the same as a stock turbo but as I've alluded to in the past - the stock turbo is ridiculously undersized for a 2.5litre engine. Trying to match that spool is unreasonable on a motor with the happy to rev nature of an RB. Even with full boost at 2500rpm, the fun won't begin until after 3500rpm! How much throttle do you regard as "a bit"? Anything over 3500rpm and any amount of load will result in the car taking off with quite a bit of vigour. On the way home I discovered that anywhere near half throttle and over 3500rpm in the wet in second equalled no acceleration but lots of wheelspeed. Below 3000rpm and it feels fairly NA, but it starts building pretty nicely after that. I guess one way of thinking about it is that I reckon with the stock turbo for a good amount of the rev range, you get hardly any difference in behaviour from 50% to full throttle. Thats something that annoyed me, it felt you could get 90% of the cars ability to accelerate by giving <50% throttle in the right situation whether you liked it or not. With the setup I have, the amount of throttle seems to bare far great relation to how hard it picks up - probably where the likening with a jet feel comes in. If you give it 1/4 throttle, it feels like it will give you 1/4 of its effort. 50%, it'll give you half crazy. Full throttle, you best have plenty of budget for spare tires. Does that make sense? I (and the only other person who has driven it so far since the tune) reckon it feels a lot more fun than a stock turbo R33 to drive, got plenty of torque to tottle around with but goes silly as soon as you get past 3500rpm at any real load level. I didn't really talk with my tuner about the torque dip, didn't really notice it until after the tune. I'll be seeing him tomorrow so might have a chat about it and see what he makes of it - you certainly don't feel it on the road. The waveyness is also very interesting, I noticed Cubes has it as well. After looking over my plots a little more I found that the boost curve has a similar wave through it, I wonder if the internal actuator possibly develops a bit of an oscillation when trying to stabilise at its preset boost level. In terms of the Holset turbos, there are a few EVOs and Euro cars around the place running them. Its a rather big pain in the proverbial that there is so little info around on them, the assumption often is that they have hugely wide maps and you can't go far wrong but I really like to know what I am getting myself into. I did talk and read quite a bit and found that they certainly seem to get on quite well with petrol motors in the 2-3litre area - one of my mates actually has a Holset HX35 with a 12cm housing for his 1JZGTE and another has an HX40 for his L28ET, both cars are still a work in progress so unfortunately I can't report how they have gone. Going by the reports I've seen around the place, an HX35 sounds like in a lot of ways it is a bit of an equivalent to a GT3076R - though the actual frame of the turbo is HUGE.

Zilch - Nice man I'll have to have a look at your thread. Yeah, at the boost and power level you are making the GT3076R has no major advantage over the GT3071R on a stock RB25 looking at the map. Its more the potential when I start getting more aggressive that the GT3076R has. WTF mate?? You had nothing at all to do with it. Neither you or Dale FZ1 deserve an ounce of my thanks. I had the 56T GT3076R for ages before you got yours, and had decided way before then. As far as I am concerned there is more of a chance that you copied or got inspiration from my or DP's ramblings. DiscoPotato deserves some credit for swaying me for .82 and Cubes a lot ... so thanks you guys for your opinions and help. And you are welcome for my input when you were thinking about what to change with your setup and were still fighting with the 52t: http://www.skylinesaustralia.com/forums/t1...um#entry2857161 For an additional reference, here is a dyno plot of my car running the .63a/r housing with a .6bar spring and creeping to nearly 20psi: Mr Mafia - you do realise you NEED a spacer to space a turbo too big to fit on the stock manifold away from the motor? Its not to copy you, its because you need to do it. I have no spacer now either....

I actually think a GT3076R .82a/r has MORE power potential on a fairly stock RB25 than a GT3040 .63 on the same boost level. Reason is, it breathes out the rear better and at higher boost levels will result in far lower exhaust pressures which ultimately means less restriction and you can as a result often get away with a bit more timing and therefore more power. The 82mm compressor of the GT3040 (aka GT3082R) only really has an advantage in higher flow capacity for a given boost level. If the engine isn't being choked by the compressor - which you aren't likely to get with the GT3076R ESPECIALLY if you are running stock cams, you aren't going to be in a position where the GT3040 has any advantage. The .63a/r GT3040 I'd imagine would be a tad lazier than a .82a/r GT3076R given the extra inertia from the 82mm wheel. I won't swear by that however haha. At best it would comparable- though thats just theory, someone on here who has exposure or more knowledge may be able to shed some light.

Not quite sure what you are looking for with that question. I basically bought a laser cut flange for a XR6-Turbo and effectively a pair of separate dump pipes were made up - one for the turbine outlet and a 2" one for the wastegate outlet. When the main exhaust bends to the back of the car the wastegate dump pipe merges into the main exhaust flow. You can clearly hear when the wastegate opens, even though it flows with the rest of the exhaust stream. I'll see if I can get a photo of it Why did you change your setup?

While all this was going on, I had been talking to fellow SAU'er Cubes who was looking for a decent turbo setup for his RB30DET powered R32. I had sung my praises about how good off throttle the GT3076R was, and how well it spooled and how willing I could tell it would be to make lots more power. There is also how cool the anti-surge whistle is.... hehe Anyway, after some deliberation HE went for a .82a/r internally gated version of the GT3076R which made ME watch with great interest. He finally got his car going, and I'm sure a few people here know the results. In short, it made good power, drove awesomely, and most importantly for me - it held boost. After muttering and swearing about my efforts and theories as to how I was going to fix my problems, I PMd Mr. Cubes and told him about what I was pondering. He was extremely helpful, and even went to the effort of hooking up a deal with ATS to get me a turbine housing and actuator from them - as in NZ we don't have people who stock such things separately. THANKS CUBES!!! I got my nice new package in the mail, and amped for the next few days about getting it on haha. Somewhere along the line I also impulse bought a low mount stainless steel exhaust manifold because they are cheap and I was on a bit of a drop-exhaust-manifold-pressure mission. Interestingly enough, with the new exhaust manifold and the new turbine housing - I didn't need any spacer. I don't know how much to do with the design of the turbine housing that was, and how much to do with the new manifold - but either way, it sat a little lower and was a much nicer fit. Also gave the exhaust a pretty sweet tone haha. As soon as I drove it, I was stoked. In normal driving its barely noticeable, on the motorway in 5th gear from 100kph it has SLIGHTLY less urge, almost like what you'd expect driving at a higher altitude. Who really wants brisk acceleration from 2600rpm anyway? Its nice not having the thing hissing like a hissy thing the moment you get under a slight bit of load. The BEST thing was when I gave it a bootful and the needle stopped climbing after it hit full boost. COOOOOOL!! So, I drive it around a bit getting used to it - and in to the dyno. Dyno tune was a mix of good and bad news. Basically, the wastegate would open at around 10psi - I wanted to run ~15psi and I had no form of boost control other than the adjustable preload on the wastegate. We wound up the preload until it seemed like it was going to be silly going any further. As it is now, the wastegate opens at 3600rpm at around 13psi and creeps to 15psi by 7000rpm... peak power attained at 6400rpm running 14.2psi so its not TOO bad but could be better. My next purchase is going to have to be an electronic boost controller to fatten up the midrange and maybe get a little more peak power. Nonetheless, was happy being able to get a full tune into the car - make some semi reasonable power and just have a really really driveable car. The tuner asked what kind of fuel was in it, he's tuned R33 GTS25ts with upgraded turbos along the T3/T4, GT2535 and GT2540 lines and has found them to start getting a little iffy above 240kw @ wheels in terms of timing and detonation. I got NO detonation on the dyno. He'd add timing, it'd make more power. Add a bit more timing, a bit more power. Add a bit more again, and the gain is minimal... ok so thats what it needs. No pinking, no dramas. So - some pics relevant to this stage of modification: New housing Cubes sent over: Dodgey cheap low mount manifold I bought: Wasted spark setup on the firewall: Internally gated turbo on low mount manifold: Dyno plot: Hope this reads as more than a boring wank on about my car actually starting to go properly, and has some informative use. Any questions more than welcome - I post this to hopefully help other peoples mission looking for a nice turbo setup for a stock RB25 that they MAY want to take to the next level at some point... I think this turbo is the best choice for being able to cater for both.

OK - so, first things first - ignition problem kicked in from about 4500rpm.... was a nasty nasty misfire. This was fixed using a Mitsubishi V6 ignition module (Spec2 R33s don't have one ) and a set of wasted spark friendly Buick V6 (Commodore mate) coilpacks. This so far has proven to work a treat! The next and more pressing issue was the boost creep - the first direction of attack was to cut the feed back into the exhaust stream off the wastegate and just have it venting externally. This made a huge racket, and SLIGHTLY reduced the creep - but really all it did was made a bunch more noise. Not cool - I only mention this as it was a path I went down, others might as well. Naturally, I had to road test it to see how it behaved - and now that I've had both the .63a/r and a .82a/r turbine housing I feel qualified to comment on the comparison. I'd love to tell you boost threshold difference on the dyno, or loaded up from low revs in a higher gear - but unfortunately there seems to be none. I don't know if this is because I went to a tubular low mount manifold when I changed to the .82a/r or not, but nonethess with either of them I can get boost from 2000rpm in 4th gear, and on the dyno they both made 9psi by 3300rpm. On the road however, there is definitely a difference - I definitely have a bit more lag. Interestingly enough, I prefer it - it makes a MUCH more streetable car and I wish I went with the .82 in the first place. Basically think of the lag as "how rapidly the turbo winds up once you've got positive pressure". They both feel exactly the same off boost, and seem to get to positive pressure just as easily... With the .63 so long as you are over "reasonable boost" (in my case I consider as 9psi/3300rpm) threshold then if you lean on the throttle the feeling is much like someone has cut a rope tying you back when you are attached to an elastic band at full stretch. You don't instantly get fired off, but you get quite a violent brisk bunch of acceleration. Now if you do exactly the same thing with the .82a/r, imagine a brisk take off in a jet aircraft.... thats the best way I can describe the sensation of them coming on. My experience test launching both setups says a bit -- I tried launching at 3500rpm with the .63, it had enough to get the tires spinning initially - and would snap on to wheelspin as the boost rose. I would gradually back off until the tires were more or less able to hold and try and hold that balance. When the revs went further up, the turbo would get a wiff of more exhaust gas and leap into life again - all keen to start toasting tires again. Basically it felt really really jumpy with this setup. With the .82a/r, launch would be much the same - except imagine the way the turbo reacts to the throttle control as more like how a jet (there goes that metaphor again) engine would react to throttle control. Back off to a point where its nice, and it will give you that thrust. Put your foot down more, and up goes the tires in smoke. With both setups, a gear shift near redline has you sufficient revs that when you put your foot down again the car bursts into life - no worry about falling of boost at all. Soo.... I didn't like the "better spool" of the .63a/r turbine housing as much as I thought I would, and I have a boost creep problem with the setup I have. I can either completely change it all to a high mount and a proper feed to the wastegate, orrr.....

Hi all I have been lurking around the SAU forums and gaining information from here and other places from before I owned my R33 GTS25t up until now, and will no doubt continue to. I had (and many others will still) have researched and pondered furiously the not so age old "What turbo should I go for question" and I have ended up with a combination that is so far PERFECT for my needs. Its been brought to my attention that people have been following my progress, and others - and that it might be handy to post my findings.... so here goes After all my research I ended up shortlisting and considering long and hard the HKS GT-RS, the 56Trim Garrett GT3076R, the Garrett GT3071R (which I consider to have been NARROWLY my second choice), and a Holset HX35 (got ruled out when I figured I probably wouldn't fit it low mount). After all my deliberation, I ended up with an initial "winning combination" which consisted of: - Garrett GT3076R with .63a/r Ford Style turbine housing (yay ATPTurbo) - Factory Exhaust manifold with 10mm spacer (needed to clear rocker cover), wastegate mounted off the turbine housing of the turbo (BAD move - don't do it, boost creep galore) - Completely stock RB25DET - Nismo 555cc Injectors (yay Greenline for particularly good service on getting these to me) - Walbro 255lb/hr in-tank pump - TiAL 38mm External wastegate - GTSLink Plugin ECU - Cheap front mount intercooler kit - 3.25" MomoCorsa Exhaust with no cat This setup had a MAJOR boost creep problem, even after porting out the internal gate port the Ford Style wastegate setup provided - it rather sucked. I also ended up with huge ignition breakdown issues which was a big pain in the arse. Nonetheless - here are some pics of this stage being put together and running: Turbo: Turbo test fitted (note spacer): Internal gate housing with ported out wastegate feed: Wastegate fitted to turbo: Engine bay with it all in: end of stage one.... will start writing stage two going straight away..

Stock S2 RB25DET GT3076R .82a/r Internally Gated 1bar boost 600x300x76 Intercooler 555cc Nismo Injectors Walbro Fuel Pump Safe tune

Haha will do that on the dyno (maybe not to 18psi though haha) Thanks HEAPS for all your help! I'd still be trying to find a way to solve my boost creep issue if it weren't for you

Just installed one of these .82a/r IG housings on my GT3076R, its awesome Initial tests show it to hit and hold 13psi SOLID from around 3500rpm all the way through 4th. Going to have it on the dyno on Thursday for a proper tune.

Oh it'll probably have the VQ37HR thing in it - those are pretty damn grunty motors! That'd go damn well!

I couldn't possibly disagree with this all more. S13 + stock internal RB25DET with an upgraded turbo etc is a proven 10s combination at the drags. Even an RB20DET makes a hell of a fun car to drive, if its going into what was originally the CA18. Going by the fact you mention the handling, I am better you have not actually driven an S13 with an RB in it? It is a comment made often and I've never heard it made by people who've actually tried driving one. There are quite a few top NZ drift cars using RB powered S13s, even in Japan its done.