Lithium

Well my turbo is a GT3076R, is laggier but not a crap load laggier than stock - and a GT3071R is advertised by Garrett/ATP as spooling MUCH better than the GT3076R. I reach 8psi by 3300rpm with the GT3076R, I'd say it stands to reason than a GT3071R should be at that point by 3000rpm quite happily.

I'd imagine you'll probably be lucky to get much happening at 4500rpm with a T78, if what you mean by spool is "Making reasonable boost". The biggest turbo I could imagine getting much going on at those kind of revs would probably be something like a GT4088R, and that'd not be full boost...

With a bit of thought, you'll notice that none of the GTRs are tube framed or tubbed - and are 4WD.... they have more weight, more drivetrain loss, and less tire on the track. Heat Treatments (fastest GTR in the world with a 7.57) have a tube frame drag chassis in the build which will weigh heaps less, have way more traction and generally be a better base for going outright fast. The running gear from the GTR will be going in that..

You actually wondered why the dude bothered with a twin scroll on a 4G63 as they spool GT30-based turbos well anyway - after looking back on it, so I guess not necessarily knocking the setup persay...

Nice to see how a GT2871R behaves on an RB25 - sounds pretty cool. Good work and cheers for sharing results I had been looking into it and decided a GT30 based turbo would suit me more... Strange, I mentioned our discussions and decision to go with a twin scroll "real" GT3071R on a particular car and you seemed to consider it a wasted exercise?!

HKS Car = Eye candy, turned yellow and not racing. Heat Treatments = some rumours that it has grown some bigger balls than when it was in Oz for the 7.57 (was probably in the vicinity of 1600hp) We shall see

Hard not to roll ones eyes at some of these comments.... but yeah, the trap speed tells no lies which is why the time and trap was mentioned in the first place. Just a shame you guys seem to treat any result from a dyno which reads different to your precious Dyno Dynamics with contempt. AndrewD - Yeah, thats why I said that SAE is a standardised adjustment. The number which comes out the other end often comes out higher than if DIN adjustment was used on a hub dyno.

Thanks SK. As far as I understand SAE isn't an at the engine correction, but it is a standardised adjustment which ultimately results in high readings. It has already been said earlier in this thread that the dyno it ran on reads high though, which is why the fact that it ran a 10.6 @ 128mph was mentioned in the first place - to give a more realistic idea of what a .82a/r GT3540R would do. Shame there are so many angry people on here who want to call BS about everything without using the soft stuff in their skull a little more. The car was running ~21psi, and was on BP Ultimate (98) when it did the runs. It has a thicker headgasket, a tubular high mount exhaust manifold, custom plenum, the biggest dump pipe they could fit (can't remember if 3.5" or 4" even). The reason I'd mentioned 4cyl GT3540R times/traps in here is the trap speeds are always going to a be rough indicator of the power the thing is making with the turbo, and it was running on pump gas - seeing as there is so much obvious contention about dyno results. I could have mentioned that someone in NZ has managed an 8.9 running a GT3540R on an RB30/25 hybrid, but the rest of the package is so far different from anything here the 4cyl results would have been MUCH more comparable.

Yeah sorry I just got that looking over again.... is some good info here. Mine was 440nm @ hubs, no TCF for trans loss so its effectively whatever the amount of torque the engine is making less whatever it lost going through the tranmission. I'd assume yours is the same as well.

In regards to the Japanese Performance R33 GTS25t - I'd love to be reminded the 1/4mile time and ET of BU5TER which has a T51R on an RB30 hybrid.... I have a magazine article here saying it ran 10.5 @ 130mph withn 441rwkw!? Am I missing something? Thats running a drag-setup auto and I'd say with 3l it will have a torquier power delivery, and Dyno Dynamics dynos read a lot lower than a particularly high reading hub dyno. How come there aren't BS claims flying around about that time with that car? I remember the Wild 1 Motorsports guy on here claiming big power figures from a GT3540R on their R33 and ended up doing a 10 USING NOS on their one.... and that didn't go as quick as Jap Performance either, despite the huge kick the NO2 would give it. Anyway, I know of a few cars doing 10s on pump gas with GT3540Rs - a mate of mine did a 10.7 with his EVO in full street trim (including tires) using .82a/r. Consider the .82a/r a turbo capable of getting you near 130mph on your average Japanese car on pump gas.

What the f**k? I never said 900nm, I said 440nm - my car is ALSO making 274rwkw @ hubs.... and I know all about the torque thing. There is nothing wrong with my dyno reading, to me it sounds very similar to yours to be honest.

At the mid/high 200rwkw area mine makes ~440nm @ hubs when adjusted for final drive at 1bar.

ATP T3/T4 style housing with TiAL 38mm wastegate mounted off it - a setup we've tried and found to work (at least with T3/T4s on RB20s) fine. The wastegate port has been bored to 38mm. At the moment I am thinking/hoping that it might be more to do with how it merges back with the main exhaust stream, its merging back pretty close to the wastegate/turbine... which I have the impression isn't ideal. Some pics (won't show the image as not sure that everyone would be interested): http://i134.photobucket.com/albums/q95/mrlith/portedwg.jpg http://i134.photobucket.com/albums/q95/mrlith/External2.jpg http://i134.photobucket.com/albums/q95/mrlith/gtlurk.jpg http://i134.photobucket.com/albums/q95/mrlith/Engine2sm.jpg

I didn't quote peak power or post the dyno plot for a couple of reasons. 1/ The thing has boost creep, so boost climbs from 9psi at 3200rpm to 1bar at 5700rpm, where the dyno tuning stopped as I don't want boost over 1bar - and it won't stay below there from that point. The power beneath the curve is DEFINITELY where I think this setup will excel, considering it isn't even holding 1bar flat it feels VERY solid on the road. 2/ The whole dyno comparison thing - I know hub dynos probably read a bit higher than Dyno Dynamics rolling roads and know this forum can be a bit rough for knocking power figures that seem higher than people might expect so was just trying to give an impression of how the turbo actually behaves. Following the curve I expect it to make 280-290rwkw on 1bar when its holding boost and fully tuned to 7000rpm, though please note this is on a Dynapac Hub dyno so I don't think that power level would apply to the Dyno Dynamics dynos most of you seem to use. For what its worth, compared to other cars that have run on the same dyno - its looking VERY good so far. Anyway, here's the dyno plot SO FAR - I will post somewhere suitably when it is tuned to 7000rpm and holding 1bar right through the rev range but it should give a rough idea.

The 56T GT3076R with .63a/r turbine housing is ALL SORTS of fun on a completely stock RB25! I've got stock everything (block wise) with 555cc injectors, big fuel pump, ECU (ie, supporting mods) and have it running 1bar - I've been in a few other R33s with different setups and have to say I'd not have gone any other way. Its making boost by 2000rpm, drives like stock around town and gets very angry at life from 3500rpm onwards hahaha.

PowerFC is a good computer when you want minimum effort to get a decent tuneable ECU. I've heard patchy arguements that MAPs are better than AFMs - I've given answers to the AFM vs. MAP debate already SirRacer. I'm not going to join the arguement, but I vote the MAP sensor without hesitation. ST mainly tunes PowerFCs, no wonder he's pro PowerFC.... if he can't tune other things, why would he tell you to go with others? There are quite a few cases around the place of people getting over 500whp on stock internal RB25s, though at least a thicker head gasket is well recommended.

Ahh ok - I understand the turbine and compressor families, though evidently made an incorrect assumption when I was reading a compressor map that had overlays of different GT37s - I assumed that a compressor map which was titled GT37 would be for the different trim variations of the GT37 compressor wheel.

Or if you're lucky, it'll be like mine where the intercooler caught the bits. A GT30R was a nice problem solver. Edit: Oh, only small bits missing - mine chomped off big bits... eek

I needed one for my real GT3076R with T3/T4 style turbine housing, which I assume the GT30-IW turbine housing would probably be based off the general style of. I'd be very interested to hear how these go. I find it interesting that Garrett list their 52-trim GT37 as having an 82mm exducer.

1. So has anyone installed a set of these on their RB25? Yes - bought them from Greenline 2. If so, is there any customizing involved? No 3. Do I need a collar set? No 4. Will it fit straight on the fuel rail? Yes 5. Will they plug straight into the fuel sensors? Sensors?! They plugs are compatible with the stock ones 6. Are these side-feed? Because they say they are for R33's Yes, sidefeed and high impedence - no resistor packs or anything. Its like changing the stock ones for other stock ones. You will NEED a tuneable ECU though, I dropped the base fuelling by a LOT and it still fouled the plugs straight away! They flow heaps more than the stockers.

Hm. Mother load of turbos for SR20 - wouldn't one think that a bit more aggressive trim would be more suited to a 2.5l? So far I love the 56T GT3076R on the 2.5 - so far I'm not sure where the lag people talking about them having is, though mine is only at .6bar at the moment (Reached <3000rpm)... though would be interested to hear how a 52T goes on an RB25 if someone goes this combo.

Damn - some cool things going on with RB25s at the moment. I will watch with great interest at how the GT3071Rs go - I got >< close to going one, but decided a GT3076R in the end. The RB25 dyno thread will be interesting watching soon!

Car is running with a rough tune in it with the 56T .63 GT3076R, so far so good - less "laggy" on the road than I expected.... I can definitely live with what it feels like so far only using it with low throttle openings etc. In 5th gear at 100kph, leaning on it ever so slightly can push it towards positive pressure.

Cheers for all your input and my slight deviation from the topic D. I didn't realise there'd be that much in the actual scroll design, had always focussed on the wheels. Live and learn. Have you guys looked at the link I gave earlier in this thread of the dude with the GT3076R .63 on an RB25 running 16psi? His dyno plot didn't seem bad to me - aside from what looked like some queer tuning issue in the higher revs.

Nice - that must feel fun How does it drive around normally? Just verifying - Disco/whoever, what you are recommending is exactly what I have but with a different turbine housing? If so, I will report how mine goes with a .63a/r - and if it DOES seem like its a problem, I will just change to the .82a/r one and report how that goes. I never knew GT3071Rs had a port shrouded version...