Lithium

Hi all, I was wondering if someone could shed some light on this topic for me.... I notice when people go for twin turbo setups for "light tune" GTRs, they seem to go for things like disco potatos etc. Recently a mate of mine asked what would be a good turbo to go for on their Starlet GT, saying they wanted a good streetable turbo which would let them get ~270hp @ crank. He had been looking at GT28 style turbos, so I went and had a look at some compressor maps and made some wild estimates. Something interesting I found, is that at least the way I was estimating the flow of the motor etc - SMALLER turbos seemed better suited to the 1.3, but at higher pressure ratios. Funnily enough... almost so much that a GT28RS would be a worse choice than a much smaller turbo for the same power level, as at the boost level required surge lines get precariously threatening etc - but the motor didn't look like it would breath enough in the "top end" to make the size of the compressor wheel at any given pressure ratio worth while. I looked around at other maps, and feel apon the GT22 with 59.4mm 52trim compressor wheel - which for the same pressure ratios (up to around 2.5) SEEMED by my loose estimates to be a lot more sensible. After that, I pondered the fact that half an RB26 might be a bit better flowing up top than a 4EFTE - but not HUGELY so. When matching a pair of turbos to a straight six, should you treat it like a pair of 1.3s? Because if my assumptions are remotely correct - that GT22 turbo could actually be quite a nice match to the RB26 for a mild upgrade over the stock turbos?! GT22 Map

Nah, the Speedtech dyno doesn't read low - that perception probably comes from the fact that the Chequered Flag dyno reads very high high. The Dyno Dynamics dynos that Australians use read real low, definately more so than Speedtech's Dynapack hub dyno. I wouldn't be surprised if it picks up a little bit of power with more kms on the motor and a tune, though don't expect miracles. I'm not sure why you want to upgrade the fuel pump etc etc, but with a decent intake and exhaust and a dyno tune I wouldn't be surprised if you managed to stretch it out to maybe 135kw @ wheels, though I can't see it making much more than that without some serious work. A mate of mine will be running his Maxima at the dyno day which goes very well - pick his brains on what he has done to it to make it go like it does, I wouldn't be surprised if similar style tricks he has done would work for your car. He's very analytical etc, so he will be able to give you a good idea of exactly what effect each mod he has done on his car has done to improve its performance etc. I'd like to give suggestions, but most of my NA tricks are relevant to cars with motors quite different to a big 3l which doesn't rev to high heaven

Here's a video of the Heat Treatments GTR doing a 7.81... Rather insane GTR

Wow... thats pretty big news if its true!! There are a lot of places around the place which claim that the top 3 GTRs are HKS, Heat Treatments, and Advance... I wouldn't be surprised if they could knock off some huge time with slicks, the thing has insane power and not so much traction from vids I've seen.

Ummm, when did Veilside do a 7??? And there are rumours HKS used a fairly sizeable NOS shot to help along their 7.67.... also, GTRs never were turbo at all until about 1989 I think Heat Treatments will be matching or bettering the 7.67 HKS apparently ran, probably worth noting they've already gone quicker than HKS could manage in Oz - with a dirty great big single and no NOS

I was pondering that too, but in the past have been left with a bit of a blush after assuming that a thread was by a dreaming school kid - fortunately I hadn't said too much, as the guy turned out to be very much legit. Something I find very interesting, is the NZ vs. Oz culture in going for turbo setups - in NZ, huge single turbos seem to be the preferred path whereas it seems you guys like twins. Seeing as the OSGiken kits seem to make something which is very similar to a 2JZGTE, T04R.Com may have some useful information. Here is a table they have put together as a rule of thumb for power output potential and boost thresholds for different turbo setups on 2JZGTEs: Mmmm GT47

I've read of other people installing GT3071Rs (in the US) on their cars, and talk about them having an anti-surge compressor cover?! I could be completely wrong, but that compressor cover isn't, is it?? For risk of sounding "ricey" but does this turbo have a particularly "whistly" induction noise when it comes on boost?

They have Andre Simon (tuner/proprietor of Speedtech motorsport and driver of the worlds fastest EVO - DOCILE) on board tuning the car now. The team is continuing development over winter, and it sounds like they might make a mission over to Oz to have a go at Jamboree later this year. You should look forward to seeing the fastest time done by a GTR done on Australian soil if that happens They are running "somewhere over 1300hp @ wheels" now...

Using NOS like that Z has sortof makes it not an NA accomplishment, unfortunately. Also, the thread is specifically about straight 6s - not saying they are better.

Still no word on Oz's answer to this? I don't doubt something will emerge at some point... but the bar is being raised. Heat Treatments ran at Meremere with a new turbo setup this weekend (a single LARGE turbo) and did a 7.81 @ 177mph with traction issues, so wouldn't be surprised if this drops with fine tuning.

I have been under the impression the plastic wheel is slightly larger - but on the down side, if it ends up "over spinning" the tips can flex out - and clip the housing.. then snap!

My bad - sorry for putting you wrong on that I had assumed that the only Prelude that anyone would bother turbo'ing would be one with an H22A in it. B20As are pretty poos. I've got a couple of mates with stock engine'd Hondas (one a 1.8VTEC Integra, the other a 1.6VTEC Civic) both running 8.7psi (.6bar is a nice safeish boost level for a stock VTEC motor) and both do mid/low 13s quite happily and reliably.

WTF - I didn't bother signing up, but he's clearly doing something seriously wrong. One of my mates have a forged H22A and large turbo on his Prelude and did a run on 6psi (only tuned for engine run in) and managed a very wheelspinny 13.2 @ 186kph. With 11psi and a built motor (built motor is an advantage as on NA the tune is usually just to keep it alive) an H22A should be making some pretty decent power. They are at least comparable to an RB25DE in NA form, so the same would suit for when a turbo is attached to a built RB25DET.

Hey Geoff - thanks again for the blat, I've always wanted to see what an RB30DE felt like... I love the effect having the motor balanced has had on the old RB30E bottom end Sounded very nice as well, particularly the induction noise. Going in the car you can tell the motor would like to make a bit more grunt with some tuning. FYI though - that dyno graph doesn't show your car running rich down low, it shows you running lean... then dropping down to a safer but still a bit lean air fuel ratio. So yeah, if you get an S-AFC - if you're going to make any adjustments before putting it on the dyno... bump up your fuelling down low.

BADR33 - Yeah, I am from Wellington (aka Lith on SkylinesDownunder).. I've met you before - I think I was driving Dan from MIDAS's R32, but now my R33 GTS25t is running I'm usually seen driving that. I'm guessing if the car is running by Thursday I could be seeing it in the Hutt Anyway, good going on sticking to NA with the car - I think its cool, and it should go pretty good all going well. Definately something a bit different!

Hehehe - Don't make assumptions In the 90s there were a few RB30DE VL Commodores and R31 GXEs running around with them - even in the Hutt Valley no less!! There was a street machine article in the late 90s detailing how to convert the RB30E -> RB30DE using the RB25DE head, and it captured quite a few peoples imaginations. I have been quietly watching your build and am very much looking forward to hearing how it goes when it hits the dyno - and your on-road impressions. I've quite fancied the concept for a while now and have never actually checked one out close up Shame about the weight of the 4 door R33.... could make quite a sleeper hehehe!!

Not quite completely off topic - how does the GT3071R drive on the car?? Does it spool ok??

The Speedtech EVO (aka DOCILE) ran an 8.23 @ 179.5mph this weekend here in NZ, I'm waiting to see if there are any videos circulating of that run - if so I will link it up. The fastest run I am aware of being caught on camera so far of his is an 8.35 @ 174mph run that was done a couple of weekends ago: http://www.pizzaboy.orcon.net.nz/dragvids/docile_835.wmv

The current (in NZ at least) issue of New Zealand Performance Car Magazine has a write up on the car, and the time.... and the fact that it has a fair bit more in it

I'm not aware of any videos of that run yet I've been waiting for one to show up. I know it was with a 1.42s 60ft, so theres more in it - the car has run quicker 60fts. Heat Treatments have run another 7.9 since this post, not sure what trap speed - and GDS (Glen Suckling) have run in the 8.0-8.1s, but not quite cracked into the 7s. The NZ 4 and Rotary nationals are this weekend coming, I suspect there might be some more news after then

The man himself said he didn't get into top gear - they don't have a reputation of talking shit (maybe this is common in Oz???).... 256kph trap speed when they usually run 270+ is an obvious sign. Apparently they are working on what went wrong with the box with the intent of running tomorrow. I guess that will clear some stuff up?? They've already done an 8.033 @ 172mph already - so no matter what way you look at it, a solid seven second pass is inevitable... if not now, with the new motor.

WTF is that supposed to mean?

Any more happening in the GTR-700 camp? I've been keeping an eye on the website and all has been quiet since July. Reece McGregor ran an 8.03 @ 172mph in NZ this weekend just passed, and backed it up with an 8.09 - 7s should be happening really soon. I can see GTR-700 as the only GTR between him and HKS GTR at the moment...

Yeah - I wasn't 100% sure on that one, I thought the 250wkw cars were possibly running the VG30 turbine housing. There is definate varience between dynos though, is this reading done on a dyno which reads consistant with other ones which have run 250wkw? I know this could sound stupid - but were any runs tried at lower boost - such as the 1.3bar mentioned by paul? Maybe exhaust gas temperatures are becoming insane at 1.4bar, the thing might even be able able to match the power level on a slightly lower boost level? Do you have a decent dump pipe? What kind of intake/intercooler system are you using? Is there any chance that there could be an air leak somewhere?

Wouldn't the tiny R33 turbine housing (~.48a/r) end up creating HUGE amounts of back pressure, and resultantly heat when the exhaust gases from an RB25 breathing 19-20psi of boost at high revs is trying to force its way through? I would just not try to run that kind of power through the RB25 turbine housing.... I wouldn't be surprised if swapping to a VG30 one would make the world of difference.