Lithium

Where did I say they can't rev?

I disagree with most of this. RB20s are stupidly short stroke, rod/stroke ratio is what really matters and 4G63 have awesome rod/stroke ratios and have both torque and the ability to rev - partly as a result of this. One of my mates has a track car with a 2litre running a GT3582R with .82a/r hotside and the car is perfectly useable with it, I think a lot of it is the fact he can rev the crap out of it and be heavy on the throttle without fear of going from lag to no traction and back again relentlessly. RB20s lose a lot of torque probably partly to do with this, and don't do too much to make up for it - so you really have to put a lot of work into making up for it... hence this thread being so tricky. With most 2litres it'd just be a case of "get a GT3076R/GT3582R" or something like that and all would be fine.

How different would the results really be from an Rb25?? I'm going to be playing with an RB25DET Neo Powered R32 GTS4 soon, will be getting either a GT3076R, GTX3076R or T67-25G ... depending on where the owner goes with that. I'm quite interested to see how that goes.

Awesome, good luck - will be itneresting to haer how it goes

Nice, was that on pump gas? The factory setup is pretty impressive, going by that lot.

The different size/length runners make a reasonable amount of difference with this kind of thing and sloppy valve springs no doubt come into it too - but peak power for a factory RB25 by definition of Nissan is 6400rpm, and a car with stock manifolds and pretty much any turbo will make peak power around those rpm. Thats where mine makes its peak power, as with gazillions of others I have seen - I am pretty sure a T67 will be no different. You're going to need some pretty serious mods to get a 1JZ revving like that

I want to know myself! One way or another it's pretty sweet, and no doubt the 4deg retarded camgear has a fair bit to do with it though the manifolds can't be hurting, and the turbo clearly needs to efficiently flow up there. Simon - do you know of anyone with cams and a T67, or do you have any plans to do it yourself?

Lol Scott, are you trying to imply the turbos are inconsistant?

Peak power at 7800rpm... stock RB26s don't usually make peak power up there! 240kw @ axles for a GT3071R, hmmm... thats not quite right either.

Nah, its definitely nothing to do with that. The only car I have tuned so far to have a power curve that "revvy" on a Dynapack was a fully built Honda Prelude motor (12.5:1 compression, head porting and 312deg "VTEC" cams) which was starting to level off at around 8000rpm making around 180kw @ axles.

Thats very interesting, nicely setup - though I am completely unconvinced that if I put a T67-25G on my car it would suddenly start climbing in power up to 8000rpm. The T67 obviously has to be able to more the air up to there, but your actual engine has a ridiculously good ability to breathe air. Imho the T67 is being made to look particularly good up high there due to the combination of bits, but makes comparisons a bit hard. Either that or your RPM calibration is screwed.

I meant intake manifold as well, or do you have a stock one? For the car to be building power up to those rpm its not going to be a turbo thing, its the tuning of the engine itself - the T67 is dropping boost yet power is still climbing. People do all sorts of things to engines to keep their torque curve holding on up to those rpm, whatever you have done to get that happening... I want

Thats very strange, what manifolds? Full boost at 4700rpm as well!? Do you have a boost plot for that run?

So heavier car, and he hasn't done the hero tune yet? They aren't worlds apart then... I was going to qualify my statement with "all other things being equal" but then reckoned you'd know what I meant. 11.5 @ 127mph is quite nice going (well your 11.0 @ 132mph is very nice going too) in an R34 - what boost was it on? E85 I am guessing? Yours has standard cams and is gaining power to 8100rpm? Something doesn't sound right there...

Will be very interesting to see how it goes, let us know. Will it be on the same hub dyno? Would be very interesting to see an overlay. I'm leaning towards the GT3076R not QUITE reaching the T67 (if it has fully equivalent setup) power but would like to see a pretty mental midrange - assuming he will also be running E85. Slightly quicker, maybe... the extra $500 has to prove some worth somewhere I tried quite hard to convince the owner of a car I will be tuning soon to go a KD T67-25G on his Neo RB25 GTS4 but after I took him in my car (GT3076R) to convince him to get rid of the POS "T3/T4" he had he basically won't consider any other options.

Roy - what turbine housing does your 20G have? The Kinugawa TD06s look good, though the only 20G boltons for RBs are with a 12cm housing which I could see being quite laggy

How is this coming along? Any ETA on test drives/tuning results?

Definitely don't cane it around until you have a tune in it unless you're not particularly worried about popping your motor. If its going a lot better it will have to be moving much more air, so will be running leaner than before. Unfortunately any realistic GT30 vs T67 comparison will be to some degree moot as so much has been changed.

Nice - so did you go a Kinugawa T67?

Nice. Thats a little looking exhaust, is your new engine setup going to be breathing through that?

Hi, just to clarify - is the HKS manifold a T4 manifold for an RB25?

The youtube dyno vid had it at around 602kw @ 35psi on E85, if I remember rightly.

Definitely wasn't me, I posted a spool vid of my GT30R using different gears and load levels to help relate what it behaves like in different situations to people considering turbo options for an RB25 knowing full well it doesn't work that way. I admittedly am not so familiar with dynos used in Oz but if you can't really count on a dyno being consistant in terms of acceleration rates, then there is no point at all in comparing dyno results to ascertain spool.

I have enough respect for you to realise if you made the post I did you'd not mean something retarded like that, even though you don't know me in person I'd like think by now you should be a bit wiser than that. Either that or I give you too much credit. Most dynos control the rate a car goes through the revs, so while of course a car will generate a different amount of psi by xrpm in different gears on the road - if you run a car from 2500rpm to 7500rpm at a steady rate in 9s in 1st, 2nd, 3rd, 4th and then 5th gear on a dyno (if it were able to allow such a test) do you think the turbo will spool differently with all things otherwise equal?? And if so, please explain how?

I can't watch the vid as I am at work, but that sounds much more promising... like impressively so. Will check after work.