Lithium

Awesome work man - I am well stoked you pushed it that hard and got the results I hope they bring that fuel out here... Who would have thought? http://www.skylinesaustralia.com/forums/in...t&p=4336498

Haha glad you appreciated it Can't take these threads too seriously, but it is interesting to try and get to the bottom of it - I struggle to see in most cases what HKS could do to make something that is made up of essentially the same parts could be wildly different. If I were more bored (could happen still) I'll go through the RB26 dyno results to see for myself, isolate a few variables such as boost level and modification level to see if I can get a control boost/mod level - if I do, I'll post the results regardless of whose favour (if any) it swings in. I don't have a blind preference, though make no secret that I find it hard to believe that two turbos with the same part numbers would somehow be completely different... however if it turns out to be true it'll be very useful to know. It does seem weird that the GT2860-5s have an average power of just over 300kw @ wheels when its well known and proven they can go well over that power level without much trouble at all - kindof makes it seem that there are probably a few cars (if the sample is small enough it'd only need one) which are no way near leaning on the flow levels to drag the results right down, or one making a huge power level on the 2530s to drag the average up.

Problem is different dynos, different amounts of modifications and boost etc for different setups make it harder to compare apples with apples. People who have paid for the more expensive items usually would have more to spend on getting EVERYTHING up to spec and as such squeezing the best out of them. This is an interesting entry in a NZ tuners blog: http://sthitec.blogspot.com/2009/06/gtr-week.html

I might be out of date, but didn't the Hi-Octane guys take your "low mount record" with a pair of lower specced generic Garretts?

I'm running a Garrett GT3076R on it so you can't run a stock dump pipe on it, I have front pipe as well. Is an awesome sounding exhaust with the bigger turbo as well

Pretty sure the Oz publications did a turbo shootout with a bunch of twins where if I remember rightly the T517Zs provided the best all around performance? They certainly seem to be the goods.

Wow thats interesting, the spool is no better (if not a little worse) than my full GT3076R running a .82a/r turbine housing!!

14.0 @ 98mph?

Depends on the turbo setup, the car etc etc. If you are getting soaring exhaust manifold pressure then you are quite likely to get a good gain - if its all relatively under control then may not be worthwhile. If you are running a .68 housing on a GT30 and making 320wkw then I'd guess you're probably pushing it quite hard, and the .87 may free it up a bit though its really just a semi educated guess.

That looks and sounds awesome, nice work - look forward to hearing how it goes. Its an RB30 bottom end, eh?

Link make the ECU which calls the shots on the fastest RB30 powered car in the world (may be the quickest RB in this part of the world not running meth too?).

Exactly Different wheels/housings etc can relate differently. A .64a/r GT25R isn't likely to touch 200kw @ wheels, a .63a/r GT35R will crack 350kw. He actually hit 340kw, his 370kw @ wheels was speculative and I pretty much wrote that off... if he bumped the boost up he might discover hints that it wasn't going to go much higher anyway Not sure which cars you are talking about. I know mine has done low trap speeds for the power it has, but that has been more to do with me never being able to get at the power I was making on the dyno due to fun things like ignition misfires and boost leaks Ditto the other side, I am actually leaning more towards somewhere in the middle. There are plenty of people out there who have made ridiculous power (and the times to suit) on .63a/r T3/T4s for years - in our part of the world it seems they haven't been looked into or as understood as elsewhere but it doesn't mean it can't be done. I'm just saying don't bag a setup you aren't familiar with too quickly. Pretty sure the fastest pump gas EVO in the world (traps near 150mph) runs a .82a/r T3/T4 I made an estimate on what trap speed I'd hope from a Skyline making xxx.kw on a Dynapack dyno as I am more than familiar with them, much as you guys are familiar with Dyno Dynamics. I know that an R33 making ~370kw @ hubs set up "normal" should run 127-130mph or a few less with 340kw, to put it more into perspective.

I am very well aware of the difference between the two, and I always run my car on Dynapack dynos - hence my comment. My car has made 270kw @ wheels on between 1-1.1bar on a hub dyno, if you knocked 60whp off that I'd be under 220rwkw on a Dyno Dynamics.... so you guys are effectively saying that a healthy RB25 running a .82a/r "real" GT3076R tuned to make 270rwkw on a Hub dyno will make under 220rwkw (using the take 60whp off thing) on a Dyno Dynamics dyno, despite the fact that the combination normally makes way more power than that on a DD?

With all due respect while its known there is a bit of a difference between the two type of dynos, there is no way my car running a .82 GT30R on 1bar would be making <220rwkw on a Dyno Dynamics dyno? Can't really say too much without him telling what trim turbine wheel he's running and what compressor etc, there are many many different variations of "T3/T4" turbos and most of the ones people seem to use on RBs in NZ/Oz are the far less aggressive ones but looking at the lag in that plot its probably something a bit more substantial. 370rwkw on a hub dyno, because Dyno Dynamics seem so inconsistant amongst tuners I won't guess how it relates to one but if its set up the way most tuners I know run them I'd expect this car to be running in the area of 130mph trap speeds on the 1/4. As it stands, this car actually made just under 340rwkw - still plenty sufficient for 11s at >120mph, would be interesting to see how it goes.

Sounds like a lot of fun! Though definitely sounds like its in between the GT30R and GT35R in terms of spool, won't comment on power until you get it on a dyno - is this due to happen anytime soon?

Yeah, you definitely don't want that.

I was given this same run around a few years ago when trying to buy my true GT3076R - everyone kept pointing me at the T04S covered version with the different compressor wheel, I even provided them with the CHRA reference to make sure they gave it. I tried a guy who uses an Australian supplier they swore by (SAU Sponsor too I believe) and they at best glanced at it and told me "That version has been phased out, this is the newer/better one". Anything to make a sale, eh? I ended up buying my REAL GT30R from ATPturbo.com, never looked back.

Yeah that size stuff was the deciding factor on me going GT30R instead of HX35, I had one right there to go with but wussed out - the GT30R is enough of a bitch to work around if I need to change gaskets etc haha.

Nice thats no small amount of power - is that on pump gas or race gas?? Whats spool like?

Yeah definitely, we're all really hypothesising I see what you are saying and not really too sure it would cause that much compromise - you'd pick the a/r to suit the fact its a split pulse housing... ie, with twins you'd maybe go .64a/r whereas on a single you'd be looking at .95-1.06. Gases are inherantly good at being squeezed/forced places, so I am sure that the divide facing the turbine isn't going to worry them toooo much given that they are basically being forced at a bunch of spinning blades and are bound to expand, squish and swirl in all sorts of weird ways anyway. I also like the fact that with the twin scroll setup there is a constant stream of pulses hitting the turbine, it will always have leverage on it whereas each of the twins will potentially have a far greater oscillation pre-turbine due to the gap between pulses. I really don't know for sure though, though its interesting to ponder. The twin scroll setups I have been exposed to honestly have blown me away in terms of response and spool, though I have never been in a car with twins that is using a similar engine spec and power level to another car running a twin scroll single to give a fair comparison. I have however been in GTR running a single scroll .82a/r GT35R making similar power (getting towards 400kw @ wheels) and similar engine spec to ones running twin GT2530s and I reckon the GT35R setup was more responsive (at worst equivalent), so given the range of advantages a twin scroll 1.06 T4 setup on the same car would bring I dare say there would be no comparison between such a setup and a pair of GT2530s. It may not be apples and apples though as I suspect GT2530s might be capable of making more power.

Which is what you want? The turbine gets the full force of both.... without any "mess" from collisions before hand I am not actually sure what to really expect, it would be interesting to know how they would compare but I personally can't see any obvious reason why twins would be more responsive. To be honest I'd almost expect a single to be a bit better in overall efficiency. The twins have a bit of a bonus in that they can have REALLY short runners, thats about it that I can think of.

Guess it depends on what you started with and what you want from it etc. If you go a twin scroll T4 based turbo upgrade you potentially don't have to change much in future, you have a more efficient setup (nicely designed manifolds/external wastegate setup), the engine bay is much more maintence friendly etc. And of course there is the whole obvious fact its just cooler

You're definitely not the first to notice the fact the sets of 3 cylinders are separated in the factory log manifold, I've pondered it and decided that I'd still rather use a custom manifold if I went to a larger twin scroll turbo though it is interesting to note and I am sure it has its advantages even with a single entry turbo. I look forward to hearing how the HX35 goes as I got SO close to getting one for my own Skyline years ago before I ended up settling on the GT30R.

Talking about GTR or GTS25t? My Series 2 25T hit 10psi by ~2500rpm with intake/exhaust.

That is awesome, congratulations!!! Look forward to hearing how they go for you