Lithium

Nah slow ramps tend to give more impressive looking numbers overall - has nothing to do with what is attached to the hubs, it's how long the engine and turbo are under load. Sometimes the power numbers can drop with a slow run if there is inadequate cooling/airflow because obviously everything gets too hot but spool especially makes a huge difference, a 20 second run will give a really unrealistic impression of spool! At least you know with a 20s run that if your tune doesn't get upset during it, it should be fine for a lot of thrashing With cars not struggling with heat on a long run you actually often get bigger numbers on slower runs, it takes up some of the inertia of the rollers/drivetrain etc by not needing to accelerate them as quickly.

If you were looking for RIDICULOUS spool mainly then something like the PE1520TR kits (if they are still around) would be pretty awesome. I've driven a Silvia with a single PE1420 and it was ridiculous, transient response and outright spool is mental and they flow OK too.... just not really what you are looking for if you want big power. A quick nosy had me find they do a 800+PS kit for GTRs too, the PE1920TR kit - if the PE turbos I've had any (albeit minimal) exposure to... they are pretty serious kit. http://www.zshop.ca/parts/r33-pe-pe1920tr-upgrade-kit-rb26dett/

Yeah I figured that - any earlier than say 4300rpm on E85 with an RB26 would really impress the hell out of me!

On a 6262? I would have expected mid 4000rpm at best?

Wow, the 6466 actually looks pretty big there

Cool - fingers crossed that sorts it and you get to reap some rewards soon!

I would say the difference there is the smaller frame housing they used on the GT28, definitely nothing to do with the turbine and I am pretty sure it us the same wheel. In terms of the GTX2867R versus the 3067 I believe they have the same housing and wheel so comp map should be the same... I haven't checked back to back but I have checked the GTX3067R maps in context of a stock Bolton RB25 setup and I am content that it should be a nice fit for what it seems like you are after. I am on my phone so won't get too long winded or animated but the simplest and most to the point part of where the attraction of this on an RB25 versus a GT28 based unit comes down to a mixture between driving the compressor, as you mentioned ... but a big issue with GT28s or trimmed GT30S is the outright turbine flow versus what is got out of it. Overly simplified, imagine for a given amount of airflow into an engine two different turbines will create different amounts of back pressure between the engine the the wheel...all other things being comparable. Imagine that amount of pressure is more or less comparable regardless of the engine setup and boost level, it's just how hard it is to force that amount a mass through that kind of restriction. Now imagine two different engines with exactly the same turbo and making the same power but different boost levels required to make that power...whether that be due to engine size, head flow, or any combination of things. Let's say one engine needs 14psi and the other needs 20psi to make that same power figure, and we are sticking to the assumption that they both generate the same pressure at the turbine due to moving the same mass (ie, whatever lb/min of air and the relevant amount of fuel to attain target AFR)...and say that magic pressure amount is 22psi. What will be seen by the tuner when tuning these two setups is on 20 psi this are pretty happy...the fuel curve should look pretty kosher and it's not hugely knock limited or anything for that boost level, however on the same note the 14psi setup could be starting to show signs of being past it's best. That all comes down to the relative pressure across the engine, the whole idea of increasing performance especially from a VE stand point is making it as easy as possible for stuff to flow through the engine. Gases like to equalise pressure so the bigger the pressure difference one way or another, the higher the want for the flow to change direction to the lower pressure . Reducing the exhaust side pressure relative to intake pressure has a positive affect on both VE (ie kw per psi) and also helps avoid onset of knock due to hot gases flowing slowly out of or back into the cylinder and making it too easy to burn when it's not quite time to. RB25s can be pretty efficient engines when not choked, so putting GT28 turbines in tight a/r housings on them is just cruel and unusual. I think the GTX3067R has the potential, especially with the 0.63 housing, to manage the relative flow on a boltona RB25 to make the most of that compressor while being a responsive wee beast and not choking the motor...at least in an unbalanced way. Looking forward like everyone to see how the theory matches up, hope they can suss out the boost control to do I some justice

I bet. So have they not even given an idea of how it is going so far? I'd expect that if they have started trying to tune it that despite boost control issues (whether over or under shooting their targets) they'd have a reasonable picture of if things looked like they were going to be on target or not when kinks are ironed out. Regardless, hope it all gets sorted out soon! PS. In regards to the compressor a/r conversation - I have seen and considered the compressor maps for the GTX3067R compressor wheel and housing combination, and while hypothetically speaking there may (or may not) be gains to be had from a better housing match to the comp wheel etc - I feel that with the information given from Garrett in regards to the comp and turbine sides that a 0.63 a/r and the off-the-shell wheel/housing cold side would give the results you appear to be searching for... at least with suitable boost control. Not sure what to expect from the 0.82a/r setup. PPS. If I had an ethanol content sensor plumbed into my bloodstream - there would be some amusing logging to be looked at. I look forward to reading this post tomorrow, and seeing if I managed to come across as coherant as I am trying to. Apologies in advance if I failed at that, or my pleasure - depending on how entertaining - or useful this post is

Bugger! I don't think you are likely to have boost creep issues even with the .63 - compressor isn't big enough to push more boost than you are aiming for, really. My reasoning for the .63 versus .82 comes partly down to exhaust volume/speed versus compressor size - your compressor will need more shaft speed (ie, spinning the same turbine) to move enough air to keep an RB25 happy versus say a GT3076R or even GT3071R. A smaller a/r will cause a higher shaft speed versus flow through the engine, and a higher turbine speed is a happier more efficient turbine - the fact the compressor won't be pushing all the air in the world at those higher speeds is a good thing (in my head) for keeping differential pressure a bit more in check than some combos shooting for similar power would achieve. On the flip side, I think the 0.82 may take some of the wind out it's sails for the same reasons - so without really good boost control it'd not surprise me if there was a bit of a lazy boost curve (not to be confused with lag - more boost control), though there is also the potential for it to really take the octane limiting edge off it - so per psi you may get reasonable numbers considering the size turbo and the whole stock manifolds etc situation. It's a very different combo for an RB25, no doubt part of why there is so much interest.

We don't agree on everything, but it feels sporting and at the same time I don't think we're on different pages either EFR9180? That is certainly not going to compare with a GTX45, a GTX4088R (or really somewhere between that and a GTX4294R) would probably be the closest comparison you could get from the Garrett line - but still be very interesting to see how it performs!

That could be quite an interesting combination. If you are exploring that kind of idea - why not see if twin GTX3067Rs can be made up, using the 90 trim turbine?

I shall re-iterate my Never said anything about fairy dust, like anything it's all about matching components in a setup - the mood of this whole thread is basically identifying that fact. There are *some* HTAs which are very well suited to some requirements for RBs, and a lot of the time they are overlooked - which is the only reason they come up. There are also GTXs which work very well, when combined with the right setup - I'll give them credit. I "pud pull" over anything which I believe is capable of providing a particularly sharp combination, it's nothing specifically about HTAs... unless you count the fact there are quite a few of them which are better matches between compressor, turbine, and to the engines we like- or at least should like if we're here as enthusiasts. I know of HTA failures (as with GT, GTX, EFR and basically every type of turbo I know of people using) but on the same note, none of the guys I know directly have had one. A mate had an HTA3586 which he first fitted to his EVO in 2008 which was used for drags, time attack, off road sprints and street use and is now on an RB30DET (which I've referred to in the past) and the EVO guy replaced the HTA86 with an HTA82 for a bit more response. Both of these cars are built and used properly, and have been for YEARS, and are both very strong performers, and are a lot of the reason I am pretty convinced by these things performance. So, I've not specifically counted kms but I know ones which probably had been thrashed as much (or more) than your GTX has yet had thrashed before your GTX was even available to be bought, provided better power versus response than a GTX3076R will, and are still going strong now. Regardless of all that, yes - your point is right - the HTA (and shock horror also the GTX etc mentioned) in the post are more expensive than the T67s, and they aren't proportionally better performing, but to expect that ... let alone to focus specifically on one and not the other, is below anyone who isn't a blatant troll. At the end of the day we decide what we want to spend, what we think we're going to be happy ending up with, and decide if we can find a balance which is worth it cost wise versus result wise, unfortunately the cost goes exponential as we strive for better overall performance. The old T67s are by all accounts really good units, especially for their price - different people have different views on what is acceptable so it's really hard to have this kind of conversation with people, one person might find the lag/operating rev range of anything worse than a GT2835 unacceptable and on the other hand I know people who find T51R's perfectly acceptable. Two T67s however, that's a whole pile of silly haha.

I sense a lot of butt hurt about HTAs, Mr Scotty

Is that stock cams? That's a fair bit of power on E85 with 4x ID1000s!

^ yeah agreed, that will be one of the best ways of dealing with this turbo - though again would have been particularly ideal with the .63. Still very keen to hear how it went... hard to find the silence unnerving when usually a good result comes with a "W00t - it did <insert positive result details>!!!" Hope it has all been done and come together well

Makes it sound like it might be done? My AVCR wasn't up to controlling the way my old Garrett internal gate needed to be to make it aggressively go to and hold full boost so it had a lazy boost curve. It wasn't laggy, the gate just cracked open too early. Looking forward to hearing how it went!

WOW. Any more info on that car? I can't find anything on google Your car makes me very jealous.

Oh right - he's a good man, I believe he works for NZEFI who actually are a reputable Kiwi company Arrrr! Refer to above quote, hahaha But yeah, I've only tuned PowerFC, ViPEC and Link out of that list and the Link/ViPEC are really nice to use and it seems they are in a development phase post G4+ release.... I suspect the G4+ base (ie, ViPECs too) is going to get better and better with coming firmware updates. No point over doing what you are getting if it costs a lot more, you don't have much to spend, and you aren't going to use the features - but IMHO an ECU like this is a one time purchase so you may as well do it right the first time... as it can be a pain feeling held back if you decide you could have done with more.

Ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh. Sorry, ignore me

Seriously? RIPS is potentially one of the most trusted and respected Skyline related builders/tuners (hardly a non-company) in the world, people have been sending cars there from around the world for near a decade now - and there is nothing but good reputation surrounding them, if there was going to be anything to doubt about them I'd say something would have been said by now. Realistically, it's hard to not get bad stories even if there ISN'T something bad to say... to have the kind of name they have with the level builds and distant customers they have is pretty huge.

Looks the business! It's really going to look tough in there, and that's not even touching on the insanity it's capable of creating. Your car really really is going to be a complete monster, soon. Nice work.

On petrol, or E85? What is "fully built"? Please elaborate on specs, and the rest of the setup etc? External gates? GTX2867Rs are the first thing that come to mind on the assumption you will be running E85.

Haha yeah man, I bet you are chomping at the bit!!! It's been ages since I've been in that position and I still remember it pretty clearly. Good luck!

The bigger FP turbos have T4 open and twin scroll options

Pretty sure it's a twin scroll Super94 HTA So, how much work is lined up to be done before this thing comes to life and finds a dyno?