Lithium

Ahhhh... ok, well it really is going to have monsterous power delivery then!

Yep, I tried to edit my post to clarify that when I discovered people had responded while I was typing that out and my interwebs got its glitch on and wouldn't let me. If you aren't going to be shy on boost then I'd be surprised if you didn't blow that figure out of the water - even on a harsh dyno. Who is tuning it/what kind of dyno is going to be used? On E85 and a bunch of boost I'm expecting there is a good chance it'll make quite eye opening power, and bring it on quite quickly Will be particularly interested in seeing when it cracks 200kw...

Oh hell yeah. This thing is going to be insane, hope you have a large fuel system and a dose of crazy!

^ that should be epic, there is a guy in Europe on the way to his tuner with his R33 GTS25t running a FullRace twin scroll GTX3582R as we speak, that'll be interesting to see the result of too. Whats the rest of the setup? Are you going to be able to lean on it a bit?

I'd hold back any comment on AVO until its actually run on the familiar dyno, it could easily come down to ramp rates.

So has it already been on the dyno?

I've got a divorced wastegate feed which stays split for some distance, seems to work really well - car appears to make respectable power (and spool) for a car running all stock manifolds etc. Sounds pretty awesome when the wastegate opens, too - and yes, it does merge back with the exhaust. Out of interests sake, a mate of mine has a Honda Prelude which he's been building up over the last couple of years using just the skills and knowledge of himself and his friends, and after many an evening of drinking and plotting the "best way" of doing everything he's (within reason) implemented the hairbrained ideas we've come up with, one of which included a large tube header with a 2.5" collector and 3" exhaust on a 2.2litre naturally aspirated engine. After I tuned it, he ran it on the local dyno most people use around here for reference and it basically has the most solid power delivery out of any NA motor up to that engine size on that dyno... its pretty loud, but being a 3" exhaust has certainly not caused it any issues.

There is masses of information on this subject on this forum alone which even if you know next to nothing - you'd be in a better position to determine what turbo you'd like than we would given you know what you want from the car, how much you want to spend on buying and fabricating, and what you can live with in terms of power delivery. If you have a motor built to rev to 11,000rpm (and all supporting mods to make use of it), don't mind full boost at 7500rpm and of course are after over 800kw @ wheels then that turbo should be sweet.

GT4708R would be way more responsive and still make enough power for a bit of fun.

This probably wouldn't be an aweful option... http://store.forcedperformance.net/PROD/49178-04600.html

So you don't think the GT-RS is a bit undersized a beast to put on a 2.5litre that likes to breathe? Interesting that disco-potatoes and TD05s come up, I've had STI/EVO owners drive my car and say it feels more responsive than their cars running the stock turbos - I run a .82a/r GT3076R, why is that response acceptable on a rallybred machine yet not on a tourer? I've certainly not been caught out with my car when racing, if you get lag in shifts with it then you are that bad that you are always going to have some kind of issue. I bet a GTRS would feel neat to drive (how much laggier than stock does it feel?), but I personally have too much mechanical sympathy to run something like at more than 1bar on a 2.5 - and I bet the poor little thing is probably working itself into quite a frenzy even there.

Nice - good luck, and look forward to seeing the results Trent has a Dynapack?

Have thought about that, but it still feels mechanically mean - smallest I'd try that with would be a GT2835. Having said that, have been really interested to see how a stock turbo would go on the generally accepted "safe" boost level on E85

As per my video I posted, mine is 15psi by around 3800rpm in 3rd or by 3500rpm in 4th so it makes it maybe slightly laggier than an equivalent GT3076R which isn't too surprising

Is it only running a .63 hotside? Fwiw I've been in an R33 running a .82a/r GT3582R which would reach 20psi by ~4300rpm...

17psi by 4100rpm in 4th? In 4th thats not as bad as the dyno looks but not that flash imho, in 3rd I would say reasonable. Do you have VCT engaging? When does it reach 14psi? (to rule out a lazy actuator)

+1 on going GT3076R, very proven unit

That sounds better... to explain what I mean, it doesn't matter really what gear the dyno is done in - what matters is how fast the dyno allows the car to go through the rev range. The more time the car spends going through the rpm, the more time the turbo gets time to build boost. If they have a 6 second sweep starting from 2000rpm to 7500rpm it might be a bit more like starting in 2nd gear, if they have a 14second one it might be more like doing it in 4th - just plucking numbers off the top of my head to explain what I mean. Here's a video I made ages ago of a normal GT3076R .82a/r with internal gate back before my car was fully tuned, maybe try and compare the same kinds of pulls with your own to get an idea: I would expect it to be SIMILAR (give or take) to what I had there, if its substantially laggier than that then I'd be looking at the overall setup. I'd expect in 4th gear you should be able to make full boost by 4000rpm on the road. If that all works, there is no problem - the dyno run was probably done with a really fast sweep and will make any car on it look laggier than you'd experience on the road, and also a pretty unflattering impression of how the car goes relative to others. Perfect example of how dyno plots are only part of the picture...

I had a thought regarding this - ShiftTys, how does the car actually drive from your perspective? Does it seem that laggy?? If you put it in 4th at say 2500rpm and floor it, what rpm does it reach say 7psi, then 15psi (if its not too dangerous to do that)? Were you present for any of the dyno runs? Looking at those plots, it makes me wonder if there was a very quick sweep rate used - like 6s or quicker for a run? Thats potentially too quick to give an equal comparison to most dyno plots out there, and potentially too quick to replicate what you might experience in the real world.

In my opinion your best bet is working out what is causing the excessive lag and fixing that up, I really don't think thats its due to the type of turbo- that is TOO laggy. I suspect any other equivalent turbo will be similar +/- a bit, and that if you change turbo setup you could end up finding the exact same thing. I am sure that the GTX3076R may be a bit laggier than a GT3076R, but the amount of lag I see there looks more like what I'd expect from a GT40R or something like that.... there is no way a properly operating GTX3076R would be like that on an RB25.

Thats interesting, with completely stock engines (including cams etc) the SR20s I have seen here seem to usually hit a wall at around 220kw or so on 98 if you are going to be sensible about boost while RB20s will happily venture past 250kw. Psi for psi the RB20s usually seem to have it (ie, outright engine flow). I am more curious about how my flatmates S14 track car will go, now - I had assumed we would need E85 and a healthy dose of boost to give it a little madness.

Hence me politely contradicting GTScott

Basically nothing I can see. ForcedPerforce have a range of turbos which are imho better answers to the existing Garrett range.

I've never seen a bone stock internal SR20DET make 260+kw on pump fuel?! From my experience, even calling an SR20 better flowing than an RB20 is quite a stretch, let alone RBs in general. Using how SR20s go with a particular turbo would more accurately be what minimum power figure to expect with an RB20, but also bear in mind RB20s low down/midrange tend to be lazier for a given peak power than an SR20.

I do remember the first releases on the GTX implied they would be at least as responsive as the GT, but I have been suspicious of that claim from the start... however this result looks too laggy. I suspect something isn't right somewhere, probably a leak of some sort more than boost control. For what its worth, the GTX3076R would really be a GTX3077R if Garrett stuck to their normal naming conventions.