My 300rwkw Adventures

[Cubes]

I'm with Dale.

The more I look and think I'm really not sure the GT3076 is a good thing in the .6 as without better than pump fuel or water/meth injection it really doesn't do any better than the GT3071. Much like dropping a GT3040 in to a .6 rear on pump fuel. Its a waste of time.

For a stock rb25 and 270rwkw ish The GT3071 with a .6 really is the best bet for the RB25.

Track use or if you simply want to crack 300rwkw the GT3076 .8 is the go. BUT its most likely still going to need a set of little cams to get there on a safe pump friendly boost level.

[Dale FZ1]

Just to clarify. Targeted 270rwkW, street use. I think it's splitting hairs to say that there's much on-road difference between the 3071 + 0.63 IW and the 3076 + 0.63IW setup, primarily due to the combination of flow capacities and efficiency ranges that the compressors would operate in over the most often used engine rpm range. Let's face it, a street car might use up to 7000rpm somewhat regularly (relative term here), but can't do it for extended periods or else face loss of license or the lockup.

So each may offer a technical advantage (3071 = transient response; 3076 = high rpm efficiency) over the other, but I don't believe the practical difference would be significant. Detectable yes; significant - no.

Using a 0.5 compressor cover with 70mm snout on the 3071 may allow easier inlet plumbing and keep the compressor noise down (no ported shroud housing) compared to the 3076, and that may be a telling feature for some people. For me it's a case of look at the whole of picture and then decide.

Edited November 7, 2007 by Dale FZ1

[discopotato03]

I still like reading this thread from time to time even though its 6 or seven years old . 300 RWKW in a GTS25T is a good number by todays standards and the only real difference now is E70/85 and turbo technology has come forward with the HTAs GTXs and EFRs .

The same choices remain with 2.5 or 3 litres and if staying 2.5 where to find the sweet spot turbo wise . I agree that twin scroll systems are nice but the effort and expense as Mr Mafia said make the RB30 look better all round .

Turbo wise its a fine line between just getting or just falling short of the 300 RWKW mark and it's still a juggle of turbine housing size vs detonation as Marfia mentions several times . Hands down a GT3076R 56T or a GTX3071R both blitz 300 with a 0.82 AR GT30 IW housing and I believe that's on 98 PULP too . I think Jonno eventually got to ~ 320 Kw/700Nm with the 0.63 and the WMI allowed him to keep the timing up to make the power . At some stage it was changed to a 0.82 and I'm not sure he liked it as much .

Right now if you set the bar at 300 max and didn't intend to spend much time at 7000 revs the 63 is probably Ok for a roadie if you can control detonation . The range of Garrett GT30 turbos that probably fit the power ask would be the GTX3067R maybe and the GT3076Rs probably in either trim .

It would be great to know exactly what the GTX3067R tops out at as its probably going to be the most responsive of the three . It has the most compact compressor housing of the three and a 3" vs 4" inlet boss which would be a little more stealthy .

Mr Lith has said that today you probably wouldn't opt for a GTRs or 2835 Pro S if buying new for a mildish RB25DET .

Jonno if still here I'd like to hear your thoughts on how you'd do 300RWKW GTS25T if starting now . In some ways WMI looks attractive compared to Ethanol in the long run . Also BTW looking at your dyno sheets early in this thread they give the impression of being more NA V8 like than most turbo car graphs .

Cheers A .