Duke

None, "GT30R" is the old name for the GT3076R.
Don't go for anything larger than 0,82 a/r T3 hotside if you want good response.

If you aren't looking for anything more than 400 crank hp a GT3071R with 0,63 a/r T3 would do the job with an insane response.

I'm running a GT3582R with 0,82 a/r T3 turbine housing - a true 600-650 hp turbo - and still reach my max boost (currently only 0,6 bar) at 3000 rpm or lower.

gt37vgt

well a gt3076 is a gt30 your just given a little more info ..the size of the compressor so a gt30 is gt3071 or a gt3076
another turbo wich i think is worth wile is a GT3576 wich is a rough truck turbo kicking around cheap every where..
http://www.turbobygarrett.com/turbob...ochargers.html

333pg333

Wouldn't you run the risk of too much backpressure with that small a turbo on a 3L 16v motor though Duke?

nick_968

Just to be clear, the turbo discusion we have moved onto from my point of view is based on my current 8v setup as that is where I am headed in the short term. Especially as there is no clear conscensus on being able to use my 8v pistons it is unlikely I will go 16v this year.

The turbo I looked at was basically this one below as when I checked the compressor map for my engine it seemed to be the best match. Still undecided if its worth the extra work to go to full garret turbo.

http://www.034motorsport.com/turboch...rbo-p-107.html

Using a 0.63 A/R

Duke

Not for as low as 400 crank hp. It's still bigger than most of the KKK hybrids people used to run in the old days. Running a turbo with more capacity than needed is just a waste of performance.

Duke

That turbo won't bolt on. The problem is the GTBB center section which is too narrow.

thingo

Be aware that map is not the same as the gt3076 that garret sell now here, I would expect they changed it for good reason.

gt37vgt

hmm so does that mean the back of the comp cover will foul on the engine mount ?
so more than a little grinding on the mount ?

nick_968

What is required to bolt up the true GT30 (3076) thingo mentioned above then?

thingo

I've got a gt3071 on my 951(same centre section as gt3076). A lot of work was required on the mount.

gt37vgt

grinding and a spacer or cut it off and make a new one ?

thingo

Yea mostly that and swearing, the tial mount might be a better option.

nick_968

No mods to the crossover or downpipe?

fast951

Nick, your turbo dates back to 2004, it's totally different than the newer S5 others refer to. The newer S5 is making 1bar boost at 3000RPM and putting down close to 500/500 at the wheel at higher boost.
However, others who ran similar turbo to the one you have, reported much better spoolup than you have experienced.

Many things affect the spoolup: Any exhaust leak or restriction before the turbo, boost control, tuning, camshaft, restriction in front of the turbo.... As a example, we did a aggressive perf. cam swap and recorded the before and after spoolup. Spoolup was delayed, the power band was shifted to the right, power gains were noticed up top.


The turbo you have can be easily modified to reduce spoolup by around 300-400rpm (and will reduce the top end potential, which you are not after), it's a simple part swap you can perform yourself. Someone recently made this change, even though the turbo was not a good match to the engine size, on a 2.5L they were seeing 1bar boost at 3400-3500RPM in 4th gear.

Since 2004 there are many new offerings on the market. A smaller turbo will give you better spoolup, in some cases you will need to run higher boost. For 400bhp, there are many options. A GT30R on a 3L will spoolup nicely, but will not be a direct bolt-on.

If you have any questions, feel free to drop me a note.

thingo

Mine is a twin scroll turbo, mostly everything is custom, it involved a lot of work.