Water cooled turbos.

[JimX]

I am going to speak to my mechanic about this tomorrow, but thought I would ask you guys about it too.

I'm considering buying a water cooled turbo (Garrett), but I was wondering if I would have any hassles installing it onto an RB25 engine. Does anyone know of the extra parts and labour costs I would be up for?

Also, since they are sleeve bearing turbos, does that mean it needs the water cooling to last as long as a ball bearing, or that it will end up lasting longer than a ball bearing that isn't water cooled?

Lastly, can someone please translate this for me? I don't understand the numbers at all, I just need to know if it's suitable for an RB25 and at roughly what revs it makes full boost.

Compressor: 0.6AR POLISHED compressor housing with rare bolt type discharge flange. "S" trim wheel, 1.904" (48.4mm) inducer, 2.75" (69.9mm) major.

Turbine: 0.84AR-split pulse-T3 style turbine housing with custom 6 stud (8 x 1.25 metric) discharge flange, grit blasted and painted in high temperature paint. "O" trim wheel, 2.922" (74.2 mm) major, 2.296" (58.3 mm) exducer.

If someone can give me a brief explanation of what the AR and trim etc means, I would also appreciate that.

[Warpspeed]

Well your compressor is a TO4 "S" flow, according to the wheel dimensions, and the 0.6a/r cover is pretty standard with that wheel.

According to my flow-map rated flow is about 35Lbs/min airflow, or 457cfm, or 305BHP, or 227Kw, depending on how you want to rate it.

Your exhaust turbine is also TO4 "O"flow split pulse 0.84a/r, as the guy says, but it apparently has a T3 flange fitted which is pretty unusual.

That sized turbo would be about right for a three or four litre sized engine I would think, but it will need an external wastegate.

[JimX]

Thanks for the info Warpspeed.

Have you got a copy of your flowmap handy? Or know somewhere I can download one if you only have a hard copy?

[Warpspeed]

Ray Halls site has some compressor maps.

http://www.turbofast.com.au/FlowTO4B.html

Look at the S-3 map, turbos are rated at a pressure ratio of 2.0 (15psi boost) and at the 60% line. Flow is across the bottom, about 35Lb/min I would think for that one.

[YBSLO4]

As for the watercooler part... all stock R32/33/34 turbos are water cooler anyway. Just a matter of getting custom lines that will reach the outlet points on teh block for the water lines and the same for the poil line aswell. Nothing ya wouldn't have to do for any turbo upgrade other than a high-flowed stock one.

[JimX]

Wow, you learn something everyday. I thought our turbos were oil cooled Thanks for that, makes my decision-making a lot easier.

[YBSLO4]

they run oil to the bearing but they are water cooler, thats what the too banjo bolts are on the side of the bearing housing, the one on top is the oil, and the one under neath is the return feed to the sump for the oil.