turbos?

[powaw]

I have been leaning towards getting a gt2871r. Its my understanding that this choice will give me up to 400bhp and a quick spooling setup. That will be great for autocross. However I hear that the garrett center sections aren't really rebuildable and they cost about 1200 usd. Last weekend I ran across the hx35w for sale @ 300 usd nib. I'm wondering if anyone is using this one on an AAN when boost comes on and how they like it. Opinions?

Also when plotting compressor maps what values are you using for BFSC, and vol. eff.?

[A80Avant]

an HX40 hybrid with RS2 hotside has been used and gave full boost on 3d gear @4000rpm. But it had 56mm compressor wheel and larger turbine wheel which would give close to 500hp on high boost levels.

the HX35 would be around the 3071R region for spooling i suppose(3500-3800rpm) i would guess,and could possibly make around 400-450.

The 2871R may be able to spool fast but it surges, and therefore might not bring the fast spool you are looking for. The 3071R surges as well and the best rpm i can get 2bar of boost on 3d gear is 3600rpm roughly.

[Jamo]

Search for holset on the forum for some responses over these turbos.

Garretts are extremely expensive to repair, you'd be better of with a CT or Turbonetics turbo in this regard if using it for racing.

The main thing about the Holsets is they are cheap as chips, quite a few have used them with HX40's I think

[powaw]

I searched the forums and read what I could find. Has there been any surging issues with the holset units?

[A80Avant]

no surging with holsets so far. they are not the kind of turbos that would surge anyway. they have antisurge housing and large wheels.360deg thrust bearing as well

[powaw]

So what values is everyone using for bsfc and volumetric eff? Using the holset would allow me to remove more cooling system parts also.

[quattro84]

Do you have more specifications of the HX35 you found? Hotside # is always good to know.
A lot of DSM/Talon drivers use the HX35's, so you can have a look there for answers in terms of spool up and boosting behaviour.

BSFC and VE are always guessing. I'd take BSFC = 0.50 or 300 g/kWh for max torque, 0.55 for max performance (if you are going to run on Lambda = 0.8). You can calculate it afterwards.
VE is showing your torque curve. Follow that trend when calculating it. 85% max for a standard 20v head. No way to calculate the value without sticking it on a dyno.