[s-cars] Ball bearing turbo

Jim Green jim.green at gmail.com
Wed Oct 19 17:22:44 EDT 2005

On 10/19/05, djdawson2 at aol.com <djdawson2 at aol.com> wrote:
>   The GT30R works well in Denver. I was running a .63 A/R turbine housing,
> but that led to some undesireable surge in the higher gears. I have since
> changed back to a .82 turbine housing, and have changed to an RS2 exhaust
> cam. I also incorporated the stock intake horn (with the internal flow
> dividers) into my intake setup. This combo has eliminated the surge problem.
> You can still "make" it happen by loading the engine excessively in a high
> gear (5th or 6th), but in normal driving, it never happens.
>  Dyno numbers... well, it has not been to the dyno in awhile. Last trip
> was 442hp/430ft-lbs at the wheels. This is a corrected figure. However, I
> tried to end the correction factor arguement by going to the dragstrip. A
> lot of folks said they thought the only true way to determine hp was via the
> 1/4 mile trap speed, using a 1/4 mile calculator and vehicle weight. So I
> did this too. The best results were 12.400 @ 113.35mph. The hp calculator
> says this mean 455hp at the wheels. So you can draw your own conclusions.
>  As a side note... the clutch won't take the power. Javad (034efi) is
> setting me up with a stronger unit, and this should result in some 1/4 mile
> improvements.
>  Sounds like you've got a fun engine planned. However, I'll eat my hat if
> you get to 450whp "uncorrected" in Denver. I think it has been shown that
> some correction is required to deal with our altitude. I'm currently working
> in Boise, Idaho... and the S4 is here. Boise is at 2200ft, and the
> dragstrip is at 2700ft. From a butt dyno perspective (and I'm not a butt
> dyno fan) I can tell you that it feels like something is wrong with the
> car when I return to Denver. However, 450 corrected wheel hp isn't a
> difficult task... no special tricks required. I'll try and get mine back to
> the dyno soon, and see what it's doing with the cam and turbine changes.
> HTH,
> Dave
 Nice, that's exactly the info I was looking for. I'll be running the
shrouded compressor housing and a 7A exhaust cam. Not sure what turbine
housing I'll go with, probably the .63 since my gears are so low(4kq 016)
and my car is lighter so it will accelerate quicker out of the surge line.
I'm planning on trying my 6 puck metalic Kenedy disk with Centerforce
pressure plate for the clutch. What clutch are you running currently? I'm
not really doing the 20v thing to hit some magical # that sounds cool, I'm
doing it for simplicity and reliability. This 10v of mine goes like stink,
especially on race gas and cool weather. I want that feeling and a little
bit more on a daily basis. I estimate by the butt dyno and 1/4 mile times
that I'm around 370 whp tops. Based on that, 450 whp is what I'd like to see
for this kind of investment. I'm headed to the dyno probably next weekend.
If the car comes in low( I kind of expect it to), like 320-330 uncorrected,
then I'll lower my expectations a little to closer to 400 whp uncorrected.

Jim Green
'89 90tq
'89 80q

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