[s-cars] RS2 "Killer" dyno results

[Djdawson2 at aol.com]

This morning we spent some time on the dyno with the Garrett hybrid RS2 
"Killer" turbo.  This turbo is a 50 trim cold side using the Turbonetics #8 hot 
side with a stage 3 turbine wheel.

The car is a 94 in good health.  The only mods are RS2 injectors, MAF, EM, 
the above turbo, and Eiche/Pastore software with a VMAP transducer... no other 
mods.  The goal is to produce a very strong/lightly modified AAN.  No real high 
dollar stuff.

The dyno is a Dynojet Research... same one as was used on the previous Denver 
area dyno day in January of this year.

Dyno results netted a peak reading of 337.79 hp at approximately 5400rpm, vs. 
325.86 hp at 4700rpm for the RS2.  Not a bad hp number.  However, the curves 
tell a different story.  Peak torque came in at 372.76 at 4500rpm vs. 402.36 
at 3800rpm on a car with the same mods using an RS2 turbo.

Since we were at the same dyno facility, I had 3 graphs overlaid.  An RS2 
equipped car, an RS2 equipped car using the Garrett hybrid, and just for 
fun...the Happermobile.  (BTW, I won't email copies of the graph unless Hap is OK with 
it.)

Reviewing the curves, a couple of things become clear.  1st, peak torque 
seems to be made at peak boost, every time.  With that in mind, the "RS2 Killer" 
doesn't do it's job.  It is incapable of spooling up early enough in the rev 
range to produce a torque value as good as the standard RS2.  It does, however 
do a good job of moving sufficient air to produce over 300hp for about a 
2500rpm band, as opposed to the RS2, which can only do it for about 1700rpm.  Bottom 
line, however, is that the RS2 would be a much more livable turbo in daily 
life... significantly early and larger torque peak, and better overall area 
under the curve... peak hp doesn't make a car fun to drive.  If you typically 
operate your car between 3 and 6k rpm, the RS2 turbo is the clear winner.  2nd, 
the RS2 killer seems to be suffering from one or both... too large of a 
compressor, and/or an overly large turbine wheel/exducer bore.  The numbers support 
the compressor theory, as the engine is unable to consume the amount of air that 
a 50 trim can move.

Next... we will be testing a turbo that addresses these issues in the hopes 
of coming up with a true RS2 killer for the lightly modified AAN.  We expect to 
see a significantly lower boost threshold, a 30ft/lb improvement in torque, 
while maintaining a peak hp value greater than 300.
Take care,
Dave in CO