Ok, I'll throw my $.02 in...
> >A stock T25 Talon makes about 14-15 PSI at 3500, falling to 8-9 PSI at
> >7400 -the tiny turbine can't move any more air.
>
> Bummer for you, though. The SVO is adding boost at max revs, not losing
it.
> But the turbine and its housing, though, have nothing to do with boost
> *falling* at high flows. The *compressor* and its housing might, if it's
> falling into very low efficiencies, but I'd suspect something in the
factory
> engine management system instead.
It's definitely the compressor. The T25 compressor wheel maxes out at
around 25lb/min, according to Garrett (something like 325cfm). Working on
some partially realistic assumptions, this comes out to around
17psi@5500rpm for a 85% efficient 2.0L engine. Right about where the boost
starts to fall off on an ESP-preped car. One magazine did a dyno run on a
modified Eclipse with the T25...the horsepower curve was perfectly flat
after ~5000rpm (something like 240hp), indicating a pretty constant
air-mass flow. Swapping in the older TD05H-14B turbo yields 15psi to the
rev-limiter (even more with creep). Temps at the throttle body seem to be
lower w/ the 14B, which means the T25 is running in a low-efficency range.
Hence the popularity of the 14B swap in ESP, it's good for 405cfm, or about
18psi@7500rpm (which it can creep up to on cold days). The boost level
with a stock control system is a bit lower (15 vs 17psi, after SP-legal
intake/exhaust mods) from 3500 to 5500rpm, but the pull from 5500 to 7500
is vastly improved.
> >What's the displacement of this car?
>
> 2.3 liters. With legal SP mods, it makes about 100hp/liter minimum, and
> will be making more with the rest of the legal SP mods. But I need to
> concentrate on suspension changes, such as the 65# roll cage that'll go
in
> this year if I'm lucky, etc. Don't need any more power now in a 2900#
car,
> I'm matching the Camaros for power-to-weight already, now I have to play
> catch-up in the chassis and in skill.
Hmmm....2900lb/230hp = 12.6lb/hp. A stock LS1 Camaro SS: 3400lbs/320hp =
10.6lb/hp. You are correct, of course...you'll be much better off working
on the suspension than the engine. But you can never have too much
power...arh! arh! arh!
Mac Crossett
'96 Eagle Talon TSi AWD #49ESP
My pappy said, "Son, you're gonna drive me to drinkin' if you don't stop
drivin' that Hot Rod Talon"
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