KeS sez:
> If all this is correct, the implication is that in lieu of an "official"
> response, you just have to take your (and/or Howard's) best
> guess, and wait to be protested, appeal, and then have the
> SEB rule.
Well, you said it better than I did. I can see perfectly valid arguements
for restricting turbo backdates to full engine swaps (although I think
Dennis' proposal is better, allowing it with similar engines), and I can
even see splitting the DSM entries in Appendix A (although that would mean
I'd go CP instead of swapping the 2G BOV back on, and there *are* plenty of
other cars that share the same line that have different generations). But
this whole deal with SEB is what really has me upset.
Gary sez:
> I feel a better solution is going to be some form of flow restrictor
> or pop off valve. In the prepared rules they alow any turbo with
> an inlet restrictor. This is easy to police. A range of sizes would
> be needed, but inspection only requires a dial caliper. Pop off
> valves can be tested with a simple air compressor and regulator.
> Just come up with a max boost or flow for each class or by
> weight or something. Then turbo size and boost control
> is no longer as gig of an issue.
My inlet pipe to the turbo meets the Prepared flow restrictor anyway...and
this only restricts peak horsepower. I could still run lots of boost at low
rpm with no problem, provided I had some form of non-stock boost control.
This is very much like what a T-25 equipped DSM does. It's got lots of
low-end, but dies off at high rpm, because of the restriction of the small
turbo.
By "pop off valve" do you mean some sort of small "tattle-tale" that would
indicate excess boost, or some sort of dump valve? The problem with the
pop-off valve is spike...even a bone-stock turbo can occasionally spike to
high boost levels, esp if you nail the gas at high rpm...the boost simply
spools up faster than the wastegate can react. My stock system, before any
mods, would spike up above 18psi for an instant on occasion, before quickly
settling down to 13-14psi. You'd either have to set a manual controller
much lower than the pop-off pressure, or run a very good electronic
controller somewhat lower in order to be sure of never spiking above it.
A dump valve, although it's used in some racing series (CART?), isn't a good
deal. Besides the additional cost, no street-driven car is going to have
one put on. If it's vented to the atmosphere, it will totally screw up the
EFI system, and you'll be running so rich you might do serious damage to the
turbine when the raw fuel ingites on it, unless you spend big bucks on a
custom EFI system. If it's run back through the intake, it'll re-introduce
heated air back into the turbo, increasing the chance of detonation, and, if
it opens before the wastegate, can easily cause the turbo to spin too
fast...I've seen the results of over-spinning a T-25 and it ain't pretty.
Again, you'd have to set the boost somewhat lower that the actuall opening
pressure of the valve.
Of course, no turbo car could show up off the street and be able to run SP
with any of these plans, either. Even the simple tattle-tale valve could be
problematic. Some new drivers don't know their cars very well enough to
install one, and if a tech inspector installed one and the hose came off or
something and caused it to overboost, there's a whole new world of liability
there. I don't think there's a good, cheap, safe, effective way to police
boost in SP. Not with the number of street driven cars there are in SP. I
don't think the turbo owners want SEB coming up with the boost and/or flow
limits, and I don't think SEB wants to try to go through the whole list of
cars and come up with the limits either. I'd just as soon run BSP or even
ASP with open boost control, than have to play games like this.
Mac Crossett
1996 Eagle Talon TSi AWD #49ESP
|