I was reading through the Street Prepared section of the 2007 solo rulebook and found some interesting allowances for the turbo cars. If you want to download and read through it you can find it here:
http://www.scca.com/_FileLibrary/File/2007SoloRules.pdf
Anyway I'll post the important sections so you don't have to read the whole thing.
Here is the section directly talking about the turbos and allowed modifications:
15.10
C.
4. Turbochargers and/or superchargers (“forced induction”) may
not be added, changed, or modified. On vehicles originally
equipped with forced induction:
a) No hardware changes or alterations to turbocharger(s) or
supercharger(s), in size or number, are permitted. Turbochargers
or superchargers may be updated/backdated only
in conjunction with the accompanying complete engine
unit.
b) No changes are allowed to waste gate(s) size, number, or
location. No changes are allowed to variable-geometryturbine
(VGT) hardware.
d) No changes are permitted to blow-off/pop-off valves.
e) Compressor bypass valves (CBVs) are considered part of
the air intake system, and may be replaced or updated/
backdated independently of the other components of a
forced induction system.
f) Boost regulation systems, either electronic or mechanical,
and electronic fuel cuts referencing boost pressure may be
altered or modified except as prohibited herein. Boost
pressure changes resulting from authorized changes are
permitted.
and
So that means that boost controllers, FCD's, and Intercoolers are legal. But it also says that the turbo must remain STOCK.15.10
C
3. As utilized only on engines originally equipped with forced
induction, induction charge heat exchangers (known as “intercoolers”
or “charge air coolers (CACs)”) are unrestricted in
size and configuration. Air-to-air CACs and radiators for airto-
liquid CACs must be cooled only by the atmosphere, except
for standard parts. Body panels, fascias, or structural members
may not be cut or altered to facilitate CAC installation.
Here are the ECU alowances:
The only mention of fuel pressure regulators in the rule book is this line in street touring. All the rules from lower classes carry over to the higher ones.15.1
D. Alternate computer control modules may be used whenever an
equivalent change to the conventional system is allowed. For
example, alternate computer module control of ignition settings or
fuel injection is allowed.
The Street Prepared section specifically says you can use alternate computer modules to control fuel so I think that means you can do both in Street Prepared even though you can't in Street Touring.14.10
3. Fuel pressure regulators may be replaced in lieu of electronic
alterations to the fuel system. It is not permitted to electronically
modify the fuel system AND replace a fuel pressure
regulator.
So figuring all this in what are the absolute limits of the stock turbo? Forget efficiency, if it makes any more power with more boost it's worth it. Granted all of the power with the stock turbo is going to be low to midrange with limited topend. But in autocross you spend most of your time between 2500 and 4500 so that would be fine. How much boost can it make and what is it going to fall off to by redline?
Heatsoak of the intercooler is probably going to be a big problem so I figure you'd have to soak the intercooler down between runs (maybe even with ice water in a garden sprayer). Would the water/air intercoolers be effective or would they just heatsoak too?
There is nothing in the rules that says you can't run octane booster, and you can retard the timing so detonation should be easy to avoid. Water injection is legal too so that may help.
So what would someone with this setup be looking at power wise?
Would it even be possible to up the boost much without introducing too much heat to manage? Or would icing down the intercooler between runs be adequate to manage it?
My theory is that if you could get a decent amount of power with these allowances you could pretty much dominate FSP. At least until SCCA figures it out and moves it to ESP.
Sorry for the long post. I thought this was better that just giving you a link to the rulebook and telling you to go read.
Anyway I'm just looking for some of your thought/ideas on the topic . I'm leaving to go camping tomorrow so I won't be able to see your responses until Sunday afternoon.
