Lots of debate on this, but it appears there's a bit of confusion. So,
let's sum up, shall we?
First, let's clearly separate a "rev limiter" from a "shift light" or
"tachometer":
Rev limiter: A device used to prevent an engine from spinning faster than
a particular RPM. Can be done by ignition cut, fuel cut, both, and to
varying degrees. On most modern cars, a rev limiter is an integral part of
the engine control strategy and built into the PCM, regardless of whether
the car is equipped with a tachometer or shift light.
Tachometer: a gauge indicating engine RPM. Some aftermarket units have
additional features like a recordable memory or a shift light, but it's
still just a gauge indicating engine RPM. Some are analog, some are
digital, but they're still gauges.
Shift light: The idiot-light version of a tachometer. It simply lights up
at a pre-selected RPM, indicating the selected RPM has been reached.
Okay, with that out of the way, let's see what's possible in Stock (keeping
in mind the Prussian "if we don't say you can, you can't" philosophy behind
the rules):
- Rev limiter is part of the PCM strategy, thus is off-limits in Stock.
- Tachometer and shift lights are two different types of "gauges and
indicators" and thus would be legal under the C&C provisions as they serve
no *direct* control function -- their output is filtered through the
wetware of the nut behind the wheel before becoming control input.
In SP, you can legally add/change the rev limiter.
Whether or not you think of the C&C provisions for gauges and indicators as
performance-enhancing devices, the rules *as currently written* are fairly
clear that gauges and indicators are expressly permitted. One could make a
variety of arguments against this, from "Stock is Stock" to calling any
additional information on the operation of the vehicle that the OEM decided
the driver didn't really need (tachometer, oil pressure, water and/or oil
temperature, etc.) a "performance enhancement" as it gives the driver an
opportunity to adjust his operational inputs into the vehicle accordingly.
But again, the rules *as currently written* permit the addition of a
tachometer and/or shift light.
Taking this additional-input-to-driver restriction to extremes, how 'bout
"Tommy Stock" - driver must be blindfolded and use active noise
cancellation earphones to prevent any visual and aural feedback...
Unfortunately, we'd need to use the Bonneville Salt Flats or Black Rock Dry
Lake to get sufficient runoff safety margins, but think of the television
potential of Sensory Deprivation Autocrossing!
Jim Crider
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