Time Better Spent
NASCAR and major touring series may choose to continue to police ETC, and will likely restrict its use, but it's unlikely to be totally eradicated. They might take a page from Formula 1 or CART's rule book and legalize ETC-those sanctioning bodies recognized the futility of trying to police it versus the formidable technical resources of their racing teams. Then, they could apply their resources to bigger problems.
ETC is just one of the many pieces of creative engineering going on in racing, and it's become one of the most difficult to detect. Legalize it and the price could come down to the $500 to $1,000 range, and then expend the tech inspection efforts on finding ways to improve driver safety, for instance. That has more return on investment in the long run for racing's future.
What is ETC?
ETC used in stock car racing is often defined as the electronic management of engine power to the driving wheels to achieve optimum grip from the tires. Engine power can be reduced or "softened" by sensing wheel slip and then: retarding the ignition timing; or applying brakes; or electronic control of the throttle blade angle or fuel injector pulse duration; or a combination of all these. Current stock car racing ETC isn't that elaborate; they typically affect the engine timing or adjust the braking system.
We're only going to consider ETC for carbureted, rear-drive race cars without electronic engine management controls and using a battery-powered ignition system because the majority of stock cars fit that profile. They typically have a separate ignition control ("spark box") wired into the car's harness. Note though, that ETC is now available for MSD's Pro Mag magneto ignition-it's worth 0.5 second a lap at Phoenix's (Arizona) track in a Silver Crown car, according to one source-and HEI-type ignitions can also be mated to ETC.
If you're a sanctioning body thinking you could eradicate ETC by reverting back to contact-point ignition systems, don't bother. It can be adapted to them, too.
A limited amount of slip from the driving tires is desirable for maximum traction-according to most sources, 8 to12 percent depending on the track conditions and tires. Racers learn through years of making laps to manage the application of throttle to control engine power to get the best grip via a calibrated accelerator foot. They learn to sense and absorb inputs from the car and conditions, process them, and then adjust the throttle for best grip. ETC uses digital electronic components to approximate this throttle management, and in many cases the sensitivity and adjustability of the electronics are superior to the racer's throttle control ability (especially newcomers). Lap times can improve, or stay consistently good.
ETC detects tire slip and then uses different methods to manage it, although all the methods rely on reducing engine power to the driving tires. What defines the current racing ETC units on the open market is:
* How they detect and discern excessive tire slip, and once doing so;
* How they control the engine output to reduce it; and
* Their packaging of the sensor and control circuitry.
Detecting tire slip can be done various ways. Some ETC units use wheel speed proximity sensors mounted on the wheels to detect a difference in wheel speed between the front and rear tires-a big difference indicates wheel slip. Other units compare ground speed registered with a small radar gun to rear wheel speed. Others monitor a speed signal indicative of engine rpm and use software to check the rate of change of this rpm signal-if it exceeds a certain rate of change (a fair indicator the drive tires are slipping), then engine power is affected. For example, flywheel teeth can be counted to get this rate of change of engine speed, as can transmission gear teeth (both requiring a potentially detectable proximity sensor). Or the ETC can closely monitor a tachometer signal via a direct connection or an inductive pickup mechanism like that used on an ignition timing light.