doug@terak.UUCP (Doug Pardee) (04/26/85)
Being an excessively proud owner of a Turbo Daytona, I was curious to see what Road & Track magazine's annual "Sports & GT Cars" publication had to say about the Laser/Daytona. I was a bit surprised to find that they reviewed it only from the perspective of racing in SCCA SS-GT. Of course it is no match for the Corvette, which also competes in SS-GT (The 'Vette costs about 2.5 times as much). But what surprised me was that R&T seemed unaware that except for low-powered cars like the Renault 5 (Le Car), one just doesn't race front wheel drive (fwd) cars. So that you will know what the editors of Road & Track apparently don't: You might have noticed that there are no fwd cars in any of the big-time race circuits. This is not a coincidence, and it's not tradition. Fwd cars have a quirk that makes them unsuitable to racing. Not to worry, it doesn't affect street driving. But under serious racing conditions, 4-wheel drifting through curves with the driver holding the accelerator pedal down, fwd cars are hazardous. Consider the following set-up. A race course with a long, sweeping left-hand turn. Most of the curve will be run at a constant speed, the fastest speed that the car can make that curve, although the driver might enter the curve just a bit faster than that speed. Let us assume that for our example car, the fastest unaccelerated speed it can hold the curve at is 60 mph. Some points that should be obvious... >All else being equal, the slower the car goes, the tighter it can turn. >In a 4-wheel drift, the car will lose speed unless the driver mashes down on the accelerator. When a rear-wheel drive car enters the curve, and the driver presses down on the accelerator to maintain the desired speed, the acceleration forces try to widen the turn. The driver has to increase the drift angle to compensate. He will be unable to achieve the 60 mph max unaccelerated speed because part of his turning "power" is being used to overcome the outward component of the rear-wheel acceleration. When a front-wheel drive car enters the curve, and the driver presses down on the accelerator to maintain the desired speed, the acceleration forces try to *tighten* the turn. The driver has to decrease the drift angle to compensate. Presuming his engine can provide enough acceleration, he can negotiate the corner *faster* than the 60 mph max unaccelerated speed because the acceleration is helping the car to corner. Looks good for the fwd car, right? And it's true, an fwd car will corner faster than an equivalent rwd car. But if the fwd car *does* exceed that 60 mph max unaccelerated speed, it does so at its peril. Above that speed, the only reason that the car is able to hold the curve is because of the acceleration. Take away the acceleration, and the car will run wide until its speed drops below that 60 mph point. An obvious case is if the engine takes a holiday at that point (not unheard of in racing conditions :-) When the engine quits, the driver finds himself in the curve at too high a speed. Will he get it slowed down before it runs off the track? Case 2: The driver has messed up. The only way he can hold the curve at his current speed is by accelerating harder than is necessary to hold his current speed. So the car gains speed, and now he has to accelerate even harder, and the car gains more speed, and the driver sure hopes the straightaway is coming up pretty soon... Case 3: Nearing the end of the curve, we approach a slower car (we have been hoping that *all* the other cars are slower, yes?). At this point the racing groove is nearing the fence, so there is no room to get around on the outside. We want to pass on the inside, but there is no more oomph in the engine so we can't tighten the turn. We can't pass on the left, we can't pass on the right, and we can't slow down because that would cause our turn to widen and would put us into the fence. I wonder what happens next?? To summarize: rwd cars fundamentally cannot get into a situation where cornering power is dependent on acceleration. Low-powered fwd cars can't develop sufficient acceleration to propel themselves at those speeds in a maximum-effort corner. But high-powered fwd cars can. Unfortunately, there's no signal to the driver that he's passed the magic speed and is playing with fire. Fwd race cars don't last long. If you have any comments, please e-mail them to me. Our newsfeed site no longer forwards net.auto :-( -- Doug Pardee -- Terak Corp. -- !{hao,ihnp4,decvax}!noao!terak!doug