Quote:
Originally Posted by theholycow
That's a cop-out. While an open differential is technically two wheel drive, it's effectively one wheel drive. I don't know exactly what you mean by "blocked", but for one wheel to spin, all you need is a slight loss of traction at one wheel, or slightly too much power even with equal good traction at both.
I agree that traction control will surely be good enough compensation.
AFAIK it's quite common to do that, and your MPG idea is a big part of it.
Did you forget the torque converter letting the engine rev up? It's never locked in 1st. The auto will be pretty close, though maybe not close enough for the drag strip (but V6 auto Camaro buyers will mostly NOT be going to drag strips anyway).
This has an additional advantage that people don't consider very often. People think a LSD is better for snow/ice. Well, with RWD, it's less safe than an open diff. Getting stuck means you're not going anywhere, no big deal...it's also protecting you from driving in conditions that you're not skilled enough to handle (as proven by your getting so stuck that you can't get out). OTOH, spinning both rear tires means the rear is likely to kick out sideways. You don't have to light 'em up spinning at +80mph to make it happen; an undetectable +2mph spin (you're going 50mph, but the tires under steady throttle hit a slippery spot and get up to 52mph) will do it. With only one tire spinning, the other will retain lateral traction and keep you steady.
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theholycow, all excellent points. What I mean by "blocked" was simply for theoretical explanation. In practice, this "block" could very well be one tire on a stickier surface than the other. In this case, when the other tire spins on the less tractive surface, you effectively have "no-wheel drive" as neither the stationary nor spinning wheel is providing effective traction to move the vehicle. My point in the above, however was simply to say that saying "one-wheel-drive" is a mechanical misnomer, because there is equal power being sent to both wheels, the differential just isn't designed to make sure it stays there. The rotational energy is NOT being channeled into a single wheel. You can imagine what kind of steering problems this would cause were it actually true. (think tank tracks.)
I agree that V6 auto buyers for the vast majority will not be visiting the drag strip. For this reason, I understand why GM made the cost cut to eliminate the LSD for it. (I'm sure someone who was well acquainted with costs, demands, changes in assembly, marketing made the decision and that it made sense to that person fiduciarily.) As far as times though, when a torque converter isn't locked up, it's similar to a slipping clutch, which transfers a significant amount of the engine's energy to heat via friction. Sure, this allows the engine to operate at a more powerful RPM, but how much is lost to slippage? Contrarily, while the time between clutch take-up and the shift to second gear is mechanically much more efficient than a 1st gear run with an unlocked TC, the engine is running at RPMs that are linear to the acceleration of the vehicle (assuming the tires are planted), which are (potentially) not as powerful as the setup in the auto. Obviously, neither of us has these exact figures in front of us, but with as flat and wide a torque curve as this engine has, I'm still placing my bets on the manual by .2 seconds if the driver's good.
Very good insight on the open-diff lateral traction versus posi. Which brings up another point though: What type of LSD is it? Because it it's a centrifugal type, the vast majority of the time it behaves just like an open diff. If it's viscuous, though, then it very well could be a racetrack-only-friendly option (not that it's optional.)
And I don't know why I said rental. Even an LS looks like a sexual experience on wheels.