HunterKiller89

iTrader: (1)

porches are RWD, so a 40/60 split would actually make them faster in a straight line as well as turning

1gmfanatik

Actually, for those that think that putting the windows down causes too much drag, which in turn gives worse fuel economy, you incorrect. Mythbusters BUSTED that one. Using the A/C doesn't make that much of a difference in fuel economy either.

Now, I don't know about all the complaints about peoples A/C's not working, but mine works fairly well. You have to keep in mind that when it's like 100 degrees out, that A/C just won't ever feel cold enough unless it's been on for some time, especially if you have been outside burnin up for a couple hours beforehand.

hobbie2k

True, the Porsche reference was meant to be only for turning. The comment on straight line traction increases due to a front weight bias are applicable only to FWD cars (like our Cobalts).

Basically, (and my physics is rusty so I apologize if I use incorrect terminology or conclusions, please correct me if I do) in order to initialize the turn, the front wheels have to apply a lateral force to the front of the car, shifting the front left or right. The rear tires then simply follow the fronts. Because an object in motion tends to stay in that motion, the engine, transaxle, and A/C system in the front of the car resist these forces trying to shift them left or right. The level of resistance, and thus, the level of force required to make the shift, is dependent on the inertia (or momentum, can't remember correct term), and the inertia or momentum is determined by two factors; velocity and mass. If you increase either velocity or mass, then the amount of force required to alter the motion is also increased.

So lets say you have a corner that you can just barely negotiate at 60mph with your stock Cobalt. Likely, you are understeering the whole way through. If you were to remove the A/C, then front end mass would be reduced. Because inertia and/or momentum are determined by two factors mass and velocity, when you decrease mass, you can increase velocity and still end up with the same inertia or momentum. Therefore, since you can increase velocity while maintaining the inertia or momentum, you can now negotiate the corner at, say, 62mph (these numbers are just a representative stab-in-the-dark, I don't know if removing the A/C alone would make that much difference).

The heavier the front end of the car, the more force (and traction) is required to shift the front end and initiate the turn. When the inertia or momentum of the front end of the car is too great for the tires' traction then you end up with understeer.

While increasing weight on the front wheels also increases the traction you have from them, as speed increases, the amount of inertia or momentum also increases, while the traction gained stays the same. It doesn't take long before any gains in traction due to the extra weight are more than offset by the increase in inertia or momentum.

That's why FWD drag racer put as much of their weight on the front wheels as possible, to increase launch traction, and since they don't have to worry about turning, the inertia issue isn't a problem, in fact, it's a good thing since it also helps keep the car stable. However, cars that have to turn well do better with well balanced front end.

OrngBalt

bravo hobbie. That is one hell of descriptiong +rep for that.

Maybe its just the geek in me, but I love reading **** like that.

hobbie2k

Me too. I love physics (but hate math). If you like this sort of theoretical stuff, but don't want to be bogged down by endless equations, try reading the Brian Greene books, "The Elegant Universe" and "The Fabric of the Cosmos." I'm reading the latter right now and am really enjoying it.

It's not specific to cars, but it did really help me begin to grasp the concepts of physics beyond the basic Newtonian.

an0malous

ahh I got caught up in that typical "drag racing" frame of mind. forgive me.
where basically a fwd needs every pound it can get on the front wheels to reduce weight transfer and front end elevation.

Im with ya on the turning though

the cobalt is actually balanced quite nicely from the factory, almost a 50/50, which is where its gets its above average autocross performance.

Area47

on a friends 07 ss, his a/c wouldn't shut off.

he would do 14.3 all night long, got it fixed.
first pass. 13.8

just some random thoughts that go into this

Alex47

Most cars Turn the compressor off at WOT so nothing should change at WOT

HunterKiller89

iTrader: (1)

the cobalt is one of those cars