Quote:
Originally Posted by 101Volts
Correct, But I think you should have most of the tire contacting the road at a given time so the tread wears evenly and for other reasons; I did some comparison tests today between 55, 50 and 45 PSI and the car could accelerate quicker at a given engine LOD when at 45 PSI than at 50 or 55 PSI, Thus = Higher fuel economy (In theory.)
After you get the ScanGaugeII, You can try comparing tire pressures. See how fast your car accelerates to a given speed at a LOD of 17 or so with 55 PSI compared to 50 PSI and 45 PSI and perhaps even 40 PSI.
Perhaps I'm not thinking of this quite right but I know for one trip I averaged over 38 MPG in Moony with a tire strapped to the roof and very mild pulse and gliding (Without turning the engine off) when the PSI was 45ish and I didn't manage that on a recent trip without the tire strapped on or with roof racks, With an oil change and pizza pans with the tires set at 55ish and heavy load pulse and gliding.
Also, This specific paragraph is a bit off-topic but using the tire pressure pumps at gas stations to deflate the tires may take a lot more time than deflating the tires a bit lower than the PSI you're aiming for with a paper clip and re-inflating them.
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I can't imagine how the car would accelerate better with lower pressure tires, unless if your tires under high pressure were skidding and you didn't know it because of traction control and the such.
Concerning the trip there are a lot of factors there. I would never base that sort of mileage discrepency solely on tire pressure. For example, if the car is older, then maybe heavy pulses lead to compression losses. Or maybe you had a headwind and it was a cold, rainy day the latter time, but a tailwind and a clear, warm day the former time.
Although I too may be wrong, and I have no hard data to back myself up. But once I get the scanguage I do want to test that out.
Another thing I was thinking of testing concerns an auto tranny's low gears. I was thinking, why is it that manually shifting into low gears slows you down so well? In my car the manual low gears can slow me down really quick even if It's only doing 2500 rpms. The only other thing I could think of that could cause that is if there was a direct connection occurring, or in other words torque converter lock-up. So then, if it is true that the torque converter locks up when manually using low gears, then wouldn't that mean it's more efficient to accelerate in those low gears? I accelerate out of stop signs in low gear because I found I could have really high throttle/load and the car wouldn't shift down (100% throttle possible in an auto with less than 2000 RPM's!), and I feel like I've been wasting much less gas that way.
Anyone know about this?