Quote:
Originally posted by buzz70@Oct 15th 2004 @ 3:27 PM
When the car is coasting in this mode, the RPM doesn't change immediately. Sure, the car is slowing down at a very slow rate. The active cylinder isn't really "driving" the rpms, the inertia of the car going forward with the transmission engaged is driving the rpms. On the other 3 cylinders, the valves are closed, causing very little drag to occur from them. This is done so that maximum transfer can go to the regeneration of the batteries. However, by pressing the gas pedal slightly, you can "tell" the car not to go into regeneration mode, because it thinks you want to accelerate. Your foot isn't pressing the gas pedal enough to actually accelerate, however, so what you get is pretty much coasting -- except the transmission is still engaged, and the engine is only running on one cylinder, giving you the best of both worlds. You get coasting with very little engine dragging, and the engine running only on one cylinder using very little gas because the inertia of the car is helping to keep the engine running by way of the transmission. It's not obvious when running at highway speeds, but at lower speeds -- 40 mph and under -- where I can really note the difference. Since our FCD can only go to 120 mpgs, the slower speeds will show the difference. Shifting to neutral while only going 25 mph might get you 90 mpg, but if you stay in 4th gear and let off the gas without getting regen, you'll get 120 for sure.
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Well, I think I understand, sort of. :blink:
But you are talking about the VTEC method of reducing engine friction when engine braking, are you not?
If that's what you mean, that's fine, but your method still slows the car down much more than just coasting in neutral, does it not? With the manual tranny, if you leave it in gear at 40
mph and take your foot off the gas, it will coast to a dead stop in less than a block because of the engine braking/regen function.
So what you are telling me is that if I leave it in gear but do not press the pedal enough to actually increase the speed, it will slow down less quickly and increase my MPG higher than letting it just coast out of gear?
When taking the car into neutral at speed when I know I can coast a while, I can coast for stretches of 1/4 to 3/4 a mile, some cases farther, while only losing 8-10
mph at most from the time I shift to neutral until the time I must engage the tranny or else start stopping. The whole time, the engine is idling at it's lowest RPMs.
I still cannot understand how forcing the engine to push the car even with one cylinder, while still having the tranny engaged, can possibly be more fuel efficient than the car idling at it's lowest RPM with no tranny engaged......???