driving technique: pulse & glide (long)

[1993CivicVX]

[quote=let's say the prius gets something like 75 mpg (US) at a steady 36.5 mph. then to achieve 109 mpg using P&G, you just have to achieve 54.5 mpg while accelerating from 33 to 40. and it turns out you can, in a prius.[/quote]

That's a little misleading though, because you can't achieve 54.5mpg accelerating from 33mph to 40mph. What you *can* achieve, though, is 31mph but in a short enough time that the glide lasts over three times as long as the pulse. 3.5 x 31= 109

[1993CivicVX]

Originally Posted by Matt Timion

So think of this. modify your cruise control to have two modes. If mode 1 is selected it will do pulse and glide. If mode 2 is selected it's normal cruise control. mode 1 is obviously for people like us, and you select mode 2 when your family is in the car and doesn't want to jerk back and forth for the entire trip.

that's a pretty cool idea but a safety liability like none other!! The guy in front of you starts breaking and your cruise control starts pulsing.....

[1993CivicVX]

one thing I wonder about a lot as to whether it would be the ideal one way route. A steep incline of about 20% grade (equivalent of a hard acceleration for a pulse on flat) and then a long gently sloping grade of about 4% grade or whatever grade would enable you to coast at a constant speed that was the same as the speed limit (say 45mph) So let's say the uphill is a mile long and is driven at 40mph and 15mpg and the gently sloping down hill was 10 miles long. Would be interesting to see the actual math numbers for this and what the mileage would be. A totally wild guess might be something like 15mpg for the up hill (1 mile) (in say a second gen prius) and zero gas use for the 10 mile down hill. That would be 150mpg? Not that you'd ever get conditions like that, but would be cool to test on in such a scenario. Is that not the most efficient possible scenario? Obviously coming back the same route would not be good gas mileage!

[bowtieguy]

the only pulse and glide i perform is on overpasses(no hills here), but with engine on. if that's not true pulse and glide, so be it.

i am able to EOC to end long strips of road to work and home both.

[dkjones96]

Originally Posted by MetroMPG

but... be careful. efficiency peak doesn't necessarily = torque or hp peak. but i also don't know any more about it to say more than that.

Actually, wide open at the torque peak is where engines are most efficient.
Above that and mechanical losses become an issue along with the bottom-end trying to out-flow the head.

Below that and the engine tune (cams, intake, exhaust, ect.) affects how well the exhaust leaves the chamber and a new charge is brought in. If revs fall low enough you can also start losing an excessive amount of heat per cylinder charge to the chamber walls, reducing efficiency.

[theholycow]

Originally Posted by bowtieguy

if that's not true pulse and glide, so be it.

Tradition on this forum seems to be that P&G means what you're doing, and if the engine gets turned off then it's called EOC instead. Using those terms that way makes sense to me (though IMO the latter would be best called P&EOC).