Newton is costing me MPG - The hills thread

[gone-ot]

..per (fig) Newton: "...what goes UP, must come DOWN..." (except in space where there *is* no UP or DOWN!)

[dcb]

Originally Posted by Arragonis

I'd still be interested in how others tackle gravity.

Hills are my friend, and the mpg gauge agrees. I can stay near peak bsfc rpms for longer with the throttle open more towards peak bsfc load, and extended glides on the back side. Ascending hills is like uber-efficient energy storage, manage 'em wisely.

[California98Civic]

Originally Posted by dcb

Hills are my friend, and the mpg gauge agrees. I can stay near peak bsfc rpms for longer with the throttle open more towards peak bsfc load, and extended glides on the back side. Ascending hills is like uber-efficient energy storage, manage 'em wisely.

I try for this too, but I can't call them friends. How does your situation compare to this: the speedlimits around here are generally 45 and 50 mph, with people driving faster. There are frequent lights at the bottom and top of hills. Often, I get stopped on the incline, really ugly steep inclines too, the kind only Tour de France riders would climb for training. How does that compare to your hills?

[dcb]

Well being in a lighter vehicle helps you too if you cannot reclaim all your climbing energy on the back side (you lost less energy during ascension). Stops at the bottom of hills just suck, best you can do is to (when traffic allows) shut it down early so you barely coast over the top, then coast it down. But as long as you are with legal speed range (and especially if there is ample passing room) I don't worry too much about what other drivers are doing, their reasons for wanting to race down a hill to a stop are no better than my reasons for driving as I do. So you can legally roll over the top of the hill at like 25mph, so you don't have to ride the brakes so much on the way down. <insert noise about bla bla legal bla bla outtamyway bla bla here>

[Frank Lee]

I'd still be interested in how others tackle gravity.

COZX2 claimed over 100 mpg with his Escort. Personally I think he took liberties with his claims i.e. showing a scangauge pic while going downhill, and doing hundreds of little sub-1 gallon microfills during "testing" then editing them out of his gaslog when I mentioned how small fills are subject to massive fill errors. But no doubt he was getting good fe.

[PaleMelanesian]

Rolling hills with no stops are the best for mileage. I'm convinced they're better than flat terrain. It's good as long as they meet these conditions:
- reasonable speeds
- traffic allows you freedom to vary your speed (slow at the top)
- no stops at the bottom (at the top isn't too bad)
- not too steep (up requiring a downshift, down requiring brakes to prevent overspeed)

My commute mostly meets these conditions. There are a couple poorly-positioned lights, but by approaching slowly I can usually hit the green. 45-55 speed limits are ideal.

[California98Civic]

Originally Posted by dcb

I don't worry too much about what other drivers are doing, their reasons for wanting to race down a hill to a stop are no better than my reasons for driving as I do.

My mantra all morning. I don't drive that slowly. It's the difference between my slower than limit and their higher than limit that makes it seem so.

[wdb]

Originally Posted by Arragonis

I'd still be interested in how others tackle gravity.

It depends on the hill.

For example I have one nearby that has a really long downslope on the other side; I let the car lose speed all the way up, and dump the clutch as far from the crest of the hill as possible, knowing that Newton will reward me soon.

For that steep bear of a hill in last mile of my drive home (with no downhill payback), I carry as much speed as I can into it and then use as little throttle as possible to maintain speed. I also use the flatter sections to add speed and let it bleed off on the steeper sections. Essentially I'm holding the throttle at a particular position and trying my best not to push it any further. I've tried low RPMs but in my torque-free Honda that just seems to make me have to shift, which costs mileage. Better to keep the same gear the whole way, in my experience.

[UFO]

I'm constantly using a combination of coasting and DFCO to control speed down hills. Conditions and vehicles are too variable to develop a hard rule.

[jakobnev]

Princess likes to accelerate up any hill at any speed in any gear, so that's usually what i do. If the hill is too long i have to split it up into several pulses.