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-   -   hypermiling on hilly curvy roads? (https://ecomodder.com/forum/showthread.php/hypermiling-hilly-curvy-roads-27913.html)

Toe_cutter 01-05-2014 07:41 PM

hypermiling on hilly curvy roads?
 
whats the best method for dealing with frequent short steep hills that always seem to have a sharp curve at the bottom? The parish roads where i live are crazy! Like 30 short but speed killing hills on my way to town. And u cant build up speed downhill on most of them because theres a 35mph turn at the bottom. And yeah there are no alternative routes....

MetroMPG 01-05-2014 08:02 PM

Nothing worse than a stop or sharp corner at the bottom of a hill!

One solution: drive a hybrid or EV. Not being facetious. That's one of their strengths: instead of wasting the kinetic energy you built up going downhill on burning through brake pads, you can stuff a good amount of that energy back into the battery through regenerative coasting/braking and use it later when it's most useful (ie. going up the next hill).

Next car, maybe? :D

1) Regular vehicle: your best bet is to crest the hill at the slowest practical speed (meaning: you haven't wasted fuel by building more speed than required, because you now have to decelerate)

2) Engine brake to the bottom using as little (or no) fuel as possible.

3) Use 1&2 together to avoid using the friction brakes as much as possible.

Does your pickup have deceleration fuel cut-off? If so, depending on the RPM at which it activates, you may have to downshift to activate it.

Xist 01-05-2014 09:10 PM

Metro, I must be a genius! :P

I actually tried to look up the 1995 F150 to see if it does DFCO and I did not find anything relevant, but happened to see some fine gentleman named SkyKing in another forum.

user removed 01-05-2014 09:23 PM

It's fairly easy to check for DFCO, decelerate using engine drag in gear and when DFCO shuts off you will feel the difference. My 92 had it but the idle speed was so high it would go 25 MPH in 5th gear with your foot off the gas.

regards
Mech

XYZ 01-05-2014 09:55 PM

Quote:

Originally Posted by Old Mechanic (Post 405850)
It's fairly easy to check for DFCO, decelerate using engine drag in gear and when DFCO shuts off you will feel the difference. My 92 had it but the idle speed was so high it would go 25 MPH in 5th gear with your foot off the gas.

regards
Mech

FYI, apparently he has this beast: click here

I'd say get it to the top of the hill, reaching the crest of it at a crawl, without inconveniencing anyone behind you by being a turtle. Then put it in neutral and coast to the bottom, braking only when necessary.

Repeat, until you leave Louisiana... :D

Xist 01-06-2014 12:25 AM

Quote:

Originally Posted by XYZ (Post 405853)
FYI, apparently he has this beast: click here

I'd say get it to the top of the hill, reaching the crest of it at a crawl, without inconveniencing anyone behind you by being a turtle. Then put it in neutral and coast to the bottom, braking only when necessary.

Repeat, until you leave Louisiana... :D

I brake when my instantaneous MPG reaches my average. In Bacon, my idle GPM is 0.25, so I guess that would be 7 MPG, although I never lose that much speed.

justme1969 01-06-2014 07:15 AM

one word begins with R
 
Regen!

basjoos 01-06-2014 09:35 AM

Quote:

Originally Posted by Old Mechanic (Post 405850)
It's fairly easy to check for DFCO, decelerate using engine drag in gear and when DFCO shuts off you will feel the difference. My 92 had it but the idle speed was so high it would go 25 MPH in 5th gear with your foot off the gas.

regards
Mech

On a lot of cars you can also detect when DFCO engages by tuning your AM radio to a vacant frequency and turn the volume up so you can hear the ignition static noise on the radio. When DFCO kicks in, that noise goes away.

bobo333 01-07-2014 07:20 PM

Or if your car has an instant fuel usage readout like mine does it goes 0 when DFCO kicks in (or 999 depending how its configured)

D.O.G. 01-07-2014 10:11 PM

My commute has me coming down out of the mountains to the plains and climbing again in the afternoon, so I understand your situation.

There's no painless way of climbing hills, you can only experiment with different speeds and gears to see where your vehicle returns the least fuel consumption.

On the plus side, you use a lot less (if any) fuel going down those same hills, so the two directions average out to a more reasonable FE figure.

Others have already noted that DFCO can work for the down hill section, but can be limited to certain rev ranges that aren't always practical to maintain.
I use an injector cut-off switch so I can leave the car in 5th, 4th or 3rd gear (depending on how steep the hill is) and keep near the speed limit while using no fuel.
For the tight curves at the bottom of those really steep hills I supplement engine braking with the foot brake as required. I always have full brake booster vacuum (and power steering) due to the engine braking.

My injector switch is a maintained push button mounted on the gear stick, that operates a relay in the engine bay.

It works for me.:thumbup:

ever_green 01-07-2014 10:19 PM

every car is different. On my Subaru with a modified drive by wire, fuel map and ignition timing map, keeping loads and RPMs low helps a lot (variable valve lift in my Subaru avoids pumping losses traditionally associated with conventional SI engines). So if i wanna be efficient I accelerate at 60% load at around 1700rpm up a hill then coast down. This can cause my speed to bleed depending o grade and length of the hill therefore I might downshift to get back to speed then start the bleeding process all over. I usually go DFCO on the way down the hill (my car enables DFCO above 1100rpm which means I will be using no fuel down the hill no matter what gear i'm in, unless i'm going slower than 25mph which is rare). RPM or engine load spikes ruin my daily trip mileages as my car goes open loop above 85% relative engine load and/or 3200rpm. Also for me high engine load results in significantly lower ignition timing vs moderate loads, means lower volumetric efficiency. It all DEPENDS on the car. Master feathering the throttle and you are good, kinda like having an egg shell between your foot and pedal and you don't want to crack the shell.

On my honda I just drive the car hard and the outcome is not so different from babying it.


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