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GeekGuyAndy 07-23-2007 11:27 AM

Technique on Hills
 
I'm interested in finding out the best way to handle hills while still keeping a good mpg average. Driving a steady speed seems pretty bad overall since the gas is flowing and the mpg are low. I originally thought that trying to only accelerate on the less steep sections would help, which I think it did compared to my driving before. But is it even better to rev high for best power for a few seconds or to try to stay slower the whole time?

In high rpm, gas is used faster, but less time is needed. I guess what I really need to do is try different techniques on a hill nearby. Has anyone done a test about this?

How do you drive up hills?

Thanks

Hockey4mnhs 07-23-2007 11:36 AM

what i do and some outher people do is hold your foot at the same level the whoal time keeping the rpm's about the same but letting the mph fall. once on top i throw it in N and coast down the outher side.

Bill in Houston 07-23-2007 11:45 AM

Whatever you do, make sure that you end up with a speed at the top that will not cause you to have to hit your brakes on the way down. If possible, anyway.

GeekGuyAndy 07-23-2007 12:10 PM

Hockey, that's what I did last time. But reading more into WOT and Burn and Glide, I wonder which is better.

GasSavers_DaX 07-23-2007 12:14 PM

Quote:

Originally Posted by Hockey4mnhs (Post 64949)
what i do and some outher people do is hold your foot at the same level the whoal time keeping the rpm's about the same but letting the mph fall. once on top i throw it in N and coast down the outher side.

Pretty much how I do it, except I turn the engine off and coast down. I typically let my speed drop to 60 km/h before bump starting in 4th to continue up the next hill. If I continue to slow in 4th, I'll downshift to 3rd until I can climb to 1750 RPM, then I upshift.

QDM 07-23-2007 12:29 PM

I don't know if this is correct or not but it seems to work for me. Like anywhere else, I drive in the hills in as high a gear as possible that will let me keep the speed I want. I use full throttle in a higher gear rather than less throttle and higher RPM in a lower gear. I don't do anything special on down hill runs. My Swift still seems to get about 50 mpg in the hills, and we have a lot of hills in my area.

Q

MetroMPG 07-23-2007 12:52 PM

My preferences, depending on the size of the hill & traffic:

1) Pulse up the hill (if it's the right size for a pulse), glide down the back - probably best FE, 2nd slowest avg MPH

2) DWL up & glide down - probably 2nd best FE, slowest avg MPH. I'll do this if the hill is extra long (too long for a 2nd and/or 3rd gear pulse).

3) DWL up & DWL down - 3rd best FE, probably 2nd fastest avg mph. I'll do this if it's a long hill and I don't have the patience to coast down the other side (or if the other side's not steep enough for a coast).

4) Frozen throttle up & down - 4th best FE, fastest avg. mph. Usually I do something like this if there's traffic - trying not to vary speed so much that I hold people up.

(True DWL would actually have your speed falling AND you backing off the throttle on the ascent, potentially also downshifting as well. That's the only way you can actually achieve a constant load / maintain a target MPG. Remember if you hold a constant throttle as speed changes, load also changes.)

GeekGuyAndy 07-23-2007 02:19 PM

Metro, by 1) do you mean speed up before the hill, and roll up to the top in N/EOC? That's what I'm picturing which would be good on smaller hills if there's no traffic behind me.

skewbe 07-23-2007 02:22 PM

No, he means follow the target BSFC up the hill in one big pulse, kill it before the top so you will slow down before going down the other side.

MetroMPG 07-23-2007 03:03 PM

Yup, what skewbe said.

Sometimes the hill grade/length or both just isn't optimal for a pulse for the whole incline (or I don't feel like doing P&G). That's when I'll look to another option.

Sometimes I'll even combine methods, like DWL most of the way up and then pulse the last bit up to the crest, if the hill profile is good for it.


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