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lancer 03-27-2008 10:34 AM

Big hills in a automatic
 
Does anyone have any good techniques for BIG hills in an auto? There is one that is killing my MPG. This hill is extremely steep and about a mile long and to top it off there is a red light at the bottom of it. I’ve tried just creeping up it at about 20- 25 but my car will not shift into final gear until I reach at least 30. And the hill is so steep my car won’t shift anyway.
Thanks

Who 03-27-2008 11:15 AM

Do you have a ScanGauge? That might help you find an optimal climb speed. It's pretty tough doing a climb from a dead stop. That totally eliminates the option of just bleeding speed all the way to the top. Forgive me for saying the obvious but the easiest place to start would be taking out anything that is in the car that doesn't need to be there.

I take it that aren't alternate routes??

s2man 03-27-2008 11:57 AM

Can you get up to 30 or 35, then let off the gas briefly to get the trans to shift into high gear?

bhazard 03-27-2008 11:59 AM

I wouldnt want top gear. If youre going up hill and in top gear the torque converter is most likely just gonna be all over the place, keep it in a lower gear unless you want to burn your trans up.

LostCause 03-27-2008 12:01 PM

One of the most important things is keeping as much momentum as possible before the hill. If there is a red light, then learn how to time it so you can stay moving as fast as possible when it turns green.

Ideally, you want to be going much faster than the speed you expect to maintain on the hill. If you want to maintain 45mph, then try to start at 55-65mph. The most important thing is to not accelerate when going up hill. If anything, try to deccelerate.

On a hill that long, I just let my car deccelerate to a point where I'm ~5mph above where the torque converter locks up. That usually happens relatively early because my car is so heavy, so I just plod along up the hill maintaining that speed. When I crest the top, I let off the gas and allow my car accelerate on its own on the downhill.

- LostCause

8307c4 03-27-2008 01:18 PM

I am unsure whether maintaining speed is worse than losing speed, but I do know that accelerating up a hill is the worst thing. What I do is give it a little gas some distance ahead of the hill and build a few mph's of speed then as I enter the up hill I give it a little more gas as the car loses speed...
It's a trick, how much gas has to do with how long and how steep the hill is.
I don't mind losing 5-10 mph's but too much more isn't practical.

Then nearing the top just before I crest over it I let off the gas a little and then get back up to cruising speed afterwards.

Sort of try to 'flow' over it, but in actual practice it ends up acting much like 18-wheelers do... Sometimes I let it down shift, other times not, all depends.

Works much like IDPE as well, (Identify-Predict-Decide-Execute).
That is, identify the hill ahead of time, predict what it's going to take to get over it, decide how much fuel she'll need, then execute all that.

The perfect hill would be entered at about 5 mph's over the cruising speed and exited about 5 mph's below said limit. So if I'm cruising along at 35 I might give it some gas 1/4 mile ahead so as enter the hill at 40 and gradually lose speed going up it to where I'm doing 30-32 as I let off the gas some to crest it... Then after I'm over it I let the car gradually build back up to 35.
Of course if the car's shift point is 32 mph, again this varies from one car to the next and I wouldn't exceed the speed limit by more than a few mph's either (+5 MAX).

It does take practice, such as knowing the car's shift points...
That is, either let it shift or not, all or most of that has to be decided ahead of time or it may or may not work... It helps to practice on known hills first, once you get it down it's not so bad, and the actual tactic will vary some from one vehicle to the next.

Again I'm not sure if this is any better than simply maintaining speed, but it does somewhat guarantee that I never accelerate going up a hill.

Duffman 03-27-2008 03:16 PM

I found in my old concorde that I did best by keeping the torque converter locked up as long as possible did the best for me. It takes some practice but eventually your foot will learn the max throttle position that you can hold and stay locked up. Accellerating before the hill and losing speed while going up the hill in conjunction with this method worked best for me on the overhead meter.

Lazarus 03-27-2008 03:55 PM

What the speed limit on the hill, what's on the other side and is there an, as Who points out, alternate route?

Oh and welcome to the site.

Cd 03-27-2008 05:58 PM

On my trip to work, I have one ( small-3/4 mile distance ) hill that slows me down. I would shift into neutral ( yes it is an auto ) and coast from 55 at the top of the hill and shift back into 'D' right as I hit the bottom of the hill.
As I drove up the hill, I could hear the engine struggling.
I found that shifting into 'D' and giving the car gas around 100 ft. before the bottom of the hill allowed the engine to struggle less up the hill, despite the speeds being the same at the bottom of the hill.

I don't know if that helps at all.


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