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-   -   Basic questions for fuel effiency (https://ecomodder.com/forum/showthread.php/basic-questions-fuel-effiency-17692.html)

actwithclarity 06-03-2011 08:16 PM

Basic questions for fuel effiency
 
I learned myself to drive standard from reading a page on the internet. Basically I can drive around half smoothly but I have no idea:

~ how much gas to apply [just hard enough to not stall .... burning rubber]
~ when to shift [lowest rpm for next gear .... highest rpm for this gear]
~ what gear to shift into [next number gear, skipping one, highest possible, etc]

(to get good fuel efficiency)

Please help me understand these basics. A video would also be helpful if anyone has one.

Odin 06-03-2011 08:30 PM

it depends on what car you have as to what rpm you should be in for what gear

actwithclarity 06-03-2011 09:09 PM

I have a 91 Sprint but since I have no tachometer, the exact RPMs do not matter, I am just looking for general principles.

Bill in Houston 06-03-2011 09:26 PM

drive nice and easy. try to keep revs low. don't skip gears.

post a video of yourself, and then we will critique you.

slowmover 06-03-2011 10:39 PM

Owners manual should have some info on shift points. May be copies online for download.

Kodak 06-03-2011 10:55 PM

How much gas to apply: That can be tough to learn. Especially if you're starting out uphill. It sounds like you've already experienced both extremes, so try to find a happy medium. Wish I had more info for you, but this you'll have to learn on your own.

When to shift: It's going to be a bit tougher without a tach - at least at first. As far as shift points, try to hear when the engine sounds like it's doing too much work for the speed it's going. If you shift too early the engine will lug - that is, it will have very poor acceleration and will sound like it's struggling. It might make a 'put-put' kind of noise. You'll know. Lugging is pretty bad, so try to keep your engine at a healthy rpm. Just remember that if you need to accelerate quickly for some reason, you may need a lower gear.

Gear selection: I'm not a huge fan of skipping gears. Sure, you can blast first gear and then jump to third, but it's better to stay in the power band and use each subsequent gear as it was intended. Just go in order when accelerating, and when you're up to cruising speed try to hold the highest appropriate gear for the speed you are traveling, again avoiding any lugging of the engine.

I hope this helps. I'll try to chime in if you need something clarified or have any further questions.

Ah, before I forget. Here's a stick driving tip that my dad taught me, which he got from a driving school owner. Not one of your questions, but it was extremely useful when I was learning. A good way to get used to your clutch's friction point (that is, where it engages) is to pick an empty parking lot, put it in 1st, and then slowly release the clutch until the vehicle starts to crawl forward. No lurching. Keep it nice and smooth. Finding this point is crucial.

bestclimb 06-03-2011 11:31 PM

What you do with the kinetic energy you have at the top of an acceleration is more important than how you get up to speed. (Within reason, don't lug it and keep out of enrichment) If you can avoid the brakes you won't be wasting fuel used to accelerate.

I skip gears to get into 5th if a lower gear is not needed to get up to speed. Going up hill I go a little farther into the gear (let the engine rev a little higher) Going down hill I shift up sooner.

Instantaneous fuel consumption information is very key, an MPGuino or the like will help a great deal.

The method I use is to push the throttle in until the rate of acceleration stops increasing then back off a fraction.

Frank Lee 06-03-2011 11:45 PM

I think you "don't skip gears" guys are wrong. I can oftentimes easily go 1-3-5. Less shifting = less high rpm operation, less sudden engine decelerating cycles, etc.

In fact, GM had "skip shift" logic in Corvettes for the express purpose of saving fuel.

Bill in Houston 06-04-2011 07:25 AM

I knew that if enough people weighed in, we'd give conflicting advice. :)

I agree that the original owners manual prolly had shift point info. might even have a "do not exceed" and a "for best economy" shift point.

Ford Man 06-04-2011 03:29 PM

In my cars I accelerate slowly and just guessing (since I don't have a tach) I'd say I shift in the 2000-2500 rpm range. For best efficiency always shift to the next gear as soon as possible without lugging the engine. Most of the time I go straight through the gears 1,2,3...., but occasionally I will go from 2nd to 4th if I'm on a downhill incline and can do so safely without lugging. Using this method I can usually beat the old EPA highway rating in mixed city/highway driving and on the highway often beat the old EPA highway rating by 5-10mpg. You want to engage the clutch at as low rpm as possible to prevent excessive clutch wear. The last clutch I replaced in my '88 Escort had 260K miles on it and the current clutch has over 200K miles on it.


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