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Execut1ve 12-30-2010 01:49 PM

shift points
 
Hello all,
I have a 2000 Honda Civic 5spd with the 1.6L 4cyl engine. Can anyone give me any info on the best shift points (by mph or rpm) for fuel econ? thanks!

Daox 12-30-2010 02:31 PM

Keep rpms below ~2500 most of the time and give it a healthy amount of throttle.

endurance 12-30-2010 08:28 PM

I concur for the most part with Daox. There's some trial and error with every engine. My pick up is comfortable shifting at under 2000rpm, my Acura bogs at under 1750, so I usually have to let it get up to at least 2300rpm to 2700rpm before shifting because it has no low end torque. What you want to prevent is lugging the engine at the one extreme or getting into the VTEC performance end of your powerband on the other end. Any time over 3500rpm is just wasted fuel (says a guy with a 7800rpm redline).

Learn to shift early and use a lot of throttle getting up to speed (most engines are most efficient at 55-75% of throttle), then backing off when you reach cruising speed to the lightest throttle position you can use to maintain speed.

pounsfos 12-30-2010 09:56 PM

Learn to shift early and use a lot of throttle getting up to speed (most engines are most efficient at 55-75% of throttle), then backing off when you reach cruising speed to the lightest throttle position you can use to maintain speed.

hold up, so to save gas i must floor it more to make my car more efficient when accelerating???

and here i am trying to use 10" of vac for accelerating!!

im going to test this one out next month

endurance 12-31-2010 12:18 AM

I know it's counter to what we all learned, but try it and you'll likely be surprised. Part of it is just where the engine was designed to be most efficient. The other part is the math of accelerating slowly. Which is more efficient, accelerating at 5 gallons per hour for 10 seconds or accelerating at 2.5 gallons per hour for 30-40 seconds? That's why I always keep both gallons per hour and miles per gallon displayed on my ScanGauge. It teaches you things that don't make sense until you do it and see the numbers right before your eyes.

bestclimb 12-31-2010 02:09 AM

I have a 95 civic with a 1.5l. I typically use around 2000rpm. If going up hill I let it get a little higher, if down hill I shift sooner. Though I have noted when I get on it a little more and let the revs get higher my mileage does not drop by much if any. The biggest gains IMO for driving efficiently are found in how you slow down rather than how you accelerate.

when using high throttle and high gears for accelerating you may find that by backing off the throttle will not reduce the rate of acceleration. By backing off till right when you feel the rate of acceleration drop slightly you will be pretty close to optimum throttle position for acceleration.

320touring 12-31-2010 08:17 AM

Saab 2.0 Low pressure turbo 5sp manual

1st- shift at 2000
2nd- shift at 2000
3rd shift at 2000
4th shift at 2000
5th use up to 2500 (65mph) then neutral for P&G on the motorway.

I find 1/3 pedal gives me good accel, over a short period.

Also I make sure i'm in the highest gear possible for accel- e.g going 35-50 is 5th, 25-35 is 4th

seems to work ok as currently at 117% of UK combined MPG

SentraSE-R 12-31-2010 10:37 AM

I determined what worked best for my cars with trial and error - back to back tests using a Scangauge while varying my acceleration load. I couldn't find Brake Specific Fuel Consumption charts for any of my engines, so ABA testing was the only way to identify what works for me.

If Executive can find a BSFC chart for his engine, that's where he should start. Otherwise, I suggest buying an SG or an Ultragauge, so he won't be flying blind. 85% load works best for both my 2.5 l Nissan engine and my 1.5 l Toyota engine, but it's rapid acceleration on my Nissan, and very mild acceleration with my Scion. I have to use <70% load on my wife's AT Hyundai (2.0 l engine), because any more causes the torque converter to slip, 65% load on the Hyundai is like 85% on the Scion - very mild

comptiger5000 12-31-2010 11:34 AM

I've found that with my auto, it doesn't actually make that much difference. Normally, I let the big V8 shift around 2200 - 2500. Below 2200 the torque converter is too slushy for it to be efficient, and mpg drops. Unless I start pushing it above 3000 or so, I don't notice a difference on the high end.

BHarvey 12-31-2010 11:14 PM

Quote:

Originally Posted by endurance (Post 212167)
I know it's counter to what we all learned, but try it and you'll likely be surprised. Part of it is just where the engine was designed to be most efficient. The other part is the math of accelerating slowly. Which is more efficient, accelerating at 5 gallons per hour for 10 seconds or accelerating at 2.5 gallons per hour for 30-40 seconds? That's why I always keep both gallons per hour and miles per gallon displayed on my ScanGauge. It teaches you things that don't make sense until you do it and see the numbers right before your eyes.


That was going to be one of my first tests when I get the Scangauge, time vs throttle and such. I had thought that in a flat mile from still that a shorter accel time with a longer cruise time would be more efficient than taking a full mile to get up to speed.


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