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-   -   Which technique gives better mileage? (https://ecomodder.com/forum/showthread.php/technique-gives-better-mileage-22960.html)

Mcgiiver 08-17-2012 12:24 PM

Which technique gives better mileage?
 
Car is 1995 Toyota Corolla, 1.6 l auto, in good condition. Starting gently from a stop, the car shifts up to top gear rather quickly, about 20 mph. I need to reach my normal cruising speed of 51 mph, torque convertor is locked up at that point, and I am in no hurry to go anywhere.

Which would yield better gas mileage ?:

A. from top gear, at about 20 mph, accelerate very slowly, just enough to keep the speedometer rising until I reach my cruising speed. Sometimes this may take up to a minute. Watch vacuum gauge and keep vacuum as high as possible, usually above 5 inches.

B. from top gear, at about 20 mph, accelerate moderately hard, without letting the trans downshift, until I reach cruising speed. Obviously this will happen quicker than one minuet as in scenario A. Watch vacuum gauge, but under this technique the gauge would go to zero.

Fat Charlie 08-17-2012 12:32 PM

I'd expect B to. Harder acceleration is less acceleration.

PaleMelanesian 08-17-2012 12:50 PM

I agree - B is better. BSFC wins.

user removed 08-17-2012 03:31 PM

You should do best in an auto by acelerating as fast as possible without delaying transmission upshifts. This gives you the highest practical load, which in turn gives you best BSFC. If you can't stay in top gear (converter locked) then pulse (engine on) and glide. No engine off when moving in an auto, or you could hurt the transmission.

regards
Mech

redpoint5 08-18-2012 02:28 AM

My guess is also B, brisk acceleration.

I recently played on the back roads, taking the engine to the end of the redline, and I got one of my best mpg scores. Of course, I wasn't touching the brakes for anything, but instead coasted. It didn't seem to affect mpg as much as I thought it would.

Weather Spotter 08-18-2012 07:27 AM

Quote:

Originally Posted by redpoint5 (Post 322324)
My guess is also B, brisk acceleration.

I recently played on the back roads, taking the engine to the end of the redline, and I got one of my best mpg scores. Of course, I wasn't touching the brakes for anything, but instead coasted. It didn't seem to affect mpg as much as I thought it would.

If you engine off coast, then the engine is only working to get you to speed, so the amount of fuel used to get you there is the major factor in MPG, aero being second (first if you go about 50 MPH). hard fast acceleration tend to be at the ~80 load where the engine is most efficient. so your example sounds about right.
I would stop just short of red line though :)

Gealii 08-18-2012 07:52 AM

I also would go with B in my auto i seem to get my best mpgs at 70-80% engine load

redpoint5 08-18-2012 06:35 PM

Quote:

Originally Posted by Weather Spotter (Post 322343)
If you engine off coast, then the engine is only working to get you to speed, so the amount of fuel used to get you there is the major factor in MPG, aero being second (first if you go about 50 MPH). hard fast acceleration tend to be at the ~80 load where the engine is most efficient. so your example sounds about right.
I would stop just short of red line though :)

I'll start employing EOC when covering distances of 1/4mi or more. I've been leaving the engine on, but there is no reason to do so in a manual since I can bump start.

I normally accelerate at 85% load and shift at 3000rpm. I'll cruise at around 1500rpm.

The V-Tech kicks in at 6000rpm and the maximum rpm is 7500. I was just playing since I have never seen what my car is capable of. No sense driving a sporty car if you don't have fun with it every now and then. :D

cfg83 08-18-2012 07:11 PM

Mcgiiver -

This would have made a great poll :

Quote:

A. from top gear, at about 20 mph, accelerate very slowly, just enough to keep the speedometer rising until I reach my cruising speed. Sometimes this may take up to a minute. Watch vacuum gauge and keep vacuum as high as possible, usually above 5 inches.

B. from top gear, at about 20 mph, accelerate moderately hard, without letting the trans downshift, until I reach cruising speed. Obviously this will happen quicker than one minuet as in scenario A. Watch vacuum gauge, but under this technique the gauge would go to zero.

C. A and B are equal

D. Other

CarloSW2

Fat Charlie 08-20-2012 09:20 AM

Quote:

Originally Posted by redpoint5 (Post 322422)
No sense driving a sporty car if you don't have fun with it every now and then.

No, you were being responsible. The gliding deniers keep pointing out how dangerous life is when you're not in gear (if your engine stalls, you lose power steering and the ability to accelerate away from danger). Familiarizing yourself with that safety feature called acceleration is only making you more ready to use it to avoid a hazard. :D


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