Fuel Consumption : How to improve or retain efficiency

**jaypee10** · September 13th, 2016 05:04 PM

tire pressure also always check.

**dr. d** · September 13th, 2016 05:27 PM

lest we forget, fuel (in)efficiency in non-moving traffic, regardless of vehicle, is in the neighborhood of 0 km/li.
i now turn off my engine, in non-moving traffic.

**GTi** · September 14th, 2016 07:45 PM

^I've always wondered. How much fuel is used in starting the engine? Is the fuel saved enough to offset the constant restarting?

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**Gian Paulo** · September 14th, 2016 08:04 PM

Originally Posted by GTi

^I've always wondered. How much fuel is used in starting the engine? Is the fuel saved enough to offset the constant restarting?

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Also to add, Which affect most in terms of A/C operation which affect FC, Is it the thermostat or the Fan at its max.?

**GTi** · September 14th, 2016 08:50 PM

Originally Posted by Gian Paulo

Also to add, Which affect most in terms of A/C operation which affect FC, Is it the thermostat or the Fan at its max.?

AFAIK its the thermostat. The fan is basically just an electric fan, while the thermostat controls the compressor.

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**niky** · September 15th, 2016 12:26 AM

Originally Posted by unmarked

guys, question. is 5 to 6 km/l reasonable for 100% pure city daily drive on a 9 year old Altis 1.6 A/T? moderate to heavy traffic mornings, light to moderate traffic afternoons (makati > ortigas, vice versa)

Given the traffic nowadays, that's, sadly, fairly typical.

Originally Posted by GTi

^I've always wondered. How much fuel is used in starting the engine? Is the fuel saved enough to offset the constant restarting?

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Turning off is worth it if you will be standing still for more than thirty seconds. Sometimes, I can have my engine off for up to five minutes at a time.

It's tough on your battery, though, unless you're willing to go the fully monty and have your windows down and blower off.

Originally Posted by Gian Paulo

Also to add, Which affect most in terms of A/C operation which affect FC, Is it the thermostat or the Fan at its max.?

The cabin fan at maximum draw is typically 100-150 watts of electric juice (modern alternators produce between 800-1000+++ watts of electricity).

The AC compressor draws 3,000 - 6,000 watts of power, straight from the engine.

(I just penned an article on electrical engine load.

)

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For some interesting reading, I'll leave this here:

https://cumminsengines.com/uploads/d...whitepaper.pdf

Lots of good information, plus some (not all) of the tricks good hypermilers use.

Uh... don't use the 100 psi discussed in the paper in your tires. Truck tires are built to run 100-120 psi (they burst at around 300 psi). Car tires burst somewhere in the 100-150 psi range. (To translate the graph to cars, consider the 100 psi load point as about 35-40 psi)

**dr. d** · September 15th, 2016 12:34 AM

Originally Posted by Gian Paulo

Also to add, Which affect most in terms of A/C operation which affect FC, Is it the thermostat or the Fan at its max.?

it's the thermostat, po. it turns the compressor on and off. in the olden days, we all have experienced the engine rpm dropping when the compressor turns on. fortunately, the idle-up mechanism today, ups the rpm, making the drop almost non-existent.
i read before, that aircon compressors eat up 5-10% of a typical car engine's power.

**GTi** · September 15th, 2016 12:43 AM

Originally Posted by niky

Given the traffic nowadays, that's, sadly, fairly typical.

Turning off is worth it if you will be standing still for more than thirty seconds. Sometimes, I can have my engine off for up to five minutes at a time.

It's tough on your battery, though, unless you're willing to go the fully monty and have your windows down and blower off.

The cabin fan at maximum draw is typically 100-150 watts of electric juice (modern alternators produce between 800-1000+++ watts of electricity).

The AC compressor draws 3,000 - 6,000 watts of power, straight from the engine.

(I just penned an article on electrical engine load.

)

-----

For some interesting reading, I'll leave this here:

https://cumminsengines.com/uploads/d...whitepaper.pdf

Lots of good information, plus some (not all) of the tricks good hypermilers use.

Uh... don't use the 100 psi discussed in the paper in your tires. Truck tires are built to run 100-120 psi (they burst at around 300 psi). Car tires burst somewhere in the 100-150 psi range. (To translate the graph to cars, consider the 100 psi load point as about 35-40 psi)

3000-6000W is around the output of 2-3 large window type household A/C's! 😱

For our heavy loaders (the Revo and Granvia), I load up to 38psi on the tires. 35 on all the others.

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**niky** · September 15th, 2016 01:31 AM

Originally Posted by GTi

3000-6000W is around the output of 2-3 large window type household A/C's! 😱

For our heavy loaders (the Revo and Granvia), I load up to 38psi on the tires. 35 on all the others.

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I'm at 45 psi for the CR-V, the sedan, 50. Ride is stiff, but only annoying over potholes.

The car gets higher pressure because the tire sidewalls are much softer. There's still some squidge in the tires, even at that pressure, and the sidewalls still roll under in hard cornering. Can't wait till these wear down so I can put on proper rubber.

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The 3,000 - 6,000 watts are estimates based on the load draw of electric AC compressors in hybrids... but are relatively accurate as far as horsepower loss goes (6kw equals 8hp)... perhaps even on the low side.

Dyno data from overseas suggests between 8-15 hp lost from AC compressor use. I recall one dyno we did at Speedlab which showed about 10 hp loss on a Honda Civic from turning the AC on.

Yes, perhaps it's better to simply install a wall AC into your car, then run a separate alternator for it.