Effect of Engine load on FE

[Frink]

Hello, just installed the scangauge last week and was wondering what effect higher or lower engine loads (LOD) will have on fuel economy.
Basically, is it better to run the motor under heavy load, light load or somewhere in between?
Forgive me if this has been discussed before, I did a quick search on this but could not find anything...

[Matt Timion]

Originally Posted by Frink

Hello, just installed the scangauge last week and was wondering what effect higher or lower engine loads (LOD) will have on fuel economy.
Basically, is it better to run the motor under heavy load, light load or somewhere in between?
Forgive me if this has been discussed before, I did a quick search on this but could not find anything...

It's my understanding that engines are more effcient under heavier loads, but just because they are more efficient it does not mean that you'll get better gas mileage.

I have heard of very small engines running at high load doing well, but since it was a smaller engine (1.0L) running at a higher load was normal. for a 1.5L+ sized engine, higher loads are going to cause you to be going very fast as well, which will also take a toll on your fuel economy.

So in other words, I don't know :P

[zpiloto]

Here's a thread that talks alot about that http://www.gassavers.org/showthread....&highlight=WTO
But generally I think that once you get up to speed you want the lowest load that will propel you down the road. Metro did some high verses low rpm runs. Look in the experiment forum or his website.www.metroMPG.com

[MetroMPG]

Moderate to high load - at low RPM - is the best way to accelerate (assuming you don't have to stop immediately afterwards).

Though the difference between that and light, slow accel. is probably not as huge as you might think.

Once you're up to speed, as zpiloto says, you want to be at the lowest RPM you can be at, regardless of load. High RPM is the killer for sure.

[rh77]

Originally Posted by MetroMPG

Moderate to high load - at low RPM - is the best way to accelerate (assuming you don't have to stop immediately afterwards).

Though the difference between that and light, slow accel. is probably not as huge as you might think.

Once you're up to speed, as zpiloto says, you want to be at the lowest RPM you can be at, regardless of load. High RPM is the killer for sure.

Do you know if this includes cars with the manu-matic? Whenever I drive the TSX, I get into the highest gear that the ECU will allow, and give it heavy throttle at lower RPM. That tends to work better than lower-load, fully automatic shifting (just informally on the cumulative FE display). The thottle-by-wire is wierd, tho. I really need to sit down and figure out this drivetrain.

[MetroMPG]

Yeah, I can't really comment on autos or drive by wire. No experience there, sorry. Just the old-fashioned technology for me!

[JanGeo]

Basically if you put your engine in neutral and measured the fuel consumption at various RPMs you would see just how much fuel (GPH on SG) it takes to operate at various RPM's. There is considerable fuel being used at 3000 and above even in my xB engine so if you are spinning it at that speed it uses that and more to make the car go. Im my case however it has to spin at higher RPM to develop enough power to push my box through the air. LOD at 50-60 mph is in the 50% range.

[zpiloto]

Originally Posted by rh77

Do you know if this includes cars with the manu-matic? Whenever I drive the TSX, I get into the highest gear that the ECU will allow, and give it heavy throttle at lower RPM. That tends to work better than lower-load, fully automatic shifting (just informally on the cumulative FE display). The thottle-by-wire is wierd, tho. I really need to sit down and figure out this drivetrain.

With my auto the best FE comes from accelerating at 80% load on the SG to get it into the gear required for the speed limit. Once at the right gear then the lowest rpm that can keep me moving.

[psyshack]

I dont use the LOD at all with my SG. Its a very flawed read out. Ive seen it read high load on a in gear fas and all sorts of weird stuff.

I use the MAP read out alot at times and the TSP some.

I was working on some P&G tatics yesterday in the Civic on Interstate 40. Also really watched fuel useage pulling hills.

With P&G my target speed was 60 mph, with target coast down to of 50 mph. Min. speed limit is 40 mph. I found the gental approach far better on the pulse. A mild to aggressive foot on pulsa drank gas. I could make it act like a big block drinking gas.

For pulling hills. It was shown that I could ever so lightly accel up hills if I carried speed into them. It wasnt as good as load driving up the hill. But not painfully bad either. This is intresting for me because I can at times pull 1 to 1.5 mile fas if I top a hill with enough speed to pull the long fas off and stay above the min. posted speed limt.

psy