Accelerating for good fuel consumption.

[roosterk0031]

http://ecomodder.com/forum/showthrea...oad-19594.html

Yes you can.

[JohnAh]

Some years ago I had a little 1980 Fiat 127 with quite poor fuel efficiency and a worn out engine. Eventually a conrod bearing seized and as a quickfix I simply ripped out two pistons, disconnected the valves and put it all together again re-using the same gaskets. It then worked hard for another year until I sold it.

Projektblogg - Fiat 127 engine downsizing
(try using Google Translate, the webpage is mainly in swedish)

Those experiments gave me the first important lessons about successful ecodriving. The downsizing gave 10-15% improvement and I soon learned about the fuel enrichment that appears at full throttle and noticed quite an improvement by keeping the throttle at 70-80% of maximum opening. (carburetted engine) I also experimented with staying in 3:rd gear all time instead of continously shifting up and down between 3:rd and 4:th (as you have to do with such a weak engine (about 20 hp maximum I guess). Keeping revs down was definitely a winner! I never tried "Burn & Glide" (pulse & glide, burn & coast) with the little Fiat, mainly because I didn't know about that by then, but with that tiny engine I also needed the engine active all the time to get a decent average speed...

If you run an ICE at a realy low rpm I guess more of the combustion energy will get time to get lost as heat in the cylinder walls and head. At higher revs the losses increase due to pumping and friction, and if you close the throttle to match the actual need for power to keep a steady speed, things will get even worse.

It's all about finding the BSFC sweet-spot and keep the engine there. When that is not possible, turn it off completely! If that's not possible (power steering, power brakes and sensitive engine control computers that go crazy), keep it in idle, out of gear.

I once got a 15-20% improvement in a good friend's cool 400hp BMW coupe, a quite modern car with dual turbos and automatic transmission, using the Burn & Glide method. A nice secondary benefit was to enjoy the acceleration again and again. :-) Since it was an automatic, I put it in neutral after every acceleration cycle, and kept the engine running. After 15-20 minutes the ECU got crazy and started flashing strange error codes on the dashboard. We stopped and let the car rest for a while and everything was back to normal.

Ecodriving worth it's name can be difficult with modern cars, so you can definitely ask if all the electronics are realy a development. I feel we are in some sort of crazy limbo between old simple cars and a true change of paradigm, where everybody rides with hyper efficient automated taxis instead of owning their own cars.

[PaleMelanesian]

I lean toward the philosophy of "low rpm first, then anything else". I rarely go above 2500 rpm at the top of my pulses, usually running 1500-2200 rpm. Of course, I have the 1.5L engine, so as you said there will be places where you NEED more rpm for more power. That's a good thing, it means your engine is actually the right size for efficiency rather than for power.

You might look at MAP on the gauge for accelerating instead of TPS if your TPS is jumping around.

[JockoT]

Thanks. I'll check MAP out. What am I aiming for?

[Nautilus]

Originally Posted by PaleMelanesian

I lean toward the philosophy of "low rpm first, then anything else". I rarely go above 2500 rpm at the top of my pulses, usually running 1500-2200 rpm. Of course, I have the 1.5L engine, so as you said there will be places where you NEED more rpm for more power. That's a good thing, it means your engine is actually the right size for efficiency rather than for power.

Back in carburetted DOHC engine days people would say: enjoy your coked bearings and valves

The only logical way to keep a better mileage is to hold most of the time a high, but constant speed. Unless the cops and speed cameras are around.

It takes only about 60 hp or so to keep a Veyron running 60 mph. It takes over 1000 hp to get there in 2.5 seconds. Even getting the best efficiency in the realm of road vehicles, given by electric motors, it still takes 500-600 hp for the same feat, as in Tesla P100D.

In my car (1.8T, gasoline, turbocharged, 234 peak hp, a lot of minor aero tweaks) I can get up to 34-35 mpg (in US gallons) running with constant speed. From 30-31 mpg when bodywork was in stock form. With some acceleration, in the 1.0-1.4 bar on the boost gauge, but only where needed. Sporty road driving may drop to 29-30 mpg.

This is not modding of the car itself, it's modding of the driver - one adapts himself or herself. It takes training.

[JockoT]

I've been told accelerate briskly with the throttle well open, accelerate gently, keep the speed up, keep the speed down. I have more or less decided just to accelerate as I have done for the past 50 years (neither one thing or the other) and make my gains when coming back down the speed range (DWB, coasting, anticipation, avoiding stopping if possible and conserving momentum).

[Fat Charlie]

Originally Posted by JockoT

I've been told accelerate briskly with the throttle well open, accelerate gently, keep the speed up, keep the speed down.

And they're all the right thing to do, depending on conditions.

An SG or UG will let you see which is right where and when.

[JockoT]

According to my ScanGauge there is very little to choose between the options, at least on my 1200cc engine.

[Daschicken]

Originally Posted by JockoT

I've been told accelerate briskly with the throttle well open, accelerate gently, keep the speed up, keep the speed down. I have more or less decided just to accelerate as I have done for the past 50 years (neither one thing or the other) and make my gains when coming back down the speed range (DWB, coasting, anticipation, avoiding stopping if possible and conserving momentum).

Charlie is right, it depends on the conditions. If the road is wide open I would accelerate briskly, if there is plenty of traffic or unpredictable stoplights then accelerating gently is the better option. I need to work on that to get better city mileage.

[JockoT]

Today I monitored MAP and it is a nice steady reading. Varies from about 4.2, on a closed throttle, up to 14.5 on a wide open throttle. Short of keeping it below 14.5, what more should I be aiming for?