Basic questions for fuel effiency

[99metro]

My "how to shift" opinion:

When shifting into the next gear, there should be NO CHANGE in RPM when letting the clutch out and accelerating. In other words, when the clutch is pressed in and the engine RPM drops, after you shift gears and let the clutch out, the RPMs should be matched and not change. The RPMs should not drop, nor increase when the clutch is all the way out. Shifting like this you can easily put 300,000+ miles on a clutch. If you have to replace your clutch before 100,000 miles, you are shifting wrong.

There should be NO throttle while the clutch is [disengaged] or even partially engaged- only apply throttle AFTER the clutch is completely out. The ONLY exception is on initial acceleration from a dead stop - let the clutch out just enough for the engine RPM to drop slightly, apply easy throttle, let the clutch out, THEN apply 70-80% throttle, but not so quickly to be spinning tires! You can do this when starting out on hills also without rolling backwards and slipping the clutch.

Yes, I will have to make a video on this. I have been meaning to do a hypermiling series.

Acceleration should be just before open loop on fuel injected engines, which is somewhere around 70-80% throttle. Here's the catch though: If you are driving stoplight to stoplight, then slow acceleration is best. If you are driving in rural areas, you should use that 70-80% throttle as long as you have more than 3 miles between stops.

There you go.

[PaleMelanesian]

If you don't have a gauge, aim for something just above 1/2 and you'll be pretty good. There is a range that's pretty good, not just a single point. If you want to really fine-tune it you need a gauge. A vacuum gauge would help, too. 75% load roughly matches with 12 psi MAP (where 14.7 is ambient or engine-off).

Many bsfc charts are centered at lower rpm than the one shown above. Try this:
http://ecomodder.com/forum/showthrea...-got-1466.html

Again, my personal experience is that low rpm has its own advantage so you're better off keeping it on the lower side of what the charts show.

That being said, you're driving a Metro. That's a tiny engine. It may be that it does better at higher rpm than my 1.6.

[PaleMelanesian]

Originally Posted by 99metro

Acceleration should be just before open loop on fuel injected engines, which is somewhere around 70-80% throttle. Here's the catch though: If you are driving stoplight to stoplight, then slow acceleration is best. If you are driving in rural areas, you should use that 70-80% throttle as long as you have more than 3 miles between stops.

Faster acceleration isn't a problem, as long as you follow it with an efficient glide. If you're accelerating to a too-high speed and have to brake for the next stop, that's extra speed you didn't need and you wasted the extra gas.

I do all my accelerations at about 80%. I don't have a single clear three-mile stretch on my commute. There really is more magic in the glide than in the pulse.