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Date:         Tue, 1 Nov 2005 09:03:27 -0800
Reply-To:     John Bange <jbange@GMAIL.COM>
Sender:       Vanagon Mailing List <>
From:         John Bange <jbange@GMAIL.COM>
Subject:      Re: Fuel ponderings
In-Reply-To:  <>
Content-Type: text/plain; charset=ISO-8859-1

how does one increase fuel efficiency, i.e., increase > the miles per gallon on fuel? > > Reduce vehicle weight is one way.

That's an easy one, though it only makes a BIG difference if you do a lot of accelerating and decelerating.

Reduce friction.

Slick 50 in your oil an goose grease in your hair.

Streamlining for the vehicle.

If we set the front seats back a bit and make the nose pointier on the Vanagon it's be much better-- but it'd also be a Eurovan. EEEK!

Better fuel metering.

The Bosch L-Jetronic system with lambda (O2) sensor pretty much nails that 14.7 air-fuel ratio.

Congress legislating that it be so??

I think we need a law changing the ideal AFR for gasoline from 14.7:1 to a more fuel efficient. 7:1. Think of it! We'd double fuel efficiency instantly! Then we should also get congress to pass a law barring hurricanes from entering the country.

What else??? > > Is it really possible to get more BTU's from a pound of fuel than a > pound of fuel has?? What good does better mixture control and > vaporization actually do? Given better mixture control and vaporization, > can fuel efficiency actually be increased beyond where it is now, just > on that basis?

Well, the real problem with gasoline engines is that they convert heat energy to kinetic energy via Boyle's law. The combustion increasees temperature, which increases pressure. Pressure can then be slowly (in relation to combustion time) converted to motion by moving the piston. The conversion is limited by the pressure differential. beyond a certain point the remaining energy is too dilute and must be abandoned, mostly as heat out the exhaust.

The whole business about fuels and fuel efficiencies is about energy > exchange without energy loss. Is it possible??

Well, a combustion engine is always going to be limited by the lower end of the pressure differential, where there's still a whole lot of energy left in the hot combustion gases, but there's no mechanically efficient way of extracting it. One tactic is to start off from a higher pressure, giving the engine a greater differential to begin with. Of course the problem with raising the compression is pre-detonation. Then you need higher octane gasoline and engine timing controlled by a knock sensor. One of the reasons the wasserboxer is less efficient than other, more modern 4 cylinder engines of similar displacement is its lower compression ratio.

As far as harnessing Atomic Power (as they used to call it back when it was going to Save The World), I think we're a long way off from seeing it on a small scale. Nuclear power technology is presently about the equivalent of James Watt's steam engine, I'd say. There's still a long way to go to get to the equivalent of the modern steam turbine. Same thing with electric. We've been at a bit of a sticking point in battery technology for a long time. That is one advantage to rising fuel costs, though. It spurs innovation in efficiency.

-- John Bange '90 Vanagon "We'd tell a monkey how to peel a banana, if he said he was peeling one in a Vanagon."

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