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Kiwi_ME · 07-07-2009, 01:33 AM

Yet another mechanical engineer here. I've had a few years experience in engine test as a dyno service engineer in the UK and 20 more years designing industrial automated machinery in SoCal. Now I'm semi-retired in New Zealand.

I got interested in car fuel economy while I was in college in the mid 70's. I used to study in the secluded microfiche room in the engineering library, which by chance was loaded to the brim with SAE papers. When I got bored of studying I would read a few. After a few months I had read perhaps a few hundred. Many of the economy-related papers were a direct result of the early-70's gas crisis and described the industry's efficiency improvement efforts such as Mitsubishi's MCA-jet, Honda CVCC, and Buick's even and odd-firing V6's.

These were the days before catalytic converters and so lean mixtures and stratified charge was the talk. I learned that opening the spark plug gaps would allow the leanest-possible mixtures to be burned.

I soldered-up and re-drilled the carburetor jets in my 1952 Austin A40 (1.2 liter) until it would barely run, then added a high-energy capacitive-discharge ignition, opened up the plugs to 60 thou, and leaned it out even more. I was getting about 43 mpg (us) and this was not a light car.

Since I had a special fuel container rigged in the trunk, I started measuring the exact fuel use for my 3.3 mile trip to school. It started off at around 900 ml, but by the time I finished all those mods I got it down to 330 ml. Aside from the lean mixture, getting the car moving ASAP and off the manual choke was the key.

Since I was doing research on running a diesel engine partly on methanol I then modified the Austin to run on that too. That was fine until winter arrived and I couldn't start it, so back to gasoline it went.

Later on in the UK I had a carbureted Mercedes 6-cyl that I outfitted with a home-made continuous MPG readout and started leaning out the primary of Solex 4-barrel carb, which had a convenient mixture screw in the top. With this car I noticed the resulting power loss, but it still had enough in the secondaries to cruise at 120, during which the MPG would drop down to a pitiful 7.6 (us).

Now I drive a diesel SUV (half the reason I moved down here) which gets great mileage with little effort, but that just makes it even more of a challenge.

07-07-2009, 01:33 AM	#1 (permalink)
Kiwi_ME EcoModding Lurker Join Date: Jul 2009 Location: New Zealand Posts: 13 Swift Sport - '09 Suzuki Swift Sport 90 day: 33.69 mpg (US) Thanks: 0 Thanked 3 Times in 3 Posts	Giiday from down under. Yet another mechanical engineer here. I've had a few years experience in engine test as a dyno service engineer in the UK and 20 more years designing industrial automated machinery in SoCal. Now I'm semi-retired in New Zealand. I got interested in car fuel economy while I was in college in the mid 70's. I used to study in the secluded microfiche room in the engineering library, which by chance was loaded to the brim with SAE papers. When I got bored of studying I would read a few. After a few months I had read perhaps a few hundred. Many of the economy-related papers were a direct result of the early-70's gas crisis and described the industry's efficiency improvement efforts such as Mitsubishi's MCA-jet, Honda CVCC, and Buick's even and odd-firing V6's. These were the days before catalytic converters and so lean mixtures and stratified charge was the talk. I learned that opening the spark plug gaps would allow the leanest-possible mixtures to be burned. I soldered-up and re-drilled the carburetor jets in my 1952 Austin A40 (1.2 liter) until it would barely run, then added a high-energy capacitive-discharge ignition, opened up the plugs to 60 thou, and leaned it out even more. I was getting about 43 mpg (us) and this was not a light car. Since I had a special fuel container rigged in the trunk, I started measuring the exact fuel use for my 3.3 mile trip to school. It started off at around 900 ml, but by the time I finished all those mods I got it down to 330 ml. Aside from the lean mixture, getting the car moving ASAP and off the manual choke was the key. Since I was doing research on running a diesel engine partly on methanol I then modified the Austin to run on that too. That was fine until winter arrived and I couldn't start it, so back to gasoline it went. Later on in the UK I had a carbureted Mercedes 6-cyl that I outfitted with a home-made continuous MPG readout and started leaning out the primary of Solex 4-barrel carb, which had a convenient mixture screw in the top. With this car I noticed the resulting power loss, but it still had enough in the secondaries to cruise at 120, during which the MPG would drop down to a pitiful 7.6 (us). Now I drive a diesel SUV (half the reason I moved down here) which gets great mileage with little effort, but that just makes it even more of a challenge.