James:
I am working on two generator set-ups and would like some feedback. I am working on a Mercedes OM636 and a 3 cylinder, 1 liter [displacement] Chevy Sprint/Geo Metro/Suzuki motor. In this letter I’ll describe the 3 cylinder and why I think it will work at a retreat [to power a generator]. The 3 cylinder goes back to 1982 with GM’s Project Saturn in 1982. It achieved better than 100 miles per gallon (mpg). On a trip from Warren, Michigan to New York it averaged 105 mpg on the highway and 75 mpg in the city. It was dropped because of safety requirements and creature comforts that would require extra horsepower. (Hot Rod magazine, November 2006, page 30)
The GM Sprint 1985-1988 was the precursor to the Geo Metro. It had a carburetor intake and got around 60 mpg.
1989-1994 Geo Metro was fuel injected and got less mpg–around 45-to-50 mpg. Engine is rated around 50 horsepower (hp). They had another model called the XFi that pushed the car to 60mpg. The XFi has about 10 HP less but much lower RPM torque. Check out http://www.metroxfi.com/. With fuel injection came a better cooling in the head. The 1989-1991 engines can be run without the car’s computer. I contacted http://www.raven-rotor.com/, a company that uses the geo metro motor in ultra light aircraft. I saw they had magnetos for the engine (aircraft) and contacted them about one for my generator. They responded “Just use the early model (Vacuum advance distributor) ’89’ -’91 which has is own igniter module and needs only a coil and 12 volts DC to run the ignition.” This advice came from Jeron Smith, phone: (505) 737-9656. I have found many Geos with over 150,000 miles, some close to 200,000. These engines did have a problem with the number two cylinder burning valves. The cause of this was the EGR valve going bad. I plan on removing the EGR valve.
The engine is aluminum block with steel sleeves with an aluminum over head cam head. The engine is just over one hundred pounds which means it can be moved from the retreat easier than my diesel if the need arises. I plan on using the 1989-1991 head for better cooling and the distributor. I have an XFi cam.
Right now I can hear the moans [from SurvivalBlog readers] that it is a gas motor. I plan on running it on propane. I will use an earlier carburetor intake for mounting a propane carburetor for a 1 liter motor. The motor has a compression ratio of around 8 to 1. Propane is more efficient around 14 to 1. I hope to machine the heads to 12 to 1. Propane also allows me to move the fuel with the engine if I have to run. I will have the block squared and the crank bore-aligned. This little 3 cylinder it has 4 main bearings so it should handle the compression increase. I plan on using synthetic oil after the break in.
I can use the AC compressor that comes with the engine for refrigeration, the air pump for an air tank, will pull the heat off the cooling and the exhaust for heating water and the building. (My OM636 has an exhaust manifold that is used on inboard boats that allows me to capture the heat off the exhaust). I will be able to produce 12 VDC, and 110/220 and three phase off a 10 KVA continuous duty cycle military generator. I thought of buying a bigger unit but I am not sure if I need one. Using this engine allows me to change the RPM if the need arises for belt run machines. I plan on running the engine at 2,400 rpm.
Not sure if this will work, but with an easy supply of parts, one could rebuild/maintain it easily. Figure at 100,000 miles on a engine at an average 40 mph, it gets 2,500 hours of use. So you could run it for 500 days, for five hours per day. Figuring [the equivalent of] 60 mpg [at 2,400 rpm] you would need around 1,650 gallons.of propane. I think I will get better than that in fuel economy. Thanks,- Farmer John