Choosing a Conversion Donor Car Shari Prange c. 1992 Shari Prange In your fantasies, you cruise silently down the road in an electric dream machine. Not a puff of exhaust comes from the tailpipeÄwhat tailpipe? The only reason to pull into a gas station is to check tire pressures and wash the windshield. Tune-ups and oil changes are fading memories. Fantasies into Realities But, now you want to turn your fantasy into a reality. Your first task is choosing a car for this metamorphosis. Making a wise choice at this crucial, first step will ensure that your reality lives up to your fantasy. Size Obliviously, you won't be converting a Lincoln Continental. The heavy cars that get poor gas mileage will also be poor electric performers. Look for a car that's under 2500 pounds curb weight, if possible. Two thousand pounds or less would be ideal, and 3,000 pounds would be marginally acceptable in a special, low-speed application. Although you'll be removing the engine and miscellaneous other parts, you'll be adding a half ton of batteries. The conversion will probably be 600-800 pounds over its original weight. To check curb weight on a potential donor car, go to the library and look up Road & Track Magazine for the year the car was built. There will probably be a detailed report with all the relevant specs. Consumer Reports also carries such information. On the other end of the spectrum, some wonderfully light cars have other problems. One is limited space for batteries. Even a very light car needs a minimum of 72 Volts (twelve 6 Volt batteries) to be marginally street safe, and 96 Volts (sixteen 6 Volt batteries) is recommended. Another potential problem is the suspension to accept the added battery weight. A very tiny, very light car won't have the suspension to accept the added battery weight. The ideal size is a Rabbit, Civic, Sentra, Escort, or something similar, or a light pick-up truck. Beware of cars, like the Fiero, that are actually much heavier than they look. Body style Look for accessible battery space. Hatchbacks are probably the best choice. Remember that batteries can be sunk into the body, as long as they are enclosed in proper racks. Don't cut through structural members and don't interfere with ground clearance. This means you can have batteries and a backseat, tooÄand even cargo space in the hatchback, on top of the battery box. For weight distribution, you will want to put some of the batteries under the hood. Look that area over with an eye for any protrusions into the engine bay, or a low profile nose that reduces vertical clearance. What about kit cars? Kit cars have the advantage of being very light, since the bodies are fiberglass. They also offer lots of opportunities for modification, since you have to build the car from scratch anyway. On the down side, they are expensive and time consuming to build, so you'd better really love the car. Some kits are very sporty, and don't have much battery room. Battery access is also crucial. Finally, be sure you're dealing with an established reputable kit car company that will still be there if you need them next year. Age The rule of thumb here is to look for a car that is less than ten years old, and the newer the better. There are many reasons for this. Newer cars obviously offer better crash protection and aerodynamics, since much progress has been made in these areas in the past decade. Finally, availability of parts is poorer after ten years, and drops significantly after fifteen years for many cars. Condition The ideal donor car has a good body and interior, sound transmission, but a dead engine. For these reasons, the diesel VW Rabbit is an excellent choice. Watch the classified ads for ones that say "Good body, needs engine". Also, talk to independent garages that specialize in the kind of car you want , or local junkyards, and tell them to watch for a good candidate for you. Specialty mechanics may be able to recommend a model of a car with a tendency to blow engines. If you get a donor that runs, you can recoup some of your investment by selling the engine. This is easier to do while it's still in the car and running. Be sure the buyer knows that you will be keeping some of the the parts, such as the clutch and flywheel assembly. Make & Model In general terms, it is harder to find a suitable American donor than it is to find a foreign one. This is because American manufacturers have only recently become interested in producing small aerodynamic cars. They are often American in name more more than content. Japanese cars seem especially suitable. Stay away from orphan makes and models. Yes, Aunt Tilly will give you her old Nash for free, or your brother-in-law will give you his Yugo, but where will you find brake cylinders when you need them? Stick to a manufacturer that has a good dealer presence in your area, and a model that was very popular and heavily produced. If there are a lot of them still on the roads, someone will be selling parts for them, and there will be used parts available in the boneyards. Transmission & Drive Axle Conversions can be front wheel drive or rear wheel drive. Having the engine and the driving wheels at the same end of the car makes packaging easier, but isn't essential. Four wheel drive is not a practical option at this time. Automatic transmissions are also not realistic. For one thing, there are energy losses that an electric car can ill afford. For another, an automatic transmission depends on a continuously idling motor to provide fluid pressure. Without it, there is a serious lag in acceleration from a full stop. If you cause the electric motor to idle like a gas engine, you are wasting energy and defeating its efficiency. Adding a separate fluid pump adds one more component and level of complexity to the system. Finally, electric motors have a different torque profile and want shift points that are different from those of a combustion engine. Options In general, a "Sally Rand" (stripper) version of a car is preferable to the luxury version. Air conditioning eats almost as much horsepower as it takes to move the car down the road. Power steering is another energy-eater. Also, if the car really needs power steering, perhaps you should look at the curb weight again. Luxury models usually have more sound deadening material, which is unnecessary in an electric. Power brakes, on the other hand, are easily accommodated with a vacuum pump, and highly recommended, due to the added weight of the batteries. Power windows and stereos don't use enough energy to hurt anything. Enjoy. The right stuff There are three parts to a good electric vehicle: a good chassis, the right components, and a well-designed and carefully executed installation. Just because a particular car is readily available or cheap does not mean it's suitable, and a poor chassis will give you a poor EV. Making the right choice at the beginning will give you a good start toward getting your electric dream machine out of your fantasies and onto the road. Access Author: Shari Prange, Electro Automotive, POB 1113, Felton, CA 95018 ù (408) 429-1989