Q: I bought a used 1993 Dodge Shadow, and it had no rear defroster. I purchased an aftermarket defroster, but a mechanic advised me not to put it on, because it would cause problems with the alternator and voltage regulator. Another person said to just put it on. I'm confused. -- E.W., Shamokin, Pa.
A: There are many situations that come into play when installing an aftermarket defroster, which demands a lot more from a charging system than, say, an AM-FM cassette player. Included in the variables are the size and amperage output of the alternator, and the size of your car's battery.
However, although your aftermarket unit may well work with your present setup, it would be sound practice to have a mechanic check the alternator and battery size for proper operation. If the defroster unit is a good one, the manufacturer should have taken all of this into consideration. It's tricky, but certainly doable.
Driving alert, aware, calm and in anticipation of mistakes can turn you from a so-so driver into a great driver. If you learn to anticipate, you can learn to save your life when the time comes.
Here's an example: While rounding a curve on a country road, a truck traveling in the opposite direction starts heading directly for you. You make one of two decisions. Hit the brakes, or try to drive your car out of the situation.
Many drivers would panic and hit the brakes, going head-on into the truck. Teach yourself not to hit the brakes by anticipating a problem before it happens. Learn to rehearse in your mind "what if," and you have a good chance of making the correct evasive maneuver. If we had mentally rehearsed in the example above, i.e., "What if a car comes around the corner in my lane," then you would drive the car into an open area and miss the offender.
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Q: Greg, am I hurting my car by running 93 octane fuel in an engine that calls for 87? Racers use octane ratings way over 100, so would these unleaded racing fuels be OK, too? -- Bob P., Shamokin, Pa.
A: Bob, running the 93 probably won't hurt, but the high-octane racing fuels burn differently and aren't recommended.
Octane is the measure of a fuel's ability to resist engine detonation. Detonation, usually heard as a "ping" in the engine, is an unwanted mini-explosion within the combustion chamber after the spark ignites, usually due to glowing deposits or advanced spark-plug timing. The condition, which can also result from using too low an octane fuel, can do damage.
Octane, however, is not the only part of the fuel composition that is important. With racing fuels, selection is based on the boiling range of the fuel rather than the octane rating. The higher the boiling temperature of a fuel, the more heat is needed from the engine to vaporize it.
When you run engines at very high RPM and have the wrong fuel in the tank, the fuel comes in, goes through the intake manifold very quickly and does not absorb enough heat. Therefore, you don't want to run a high-boiling-point fuel in high RPM applications. If you do, the fuel will go into the combustion chamber in liquid form. A gasoline that is liquid does not ignite, reducing proper combustion and lowering horsepower.
You should use the octane rating recommended by the car manufacturer. However, some cars do run better on an 89 octane fuel than a recommended 87, so keep your ears tuned for that "ping" with lower octane fuels.
Write to Greg Zyla in care of King Features Weekly Service, P.O. Box 536475, Orlando, FL 32853-6475
(c) 2003 King Features Synd.
