To Charge Or Not?

By Smokey Yunick

In responding to Paul Schalk ("Track Tech", September 1993) you advised, "When you use a battery-powered ignition of any kind, be damn sure you run an alternator and ground the distributor directly to the battery."

I race a Stock class limited inboard hydroplane without an alternator. I know of no inboard hydroplane racers who run alternators. We are all under the apparent misguided idea that we would lose horsepower. Please explain. Bill Walti, San Carlos, California.

There's no question that an alternator consumes some horse power. So for qualifying and/or short races, it would appear that if your battery is fully charged and can stay in the voltage required for a given ignition system, why run a charging system?

But my experience, both on the dyno and on the racetrack, indicates that there is a gain in power and speed when you have a charging system making 10 to 15 amps. OK, why? I can't explain it. I can only assume that at higher RPM and full power, most ignition systems appreciate current flowing into the battery at the same time as it is flowing out.

The same holds true with the ignition system ground. It is reasonable to assume that the distributor is grounded to the engine, if by nothing else than the hold-down bolt. In working with various ignition systems, ignition performance, and durability problems, I've found that a direct ground wire from the battery to the distributor is the best and most bulletproof plan. I can see it on the plugs after a qualifying run.

On engines with a good ignition ground and charging system, the plug's ground and center wires and shell face look a little shiny, but without the charging system, they are a flat dull color. In my mind, much remains to be uncovered in regard to exactly what happens and why, when the fuel charge is reacted by spark ignition in a reciprocating engine. I think the ignition (spark plug) may be the weak link in the ignition chain. We assume that every time a cylinder fires under a given condition, every firing produces the same amount of energy. I'm pretty sure now that's not true.

Taken from Circle Track & Racing Technology, October, 1995.

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