Could removing the "gappers" from your spark plugs increase power and gas mileage?

Dear Car Talk

Dear Car Talk | Sep 01, 1995

Dear Tom and Ray:

I drive an old (about 20 years) Chevy which gets terrible gas mileage. Someone at work mentioned once that he had, as an experiment, removed the "gappers" from his spark plugs, and that by doing so, he had increased both the power and the gas mileage of his car. The explanation he offered is that, without a gapper, the spark had to find someplace to strike on the inside of the cylinder wall, resulting in a much larger and hotter spark which burned more of the fuel in the cylinder. Would this actually work?

RAY: I doubt it. If Champion, Bosch and all the other spark plug companies could make a better plug by leaving out one of the parts, don't you think they would have done it by now?

TOM: Here's the way a spark plug is supposed to work. You have electricity travelling through the middle of the spark plug. And this electricity's main purpose in life if to find "ground." When it gets to the tip of the plug, lo and behold, it sees ground in the form of the bent electrode (which you called the "gapper") just across the way. And it says to itself: "Self: I can make that leap." So it leaps across the little gap to get to "ground," and in the process, creates a spark, which burns the gasoline which runs your engine.

RAY: Now tell us the one about Goldilocks and the three bearings, uncle Tommy.

TOM: Here's the problem, Gary. If the electricity gets to the tip of the plug, and the nearest ground is three times as far away as it's supposed to be, the spark is much more likely to get blown out by the turbulence from the swirling gasses inside the combustion chamber. So you'd get poor combustion...if any.

RAY: So we don't think it would work. But who knows? There are lots of theories that sound completely wacko, but actually have some degree of truth to them. So we'd be glad to be proven wrong. If you can explain why removing the electrode would improve combustion, let us know.

TOM: But I suspect this is typical of the kind of advice we all get from co-workers, Gary. Which is exactly why they're co-workers of OURS, and not co-workers of automotive engineers in Detroit and Tokyo.

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