Eye on electronics

Motor,  May 2003  by Dale, Mike

• E-mail
• Print
• Link

Innovation continues to foster new automotive products. It's up to you to decide whether these products offer solid value for your customers.

Recently my friend Carl brought to work a new catalog of high-performance parts and accessories he had received in the mail. In addition to performance chips, fiberglass spoilers and the like, there were other items that caught my eye-three in particular: One was yet another new kind of spark plug, another claimed to clean engine oil magnetically and the third was a new kind of car battery.

Before looking into these claims to see what the true added value really is, it's worth noting at least some of the reasons behind these kinds of products. A good place to start is with the first item, the lowly spark plug. It's widely known that for years spark plug manufacturers have sold their plugs to the OEMs for as little as 12 cents each so their brand would be on the OE installation. They do this because they know that when it comes time to change the plugs, the owner is likely to replace them with the same brand. Selling spark plugs at cost is no bargain unless you'll later be selling replacements at $1.69 each.

This tradition of low margins pervades the automobile parts business. The story is much the same for tires, filters, batteries and the like. The problem is that the wheels have come off the bus for this particular business model. We've all seen vehicles with over 100,000 miles on the odometer still firing the original set of spark plugs. This greatly improved life expectancy and reliability is great for the consumer, but not so great for those manufacturers who depend on aftermarket sales for big profits.

One way to get around this is to convince automotive enthusiasts that a so-called performance part is really so much better than the existing part. But it takes fabulous amounts of money to tool up genuinely different parts. New designs have to be built and tested, new tools and dies have to fashioned and even new assembly lines and fixtures may have to be created.

The solution is to make a part that looks different or maybe even is slightly different, but that can be assembled and built using existing machinery. The Split Fire spark plug of a few years ago is a perfect example. Here's a spark plug that's the same as an ordinary one except the ground electrode has been split to form a V. Because it looked different, and because it seemed to be "better," people were willing to pay $5 and more for each one-clearly a much better business model than selling millions of spark plugs and not making a dime on any of 'em.

This is not to say that there's no merit to any of these products. Denso's new spark plug is a good example. These plugs have a fine-wire center electrode made of a very high-temperature melting point material called iridium. The center electrode is .4mm (.016 inch) in diameter. The ground electrode is tapered and has a U-shaped groove on the underside. The groove gives extra space for the flame kernel to form, while the taper reduces the likelihood that the ground electrode will quench the developing flame kernel.

Denso displayed its spark plug at the recent SAE show in Detroit. To its credit, Denso was willing to put hard scientific data and graphs on the walls of its display booth. When someone tries to sell you on the value of an oil additive or whatever on the basis of testimonials from "truck driver Bob," be suspicious. Facts that can be documented are always a good sign of honest or valid claims.

Denso claimed its fine-wire iridium plugs reduced the kilovolt demand from the coil by 3000 to 4000 volts. This should result in better durability for the coil and greater reserve voltage for those situations where ignition is difficult due to cold temperatures, very high swirl or heavy-load conditions.

Denso's other point was that the fine-wire plugs reduced the likelihood of misfires at idle. They showed graphs demonstrating a 2.5% fuel economy improvement at idle. One showed that on a 1600cc, four-valve, 4-cylinder engine, fuel consumption was reduced from .55 to .53 liter per hour.

As you know, the volumetric efficiency of an engine (its ability to pull a fresh charge of fuel and air into the cylinder) is not very good at idle. Due to valve overlap and the inertia of the air/fuel mixture as it starts to enter the cylinder, the cylinder fill is often incomplete and may be contaminated with exhaust gases. The fine-wire plug is able to generate more intense electrostatic forces because of its shape, which helps it do a better job of firing through the dirty mixture.

Even if the 2.5% fuel economy improvement at idle doesn't knock your socks off, it's an interesting number from another standpoint. The reason there aren't any 200-mpg carburetors out there is that not that much fuel is wasted in the first place. By law, misfires in excess of 1% have to be detected and must illuminate a warning light. There's plenty of energy lost in an internal combustion engine (primarily heat lost to the cooling system and the exhaust), but it's not because of misfires.