Robert Bosch Corporation is introducing a new breed of premium spark plug called the "Platinum+4." The new long life plugs, which retail for around $6 each, have a unique four pole electrode design that eliminates wear, resists fouling and improves ignition performance over a wide range of operating conditions.
Surrounding the center electrode, which contains 75 percent more platinum than previous Bosch platinum plugs, are four "surface air gap" ground electrodes made of a special wear-resistant nickel yttrium alloy. The angle and position of the four electrodes creates multiple spark paths that cause the spark to jump sideways. This has a self-cleaning effect on the center electrode and results in a longer, more powerful spark that reduces misfires for improved engine performance, better fuel economy, lower emissions and faster acceleration.
Bosch tests have shown the new Platinum+4 plugs can improve fuel economy up to 4.8 percent over other competitive spark plugs. Fouling resistance is also said to be 33 percent better.
Though Bosch makes no specific mileage claims for their new Platinum+4 spark plugs, they do say the plugs will meet or exceed OEM requirements for 100,000 mile replacement intervals. Bosch says the plugs show almost no increase in firing voltage requirements after 100,000 miles of operation.
Another unique feature of the Platinum+4 is that the surface air gap between the center and four ground electrodes is factory present to 1.6 mm and is nonadjustable. So no attempt should be made to adjust or change the air gap when the plugs are installed — even if the air gap specification is different from that specified for a standard spark plug. The wider gap of the Platinum+4 is necessary to achieve the advantages above.
The new Bosch Platinum+4 plugs are available initially in 11 part numbers, which provide 89 percent market coverage on cars and light trucks back to 1983. Two additional numbers will be added in early 1999 to expand the coverage to 97 percent.
Bosch says that even though the demand for replacement spark plugs worldwide is decreasing due to longer plug life, the demand for premium replacement plugs is on the rise. Bosch estimates that premium plugs will account for 25 percent of all aftermarket sales by the year 2000.
Bosch first introduced "pure platinum" technology to the aftermarket in 1985, and remains the only aftermarket spark plug manufacturer with a pure platinum center electrode.