View Single Post
DonE DonE is offline
Wo ist die Rennstrecke?
DonE's Avatar
Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
In a wasted spark ignition system, a resistor plug and wires are used because one plug fires on the compression stroke and the opposite plug fires on the exhaust stroke (hence the name, wasted spark). The higher the compression in the chamber, the more power is required to fire a plug. If a coil is firing two plugs, all the energy will find its way down the path of least resistance - the plug on the exhaust stroke (no power). In order to make each path equal, a resistor plug and resistor wires are used - in theory, there is no path of least resistance and each plug is fired with equal energy. At high rom and boost, your effective compression ratio could approach 12.0:1 - now add forced induction (swirling air in the chamber) with high compression, and you'll need a stout spark. The only way to accomplish this on wasted spark is a small gap on the plug. If you try to run a hotter plug to off-set the small gap, you'll invite detonation by creating a glow plug. By the way, I used to run Bosch DTCFR5 plugs with good results on my wasted spark.
Old 07-31-2009, 04:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)