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Platinum vs. Copper NGK spark plugs

by Dan Thompson

For lots more info on NGK spark plugs, check out NGKs FAQs.

> I have heard that platinum plugs aren't very good for is this so?

All things being equal, a more powerful spark will create higher cylinder pressure which will create more power. The power of a spark is determined by its voltage (more voltage = more powerful spark).

Aside from variables such as cylinder pressure and A/F ratio, the amount of voltage required to jump across the gap of a given type of spark plug is determined by the plug gap. A smaller plug gap requires less voltage to jump across the gap and a larger plug gap requires more voltage to jump across the gap.

There is a way to reduce the amount of voltage required to jump across the gap of a plug. By increasing the number of sharp edges that the spark can jump from and to (as in SplitFire and Torquemaster plugs) or by using an electrode material that is a more efficient conductor than the standard steel material (like platinum) you can decrease the amount of voltage required to "jump the gap". The only problem is that these "specialty" plugs will produce a less powerful spark than a standard plug will at the same gap. This means that, as long as your ignition system can provide enough voltage to jump the gap on the spark plug all of the time, with these "specialty" plugs installed in your car your engine will produce less power than it will with standard spark plugs. The only way you can regain the power lost with these "specialty" plugs is to open their gap out farther (a wider gap requires more voltage to jump the gap).

I've seen a number of cases where people have installed SplitFire, Torquemaster or platinum plugs in their car in the place of standard spark plugs and have complained of reduced power. In all of these cases the specialty plugs were installed using the plug gap specified for the car's original standard plugs (with the exception of the Torquemaster, whose gap is not adjustable). The reduced spark power due to the reduced voltage requirement of these plugs was the culprit.

Nissan DID address this problem by specifying a larger plug gap when using platinum plugs (0.039" to 0.044") instead of standard plugs (0.032" to 0.035"). In this case, the platinums will produce roughly the same spark energy as the standard plugs while providing an extended service interval (50K to 60K miles for platinums versus 20K to 30K miles for standards).

> I was also wondering if there is any way to gap a platinum plug without messin it up...

Gap them as you would a standard plug.

> has anyone ever tried the regular NGK plug in their car?

I'm running them right now. No problems yet.

It's just a question of spending $1 to $2 per plug (for standards) and replacing every 20K to 30K miles or spending $3 and up per plug (for platinums) and replacing every 50K to 60K miles.

Platinum should be gapped at 0.039in to 0.044in and Copper at 0.031in and 0.035in.