Multi ground spark plugs

[Quickstep192]

I saw an earlier post which showed a multi-ground spark plug (sometimes called multi-electrode)

I'm wondering if these have any benefit in older CDI cars?

[Quickstep192]

Like this one. Three sparks has got to be better than one, right?

[sixbanger]

I seem to remember something about those plus and using them in a 944. It wasn't good. But I don"t remember the details though.

[OldSpool87]

Ever try to gap one of those?

[911pcars]

Typically a marketing ploy to buy their not inexpensive plugs. How much? $6-$12 ea?

In actual practice, spark jumps to the electrode with the least resistance, and that’s usually just one.

However there are two or more other backup electrodes you paid for in case you need them. Those in the know also warn that the extra metal sitting there creates a shroud that could disturb the flame front. And yes, there’s an issue of setting the gap.

Unless you have a late model engine, a regular, recommended single electrode NGK or Bosch is all you need.

Sherwood

[Jeff Higgins]

Absolute garbage. I bought one set, many years ago, to run "better" in my "dirty" MFI motor. I didn't get a couple hundred miles on them before they fouled out. I parked the car and walked several miles to an auto parts store to buy simple, cheap, single electrode NGKs and drove merrily ever after.

[pmax]

Originally Posted by Quickstep192

Like this one. Three sparks has got to be better than one, right?

Some of the updated ignition units tout their multi spark features as an advantage. This appears similar.

What's the technical lowdown on this ? I tend to believe one sufficiently strong spark is enough.

[Jonny H]

Originally Posted by pmax

Some of the updated ignition units tout their multi spark features as an advantage. This appears similar.

What's the technical lowdown on this ? I tend to believe one sufficiently strong spark is enough.

No, not the same. Having multiple ground points just means the spark will scatter. Might look impressive but the spark energy is the same, just spread out.

Multispark (eg firing a spark more than once) is putting more spark energy into the cylinder. Has to be fast enough though to make more power.

[Fred Winterburn]

That picture is somewhat of a hoax. Long camera exposure time to make it appear as if all gaps are firing at the same time. Reality is that only one gap will fire for each spark event, so other than allowing the ground electrodes to last longer there is really no advantage. Fred

Originally Posted by Quickstep192

Like this one. Three sparks has got to be better than one, right?

[86 911 Targa]

Originally Posted by Jeff Higgins

Absolute garbage. I bought one set, many years ago, to run "better" in my "dirty" MFI motor. I didn't get a couple hundred miles on them before they fouled out. I parked the car and walked several miles to an auto parts store to buy simple, cheap, single electrode NGKs and drove merrily ever after.

Yup,


Used them for decades.

Gerry