Debunking multi-electrode spark plugs

[B-Man]

Are Spark Plugs with Extra Posts Worth the Money? | Enduring Automotive

[GTOJOE]

I thought the whole point of those was simply that they lasted longer?

[Keyan]

fun fact: some toyota motors come with dual post spark plugs STOCK, and don't run right if you put single post in.


your article in invalid, especially when he says "there are twice as many posts to burn through"...well, you realize it is the center tip that wears, not the fingers? And there is only one center tip


the point being, install what the manufacturer recommends. they design the car that way for a reason.

[MeTarzan]

your article in invalid, especially when he says "there are twice as many posts to burn through"...well, you realize it is the center tip that wears, not the fingers? And there is only one center tip

You realize the Iridium in the center will wear MUCH less compared to the outside posts

[Chris@Rvengeperformance]

fun fact: some toyota motors come with dual post spark plugs STOCK, and don't run right if you put single post in.


your article in invalid, especially when he says "there are twice as many posts to burn through"...well, you realize it is the center tip that wears, not the fingers? And there is only one center tip


the point being, install what the manufacturer recommends. they design the car that way for a reason.

the ground straps absolutely wear.

The great thing about multi post spark plugs is they have plenty of pieces to get nice and hot to cause detonation.

[anyonebutme]

A lot of misinformation here.

1. spark in free air doesn't test anything

2. the point of multiple ground straps is not to "split" the spark

3. A lot of manufacturers use multiple ground strap plugs stock, as do ALL aircraft. Some absolutely require them.

4. Ground straps will not cause detonation unless something is SERIOUSLY wrong with your car, the edge of the exhaust valve is where most detonation originates from.

5. The center electrode is where most wear can occur, which is why polarity is important. Some systems alternate polarity.

6. Multiple electrode plugs are a class of surface gap plug. Someone who doesn't understand the principals of those will easily confuse the point of multiple electrodes.

7. Because of 6, I can totally see why the carbon fouling issue wasn't talked about.

[Chris@Rvengeperformance]

A lot of misinformation here.

1. spark in free air doesn't test anything

2. the point of multiple ground straps is not to "split" the spark

3. A lot of manufacturers use multiple ground strap plugs stock, as do ALL aircraft. Some absolutely require them.

4. Ground straps will not cause detonation unless something is SERIOUSLY wrong with your car, the edge of the exhaust valve is where most detonation originates from.

5. The center electrode is where most wear can occur, which is why polarity is important. Some systems alternate polarity.

6. Multiple electrode plugs are a class of surface gap plug. Someone who doesn't understand the principals of those will easily confuse the point of multiple electrodes.

7. Because of 6, I can totally see why the carbon fouling issue wasn't talked about.

Then why does anyone switch to a non projected tip plug or a surface type plug to avoid detonation? I have completed melted the ground strap on a plug before and the engine survived just fine. (stock tune, 14 PSI, lots of extended 4th and 5th gear high speed pulls)

You can't say that plug wasn't glowing red hot.

Every really old plug I've seen (like ones in a car for 100+ k) had an equal amount of wear on the ground strap and electrode. Some platinum type plugs had virtually no electrode wear, but the gap opened to like 70 thousands from ground strap wear. You could see half of the strap worn away.

[anyonebutme]

Ever consider the possibility that melting the strap saved the engine? Just because the weaker strap melted doesn't mean it was the only hot thing in the chamber.

People switch to non projected tip and surface gap plugs so the can run a hotter plug than normally possible so its not fouling all the time.

Single plats wear like that because only the center electrode has plat on it.

Any case none of this has to do with multiple ground plugs. When the mix is hard to light as in aircraft or other stratified or lean burn engines, you'll usually find a multiple strap plug.

[Chris@Rvengeperformance]

Ever consider the possibility that melting the strap saved the engine? Just because the weaker strap melted doesn't mean it was the only hot thing in the chamber.

People switch to non projected tip and surface gap plugs so the can run a hotter plug than normally possible so its not fouling all the time.

Single plats wear like that because only the center electrode has plat on it.

Any case none of this has to do with multiple ground plugs. When the mix is hard to light as in aircraft or other stratified or lean burn engines, you'll usually find a multiple strap plug.

exactly. I'm glad there was only one strap to melt, if there were more there would've been a greater chance that cylinder continued to have active combustion and melted the piston.

[DocWalt]

Early Mk2 GTIs came with triple ground strap plugs from the factory. They switched to single ground strap plugs in the later Mk2 GTIs like mine. VW then switched back to the triple ground strap plugs and they still use them. Meh.