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[Taxi_Driver]

I've just noticed summat and wondering whats the difference?

According to 'The Book'

My 2.2 Omega and 1.8 Veccy 51 plate, both use the same plugs GM09
My 1.8 Veccy 03 plate uses GM32.

Ive manage to find out that GM09's are twin electrode and GM32's are quad electrode, any difference apart from that?
And I know I've shoved GM09's into the 03 plate Veccy.......would it be wise to swap them with GM32's or isnt it going make any difference?

And im now wondering as all the cars are lpg.....and need a good spark....wether to shove GM32's in all of them?? ..... I assume that quad plugs give a better spark  :-/

Cheers

[Marks DTM Calib]

Most of the later engines (i.e. 2.6 and 3.2 also) use the 4 electrode plugs....mainly to support a 80K mile service interval on the plugs (they work loose before this sometimes!)

Both types are interchangeable but......be aware that 4 electrode ones might actualy act to shield the spark and slow the flame front in the cylinder.

[Markjay]

As Mark pointed out , the quad electrode plug does not necessarily provide a better spark.

Only one electrode fires and any given point of time, and it is usually the one with the smallest gap from the centre electrode. When the firing side electrode then corrodes as result of usage and the gap increases, another side electrode will have the smallest gap and start firing. This way the wear is divided more or less equally between all electrodes, so a four electrode plug will last twice as long than a dual electrode one.

But this is all in theory – for the cost of Ł2 each it is sheer madness to leave the spark plugs in the engine for 80k/8y. I just changed mine at 40k/5y, and considering that in the older days it was a 5k/regap & 10k/replace job, I think that mine was well overdue!

GeffD did say that they were working their way loose even after being torqued-up properly at the factory, mine seemed solid enough though. But a loose plug can cause a misfire, and the cats don’t like that much… so not worth the risk.

[Markjay]

...Both types are interchangeable...

One more point –

Older two electrode engines can indeed be ‘upgraded’ to four electrode plus, though the advantage of doing so is not clear as Mark says.

As for the opposite - I don't have any specific information suggesting that the four electrode plug has anything to do with the new ECU-driven emission control system found on the later low-compression FBW 2.6 and 3.2 engines, but as a precaution I wouldn’t ‘downgrade' the spark plugs on an engine that has been specified with four electrode to a dual electrode plug.

[Taxi_Driver]

Thanks for the info guys  [smiley=thumbsup.gif]

Very interesting, MarkJay, explaining how the 2/4 electrode plugs worked, I didnt realise that!

I change mine every 10k.....vx recommend every 20k for dual fuels.....so using the general rule of thumb of 1/2ing what vx reckon, I dont think im far out.

Im still undecided wether to change the 2 electrode ones I bunged in the veccyC.....one hand it maybe advantageous, as Mark DTM says the 4 electrode ones may shield the spark, on the other hand vx spec it as 4 electrode type and MarkJay says he wouldnt 'downgrade' the plug  :-/

Perhaps i'll just leave them as they are  :-/

[Auto Addict]

Thanks for the info guys  [smiley=thumbsup.gif]

Very interesting, MarkJay, explaining how the 2/4 electrode plugs worked, I didnt realise that!

I change mine every 10k.....vx recommend every 20k for dual fuels.....so using the general rule of thumb of 1/2ing what vx reckon, I dont think im far out.

Im still undecided wether to change the 2 electrode ones I bunged in the veccyC.....one hand it maybe advantageous, as Mark DTM says the 4 electrode ones may shield the spark, on the other hand vx spec it as 4 electrode type and MarkJay says he wouldnt 'downgrade' the plug  :-/

Perhaps i'll just leave them as they are  :-/

Change the cam sensor on the Omega instead.

[Markjay]

Thanks for the info guys  [smiley=thumbsup.gif]

Very interesting, MarkJay, explaining how the 2/4 electrode plugs worked, I didnt realise that!

I change mine every 10k.....vx recommend every 20k for dual fuels.....so using the general rule of thumb of 1/2ing what vx reckon, I dont think im far out.

Im still undecided wether to change the 2 electrode ones I bunged in the veccyC.....one hand it maybe advantageous, as Mark DTM says the 4 electrode ones may shield the spark, on the other hand vx spec it as 4 electrode type and MarkJay says he wouldnt 'downgrade' the plug  :-/

Perhaps i'll just leave them as they are  :-/

Don't listen to me - when having to choose between my advice to Mark DTM's, I would take his every time... My knowledge comes from reading stuff on the Internet (and we all know that if it is on the 'net it must be true), Mark DTM's is a bit more well founded I suspect...

[Markjay]

From http://jobs.boschusa.com/AutoParts/SparkPlugs/PlatinumPlus4/ :

'Four ground electrodes provide multiple spark paths which allow the spark to travel the most efficient path and deliver a longer and more powerful spark than conventional single electrode spark plugs. This offers superior burn characteristics for ultimate engine performance.'

Well that's the official Bosch sales pitch anyway.

By the way, this is no new technolgy - my 1979 Alfa Romeo Alfetta was fitted with OE spark plugs Lodge 2HL which were unique in that they were... 4 electrode plugs. And that was standard on all Alfa Romeos... nearly 30 years ago.

[Markjay]

Also found on the net....

'One thing to keep in mind about all "performance" spark plug designs is that no plug can magically create horsepower out of thin air or add horsepower that wasn't there in the first place. But improved ignition reliability can minimize horsepower losses caused by misfires. That's why some plug manufacturers claim their spark plugs improve power. The gains come from power that was being lost to misfires.'

And that's from http://www.babcox.com/editorial/cm/cm120032.htm .

[Markjay]

Last one, I promise...:

'Increasing the number of side electrodes gives the spark more paths to ground and reduces the risk of misfire, while extending plug life by spreading wear over more electrode surfaces.'

http://www.aa1car.com/library/2004/us30428.htm

[Markjay]

OK, I lied:

http://www.miata.net/products/perform/boschplugs.html


The Mazda Miata is the American version of the MX-5.

[Taxi_Driver]

Thanks for the info guys  [smiley=thumbsup.gif]

Very interesting, MarkJay, explaining how the 2/4 electrode plugs worked, I didnt realise that!

I change mine every 10k.....vx recommend every 20k for dual fuels.....so using the general rule of thumb of 1/2ing what vx reckon, I dont think im far out.

Im still undecided wether to change the 2 electrode ones I bunged in the veccyC.....one hand it maybe advantageous, as Mark DTM says the 4 electrode ones may shield the spark, on the other hand vx spec it as 4 electrode type and MarkJay says he wouldnt 'downgrade' the plug  :-/

Perhaps i'll just leave them as they are  :-/

Change the cam sensor on the Omega instead.

Carnt ! Its been at vx dealer since sat lunchtime.....hopefully they will change it tomorrow  

[Taxi_Driver]

Last one, I promise...:

'Increasing the number of side electrodes gives the spark more paths to ground and reduces the risk of misfire, while extending plug life by spreading wear over more electrode surfaces.'

http://www.aa1car.com/library/2004/us30428.htm

Oh i do listen Mark, your input as with others is very helpful to me.....Thanks for your time looking up 'plug' websites......i think i will leave the 2 electrode ones in the veccy....as i change em every 10k i reckon i should be ok.....if it does start missing before the 10k is up.....i can always revert back to 4 electrode ones  

[Martin_1962]

I have heard somewhere that 4 electrode plugs are not great for LPG

I don't know what mine has!!!!