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I ordered those DENSO IXU27 plugs from sparkplugs.co.uk and they arrived yesterday and I was going to fit them tonight...

...I remembered when I ordered them I thought "how many cylinders do I have... 2... so that'll be two spark plugs then."...

...oh how wrong I was!

Second order sent, maybe I'll fit them the weekend instead

So why two plugs per cylinder? Surely one spark is enough??!

Why 2? Dunno, possibly emissions(?)

Because it just does ok!!

And if one of em fails you'll still get home on the remaining three.

Some say, the Falco has a V4 engine

rick wrote:So why two plugs per cylinder?

Something to do with more efficient burn

Because there's two plug holes in each head. Simple.

to be better than the boys from bologna

FlyingKiwi wrote:

rick wrote:So why two plugs per cylinder?

Something to do with more efficient burn

You're correct. The combustion chamber will be huge compared to the same displacement in an in-line 4 arrangement. One spark will ignite the fuel/air mix, but some will remain unburned or burn after it's most effective. Twin plugs give the fuel/air mix a better chance to fully combust at the right moment giving you more oomph.. it's not just a gimmick.

It has to have 4 so that the front one can be in a position to make replacement awkward and allow its well to fill up with crap that falls into the chamber when you take it out. Then it's too hard to tighten so it gets left loose then drops out causing all sorts of interesting noises!

So Willop..., how come the newer engines are single sparks?

better combustion chamber design .... twin plug heads help the combustion but better designed combustion chambers don't need twin plugs

A simple thing like inlet design on later engines can negate the need for twin plugs as they have better swirl inducing properties, meaning the fuel mixes better, ergo burns better. Link that to better volumetric efficiency and youre onto a winner.

Sparkplug design seems to get better by the year too, the same effect can be achieved from a well selected design of sparkplug as can from having two sparkplugs of a more standard nature.

lol..or in less words, wot DR said.. ffs should have read the bloody thread

Kwackerz wrote:lol..or in less words, wot DR said.. ffs should have read the bloody thread

+1

They only need one/pot snce Andy invented the iridium plug.