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Keying spark plugs

  Megane 2 GT 165
Wandering through some threads here on I found a thread about exhaust heat wrap in which this link was given.

On that particular site there is also an item written about keying your spark plugs.

In general it is positioning your spark plug towards the inlet side of the gas chamber inside your engine. Which would result in a better ignition of the mixture.


As you can see in the picture the grounding strap (the thingy that is bend) blocks the spark. This makes clear why you should not want to use those spark plugs with 4 of those grounding straps.

Anyway, has anybody tried this? I still need to change my spark plugs and wonder if anyone have any experience with this...
  172 cup
if it didnt work well, why would renault use it? bearing in mind renault being a manufacture thats spent hundreds of thousands trying and testing new methods
  Megane 2 GT 165
Sorry I might did not explain myself clear.

The picture is a spark-plug giving a spark. The yellow / orange color is the ignition or spark itself. The dark part behind the grounding spark (shadow of the spark), actually shows that the spark does not (or less) reach that spot.

@ Riley:

I do not really understand what you are stating, but the spark plugs might already be facing the inlet side of the cilinder chamber.
If you are talking about the spark plug I'm using the one that is prescribed by renault. I was trying to mention that the spark plugs with four grounding straps (four point??) might obstruct the spark even more.
Meaning spark plugs like these.
  vers le haut doigt milieu
keying is good if you use shite plugs, I posted the link to the car bibles site. It just basically exposing the metal to aid conductivity. Decent plugs don't need such treatment. You will also notice the plugs in your 172 will have 3 prongs rather then just one so positioning it is not an issue.
  Megane 2 GT 165
NGK PFR6E-10 I believe have only 1 prong (is that how you call it? sorry i'm dutch). I think these are the plugs that are advised by renault?

But anyway if keying spark plugs is only worth doing with bad spark plug I might not try at all.
  PH1 172 Sport
NGK PFR6E-10 are the ones renault recommend the prong as we are refferring too is actually the ground electrode on the plug.

The theory for keying sparks plugs is sound but the way an engine works the air fuel mixture get drwan into the comustion chamber on a down stroke and then is compressed on the up stoke this compression will ensure that the chamber is full of an air fuel mixture before it is ignited by the spark plug which IMO makes it aload of old rubbish!