tw2":xl14zysi said:
Someone posted up a short guide ages ago with boost level to show which range to get and always gap them at 0.31" or whatever is stock. I think it was something like- you want to use stock up to 14psi, go a step colder up to 22psi and something special over that.
I have NGK 7's at the moment on 13psi and I am pretty sure they are causing some hesitation down low especially when cold but I am waiting on new ignition leads to make sure. I will swap 6's back in to see what happens. I imagine since most people who run low to moderate boost still spend almost all their time off boost anyway 6's would be the way to go.
Are there any merits to going 0.28 instead of 0.31?
This shows a miss understanding of how the plug works. The spark energy remains the same as the coil remains the same. A hotter plug will not 'boost the spark'. The plug heat range is a measure of the plugs ability to move heat energy away from the electrode. A hotter plug will have a hotter electrode. The electrode must be above a given temperature to burn the combustion deposit off so not to foul.
You only need to go down in plug temperature if the eletrode shows signs of over heating. This is influanced by the temperature of combustion and not the boost level.
A wider plug gap gives a greater surface area for which to ignite the charge. The down side it is harder to fire electrons over a greater gap especially when the charge is more dense. A reduced plug gap will reduce peak VE miss fires.
The stock plug is BKR6EP8. i.e. 14mm thread, 5/8 hex, projected tip, resistor type, NGK heat range 6, Platnuim plug gaped to 0.8mm.
If you run a non presious metal plug you will have to run a smaller gap.
The BGB has both metric and imperial gaps. Not that it makes any difference.
Roger