TOPIC: Gapping Spark Plugs

Hi Ron,

Can you reccomend the optimum gap increase for my 2003 Volvo XC90 2.5 gas turbo?

Thank you./b]

I've just been informed by my mechanic that gapping Sparkplugs in turbo engines is actually a bad thing.

Appreciate any feedback, thank you.

the rule of thumb (as I understand it) is as you increase boost, decrease gap.
I'm tempted to agree with your mechanic
think about what all is happening in any engine when it's running, and then extend that out to include a turbo.
when we adjust the gap on a naturally aspirated engine, we're essentially adjusting engine timing - how long it takes a spark to jump the gap. add in a whole bunch of induction complexities and you might mess some (expensive) things up if you take them too far in the wrong direction...if it keeps running at all, which is another issue entirely, right?
If I have my information correct, you've installed a grooved TB on this engine. what are your results so far? where else in the induction system could you place a groove for the benefits - the turbo intake? the turbo outlet? intercooler outlet?

No, I have not yet had the Groove installed, I simply was investigating the gap thing, which I won't be doing now./b]

Simon,

Whatever you decide to do (or NOT to do) is always your choice.

I will tell you that most mechanics never consider doing anything other than what the manufacturer recommends. As you already know, it's not always the best for US.

One day, you will try it. Then you'll see.

BTW, what reason did he give that it was a BAD 6thing to have more power to your spark tip?

Ron