Plug Gap

[AutoX47]

Hey guys,

My car originally ran ~9.6 psi and ran .028" spark plug gap. When I upped the boost to 1.2 bar I changed the gap to around .023" per suggestion from other volvo owners. Do you think I need still to make the gap even smaller now that I will be installing WI this weekend?

Thank you,
Andrew Zizzo

[Charged Performance]

You shouldn't need to change the plug gap for the addition of water injection.

[perry190]

Is it normal to close the gap when going FI ?

I have recently added a Power Enterprise turbo conversion to my 2003 MR2 Roadster (NA) and changed the plugs to Celica 190 iridium plugs (one step colder) but nothing was mentioned with the kit reagrding gaps?

cheers :wink:

[Charged Performance]

Frequently when increasing boost or when adding FI to an NA engine the gaps are recommended to be tighter. Reference is usually to the idea of the spark being "blown out" like a candle or something. I don't exactly buy the explanation but the gapping method is pretty common.

As someone who used displacement and high compression for quite some time before going the FI route I usually reduced my gap as I would increase CR. I don't know all the technical reasons that it works but I suspect in higher compressions (whether high CR or FI) of air/fuel charges the spark is stronger or more consistent or something when the gap is tighter.

[perry190]

thanks matey, will get the garage to tighten them up a bit ;-)