I haven't seen anyone post about spark plug indexing on here. Just wondering if anyone, probably tuners mostly, have noted any gains from indexing the spark plugs.

For those that don't know, this practice is facing the opening were the electrode and tip meet towards the intake, providing a clearer path the the air fuel mixture.

That being said I understand the the fuel isn't mixed in the intake but the injectors do point in the same direction as the intake. we know this works for marginal gains, but gains none the less in pfi applications, so I was just wondering about Di applications, thanks!

 

I would like to know this as well. Id Place a mark on the ratchet extension for easy reference to where the plug is at. Summit sells indexing washers.

 

Theoretically, the mixture is so fine and well dispersed, and the bowl it sprays into in the piston is shaped around the plug, any gains you get should be almost too small to measure. The whole point of DI is more efficient combustion, so the other methods we used to get maxed efficiency are all diminished slightly.

Try some back to back dyno pulls and see what happens, i'd bet there would be no measurable difference on an LNF.

 

ive never really seen plug indexing to be really worth it

 

Same thing my dad has told me and he has been doing Chevy small blocks for decades. Might be worth it if you are trying to squeeze each and every little 1/4hp out of it.