Disclaimer: this thread not meant for debates on whether there are any hp gains from spark plug indexing
When it comes to spark plug indexing I've heard 2 different "correct" ways to do it. Gap facing intake, and gap facing exhaust.
Traditionally, domestic guys and NASCAR race teams have indexed with gap toward intake valves. Justification was to promote equal flame front travel on both sides of the plug, more complete combustion, more power.
On N5x Enthusiasts I've heard the opposite, index with gap facing toward exhaust valve. Justification was to promote spark plug cooling under load and protect against spark blow out by putting the ground strap between the intake and electrode tip.
I'm about to install new spark plugs and will be indexing them. 6266, E85, high boost, port injection, NGK 2 step colder plugs, and R8 coils. Which way should I index my plugs and why?
When it comes to spark plug indexing I've heard 2 different "correct" ways to do it. Gap facing intake, and gap facing exhaust.
Traditionally, domestic guys and NASCAR race teams have indexed with gap toward intake valves. Justification was to promote equal flame front travel on both sides of the plug, more complete combustion, more power.
On N5x Enthusiasts I've heard the opposite, index with gap facing toward exhaust valve. Justification was to promote spark plug cooling under load and protect against spark blow out by putting the ground strap between the intake and electrode tip.
I'm about to install new spark plugs and will be indexing them. 6266, E85, high boost, port injection, NGK 2 step colder plugs, and R8 coils. Which way should I index my plugs and why?
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