the car is an 87 XT Turbo, intercooled and running about 14.5psi out of a legacy turbocharger...

 

on full boost im getting pretty consistent ping at about 14psi but im using 93 at the pump and nothing less. yes, the car runs rich and the plugs in it now are soaked with gas...

 

the timing is already retarded 12 degrees to compensate for the increase in boost, any idea what i should gap the plugs at? should i go less then stock or stay at OEM reccomendation?

It may benefit from a colder plug. I see a lot of guys coming into the store(NAPA) that run a colder plug in their supercharged cars, mostly mustangs.

It may benefit from a colder plug. I see a lot of guys coming into the store(NAPA) that run a colder plug in their supercharged cars, mostly mustangs.

colder plugs will help with the pre-ignition but will burn cooler and foul more easily, I believe. They shed more heat to the bock by having a shorter ceramic insulator.

 

I would not go very far off factory gap as I have heard of spark blow out at higher boost levels.

 

Are you running an aftermarket ignition system?

I can't remember if Brian ever got the MSD system to function properly.

 

If so -

Does your car still retain the anti knock circuitry with this ignition system you are running?

nope, no MSD

 

thats probably one thing on this car that hinders performance more than anything. when you check the spark its yellowish instead of glowing blue...if one were to put a 6AL unit on it, you could probably hear the plugs sparking from across the garage, brian did say he had one on it.

 

id love to be able to come up with one to put on the car but i dont know how it would react (i.e. anti knock as you say)

 

so stay close to stock? over or under?

bump, 53 views and 2 replys?

if i remember right a colder plug is called colder because it will dissipate its heat to the head, wheras a hot plug will not.

 

its has to do with heat conductivity, not the spark...... otherwise a plug that is not of the "cold" variety may act as a 'hot spot' for preignition.

 

what is your gap at now? you would want to stay oe spec if you have no ignition mods, but if you got the coil and all that you could go up to .050

 

would your timing need to be advanced, rather than retarded?

 

if you retard the ignition it will make the motor lug, and advancing will make it idle up........

what your going to want to do is put less gap in the plug. The higher pressure in the cylinder, the harder it for a spark to form, this will cause problems. If your running twice or more boost you'll prolly want to drop about 3 thousandths off the gap, so instead like .043 your gonna want to run .040 That should helps things out a bit.