Sorta Poll : what plug gap are all you turbo guys running?

[zdriffter]

Ok I Have 240z L28et Im Running Regular Ngk's From Autozone Gaped @ .44 What They Recommend On Their Specifications...... Could That Be The Reason Why My Car Does Not Run Like It Should (rough Idle, Theres A Misfire At Iddle Sometimes @ Boost, Rpm Needles Jumps Around Sometimes??) Everything On My Z Is Stock L28et Swap. What Plugs Should I Go With And At What Gap Should I Set Them At ??? Thanks Guys

[akeizm]

I'm running NGK's at a gap of .026" (Running at 6psi, using msns-e, i/c, gt turbo, 440cc injectors, walbro 255 pump) And they will most probably be smaller after today. Its being tuned at the shop for 15psi.

 

That gap is too large zdriffter. I used to run .040" gap like a manual told me for solid spark but that gap was WAY to big. So that will be a pretty good reason for your problems. Just gap them to around what other people have them at (like the examples in your thread).

[Guest bastaad525]

Ok I Have 240z L28et Im Running Regular Ngk's From Autozone Gaped @ .44 What They Recommend On Their Specifications...... Could That Be The Reason Why My Car Does Not Run Like It Should (rough Idle, Theres A Misfire At Iddle Sometimes @ Boost, Rpm Needles Jumps Around Sometimes??) Everything On My Z Is Stock L28et Swap. What Plugs Should I Go With And At What Gap Should I Set Them At ??? Thanks Guys

 

 

zdriffter - my turbo swap has ALWAYS run that way as well. I've tried all kinds of different things to get rid of it... I've always had a slight misfire at idle and it's felt a little lumpy.

 

I've tried different plugs, different gaps, upgrading all of my ignition components (wires, msd unit, msd coil), replacing everything else (cap and rotor)... nothing ever got rid of it, finally i've just accepted it.

 

Funny thing, I just bought a brand new Dodge SRT-4... it idles EXACTLY the same as my Z!!! This is a brand new car doing that!! a little popping at idle and you can feel it loping. So... that kinda make me feel like okay this must not be such a bad thing

 

My Z runs great though and doesn't misfire under load, only at idle or revved in neutral. I had some high rpm/high boost misfire as well but that was because I had my plugs gapped way too wide at .050, thought I could get away with that with the MSD... gapped it down to .035 and never done it since, though again, it had NO effect on my idle misfiring.

[dapiper]

NGKBP8ES gapped at 0.035".

 

L28 N42 at 20 psi, 435rwhp, intercooled, 100 octane unleaded, 18° initial, 35° total, retarded to 28° with MSD 6T, MSD helicoil wires, RC550's, analog ECU with hotwire mass air sensor. Cam is old Racer Brown turbo grind 226/246° at 0.050" lift. Arias, O-ring block 8:1 CR. Total seal second ring. Turbo is Turbonetics H3. Exhaust is 3" with Dynomax oval. Much chamber work with 3.5 cc removed to unshroud valves and polished. A/F estimated in 10's at boost.

 

New engine same, except added Swaintech coatings on piston domes and skirts. Not on dyno yet, since still breaking in at 12 psi on 93 octane. A/F in high 11's at boost.

 

Noticed poor idle since rebuild with RC inj, suspect pencil thin spray pattern prone to fouling. Will experiment with gap and report results.

 

Anyone called plug mfr for info on trends for gap vs A/F, CR and boost parameters?