This spring I installed some low mileage oem plugs gapped at .048. Felt like it lost a little kick. Im going to go back to the Iridium one step colder plugs. Any new opinions on the best gap? I have magnacore wires about 21 lbs boost and have not had any misfire issues. Thanks in advance.

 

I'd say .040 is the normal gap, .048 is like they are burnt .

 

I had great results with 1 step colder iridiums at .035 when I was running stacked. Any tighter than that and the car seemed to lose power. You're logging 21 PSI? Damn, I can't get this 61.9 pulley to hit 19 PSI without spray.

 

Yeah 21 in cool weather measured at the plenum runner, stock manifold. Correct me if I am wrong, I thought the largest gap possible before misfire was the best?

 

I'm sure it is, but the trial and error to find the sweet spot can be a huge PITA.

 

What spray?

Cant be the altitude....Maybe just the latitude....cooler meaning 40F in MN whereas cooler in TX means 70F.... Theres 0.4psi - but more importantly 29F on the IC inlet temp.

PS - calc suggests 61.9/155 should give 20.4 if everything was puurfect and the SC hadnt dropped eff. but of course it does.
Plus for 70F ambient - u r up at >220F into the IC - ouch HOT!! (stock = 170F)
Miles on SC?...wear/tear?...leaks?

Because changing Plugs is a PITA - All 12 of the knuckle busting buggers, what's good about this 0.48 is it might serve to challenge some thinking - good liuck!

 

When I run the nitrous it increases the boost by 2 or 2 1/2 psi.

 

Ok done. I went with .045 gap. Seems to run the same. It's 70 out and I only saw 18 psi at the top of 2nd gear I'm too afraid to really speed around here. I have datalogs of 21 psi but that was at the drag strip. Yes I think it was in the low 50s back then.

 

Thanks for posting your current peak boost number. I was starting to think I had an intercooler leak. I hit 17.7 today at the top of 2nd, so I'm in the ballpark.

I think the .035 plug gap I used on my old car may not be working well for John. I'm going to advise him to open them up to .045, since you're running fine with that gap and similar setup.

 

Cool yes no misfire codes. Seemed fine. I wish it made my car seem faster but it did not.

 

My setup is a 181 pulley, gasket matched runners, teflon y pipe, teflon snout , big *** single intake.

 

If I remember correctly, Rob at Needswings recommended .039 when I went one range colder, seems to be good.

 

Mine are at .035 Maybe I should open them up a bit.
FWIW, I hit (max) 20.5 psi w/ the 61.9mm and 19.5 psi w/ the 65mm. Of course, people running a free-flowing exhaust, downpipes, etc may see slightly less boost.