Spark Plug GAP

[duffner]

Well I've read all the posts on plugs, wires, air filters, etc.... and finally changed my plugs and wires; YES, big difference; hesitation/popping is gone until full throttle. Used Iridium plugs and a high performance wireset 8.5 low resistance.

Question - I gapped them at .040 and noticed a difference in power but still some delay(nail gas, no chugging but would expect quicker throttle reponse) So WHAT TO GAP?? What are the Pros/Cons for gapping between say .030 and .050.

Thanks - Duff.

[hharper1321]

Consensus on iridium gap for PT Turbo (don't know what you are) is .028. The .040 gap is for copper plugs, ie NGK 4306, Champions, etc.

[CREWZIN]

Most of us with the Non-turbo noticed an improvement in throttle response as soon as we changed to a free-flow air filter system. I would expect the same response with the Turbo.

Two ways of freeing up the air intake. One with a K&N or any better filter in the stock system with certain "O" rings removed and a larger pipe into the hole in the fender where the cool air is. The other is a whole new air filter system like K&N, Volant or Air-Aide system, just to name a few.

[littleblueGT]

After a lot of testing with the iridium plugs I found a "sweet" spot from .045 to .047 with my 03 GT.In that range the idle was good and the performance to red line was great. Over that range there was spark blow out in the upper RPM range, and below that the performance seemed to drop off, but the idle was still good.

[duffner]

I still LittleBlueGT nailed it. If the factory gap on iridiums is about .050-.055 and it was reduce to .045ish, that sounds reasonable. Why would you want to gap near .030 though? Sounds too aggressive...

LittleBlueGT - did you do anything with the air filter box?

Thanks.

[hharper1321]

Originally Posted by duffner

Why would you want to gap near .030 though? Sounds too aggressive...

Thanks.

Because at high boost you can experience spark blow out. I forgot, no one here plays with boost....

[duffner]

Hi Boost? Is that high throttle?

[Mean Green]

Originally Posted by duffner

Hi Boost? Is that high throttle?

No, it's not the same. Some of us are running higher boost with performance mods that are significantly higher than stock which spikes to only 13 psi.

[littleblueGT]

The trick with spark plug gap is to run as large a gap that you can without blow out or missing. Not only will too small a gap adversly affect performance, but gas mileage will also suffer.
As to the question concerning my air box, I just use a K&N drop in, and I cut the snorkel short on the lower half. I did leave the white sound damper in the top section as I put a force gel pack inside of it.

[duffner]

I would also think a smaller gap will create an angle between the tip and L-metal end, and it's not designed to be very efficient that way. Doing the .045-.047 should impact that angle too much, but .030.....WOW!!!

And the last thing I need is worse mileage. It already sucks (25mpg for a 4 cylinder is pathetic)...

What is a gel pack? Sounds like dry ice...