Spark Plug Gap What & Why

MustGoFast · 01-12-2005, 04:08 PM

Well I started w/ a search and found a lot of recommendation w/ out reason and a lot of speculation w/ out support... Yes I've also read the big FAQ and while helpful doesn't really answer my ?

So I'm just going to ask.. I'm finally going out and grabbing some plugs 1 step colder for my stg4 wrx. I have found in the past that both Phil (elemental) and Nathan (txs) in the past have recommended the NGK PFR7G-11 for a quality plat plug. I have seen others say that this is over gapped for our use and I need the non -11 if so why is it such a trusted tuner would recommend this.

Further when I go to actually gap these plugs before install what should I shoot for .032 (high end of recoomendation) or .028 (low end of spec)... and what is the advanatage/disadvantage of a larger/smaller gap

In my knowledge the difference is the larger gap should allow for more power and complete burn w/ the risk of blow out .. and thus the recommendation is the highest gap your ignition system can drive w/ out this blow out.. does this mean I should attempt a gabp near .032 or even greater if I have never experienced blow out in the past?

Thanks for reading... Chuck

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MustGoFast · 01-12-2005, 05:59 PM

lots of views no thoughts?

MomoWRX · 01-12-2005, 06:07 PM

I just bought the BKR7E copper plugs and am looking for some of the same answers.

Unabomber · 01-12-2005, 08:06 PM

While I respect the opinions of those tuners, I asked the identical question to the folks at Cobb Tuning. When I get my tune there I will be using OEM plugs with ~50k miles on them. When asked about type/style/gap/heat range of plugs, I was told to not bother. :shrug:

Uncle Scotty · 01-12-2005, 09:18 PM

someone, hotrod I believe, posted a VERY concise answer to this question in one of the 'sparkplug' threads....I looked and can't seem to find the one....

BUT....

http://www.ngksparkplugs.com/techinf...200&country=US

"Q: What is the maximum I can open or close the gap?

A: NGK doesn't recommend adjusting the spark plug gap < or > .008". The reason for this is the ground electrode and center electrode won't line up properly, hindering spark plug performance."

....and THAT is why the '-11' is the WRONG plug for a turbo'd EJ engine.

Unabomber · 01-12-2005, 10:51 PM

Unabomber>Uncle Scotty at the search function.

hotrod's post

MomoWRX · 01-13-2005, 01:34 AM

Unabomber, uncle scotty, i am that much wiser after reading that post, i solute you

P.S. Unabomber i didn't read your entire Spark plug FAQ but if its not in there that post should have a reference or two from hotrod's post.

Unabomber · 01-13-2005, 06:49 AM

After re-reading his post yesterday, it's now linked in my FAQ.

MustGoFast · 01-13-2005, 04:19 PM

Yep found hotrod's thing to be exactly as I thought the wider the non problematic gap the better.....

Thank you all.

01-12-2005, 04:08 PM	#1
MustGoFast Scooby Specialist Member#: 33370 Join Date: Feb 2003 Location: Milwaukee, WI Vehicle: 2002 Impreza WRX Blue now w/ 6 fun flavors	Spark Plug Gap What & Why Well I started w/ a search and found a lot of recommendation w/ out reason and a lot of speculation w/ out support... Yes I've also read the big FAQ and while helpful doesn't really answer my ? So I'm just going to ask.. I'm finally going out and grabbing some plugs 1 step colder for my stg4 wrx. I have found in the past that both Phil (elemental) and Nathan (txs) in the past have recommended the NGK PFR7G-11 for a quality plat plug. I have seen others say that this is over gapped for our use and I need the non -11 if so why is it such a trusted tuner would recommend this. Further when I go to actually gap these plugs before install what should I shoot for .032 (high end of recoomendation) or .028 (low end of spec)... and what is the advanatage/disadvantage of a larger/smaller gap In my knowledge the difference is the larger gap should allow for more power and complete burn w/ the risk of blow out .. and thus the recommendation is the highest gap your ignition system can drive w/ out this blow out.. does this mean I should attempt a gabp near .032 or even greater if I have never experienced blow out in the past? Thanks for reading... Chuck * Registered users of the site do not see these ads. Last edited by MustGoFast; 01-12-2005 at 04:14 PM.

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01-12-2005, 05:59 PM	#2
MustGoFast Scooby Specialist Member#: 33370 Join Date: Feb 2003 Location: Milwaukee, WI Vehicle: 2002 Impreza WRX Blue now w/ 6 fun flavors	lots of views no thoughts?

01-12-2005, 06:07 PM	#3
MomoWRX Scooby Specialist Member#: 36823 Join Date: May 2003 Location: West Boca, FL/WPB at Northwood Vehicle: 03 MBP WRX Sold :( 93.5 Single Supra :)	I just bought the BKR7E copper plugs and am looking for some of the same answers.

01-12-2005, 08:06 PM	#4
Unabomber Big Ron Moderator Member#: 18062 Join Date: Apr 2002 Chapter/Region: MAIC Location: I can save you a ton of cash Vehicle: on car parts so PM me b4 j00 buy	While I respect the opinions of those tuners, I asked the identical question to the folks at Cobb Tuning. When I get my tune there I will be using OEM plugs with ~50k miles on them. When asked about type/style/gap/heat range of plugs, I was told to not bother. :shrug:

01-12-2005, 09:18 PM	#5
Uncle Scotty NASIOC Supporter Member#: 16200 Join Date: Mar 2002 Vehicle: OK Houston we have an Uncle	someone, hotrod I believe, posted a VERY concise answer to this question in one of the 'sparkplug' threads....I looked and can't seem to find the one.... BUT.... http://www.ngksparkplugs.com/techinf...200&country=US "Q: What is the maximum I can open or close the gap? A: NGK doesn't recommend adjusting the spark plug gap < or > .008". The reason for this is the ground electrode and center electrode won't line up properly, hindering spark plug performance." ....and THAT is why the '-11' is the WRONG plug for a turbo'd EJ engine.

01-12-2005, 10:51 PM	#6
Unabomber Big Ron Moderator Member#: 18062 Join Date: Apr 2002 Chapter/Region: MAIC Location: I can save you a ton of cash Vehicle: on car parts so PM me b4 j00 buy	Unabomber>Uncle Scotty at the search function. hotrod's post

01-13-2005, 01:34 AM	#7
MomoWRX Scooby Specialist Member#: 36823 Join Date: May 2003 Location: West Boca, FL/WPB at Northwood Vehicle: 03 MBP WRX Sold :( 93.5 Single Supra :)	Unabomber, uncle scotty, i am that much wiser after reading that post, i solute you P.S. Unabomber i didn't read your entire Spark plug FAQ but if its not in there that post should have a reference or two from hotrod's post.

01-13-2005, 06:49 AM	#8
Unabomber Big Ron Moderator Member#: 18062 Join Date: Apr 2002 Chapter/Region: MAIC Location: I can save you a ton of cash Vehicle: on car parts so PM me b4 j00 buy	After re-reading his post yesterday, it's now linked in my FAQ.

01-13-2005, 04:19 PM	#9
MustGoFast Scooby Specialist Member#: 33370 Join Date: Feb 2003 Location: Milwaukee, WI Vehicle: 2002 Impreza WRX Blue now w/ 6 fun flavors	Yep found hotrod's thing to be exactly as I thought the wider the non problematic gap the better..... Thank you all.