Welcome to the North American Subaru Impreza Owners Club Sunday September 21, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Service & Maintenance

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 06-29-2009, 09:20 PM   #1
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default Spark Plugs: Quenching is an issue to consider?

Hey guys,

I've researched these forums and the internet A LOT regarding spark plugs and finally decided to buy NGK V-Power copper plugs for my '07 2.5i. Yes, it is true that "Conventional wisdom says that copper spark plugs produce more power than the longer life platinum or the newer iridium" (from the spark plug FAQ). But it is also stated that, regarding platinum or iridium plugs, "These finer electrodes do not quench the flame core as much as a conventional style plug. This increases ignitability, therefore increasing HP. It's not a huge gain, but cylinder pressures are measurably higher."

So the comparison issue here is:
-Copper is a better conductor but must be built as a large electrode tip to be strong enough, thereby having a large quenching effect.
-Platinum is a worse conductor than copper but is stronger and thus can be built as a small electrode tip, thereby having a small quenching effect.

How important is it to avoid the quenching effect of copper electrodes when changing plugs in newer engines that were originally designed with a finer platinum electrode in mind?

Thank you,
Oren
* Registered users of the site do not see these ads.
ore0690 is offline   Reply With Quote
Old 07-01-2009, 10:50 AM   #2
rick-l
Scooby Specialist
 
Member#: 33868
Join Date: Mar 2003
Location: Chesterfield, MO
Vehicle:
2003 wrx
srp

Default

Quote:
Originally Posted by ore0690 View Post
So the comparison issue here is:
-Copper is a better conductor but must be built as a large electrode tip to be strong enough, thereby having a large quenching effect.
-Platinum is a worse conductor than copper but is stronger and thus can be built as a small electrode tip, thereby having a small quenching effect.
Platinum is a much better conductor than copper but very expensive.
rick-l is offline   Reply With Quote
Old 07-01-2009, 02:41 PM   #3
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

No, copper is a distinctly better conductor than platinum. Platinum's advantage is longer life, and simultaneously less flame quenching and higher spark energy. Both of those last two come by virtue of the much, much smaller electrode surface area.
bulwnkl is offline   Reply With Quote
Old 07-01-2009, 02:57 PM   #4
Lethal_Chemist
Scooby Newbie
 
Member#: 203723
Join Date: Feb 2009
Chapter/Region: MWSOC
Location: Midwest
Vehicle:
2005 Impreza STi
OBP

Default

Quote:
Originally Posted by bulwnkl View Post
No, copper is a distinctly better conductor than platinum. Platinum's advantage is longer life, and simultaneously less flame quenching and higher spark energy. Both of those last two come by virtue of the much, much smaller electrode surface area.
+1

Relatively speaking on a scale of 1-100, 100 being the most conductive. Copper is rated at about 89.3 whereas platinum is ~15. These are unitless values just a comparison to distinguish the conductivity. Silver however is the best conductor, both thermal and electrical known to man.
Lethal_Chemist is offline   Reply With Quote
Old 07-01-2009, 05:59 PM   #5
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK Houston
we have an Uncle

Default

'copper' plugs are NOT copper

they ARE nickle
Uncle Scotty is offline   Reply With Quote
Old 07-01-2009, 08:40 PM   #6
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default

Quote:
Originally Posted by Uncle Scotty View Post
'copper' plugs are NOT copper

they ARE nickle
Yes this is true, though just the electrode tip. The nickel alloy is there to protect the copper core from corrosion and such. I've looked up material properties for Nickel and Platinum, and Nickel has an order of magnitude less electrical resistivity in comparison.

For anyone so interested, you can see the material differences at: www.matweb.com

Also, I've found a neat little technical paper on Iridium tip development, apparently by Denso Corporation, here:
http://www.sparkplugs.com/pdfs/iri.pdf

And, I don't think I like the NGK 'coppers' that I installed in my '07 2.5i. Sometimes, the car seems a little more sluggish than what I remember. Is it all in my head? Since I do like to push my car hard, I think I will just go with OE plugs and call it a day. No worries, just drive. Then I will get my STI sometime in the future.

Oren
ore0690 is offline   Reply With Quote
Old 07-01-2009, 09:11 PM   #7
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK Houston
we have an Uncle

Default

I put the new Denso double platnium TT plugs in my 06 wrx recently and they seem to be doing just fine

$2.99/ea(now off sale) at Advance...

I think too many people put too much thought into sparkplugs....other than using the proper plug----MOST do NOT need ANY 'colder' plug, but think they do
and proper gap and PROPER GAP PROCEDURE!!!!!!!!!!!!!!!
1!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

IS FAR MORE IMPORTANT THAN WHAT PLUG
Uncle Scotty is offline   Reply With Quote
Old 07-01-2009, 10:12 PM   #8
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default

Quote:
Originally Posted by Uncle Scotty View Post
I put the new Denso double platnium TT plugs in my 06 wrx recently and they seem to be doing just fine

$2.99/ea(now off sale) at Advance...

I think too many people put too much thought into sparkplugs....other than using the proper plug----MOST do NOT need ANY 'colder' plug, but think they do
and proper gap and PROPER GAP PROCEDURE!!!!!!!!!!!!!!!
1!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

IS FAR MORE IMPORTANT THAN WHAT PLUG
Yeah, too much thought, definitely. haha. That's why I'm probably just going to go with OE plugs and forget about it, (which happen to be the NGK double platinums). I am fully confident in my gapping procedure; gapped to .043" which is within the range stated in the service manual.

Hey, also, I looked at the OE plugs that I pulled out of my engine after the first 30k miles, and all the ground electrodes appear to be missing the welded platinum disc that's supposed to be there. All that's left is a circular indentation in the nickel where the disc used to be.

Oren
ore0690 is offline   Reply With Quote
Old 07-01-2009, 11:09 PM   #9
z&cobb
Scooby Specialist
 
Member#: 12344
Join Date: Nov 2001
Chapter/Region: MAIC
Location: Mountains of Maryland
Vehicle:
2002 2JC
blue

Default

"Hey, also, I looked at the OE plugs that I pulled out of my engine after the first 30k miles, and all the ground electrodes appear to be missing the welded platinum disc that's supposed to be there. All that's left is a circular indentation in the nickel where the disc used to be."

Where did they go?
z&cobb is offline   Reply With Quote
Old 07-01-2009, 11:15 PM   #10
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK Houston
we have an Uncle

Default

Quote:
Originally Posted by z&cobb View Post
"Hey, also, I looked at the OE plugs that I pulled out of my engine after the first 30k miles, and all the ground electrodes appear to be missing the welded platinum disc that's supposed to be there. All that's left is a circular indentation in the nickel where the disc used to be."

Where did they go?
they were consumed or knocked off the plugs by detonation
Uncle Scotty is offline   Reply With Quote
Old 07-01-2009, 11:16 PM   #11
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default

Quote:
Originally Posted by z&cobb View Post
"Hey, also, I looked at the OE plugs that I pulled out of my engine after the first 30k miles, and all the ground electrodes appear to be missing the welded platinum disc that's supposed to be there. All that's left is a circular indentation in the nickel where the disc used to be."

Where did they go?
Dang. I don't know. That's a good question. Hopefully not lodged between piston and cylinder wall or something of that sort.

Oren
ore0690 is offline   Reply With Quote
Old 07-02-2009, 12:39 AM   #12
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default

Quote:
Originally Posted by Uncle Scotty View Post
they were consumed or knocked off the plugs by detonation
I see. You mean the knocking that happens when I would engage the clutch too much without enough gas (so that the RPMs go a little below idle)? Or the knocking that happens sometimes when I blip the throttle?

This reminds me that, also, one of the plugs' center electrodes looks a little..... disturbed. Like, slightly skewed, and without a level tip surface.

Could anyone say if the knocked-off discs are a danger to the engine? Or do they exit with exhaust gases easily? I guess that they might get stuck at one of the cats.

Oren

Last edited by ore0690; 07-02-2009 at 12:46 AM.
ore0690 is offline   Reply With Quote
Old 07-03-2009, 05:19 PM   #13
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK Houston
we have an Uncle

Default

Quote:
Originally Posted by ore0690 View Post
I see. You mean the knocking that happens when I would engage the clutch too much without enough gas (so that the RPMs go a little below idle)? Or the knocking that happens sometimes when I blip the throttle?

This reminds me that, also, one of the plugs' center electrodes looks a little..... disturbed. Like, slightly skewed, and without a level tip surface.

Could anyone say if the knocked-off discs are a danger to the engine? Or do they exit with exhaust gases easily? I guess that they might get stuck at one of the cats.

Oren
if you are not using 91 octane fuel....try it for a month and see if the car runs better

if so...keep using it
Uncle Scotty is offline   Reply With Quote
Old 07-03-2009, 08:02 PM   #14
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default

Quote:
Originally Posted by Uncle Scotty View Post
if you are not using 91 octane fuel....try it for a month and see if the car runs better

if so...keep using it
Thanks Scotty. Yeah, that's another question I had.... will the ECU automatically optimize ignition timing to take advantage of 91 octane fuel? My thought is that with the 10:1 compression ratio, if timing is optimized, there would be a sure performance advantage to using 91. I would reset the ECU after the first full 91 fill up. I have my first tank of what I believe to be 89 in there now (which I obtained by filling up with 91 when I had a little less than a half-tank of 87).

Oren
ore0690 is offline   Reply With Quote
Old 07-03-2009, 08:23 PM   #15
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK Houston
we have an Uncle

Default

the ecu will correct for less detonation

there are too many idiots around here that know nothing about fuel or how and why the ecu does what it does....and use the wrong fuel just because they are dumb enough to think that their engines/ecu's are obdII and the ecu will 'compensate' for low quality fuel and not have engine damage as a result of using whatever piss they can pour into it

I think your sparkplugs tell the story of why this train of thought is wrong and getting detonation, even with an na engine is a bad thing
Uncle Scotty is offline   Reply With Quote
Old 07-24-2009, 03:59 PM   #16
ore0690
Scooby Newbie
 
Member#: 153954
Join Date: Jul 2007
Chapter/Region: BAIC
Location: San Francisco
Vehicle:
2007 Impreza 2.5i SE
Black

Default

Thank you for the info. I was away for a while.

So, being that my car is stock, I would naturally go for OEM plugs. They are for what the car was designed, and I suppose the engineers at Subaru already did all the hard work to determine how it will run with OEM plugs (NGK double platinums).

However, there seems to be a fault in the OEM plugs by which the platinum pads on the ground electrodes eventually fall off, as mentioned earlier in this thread. This appears to cause a sudden increase in spark plug gap, and possibly results in loose platinum pads in the system.

Thus I have decided to go with the NGK Iridium IX for the following reasons:

1) It is the closest to stock (same manufacturer and same smaller-than-nickel center electrode).

2) There is no welded pad on the ground electrode that is prone to falling off.

3) And, I assume that the center electrode is not as prone to falling off.


Would anyone like to share their opinion regarding my reasoning?


Thanks,
Oren

Last edited by ore0690; 07-24-2009 at 10:14 PM.
ore0690 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Did Cheney make who is going to be the VP candidates more important of an issue ? ZMANNH25rs Political Playground 4 08-21-2008 04:16 PM
Intresting: What is an otter to do ? racer98 Off-Topic 28 02-12-2007 07:57 PM
Is it time to consider Liberty over Democracy? PA-Brat Political Playground 19 11-08-2004 01:49 PM
Best choice of spark plugs: NGK copper? edkwon Factory 2.0L Turbo Powertrain 11 04-25-2004 09:29 PM
Splitfire spark plugs: yes? no? if no why? BryonMorton Service & Maintenance 7 06-18-2002 10:42 AM


All times are GMT -4. The time now is 04:14 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.