Welcome to the North American Subaru Impreza Owners Club Sunday February 18, 2018
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
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 12-07-2004, 01:43 PM   #1
sneeky
Scooby Specialist
 
Member#: 44639
Join Date: Oct 2003
Chapter/Region: Tri-State
Location: They say it's the armpit...
Vehicle:
STi
the 35 awaits you...

Default Purpose of one step colder plugs?

did a bunch of searches and couldn't figure out the exact reason why people use them. also would it be benefitial for me to put them in my '04 STi with 21k and switching to a green setup in the spring (w/ all supporting mods obviously). tia.


chris
* Registered users of the site do not see these ads.
sneeky is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-07-2004, 01:49 PM   #2
dream
Scooby Specialist
 
Member#: 37003
Join Date: May 2003
Chapter/Region: MWSOC
Location: Twin Cities
Vehicle:
2015 WRX
DGM

Default

Interested in this info aswell.
dream is offline   Reply With Quote
Old 12-07-2004, 02:17 PM   #3
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

Default

Unabomber is offline   Reply With Quote
Old 12-07-2004, 02:23 PM   #4
sneeky
Scooby Specialist
 
Member#: 44639
Join Date: Oct 2003
Chapter/Region: Tri-State
Location: They say it's the armpit...
Vehicle:
STi
the 35 awaits you...

Default

ok... so should i switch them or not? i understand that you can go one step colder from 70-100hp increase, but is it a smart idea to go with the NGK's or should i replace them with stock for my upcoming setup? thanks again.


chris
sneeky is offline   Reply With Quote
Old 12-07-2004, 04:37 PM   #5
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

Helps remove heat from the combustion chamber (I think they say about ~20% of the heat leaves via the plug/cylinder head). Let's say you pull another 100C out of the combustion chamber, that's going to help with detonation considerably.

I'd only go one step colder, if you blast through the gears at least once a day to burn off the "fouling". If you have the luxury of driving like a mad man and race a lo,t you can look into 2 steps, but only take one step at a time, and then assess your fouling level. If you think avoiding det robs you of power, try fouled plugs--you'll really feel slow.

Plan on inspecting your plugs carefully after a change, and changing them more regularly until you know how they are performing. One step colder is not a huge change from the perspective of the plug, so just keep an eye on them. Read up on "reading spark plugs" too. You need to look way down inside the plug where the insulator meets the threaded case. Heat transfer occurs between the insulator and the cylinder head through the threads, that's where the fouling begins. Keep old plugs for reference.
bboy is offline   Reply With Quote
Old 12-07-2004, 07:27 PM   #6
sneeky
Scooby Specialist
 
Member#: 44639
Join Date: Oct 2003
Chapter/Region: Tri-State
Location: They say it's the armpit...
Vehicle:
STi
the 35 awaits you...

Default

thanks bboy, good info. so would these be the proper plugs for my STi?

http://www.sparkplugs.com/more_info.asp?AAIA=&pid=16602


chris
sneeky is offline   Reply With Quote
Old 12-07-2004, 10:03 PM   #7
2phless
Scooby Specialist
 
Member#: 69343
Join Date: Aug 2004
Chapter/Region: South East
Location: 'tween Lewisville&Clemmons NC
Vehicle:
1998 TransAm cnvrtbl
Black

Default

I installed DENSO IKH22-5345 plugs and they are fine. They are 1 heat range cooler. Some people bark about them but I've had no issue. If nothing else its a cross reference number. I was told from the NGK rep on the phone that there is not a colder NGK plug out yet for the STi but there will be. That was a month (+) ago.
2phless is offline   Reply With Quote
Old 12-08-2004, 12:09 AM   #8
Wombat North
Scooby Specialist
 
Member#: 21267
Join Date: Jul 2002
Location: Eats, roots and then leaves
Vehicle:
STI, EWG 8cm Green
UTEC/ECUtek/WI & SD tune

Default

Quote:
Originally Posted by sneeky
thanks bboy, good info. so would these be the proper plugs for my STi?

http://www.sparkplugs.com/more_info.asp?AAIA=&pid=16602


chris
A simple search using "LFR7AIX" reveals all the necessary info you require.
http://forums.nasioc.com/forums/show...hlight=LFR7AIX
Wombat North is offline   Reply With Quote
Old 12-08-2004, 12:22 AM   #9
rich728
Scooby Specialist
 
Member#: 40328
Join Date: Jul 2003
Chapter/Region: South East
Location: MiamiFL Pastelito Racing/SFSOC
Vehicle:
2004 WRX STi
BSP #728

Default

Can i use the 2.0L how to guide on scooby mods for my 2.5L to change the plugs???
rich728 is offline   Reply With Quote
Old 12-08-2004, 12:28 AM   #10
2phless
Scooby Specialist
 
Member#: 69343
Join Date: Aug 2004
Chapter/Region: South East
Location: 'tween Lewisville&Clemmons NC
Vehicle:
1998 TransAm cnvrtbl
Black

Default

The 2.0 plugs have different depths. Shallower.
2phless is offline   Reply With Quote
Old 12-08-2004, 04:04 AM   #11
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

The proper plug is in a post to the sparkplug FAQ as I remember. It's exactly the same as the stock plug but has a 7 instead of a 6 for the heat designator.

The part number you quote does not look correct, it's in like the 4-5th post on the FAQ.
bboy is offline   Reply With Quote
Old 12-08-2004, 03:01 PM   #12
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

LFR7AIX-11 for the STi 2.5L turbo, one step colder.

I noticed I did not include an important point about colder plugs: engines don't start as easily when cold. So, if you live in a very cold climate, think twice about going colder than stock. You can always go back to the stock, you are not going to hurt your engine with colder plugs (hotter plugs is a different story).
bboy is offline   Reply With Quote
Old 01-10-2005, 10:21 AM   #13
root
Scooby Specialist
 
Member#: 55854
Join Date: Feb 2004
Location: Central FL
Vehicle:
2004 STi
Blue/silver

Default

This seems to be implied, but I'd like to specifically ask, will colder plugs reduce EGTs to some degree?
root is offline   Reply With Quote
Old 01-10-2005, 11:27 PM   #14
Uncle Scotty
*** Banned ***
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK buy Nates beans
westcoastroasting.com

Default

Quote:
Originally Posted by bboy
LFR7AIX-11 for the STi 2.5L turbo, one step colder.

I noticed I did not include an important point about colder plugs: engines don't start as easily when cold. So, if you live in a very cold climate, think twice about going colder than stock. You can always go back to the stock, you are not going to hurt your engine with colder plugs (hotter plugs is a different story).

WRONG

By NGK definition, the ' -11' plug is the WRONG one for the STi or the WRX, according to the FSM for both the STi and WRX.
Uncle Scotty is offline   Reply With Quote
Old 01-11-2005, 09:19 AM   #15
root
Scooby Specialist
 
Member#: 55854
Join Date: Feb 2004
Location: Central FL
Vehicle:
2004 STi
Blue/silver

Default

I'm confused. Are there multiple versions of the LFR7AIX plug? Is there a LFR7AIX and a LFR7AIX-11? Is the LFR7AIX from sparkplugs.com right or wrong for the STi?
root is offline   Reply With Quote
Old 01-11-2005, 01:53 PM   #16
sparkplugs
Former Vendor
 
Member#: 79003
Join Date: Jan 2005
Default

The "-11" at the end of an NGK plug shows a different gap setting than the standard plug. NGK doesn't make a "-11" in the "7" heat range. bboy gave a great description of the heat range purpose. Too cold of a plug, and they'll just foul out, too hot of a plug will cause engine damage. You'll want to go one step colder than stock for every 75-100hp you increase in mods.

NGK's online catalog shows a stock plug with a "5" heat range and a different reach. According to NGK's tech, this recommendation is wrong. The stock plug is ILFR6G, one heat range colder is the LFR7AIX.

Last edited by sparkplugs.com; 01-11-2005 at 05:02 PM.
sparkplugs is offline   Reply With Quote
Old 01-14-2005, 05:15 PM   #17
Al_Smokemcrack
Scooby Specialist
 
Member#: 66640
Join Date: Jul 2004
Chapter/Region: Tri-State
Location: Rochester, NY
Vehicle:
1997 Legacy Outback
Glacier White

Default

Al_Smokemcrack 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
Which of these NGK Iridium one-step colder plugs should I buy? lotarg Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 2 06-01-2010 01:54 PM
does anyone around have a set of one step colder plugs? OvrClkdPmp Mid West Subaru Owners Club Forum -- MWSOC 0 01-15-2006 07:53 PM
One step colder plugs? STUDAndring Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 1 12-01-2004 05:08 PM
One step colder plugs? What gap? munkis Normally Aspirated with bolt-on Forced Induction Powertrain 18 06-12-2004 08:48 PM
One step colder plugs worth it? Davenow Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 3 01-27-2003 01:01 AM

All times are GMT -4. The time now is 06:17 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.