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Old 04-30-2004, 10:45 PM   #1
Kenneth2000
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Default Real Step Colder Spark Plugs for STi

I have an STi, with perrin modded injectors, big maf, fuel pump, vf22, txs turbo-back etc...

The car runs really rich ... for obvious reasons .. even after more air has gotten by the MAF without it reading it ....

Anyways, with the factory plugs I gurbled and burbled like crazy .....

I just installed these: (Densos)



Denso Iridium - 1 heat range colder plugs .... the car runs even better, and the rich gurgling & burbling has cut into like half of what it was before ....

The seem to work great!

I got them from www.need4speedpower.com for about $11.55 each .. like $.20 cents cheaper a plug than sparkplugs.com ....

(the had them advertised on imprezawrxsti)
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Last edited by Kenneth2000; 05-01-2004 at 12:16 AM.
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Old 05-01-2004, 12:54 AM   #2
acuratech
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What gap did you set them too?


Joe
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Old 05-01-2004, 01:12 AM   #3
brian_411
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There was a similiar discovery on this thread. Maybe this is the answer to a few of our problems Hope this helps.

http://forums.nasioc.com/forums/show...5&pagenumber=3


Quote:
Originally posted by Wombat North
For those of you who don't know here are pics of what stock STI plug NGK IFLR6B looks like against the commonly used NGK BKR7E1X 1 heat range colder plug used on modded WRX's.

The BKR7E1X for comparison is the same size as the stock wrx plug.

Question for Jeff Sponaugle
It looks the stock STI plug protrudes into the combustion chamber almost 10mm. Could this be what separates the STI's going boom and not the hybrids.


[/b][/quote]
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Old 05-01-2004, 02:11 AM   #4
odin1
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What is the model number on them? thnx.
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Old 05-01-2004, 09:28 AM   #5
Kenneth2000
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First off ... don't put those BKR7e plugs in your STi .... they are not meant for our applications ....

The Denso part is right in the picture ... it is an IKH22

The plug next to the denso is our factory plug, so, just to show that it is the same style etc...

Oh, they are pre-gapped ...... to factory specs .. so don't try gapping them either ... !


I bought it through here ....

http://www.imprezawrxsti.com/postnuk...&p=80031#80031

Last edited by Kenneth2000; 05-02-2004 at 12:38 PM.
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Old 05-02-2004, 12:08 PM   #6
TreyS
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so how much of a PITA is it to change the plugs?
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Old 05-02-2004, 12:23 PM   #7
supercompact
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Quote:
Originally posted by TreyS
so how much of a PITA is it to change the plugs?
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Old 05-02-2004, 12:41 PM   #8
Kenneth2000
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[edit] sorry .. torx tools are for the injector removal ... brain fart[/edit]

Basically, on the driver's side is probably the most of a pita, but you remove the windshield washer fluid tank and you are pretty much good to go ...

You have to do most of the install by "feel" as you can't really "see" down there .....

I'm sure there are some installation type destructions here somewhere ....

Last edited by Kenneth2000; 05-04-2004 at 09:26 AM.
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Old 05-02-2004, 12:48 PM   #9
wgknestrick
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Quote:
If you have Denso Iridium plugs PLEASE remove them. They hinder the production of power in the subaru engine because the electrode is so fine pitched. They are not suited for High boost applications in EJ motors. The spark blows out and causes misfire. In a honda at 13 to 1 on boost they are great but on a Subaru running a rich mixture with large piston diam they are not.
From Clarks dyno "to do" list. I don't think that you want to run those Densos
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Old 05-02-2004, 03:27 PM   #10
Kenneth2000
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I wonder if there is a difference between the WRX plugs vs. the STi plugs ..... not necessarily the fact that the electrode is to small ... (see above pic comparing the WRX one with the STi one)

So anotherwords, maybe the same problem won't be evident in the USDM STi ....

The Denso technicians would probably argue with you all day on that one ....

So far, they are definintely working better on my car then the stock ones did, mind you, I'm not running a 400+ HP capable setup either ...

Just basic bolt ons and a VF-22 ...


No misfires on mine whatsoever ... Besides, I encourage you to find an NGK that is a step colder that works in our setup ... (USDM STi that is)
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Old 05-02-2004, 04:23 PM   #11
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the (in)famous Denso exploding ceramic plugs.....

Go with the NGK if you want iridiums, there is nothing wrong with the shorter plug, especially if you're getting the car modded and tuned.

Paul
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Old 05-02-2004, 05:36 PM   #12
Wombat North
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Quote:
Originally posted by Pavlo
the (in)famous Denso exploding ceramic plugs.....

Go with the NGK if you want iridiums, there is nothing wrong with the shorter plug, especially if you're getting the car modded and tuned.

Paul
I posted on I-speed forums about what plugs to use and why they are longer.
http://www.i-speed.us/cgi-bin/ikonbo...act=ST;f=3;t=6

Reason is the STI head is thicker.
I would not like to have a plug sitting 5/16" up inside the plug hole.

I have phoned lots of places for plug info including Ron from Axis.

Seems the only colder plug at this time is the Denso IKH22.
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Old 05-02-2004, 10:30 PM   #13
Kenneth2000
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I did lots of research too ...

Had NGK techs on the line .. Denso Techs on the line ...Bosch ...

No one else carries the plug that is meant for our application ... not copper, not platinum .... not iridium .... (unless, you are buying the factory NGK heat range plug)

I really think the Denso's seem to work well ... of course, maybe that will be diff. with a 500+ hp turbo stuck on the car ...

We'll see ...
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Old 05-03-2004, 06:20 AM   #14
nhluhr
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Quote:
Originally posted by TreyS
so how much of a PITA is it to change the plugs?
not at all - takes me about 30 minutes to an hour.

I remove the intake box, washer reservoir, and usually the battery as well just to open up the area more.
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Old 05-03-2004, 10:15 AM   #15
TreyS
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Quote:
Originally posted by nhluhr
not at all - takes me about 30 minutes to an hour.

I remove the intake box, washer reservoir, and usually the battery as well just to open up the area more.
THanks! I was looking down there the other day and it looked like a tight squeeze.
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Old 05-03-2004, 03:51 PM   #16
jagcars26
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Quote:
Originally posted by nhluhr
not at all - takes me about 30 minutes to an hour.

I remove the intake box, washer reservoir, and usually the battery as well just to open up the area more.
Yep! Thats the way to do it. But still figure on a few choice cuss words




Rudy
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Old 05-06-2004, 05:18 PM   #17
metoo
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How do we know that it is a step cooler?

Pace Mild picante sauce is not necessarily a step cooler than ElPaso's Medium picante sauce.
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Old 05-06-2004, 06:30 PM   #18
john banks
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PFR7Bs seemed to go off on my hybrid after about 7000 miles with little hesitations even with 0.7mm gap still. A new set sorted it, but just changed to NGK Racing 9s (R7119-9). I think it revs even smoother and knocklink shows less activity over 7000 RPM. Will see if they foul. I'm carrying the spark plug socket in my glovebox and my 7Bs in case
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Old 05-07-2004, 01:20 AM   #19
nhluhr
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Quote:
Originally posted by metoo
How do we know that it is a step cooler?

Pace Mild picante sauce is not necessarily a step cooler than ElPaso's Medium picante sauce.
the "22" is the hint. That's denso's number for the heat range equivalent to NGK's "7".
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Old 05-07-2004, 10:15 AM   #20
Kenneth2000
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Just like the NGK's, PFR6g ... PFR7g being a step colder, well the Denso same a stock heat range plug for the STi is an IKH20 whilst the step colder is an IKH22

I believe they have both in stock ...
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Old 05-20-2004, 04:04 PM   #21
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Greddy offers NGK iridium plugs for the STi in a 1 and 2 step colder heat range, that have the extended thread reach. granted a bit more expensive but readily available.

NGK will possibly be releasing their racing plugs soon hopefully..... and by soon I mean 4-5 months.
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Old 05-20-2004, 06:40 PM   #22
Kenneth2000
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I'd just assume buy a Denso unit, for the same price as factory NGK's that have the proper reach, and you can get 1 or 2 step colder units ...

The two step colder should be available in the next month or so ....
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