Evo 9 Spark Plug List, Also how to read plugs.
Feb 2, 2008, 04:08 AM
#31
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I would guess these stockers have only about 8-9k on them, but they have been used with tuning meth, cams, a green, new injectors etc and haven't been changed. I think they are gapped around .024 right now.
Just thought maybe I should use the colder plugs because of my recent mods and spiking 30psi. No?
Just thought maybe I should use the colder plugs because of my recent mods and spiking 30psi. No?
Feb 11, 2008, 04:32 PM
#32
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I was about to order stock replacements and the link to both the IX RS & MR show "OE Gap .032"
http://www.sparkplugs.com/results_app.asp?aaia=1432585
(I'm running catless TBE, Walbro, GM solenoid ~26psi spike...stock everything else)
http://www.sparkplugs.com/results_app.asp?aaia=1432585
(I'm running catless TBE, Walbro, GM solenoid ~26psi spike...stock everything else)
Last edited by subaruwrx420; Feb 11, 2008 at 04:36 PM.
Feb 17, 2008, 02:00 PM
#35
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I just pulled my plugs and inspected them today at 13K miles. The were the ideal light brown color, however the gap was a little off on each of them. That would be normal since the gap does widen over time. Since the recommended gap is between .020 and .024, I set mine a .022 and put them back in. My car isn't running meth, but I do run it at 22 PSI.
They would be fine at .024 as most people recommend, however I find that gapping them in the middle of the recommended range is usually a good way to go when you consider that the gap will widen over time.
One thing I haven't seen people talking about here is how the gap length effects performance. Here is my take on that issue, so please correct me if I am wrong about anything:
A bigger gap means more electrical resistance, potentially shorter spark durations and a longer-lasting plug...which is why you usually run a larger with gap copper plugs than you do with platinum or iridium. Copper plugs conduct electricity better, so a larger gap with a copper plug has similar resistance as a Platinum/Iridium plug with a smaller gap.
Ideally, and especially with turbo'd cars that rev high, you want a smaller gap which means less resistance and a reduced chance for the spark to "blow out" at high RPM (maximum spark duration). Iridium/Platinum plugs are not as conductive as copper plugs, but they resist the detrimental effects of a smaller gap much better than copper, which is why using them in our cars is preferable. Another thing to consider about gap length is that it can effect your A/F ratio. If the spark doesn't last long enough to ignite the air and fuel in the combustion chamber, it could lead to a rich condition and reduced performance.
They would be fine at .024 as most people recommend, however I find that gapping them in the middle of the recommended range is usually a good way to go when you consider that the gap will widen over time.
One thing I haven't seen people talking about here is how the gap length effects performance. Here is my take on that issue, so please correct me if I am wrong about anything:
A bigger gap means more electrical resistance, potentially shorter spark durations and a longer-lasting plug...which is why you usually run a larger with gap copper plugs than you do with platinum or iridium. Copper plugs conduct electricity better, so a larger gap with a copper plug has similar resistance as a Platinum/Iridium plug with a smaller gap.
Ideally, and especially with turbo'd cars that rev high, you want a smaller gap which means less resistance and a reduced chance for the spark to "blow out" at high RPM (maximum spark duration). Iridium/Platinum plugs are not as conductive as copper plugs, but they resist the detrimental effects of a smaller gap much better than copper, which is why using them in our cars is preferable. Another thing to consider about gap length is that it can effect your A/F ratio. If the spark doesn't last long enough to ignite the air and fuel in the combustion chamber, it could lead to a rich condition and reduced performance.
Feb 18, 2008, 09:48 AM
#38
Evolving Member
Running colder when you do not need to can result in fast plug fouling, since the plug will be too cold to burn off all of the fuel, a buildup will form on the plug in a short period of time. Obviously that would lead to reduced engine performance.
Just pull your plugs now and see what condition they are in. If they have a chipped appearance, like you see small pieces of metal missing from any part of the plug, it is a sign of detonation and you probably need to go 1 step colder.
Feb 18, 2008, 07:10 PM
#39
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^^ i jus had my car road tuned, running the motec pnp. car has most of the bolt on stuff so i should be getting abt 400ish crank hp. i figured i should go a step colder too but my tuner told me specifically to get the ngk racing heat range 9 plugs and these plugs cost a bomb 
Feb 18, 2008, 08:45 PM
#40
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^^ i jus had my car road tuned, running the motec pnp. car has most of the bolt on stuff so i should be getting abt 400ish crank hp. i figured i should go a step colder too but my tuner told me specifically to get the ngk racing heat range 9 plugs and these plugs cost a bomb
If your tuner is recommending plugs that are 2 steps colder, which is a pretty big change, I'd be curious as to what his reasoning is because I don't think you really need those from what you just said. I have not had any detonation issues with my car as it is now, and when I re-gapped my stock plugs to .022 it just smoothed the revs out across the whole power band.
So unless you're planning to run meth or boost levels over 28 PSI - something that would increase combustion chamber temps substatially - stick with the stock plugs. If your tuner did his job right there is no reason I can think of that you'd need colder plugs for your current stage of mods.
Apr 23, 2008, 11:29 AM
#43
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This thread is awesome, just what I was looking for. I have an intake, exhaust, BC at about 23psi and a fuel pump. I just bought a set of plugs from Buschur for my IX.
I'm planning on gapping at .022, does that sound accurate?
I'm planning on gapping at .022, does that sound accurate?
