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my name says Guest, but Im really a MEMBER
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Discussion Starter #1
I've ran 7's since I put on my turbo 2 summers ago. I haven't had any problems, that I know of as far as the spark plugs go. if your running a colder plug there supposed to foul if there to cold, which mine didn't. well, they do have a like lite coat of some brownish something, they don't look normal. I'm not sure if it's even directly connected to the plugs though. but no major fouling that caused any type of misfire.

I'm thinking about just running 6's. if it's to cold you don't get as complete of a burn...... but the 7's might be helping me run 87 boosted.

curious what everyone elses opinions are. what are you running? what do your plugs look like?
 

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Boost Gets You Laid
Del Sol
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All the boosted cars I've had a slight brown tinge to the plugs has been normal.

I was running a step colder plug from 5-10 PSI. No harm in it, at leaste in my book.

I'm curious as to how you tuned on 87 Octane as to how much fuel you have to throw in, ignition curves and such
 

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98 civic ex coupe
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938 Posts
I used to run the 7's. My tuner highly recommended the ngk stock number 4554. I believe there 8's. I like how the center electrode and ground strap are set up. Imo this would allow less spark to get blown out vs a traditional plug. I always use sunoco 93 octane. Or sometimes ill throw in a couple gallons of turbo blue 104. But that is now $8.50 a gallon at my local pump. I haven't had any problems with the ngk race plugs. depending on boost i gap differently.
 

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Classic Man
Civic
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i run r5671a-9's right now. i had 10's in before, but it did run a tad rougher.

i think its a bit overkill... but an interesting thing happened to me today.

i was speaking with the NGK canada head tech and he informed me that the colder the plug you run the better the gas mileage. he also said my .25 gap was a bit small for 12-15psi. interesting.
 

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my name says Guest, but Im really a MEMBER
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Discussion Starter #5
All the boosted cars I've had a slight brown tinge to the plugs has been normal.

I was running a step colder plug from 5-10 PSI. No harm in it, at leaste in my book.

I'm curious as to how you tuned on 87 Octane as to how much fuel you have to throw in, ignition curves and such
that's interesting you have that same color on your plugs. It's not like that on any other cars I work on. I wonder if it's because the plug is to cold.

I agree, as long as you keep an eye on the plugs for fouling. a colder plug would seem a better idea to me as where a plug that's to hot can cause pre igntion and or burn the piston. plus in theory a boosted motor should run a little hotter. getting rid of more heat from the plug/spark would help counter act the added heat from boost.
 

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Brokedick Millionaire
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I ran R5671A-8's daily in a NA Z6 setup without fouling.......left them in there for spraying at the track :)
 

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my name says Guest, but Im really a MEMBER
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Discussion Starter #8
I guess my real question is if I'll gain mileage out of boost going back to stock heat range.

but in a feedback fuel system.wouldn't the ecu be able to compensate for the incomplete burn

a colder plug would disapate more heat from the plug which contributes to combustion temps. but if its not reaching the ideal temps. and power output is decreased by characteristics of the explosion slightly changing
 

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Classic Man
Civic
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16,355 Posts
i was speaking with the NGK canada head tech and he informed me that the colder the plug you run the better the gas mileage.
i asked how come and he suggested that a cooler burn ment the ecu needs to inject less fuel to keep the exhaust temps down.

i didnt question him any further. im not sure exactly how the ecu can calculate exhaust temps tho. but this man knows what he is talking about.
 

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my name says Guest, but Im really a MEMBER
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Discussion Starter #10
I wouldn't say a rep from ngk, trying to sell you something is the most reputable source of info. where you going to buy some ngk plugs from them at the time of the call??

I would think in a stock car, putting in a colder plug would decrease mileage. if a colder then necessary plug is said to foul. where's is the deposits coming from. unburn't combustion. as in not getting the most out of a power stroke.

yeah, the computer doesn't see exhaust temps. it see o2 content. I don't get the logic behind what he's trying to say. cause when the car's warmed up temp, combustion or exhaust isn't a factoring input to afr to the ecu.
 

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Classic Man
Civic
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not a rep. the head tech. trust me, im in aftermarket parts, and it was a business call totally unrelated to sales. this was no rep

seemed weird u would post this thread the day after i talked to him, so i shared. :)
 

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Registered
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i would never run anything other then a step colder plug. im running 7's the heat a turbo makes is just too great to risk being lazy and keeping the 8 heat plugs IMO
 

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my name says Guest, but Im really a MEMBER
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Discussion Starter #15
6's may be cold compared to other cars, well actually I have no clue what other cars run, but 6's are stock. the iat on a boosted car have to be hotter then a normal n/a motor without. ...... yeah, that statement alone, I should be going with 7's. i dunno, I don't understand flame fronts, peak pressure, etc..
 

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Brokedick Millionaire
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53 mpg on what??????

All my little secrets have yet to be unlocked :)

Ever tuned a V8? I'm doing NOTHING different.
 
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