Spark plugs

foreverzero89

Member
:
03.5 'speed protege
ok i searched and it seems that these are the best plugs to use for stock boost. NGKs ZFR6F-11. btw my mods are FMIC and CAI. if there are any better plugs to get the best power/MPG that would be helpful thanks!!
 
I just swapped out the stock platinum plugs for those exact plugs this past weekend (at ~60k miles). I hate to say s*** like this about spark plugs, but the subsequent tank of gas was probably the best milage I've gotten since I bought the car a year ago. Possibly just coincidence, but whatever... the plugs are under $10 for a set and I was probably due to change them anyways.

As for power gain? C'mon, they're just spark plugs and unless your current set is fouled up, they're not going to make a noticable difference. But in that case, you'd be wise to change the plugs anyways. And everything I've ever read says that copper plugs--such as the ZFR6F- are better for FI applications than fine-wire plugs (platinum, iridium) due to the lower likelihood of fouling and the subsequent issues that can result.

Just make sure you gap them correctly, since they come with something like a 0.040" gap, and the reccomended gap is around 0.030"
 
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i wasn't really expecting a power gain, just wanted to know if there was a *best* plug for both, but thanks for the input!
 
I've had 3 sets of NGK stock #3271 (oem MSP) plugs over the miles. Changed to NGK stock #4291 using a 0.031 gap and so far I am more than satisfied with them. You can get these plugs from Advanced Discount Auto or partsamerica.com for $1.99 each versus $11+ for the laser platinum plugs. The copper core V powers are being used by quite a few people with great results.
 
i just got the copper core v-power plugs yestday and they are great. these are the plugs i pulled from the car: crap i can't find them but they started with the letter P.
 
not trying to thread jack, but i just noticed this Spark plug thread. Does anybody use the Autolite Copper ones mentioned on the Modder list?, they are AR3923.
 
Most likely not, as NGK's are the choice for most Mazda engines.

The NGK V Power stock no. 4291's are ZFR6F-11, PZ's are the Laser Platinum stock no. 3271.
 
Most likely not, as NGK's are the choice for most Mazda engines.

The NGK V Power stock no. 4291's are ZFR6F-11, PZ's are the Laser Platinum stock no. 3271.

Thats what i hav now, but i wanna go 1 step colder. The Autolite were the only ones i seen on the Modder List that were 1 colder and copper.
Im on my second set of ZFR6F11's and the first set i took out seem to burning a lil hot (the ground electrode is a white color).
 
i know somebody is gonna call me a Newb, even tho i have been on here 18 months, but what does "sub" , mean?
 
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That's strange that your having problems with them because in addition to me I know a few people that use them without issue in upped boost applications. But that said you can get the NGK stock no. 5913 for a 7 heat range plug. partsamerica.com will have any NGK plug that you need. Autolites work best in Ford/Lincoln/Mercury applications.
 
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I used the champion brand and the car ran a lot quieter, surprisingly! But my gas mileage went down a bit. I went back to NGK BKR5E-11. Sure the engine is a bit louder but I don't care. :) I'll probably go for the Long reach ZFR6F-11 though. Just for the better performance and mileage.
 

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