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Spark plugs for classic and heat ranges... I keep changing failed plugs regularly...?
Just wondering classic Impreza turbos should run NGK PFR6B spark plugs as standard. People use NGK PFR7B as an upgrade and for even more NGK racing competion spark plugs with heat rating 8.
My classic is fully mapped, progrmaable ecu, many mods etc etc but when use the 'NGK racing competion spark plugs with heat rating 8' they last 200miles before start to misfire, if use 'NGK PFR7B' they last 1000miles before getting a misfire havent used the standard 'NGK PFR6B' for years so may last longer. Car runs 25psi so dont really want to go back to standard plugs or should I? Any thoughts why this keeps happening . . . . . . Have had new coils and sensors etc but with same out comes. Cheers. |
What's causing the plugs to misfire? If it's carbon build-up then get a hotter heat range plug like the PFR6B.
My personal experience is that the Denso Iridiums are better than the NGK plugs. I've had Denso IK22 on my car for 1 year with never a misfire - although I'm only running 14psi. Try the IK20s since that is the heat range corresponding to PFR6B. |
If the racing 8's are not getting hot enough, ie short journeys then they will foul very quickly. If you search the plug numbers you will find people running 6's and 7's at 400+bhp with no problems. I don't know how much 'racing' track days you do, but would think tyhe 8 would be a little to much for day to day use. As you can see below, the 'g' seems to offer more stability so may be worth a try as a 7.
Originally Posted by PeeVee
(Post 9841955)
Subaru have fitted both the 6b & the 6g to their engines but have never used a "d"
93-95my = PFR6G 96-2000my = PFR6B 2001-2007 = PFR6G 2008 on = SILFR6A The difference between the "b" & the "g" is the material that the cntr electrode is made out of. I have found the "g" to be a more stable plug and less prone to missfiring, there have been numerous occasions on classic cars where the fittment of a 7b induced a missfire which was subsequently cured by fitting 7G's. Phil |
Cheers b13bat!
car does get driven more of the time at a slower pace with a hard time weekends and several track days a year. so would make sense about the 8's getting foulded (to look at they dont look bad) When these pfr7b fail which no doubt will do will try a set of pfr7g Thanks! |
Interesting post as I have 8's in my car & they mis-fire at about 6k rpm when on 1.8bar boost albeit not when using 1.5bar. I don't use my car much either ie w/ends only & no track days ...
TX. |
What spark plug do you guys most commonly use? Are the Denso Iridiums popular for Scoobs?
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Did quick ebay search....
Which PFR6G use? PFR6G 9 PFR6G 11 PFR6G 13 etc........? Or buy any and gap myself? |
buy any and gap them yourself smaller than the suggested at around 6
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