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Heresy! Replaced NGK Platinum w/Champion Copper Plugs
Posted 02 May 2004 - 09:41 PM
The NGK plugs had been in the car for 44,560 mi.
The center electrodes on two of the NGK plugs were very worn.
The gaps on the removed plugs were: #1 = 0.047"; #2 = 0.045"; #3 = 0.045"; #4 = 0.048". The spec in the Haynes manual is 0.043". (The plugs otherwise were in excellent condition, which indicates the engine is doing well.)
I had to buy a new spark plug gauge because the two I had only went up to 0.040".
The dealer charged me $12.50 each for the NGK plugs when they were installed back in 09/07/01. The Champions cost $1.69 each.
I gapped the Champions to 0.044" per the recommendation provided by the computer at the NAPA store where I purchased them.
HOLY HORSEPOWER!! I must have gained back at least 10 HP, probably more, by installing the Champion plugs.
Subaru claims that the service life on NGK platinum plugs is 60,000 mi, but at what loss from original performance?
I plan on sticking with the cheaper copper plugs and replacing them every 1yr or 12,000 miles. I suspect I'll keep more HP and better fuel mileage with this strategy.
Posted 02 May 2004 - 09:47 PM
Posted 02 May 2004 - 10:04 PM
So, I went with the Champions. I heard that some EJ25s (the 2.5 RS I think) came from the factory with Champion plugs.
Posted 02 May 2004 - 10:17 PM
Posted 02 May 2004 - 10:34 PM
I heard that some EJ25s (the 2.5 RS I think) came from the factory with Champion plugs.
My '02 Legacy GT came with Champion spark plugs.
Posted 14 May 2004 - 12:03 PM
Posted 14 May 2004 - 04:40 PM
My theory is that if you're willing to change your plugs every 12,000-15,000 mi you're better off with copper plugs, both because they are a better conductor and they cost less.
If you go longer than that between plug changes, you certainly are better off with platinum plugs because they are more durable. But based upon observation of my EJ25, platinum plugs won't give you anywhere near peak performance or peak MPG if you leave them in for 60,000 mi. I suspect 30,000 mi is a better change interval for platinum plugs.
60,000 mi plug changes seem to be the equivalent of 7,500 mi dino oil changes: they're minimal maintenance for people who aren't very enthusiastic about keeping their cars in peak shape.
Posted 15 May 2004 - 05:09 AM
If I was going to run a cheaper plug I would use NGK V-Power.
Posted 15 May 2004 - 07:24 AM
I wonder if the plugs may have been incorrectly torqued when installed by the dealer at the car's 60,000 mi service interval. Just an idea: overtight plug draws more heat from the cylinder and leads to excessive electrode wear??
Posted 15 May 2004 - 07:49 AM
The NGK V-Power were about $3 less than the Bosch platinum, but hardly worth the savings if the performance is unchanged, and replacement interval is half that of the platinums.
Wonder what the reason is for Subaru switching to Champions over NGKs in the new vehicles?
Posted 15 May 2004 - 12:42 PM
He replaced them with NGK platinums.
Posted 16 May 2004 - 01:39 PM
Posted 16 May 2004 - 02:16 PM
Posted 16 May 2004 - 04:32 PM
Posted 17 May 2004 - 11:49 AM
I agree with your comment about the Champions, in fact it's almost universal that NGK's trump Champions, but why? I've finally dug-up some technical info that supports and explains what it is that everyone has been subjectively feeling:
Posted 17 May 2004 - 01:52 PM
Posted 17 May 2004 - 03:47 PM
I tried several different types of plugs in my EJ22. Only the NGK coppers and the Champion coppers worked well. The others either idled well and reved up roughly or idled rough and reved up smooth. Yes I indeed checked the gap and set it if needed
Posted 17 May 2004 - 09:29 PM
Nothing said so far explains why two of the NGK platinum plugs I pulled after 44,500 mi appear severely worn or why the car's power and throttle response improved dramatically after replacing the NGK platinum plugs.
Legacy 2.5: Remember that at least some Subaru EJ25s come with Champion plugs as original equipment.
My argument is not that Champion is superior to NGK or vice versa, only that I suspect that platinum plugs don't last as long as claimed and that if changed frequently inexpensive copper plugs may outperform overpriced platinum plugs.
Posted 17 May 2004 - 10:56 PM
Posted 18 May 2004 - 12:31 AM
Posted 18 May 2004 - 05:44 AM
Engineers refer to cars (like most newer Subarus) where one coil feeds two spark plugs, and fires every crank revolution as a waste spark ignition system. (There is a wasted spark during every exhaust stroke) Using a single platinum spark plug on such a car will give two rapidly degraded spark plugs for the following reason. 1/2 of the plugs always see a reverse polarity spark. The reverse polarity sparks will cause material to be transferred from the large ground/outer electrode onto the narrow platinum center electrode's exposed end surface. Double platinum plugs have the fine wire center electrode, and have a small chip of platinum attached to the outer electrode. This prevents the transfer of metal and the resulting fouled plug. I would use either conventional plugs or double platinum in a new Subaru. If you have had trouble with single platinum plugs, that is normal behavior for our cars. I have found the correct double platinum NGK for $10 a piece which is pricey, but better than $15 list, and have used Autolite double platinum for $4 a piece and found them to look good and work good so far. (20,000 miles).
Posted 18 May 2004 - 01:05 PM
champion is bad due to the poor quality of metal used to make the parts that matter
ngk is the way to go
Posted 18 May 2004 - 02:17 PM
If I follow what you are saying about the waste spark system, newer Subarus would have the front and rear plug on one side fed by one coil and the other side fed by another coil. If the same plug (front?, rear?) always has a reverse polarity spark, material would be transferred from the large, ground electrode to the small center electrode. On the forward polarity spark the material transfer would be from center to ground.
In the case of copper plugs, the ware would be uniform due to similar metals for both electrodes. The double platinums would also wear uniformally due to the platinim square on the ground electrode, but they will wear more slowly than copper. With the single platinum plugs you would see more wear in the reverse plugs because the platinum center does not transfer materail as fast as the large, ground electrode.
So how do I know if my ignition has this two plug pre coil waste spark system?
Posted 19 May 2004 - 05:50 AM
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