There has been some confusion lately about "what spark plugs should I use for my application". This info may help to make better decisions. All of this info is directly from the NGK 2006 Automotive Applications catalog.

The plug for MY00-02 and 04-05 is the PFR7G-11S (stock number 7772). This is a platinum, fine-tip plug, heat range 7. If one desires a colder plug to replace it, the IFR8H-11 (5068), and IFR9H-11 (6588) are iridium fine-tip plugs one and two steps colder, respectively. These are resistor plugs.

If you want a copper replacement, BKR7E (6097) or BKR7E-11 (1283) are the same heat range as OE and are resistor plugs. There is no 8 heat range copper resistor plug to replace OE. There is an iridium BKR8EIX (2668), but the IFR8H-11 and IFR9H-11, mentioned above, are the same "FR" series plug as OE and therefore should be better alternatives.

Racing plug replacements are non-resistor plugs. The choices are R5672A-8 (7173) heat range 8, and R5672A-9 (7405) heat range 9, which are one and two steps colder than stock, respectively. These are projected tip (like OE), but have V-cut center electrodes and are copper plugs. Should you want an iridium racing plug, the choices are R7435-8 (4895) and R7435-9 (4896) which are one and two steps colder than OE, respectively. These are fine-tip iridium non-resistor plugs.

The stock replacement listed for MY03 is IFR7G-11KS (7746). This is an iridium fine-tip plug. I don't know why the listing for 03 is different than the rest. I guess 03 owners are cooler than everybody else All other replacement info is the same as above.

I hope this helps to resolve some of the questions people have been having about spark plug replacement.

*Edit 10-24-07

I just received the 2007-2008 catalog. They now list the 7772 platinum as the OEM plug and the 7746 iridium as an optional plug for all years. All other replacement plugs remain the same.

 

Just ordered the BKR7E, I'll be sure to post any details on them after a few good miles.

 

I'm sorry... I'm a sparkplug newbie..
So I have 03... I take it I can put in any other stocks (like platinum) with no "side" effects.
What would colder/hotter spark plugs do? You would want to run colder plugs if you turbocharge it?

 

This is great info, thanks for posting. However, I'm struggling to think of a reason why the '03 would have a different part # for the plugs. As far as I know, late model '02 cars and all '03 cars have identical engines (revised ECUs, updated oil jet bolts, etc. etc.).

 

You're welcome. I have no idea why '03 is different, but that's how the book lists it.

stimpack, the plug for 03 is iridium, whereas the other years are platinum. I'd stick with what the book recommends. They'll be about the same price anyway. NGK is Honda's OEM supplier, so I'll take their word for it.

 

platium over iridium over cooper

>>Irdium will run longer without fowling. (Platnum longer than copper).

resistor vs non resistor

>>I belive resistor are required/preferred for applications where an computer (ECU) is in use. As I understand it, it supresses spark noise. Essentially when a plug fires at at a gazillion volts it can geneate a lot of electrical noise that can damage a ECU or send it in to lala land.

colder vs stock (hotter)

>> colder plugs are used to counter where you are getting too much burn and pre-igitition. The factory plug *should* be the ideal temp to burn compltely, prevent preignition and fouling. If you engine has been modified, turbo, ecu mods etc. you may have to play with the plug temp to get the proper burn. In the carborated, pre-computer days -- we used to play with heat ranges alot. Sometimes just swiching manufacturers in the same heat range would get you the result you wanted for the way you drove or raced.

projected tip vs fine tip

>> I think this is just religion. Mine will last longer than yours, but manufacturers are containtly looking for ways to give their product and edge.

 

1)the more expensive material=higher the cost, the iridium suppose to last for a long time but some owner reported poorer gas mileage and no increase(or known) performance gain.

2)read above

3)a colder range plug is required when you are going FI or using funny gas, it will not do anything if you have a stock car

4)it's related to the material they use, if you have a copper plug the top will be bigger(which will wear out faster), the tougher the material they smaller the tip they can make.

 

Re: the my03...perhaps this was the first model produced when a resistor type iridium plug was available in the appropriate size, heat range.

the 2000-2003 service manual specifies the platimum (pfr7G11 for all model years. No mention of the iridium plugs, although I believe that's what came installed from the factory. Probably a late change.

My owner's manual still specifies changing plugs at 105,000 miles (!) same as the interval in the 00-03 service manual (normal duty).

 

Interesting I was told bkr7e for my turbo application. Maybe I should go a step colder???

 

BKR7E is the same heat range as stock, they're just cheaper and made of copper. Check them at 3,000 miles and adjust accordingly.

Re: projected tips vs. fine tips: A projected tip protrudes out farther than the end of the threaded body. Use of a projected tip where one is not required can result in piston to plug contact and that would be bad, mmmkay? A fine tip refers to the diameter of the center electrode tip. The two (projected and fine) are not mutually exclusive.