Optimax spark plugs

[Low_Psi]

Yup another spark plug question.....while this is my first post here, I have been reading this board for a while and have learned a great bit about my Optis. So on to the question....

has anyone tried the copper plug equivalent to the laser iridium and platinum plugs? I was flipping thru my shop manual and it said NGK IZFR5G is the recommended plug and NGK PZFR5F-11 can be used as well. When searching locally I came across NGK ZFR5F-11 which is the copper equivalent to the PZFR5F-11. The reason I ask this question is the copper plugs are only a little over $2.00 each. Which makes a set of 12 just a little over $26 after tax. I was about to purchase the iridium plugs when I came across these copper ones. I had thought about trying the copper, at $26 if they fouled out really fast I'm out $26, no big deal. However I don't want to hurt the motor. I know there is a heat difference between iridium/platinum/copper. I assume this is the reason for the gap difference between the iridium and platinum. But since the copper aren't listed in the manual, I wasn't sure on heat range or gap.

I am not looking to save every last dollar, but if they will work I can change them 4 times for every set of Iridium plugs.... We use our boat pretty heavily during the Michigan Summers so we put a decent amount of hours on the motors. Since it is a family boat, I don't run the motors very hard (we cruise around 4000 rpm). We have twin 2006 225s strapped to the back of a 2000 Concept 30 CC. Anyone have experience with these plugs? The copper are local, but the local price on the platinum and iridium are a bit high, so I was going to order those online. But will wait to see if anyone has tried the copper. Thanks in advance!!!

Oh, I saved one of my motors by reading about the dreaded air pump. We had just bought this boat and after a few times out, noticed a knocking sound while at idle. I immediately shut it down as I instantly thought air pump. I was right and basically just lost the bearing in the pump. The piston and rings stayed together which saved the debris that is often spread throughout the air system... I have put 30+ hrs on since replacing the air pump. Had I not read about the pump here on this forum, I am sure my air pump failure would have been much worse. So I thank all of you for that.....

i included a couple of pics of her, even though it's really not reliant to this post....

[Low_Psi]

Duplicate...

[Motv18]

Nope resistance issues. The spark would be weak.

The coil will drain down to much to recover at higher rpm. Performance wise might lose 100-200 or more rpm. They also will erode fast. I know this from the older positive negative (waste spark)plug systems. If you put in copper or single instead of duble platinum it didnt work right all the voltage drained into the empty cylinder and some would not even run. The real world degree of performance difference no idea but thats the tech stuff. Once reason theirs no direct cross plug.

Look on motorcycle sites its a fairly common crotch rocket plug. Often on sale for 8-9 each.

[XstreamVking]

Buy your iridium plugs at napa. 11 bucks each for the same plug that you paid 26 bucks for.

[2jz]

Ebay 361000465557 NGK 5887 $9.25

Speed& Custom Marine

[Low_Psi]

Nope resistance issues. The spark would be weak.

The coil will drain down to much to recover at higher rpm. Performance wise might lose 100-200 or more rpm. They also will erode fast. I know this from the older positive negative (waste spark)plug systems. If you put in copper or single instead of duble platinum it didnt work right all the voltage drained into the empty cylinder and some would not even run. The real world degree of performance difference no idea but thats the tech stuff. Once reason theirs no direct cross plug.

Look on motorcycle sites its a fairly common crotch rocket plug. Often on sale for 8-9 each.

I had a pretty strong feeling the Copper plug would not work, and was just hoping someone would say different... So looks like I will just order up some Iridium plugs (as the price difference between the platinum and iridium isn't but a buck or two).. Thanks for the quick replies.

[Low_Psi]

I did have one more question, as I am trying to learn as much about my outboards as possible (I have always had I/O performance boats). Has anyone tried using another brand plug? I believe Autolite makes a plug that shows up as an equivalent when I look up the NGK plugs on some of the automotive parts store websites... Just curious if anyone has tried anything other than the NGKs...

[Motv18]

Last i changed their wasnt a cross to ngk so no idea. But auto is a good plug. Worth trying.

[staylor]

The older Optis ran just fine for several years before Merc changed the plug to Iridium. My 2002 Opti 150 came from the factory with NGK PZFR5F-11 plugs- gap was .043, and I ran these for two years with no issues. The change in factory recommended plug on 115 to 175 hp DFI engines came around 2004 or so to Iridium 1ZFR5G @.031-.032 gap and this was a forward and backward fit- model year 2001 and later. For the earlier model year 2000, Opti 150 plug was a Champion QC12GMC @.040, which was changed to the PZFR5F-11 in the 2001 models. The only difference I noticed between the two NGK plugs was that the engine no longer had a tendency to load up when going down a long channel at low speeds with the Iridium plugs. The loading up was slight- my old 225 evinrude was much worse, and I suspect Merc had to appease the emissions gods over the loading up.
Doug

[Low_Psi]

I ended up ordering the Iridium plugs @ $10.00 each shipped. But I am still curious about other plugs. I have seen some commercials for E3 spark plugs and I know some guys in the Hi-Po Car scene use them. I wonder if anyone has tried the E3 plug? Their cross-reference guide shows they have a plug for the NGK 5887/IZFR5G. But when I looked up the info on the plug it showed as copper........ Again, not looking to save every last penny, just more of curiosity.

[XstreamVking]

For 10 bucks each, stick with the iridium plugs. Merc wouldn't use em if they had no benefit.

[Motv18]

E3 work best indexed like spitfires v something the idea being path of least resistance. They were all precursurs to iridium

the low down is basic function. Each plug is a attempt to get a clean crisp hot spark. To that effect gold tips are king. Their resistance is so low that it takes a special voltage system to run them. And they last like paper in a roaring bonfire.

Think of the ignition as a rubber band it charges streaching the band and fires releasing the band. This oscillation is the operating range. Iridium coils have to deal with very little oscilation in the voltage from the materials resistance. This means you can push 100k volts for .00001 second instead of 50k for .0002 for say copper not real numbers. If you stick copper into the iridium system the oscilition of the voltage becomes to large for the coil to recover. Peak voltage is no longer attained, and subsiquent sprk event decrease the voltage more till you missfire from lack of spark. I.e same as haveing a weak powerpack. You can always upgrade but never downgrade. And realisticly the upgrade is just throwing away money.

[Low_Psi]

Good Info. I don't have a problem putting the Iridium plugs back in it (already ordered), just wanted to know the why behind it. Would have been nice to be able to run a copper plug at $2.00 a piece and change them every season or even sooner, but obviously there would be issues with that so no big deal.

[TUNNEL T]

NGk web site very cheap!!!!!

[davo94]

IZFR5G In the opti is good for around 300hrs I have found.
Makes them cheap I say considering the effort changing them on the 150 v6.