The only problem I have with the NGK 2668 plugs are that they're irridium. They cost more. With nitrous, you want to check your plugs often. I was pulling mine every month and figured that I'd just throw some new ones in. The copper 7173 plugs are 1.98 a piece at Advance Auto Parts where as the Iridiums cost more.

Scientifically speaking too, copper is a better conductor of electricity. There really hasn't been any solid evidence to say iridium, copper or platiunum are best though.

DO NOT RUN PLATINUM PLUGS with nitrous. Their self cleaning properties lead to detonation from heat.

Also, is that dried up antiseize on the threads or is that soot? If it is soot, then you need to make sure you're tightening your plugs down all the way.

 

idk where you get that iridium is not good for nitrous.. I have worked with alot of professional drag racing teams (most are setup with turbo and nitrous), they almost all use ngk iridium plugs.

all plugs have self cleaning properties, that is related to the heat range. iridium plugs work better than standard copper plugs because the center electrode is much smaller making for a much more powerful spark. Iridium is also much harder than copper and will last a very long time compared to copper.

 

Like I said, the reason why I don't like them is the price. Coppers do the same job just as fine and cost less. Especially if you're checking them and swapping them out often.

Copper plugs don't self clean as effeciently. Thats why they don't last nearly as long as platinums and iridiums. Also, the harness makes iridium last longer. Platinums heat up more than iridium and copper. The heat range is determined at how well it dissipates heat, not determined by its self cleaning properties. Platinum plugs are more prone to detonation with nitrous because it heats up more and nitrous also eats at platinum. It doesn't eat away from Iridium.

Iridium or copper are fine for nitrous. Pick your poison. I dont get what we're debating about really.

 

I went ahead and ordered the ngks from advanced when I picked up my new jets.. Is checking the plugs after each bottle of nitrous a safe way to go or do i need to check more often?

 

I checked them after every bottle for a few bottles. Then after I had everything running like I wanted it to, I would check them every month or month and a half just to make sure everything was still running fine.

Thats when I was going through a 10lb bottle every week. It gets to be an expensive addiction.

 

I see a bit of "popcorn" which is a sign of detonation, though its not an amount that is too alarming. Doing a pull on new plugs and then checking them right after is most accurate for figuring out if your safe or not, then check less often after this is established, otherwise your plugs have a chance at burning off some of the residual contaminants and you wont get an accurate indication of how its running.

Does the Zex kit intercept the oem timing? Running a colder plug may help, but its a compromise. You can foul your plugs driving around the other 99% of the time your not spraying. 8 heat range works well for FI. 9 may even be doable.

 

If a plug is too cold it wont get hot enough to clean itself.

 

I tried the 7405 plugs for about 1500 miles with no problems and no fouling. The 7405 is the same thing as the 7173 except it is a 9 heat range.

I switched back to the 7173s since I still was seeing some small specs of detonation for both sets of plugs. That was on a .038 nitrous jet.


The Zex unit doesn't change timing at all.

 

Ive had both the NGK 2668 iridium's and the NGK 7173 copper's. My car ran great with the iridium's but I thought I would talk to Ya at IP to see what he thought I should go with since the iridium's were pretty expensive. Ya said that he recommended the NGK 7173 copper's over the iridium's and that the car will run the same. Well, I took his advice and went with the NGK 7173 copper's and it ran ok for about 100 miles and then I started getting spark blowout running 25 psi and with them gapped at .028". I then gapped them to .022" and that problem seemed to go away but a new problem arrose. I was starting to have fluctuating idle and cruising hickups. I never had these problems with the NGK 2668 iridium's gapped at .028" when the tune was dialed in by my new tuner. I am now going back to the iridium's since I believe they are a far superior plug over the copper's. They also seem to last a lot longer. The point I'm trying to make is, I've had both the copper and iridium plugs and I believe the iridium plugs run better in the S.

 

^^^ The reason why you had those hiccups and erratic idle is becuase those 7173 coppers are not resistor plugs. The 2668 are. And yes the 2668 are also going to last longer due to being platinum internal and iridium tip -- on a side note).

Many members including myself have had issues with the 7173's excluding a few so they say. I had interference with my radar, however the car seemed to run ok. They are a cheap alternative, so members can decided to give them a shot if they want to play trial and error. I switched to 2668, no issues and they last a hell of a lot longer. I've got 40k FI miles on mine and they look like they could go another 40k easy. I've heard of a few guys that settle on the 7173's changing them with each oil change. They are cheap to a point I guess