I put in NGK Iridium IX plugs today. The numbers for the plug are BKR5EIX and 6341. They were $6.95 a plug. They came with a .028 gap - which I used per the NGK tech's suggestion. The Bosch plugs Sean used in February, 2500 miles ago, were in pretty good shape but I figured that I would try out the Iridium plugs that some of the VCA members are chatting about. Do they give better performance? I do not know except for one specific area of performance. The car was not rough and did not buck for the first mile after cold start up. With the Bosch plugs, the first mile or so was rough until the plugs and engine heated up. I did a few acceleration runs to heat up the engine. The new plugs continued to work. It could have been a fluke but it seemed like there was less popping on decel. The shape of the tip is very different from the Bosch plug. The Bosch is broad like a traditional plug. The Iridium is narrow - almost like a needle. The plugs I used are currently being used as original equipment by Bentley for the Continental Coupe twin turbo engine. Anyone else care to share there observations on Iridium plugs versus some other kind of plug?
NGK Iridium Plugs - Observations
- Thread starter Bobpantax
- Start date
Russ M
Enthusiast
I did a bunch of testing for Denso when they first came out with their Iridium plugs on my race car. And they did deliver supperior durability along with equal power output to the best plugs available. I even dyno'ed them against Beru silver tip plugs, which in the past delivered the most power out of anything ever tried.
They asked me to do some dyno testing on the viper with their plugs, but at the time the heat range available was about 1 full point colder than OEM viper plugs. Needless to say they could not match OEM power, came close but who wants less power. They also had a tendency of not making a complete burn and would cause flames out the exhaust.
For a car that needs colder plugs, I would say no doubt get the iridiums, but for NA stock compression you cant beat OEM.
PS. I am also not sure about the NGK iridiums, from what I understand they are no where near the plug of the Denso unit. And their price of 6.95 vs. about $20 each suggests their are severe differences.
They asked me to do some dyno testing on the viper with their plugs, but at the time the heat range available was about 1 full point colder than OEM viper plugs. Needless to say they could not match OEM power, came close but who wants less power. They also had a tendency of not making a complete burn and would cause flames out the exhaust.
For a car that needs colder plugs, I would say no doubt get the iridiums, but for NA stock compression you cant beat OEM.
PS. I am also not sure about the NGK iridiums, from what I understand they are no where near the plug of the Denso unit. And their price of 6.95 vs. about $20 each suggests their are severe differences.
The poster above said:"I am also not sure about the NGK iridiums, from what I understand they are no where near the plug of the Denso unit. And their price of 6.95 vs. about $20 each suggests their are severe differences."
Please clarify "from what I understand" and state the source of the data that has indicated to you that "they are no where near the plug of the Denso unit". The reason I ask these two questions is that it would surprise me if there really was a significant difference in view of the fact that Bentley is using the NGK plug. In the meantime, the only proven difference so far is the $13.05 price difference per plug based on your statement of the cost of the Denso plug. No flame intended but unless there is hard data on the difference in the plugs and the difference is material, someone would have to be "Denso" to buy the Denso plug.
Please clarify "from what I understand" and state the source of the data that has indicated to you that "they are no where near the plug of the Denso unit". The reason I ask these two questions is that it would surprise me if there really was a significant difference in view of the fact that Bentley is using the NGK plug. In the meantime, the only proven difference so far is the $13.05 price difference per plug based on your statement of the cost of the Denso plug. No flame intended but unless there is hard data on the difference in the plugs and the difference is material, someone would have to be "Denso" to buy the Denso plug.
I sell both the NGK and Denso iridium plugs. I have looked at both and they look of equally high quality. Denso iridium have been on the market for several years, NGK are more recent. I was told of a problem with a Denso iridium tip separating and causing an engine failure on a Subaru but with that kind of failure it would be difficult to know which came first, the hole in the piston or the plug failure......I take that report with a pinch of salt.
I am currently using NGK platinum PZFR6F plugs in my blown motor. It works perfectly, has a projected nose and come with a preset 30thou gap.
I am currently using NGK platinum PZFR6F plugs in my blown motor. It works perfectly, has a projected nose and come with a preset 30thou gap.
Russ M
Enthusiast
My source is racers that have used both.
You quickly find out how good a plug is when you make 300-400hp per cylinder.
For a supercharged Viper that requires colder plugs, the iridium plugs would appear to be beneficial based on all of the above. It does not appear that they would confer a benefit on a vehicle without boost. In fact, based on what Russ M said above, it would appear that it would not make sense to use them in a Viper without a supercharger or a turbocharhger. Stugots - do you have a supercharger? Your list of mods does not indicate same. If you do not, what specific plug are you using and what is the gap?
Viper Wizard
Enthusiast
I set them at .032
Personally I don't like them because I can't hear my left wing propaganda, WAY too much AM static!
Flame intended, suit on!
I think that glass houses and Wizard costumes fall into the same category. If you are getting static, I suggest that you check your spark plug wire routing. The manual states that it is a cause of AM static. Are you using Magnecor's? If not, you might also want to switch. Lastly, if you are wearing the Wizard suit in the car ( without the hat ), the car may be making a statement about your taste in clothing. Have fun. Enjoy your .032 gap. I am sure that it is adequate for your needs. My grandfather used to say: "If you can't take the flame, get away from the fire."
joe117
Enthusiast
"You quickly find out how good a plug is when you make 300-400hp per cylinder"
I have no data to back this up but,
the right plug for 300 - 400 hp/cyl,
probably has little to do with any Viper plug.
And,
It seems like this topic pops up over and over again.
It always looks to me that the people that have plug related problems, are the guys who use plugs other than OEM.
I have no data to back this up but,
the right plug for 300 - 400 hp/cyl,
probably has little to do with any Viper plug.
And,
It seems like this topic pops up over and over again.
It always looks to me that the people that have plug related problems, are the guys who use plugs other than OEM.
