2nd Gen RX7 Spark Plug Wires

[mbuskuhl]

Hmmm... two very different opinions on plugs.

Eckerich - 10.5 -11.5
Ludwig - 7, maybe 9

I'm picking up the Magnecor 8.5mm wires but am lost as too what plugs now. The "other" NGK plugs I had tried were some that were supposed to sit deeper in and required a special spark plug socket that had been machined down just to get them tightened. On the dyno, they did nothing and I did back to back testing. I would prefer not to buy and test more plugs. If 7's and 9's like stock is not ideal, then ???? Some part numbers would help, I have the ones for 7's and 9's but not others.

[seckerich]

Thats what is so good about this site Mark. You get various opinions that are worth exactly what you pay for them (mine included). There are so many variables that can effect your choice. I tend to run the coolest plug that makes the power and have some insurance in pocket. Others run the hottest they can looking for 1 HP (possibly) until that 90+ day and a little bad gas takes out a motor. We ran for years with 9's lead and trail with no problems. We made some changes that made a 10.5 better. The computer I sent you to run made best power with the 9's. Not a huge deal if what you have is working. Read the plug and see if it is breaking down. Good luck!!

[C. Ludwig]

I tend to run the coolest plug that makes the power and have some insurance in pocket.

Best advice yet.


A hotter plug won't make power unless you're fouling plugs by running a cold one in the first place. The only thing a hotter plug is doing is holding more heat in the insulator to ward off fouling. Use the coldest plug you can while avoiding fouling issues. In some detonation prone race engines that requires warming the engine on a hot plug then replacing them with a cold plug for high load racing conditions. This has just not been my experience with an ITS engine. You're just not loading it highly enough to require a colder plug than stock to ward off pre-ignition or detonation.

[Chris Wire]

Best advice yet.


A hotter plug won't make power unless you're fouling plugs by running a cold one in the first place. The only thing a hotter plug is doing is holding more heat in the insulator to ward off fouling. Use the coldest plug you can while avoiding fouling issues. In some detonation prone race engines that requires warming the engine on a hot plug then replacing them with a cold plug for high load racing conditions. This has just not been my experience with an ITS engine. You're just not loading it highly enough to require a colder plug than stock to ward off pre-ignition or detonation.

So not even the 7s, just all with the 9s all around?