Ok I have asked 2 different well known rotary shops about this and one tells me the 10.5's should be leading and the other tells me they should be trailing the 9's can I get some opinions here.

 

I am no wizard but the stock set up is 7's leading and 9's trailing so I would think you would follow that order. Maybe there is something I am missing? Why not just run 10.5 all around?

 

On my old tune, I ran 9s in leading and trailing. Currently I'm breaking in the engine on 8s. But, if you are running two different temperature plugs, the colder ones ALWAYS go in the Trailing. CJ

 

In my experience (limited to my two RX-7s), the top plug (the trailing) requires a colder plug (higher number) to achieve a good color.

Which number you use depends on your tune and power levels.

I am at 405 rwhp now, and I have good results with BUR9EQ in the leading and BR10EIX in the trailing (this is a "10" plug).

 

The place that has worked on my RX7 from the start had the 10.5's in the lead and the 9's in the trailing. I was asked yesterday at another place who put my plugs in. They put 10.5's all the way around and know the car has a rough idle.(I say rough idle its just not as smooth as it was with 10.5 in lead and the 9's in trail) When the 10.5's were in the lead the idle was smooth as glass. Oh I am running a single T78 set up putting out 451 rwhp on 17 lbs. The afr's are a little rich with all 10.5s installed. Im thinking of switching everything back to the way it was until I install my water meth kit and then will put the 10.5 on lead and trail and have it retuned.

 

every rotary I have ever ran was colder in the trailing or at worst the same currently I am running 9 leading 10 trailing same as Brian.

running a hotter plug in the trailing increase your chance of pre ignition.

If the car is running worse its because the origianl tuner set it up for the oddball plug combo and swapping it makes it not match the tune. better IMHO to get them set properly and retune you should be able to run a degree or so more of advance with the plugs setup properly.

kenn

 

Up to around 20 psi I run 9s all around. Anything after 20psi I usually run 25-30 psi with C16 and I run 11.5's or 10.5's all around.

Anthony

 

I'm running 9's on the leading, 11's on trailing . Shooting for 20+ psi..

 

I run 9's all around right now. For serious boost you should run either the 10.5's or 11.5's all around. I have a set in my toolbox just waiting to be tuned on...

 

I run 10s all around and due to my lean idle and cruise turning, my plugs come out clean.

My stock engine plugs never came out clean on the stock engine. They were dark brown at the best.

I use to run B10EGV but now I am trying the expensive Mazda racing plugs in 10.
R6725-9 through R6725-115, Mazda racing, fine wire platinum center and ground electrodes, 14mm, 21.5 mm/.846" reach, 13/16" hex, recessed tip, resistor, $30+, 020" gap, the best for high power but idle may suffer, uses a normal socket.

The picture was taken after 25 miles of 70mph then about 5 miles of 35 mph. They stay this way even in city driving.
These are the smoothest on boost plugs that I ever ran!

 

well i switched them back last night and put the 9's in the trailing and the 10.5's in the leading and the idle issue was gone and the car ran great the AFR's also looked good while at WOT. 10.8 to 11.0

 

I usually don't resort to insults...but, your stupid. Not my .02, but a fact.

 

trailing plugs see more of the latent heat and and thats why you should always run colder ones. Alot of people think spark plugs are just for spark but they are heat exchangers and they take the heat out of the combustion chamber and transfers it into the heads or rotor housings. Spark plugs should be torqued in at proper specs and also gapped .

 

For some reason this really made me laugh!
I really don't know who it was meant for but the way it was stated was just perfect!

 

All this time I thought you didn't know **** about rotaries!


I wonder if people also know that plugs that are not torque properly can lead to detonation.
The design of a plug have a great effect on how it operates. The stock plugs were design for one thing only and that's for stock application mainly smooth idle, best economy and emissions. Stock plugs don't belong in anything that involves the word performance. Putting hot plugs in the trailing location is like using glow plugs in your motor.

 

The NGK rep told me that the torque on a gasketed plug could effect the heat rang by up to two points. So that would mean the torque is more important than the hat range .

 

I had a friend once took a very high output car for a run and it started to detonate the minute it got into boost and he could not understand what could have change to cause that. He left all the plugs loose. He figured it out right away because I told him to check what was his last change and the plugs were.

 

dear Crispeed that post was not meant for you as i did not see any post from you in the list some people want to learn and i am just sharing information for those who want to know.

 

I was meant for Ozzman. No one else.

 

do you guys torque your plugs with a torque wrench? My most recent set of plugs I decided to torque to 13 ft lbs, before I just kinda winged it with the ratchet. The 2nd gen FSM said spec is 11-14 I think.

 

And why is that????

 

For the simple reason is, that many people have told you not to run hotter plugs in the Trailing, and yet you still do it. What will happen is you'll get some bad fuel, a little pre ignition, chip a apex seal, cry because you can't afford to the fix the car, or you'll be asking if I should do a V8 conversion, because rotarys are unreliable. Personally, I don't care. CJ

 

You could grow up a bit and act like a man instead of a grade school child. The shop that tuned my car is a very well known shop on this board. So im going to trust them seeing as how the rough idle smoothed out after putting the plugs the way they had them. And as far as what I can afford and what I cant you let me worry about that. So if you dont mind you can see your way out of my thread. I asked for opinions not insults. If it was tuned with the colder plug in the leading then it makes since that it would be safe and smart to return it to that configuration until it is tuned again.

 

This thread is both informative and entertaining.

 

I was hoping for more informative. Im sorry Im done with the comments.