I like a fresh set of plugs when I get on the track. It just makes sure they are the best they can be. How would you like to find out after a day of tracking that you had been running one fouled plug? Mad at yourself would'nt you?

Normally at a race venue teams check and change plugs several times. This is because it is your only window into the combustion chamber while it was operating. That tells you if you are rich/lean, advanced and close to detonation and more. Of course this takes some experiance at reading plugs but you might as well start learning now.

EDIT, I didn't state that strongly enough. Every race team checks the plugs every time the car comes in off the track. Every time.

 

I'm thinking of new spark plugs to start off the 06 season and/or esp. for use on track days. I've read the threads available about plugs I could find and although it all makes sense, I still confused in a couple ways.

I'd like to get this info straight once and for all time. And I'm referring to standard plugs, not the cold climate/slow driving plugs.

My owner's manual says (04 version):

NGK RE9B-T trailing
NGK RE7A-L leading AND Mazda says (1/12/04 parts flash) these are the correct plugs:

NGK RE9B-T trailing
NGK RE7A-L leading ... so good so far....but If I go to spark plugs.com they want to sell me:

NGK RE9B-T trailing
NGK RE7C-L leading
If I go to the NKG website 'How to read plug' here:

http://www.ngksparkplugs.com/techinf...tnumberkey.pdf

I can't tell what the different ending A-L and C-L is except that it's 'special design'. So that's the first problem to solve - which is the plug that is correct - what Mazda says or spark plugs.com want to sell me? Or maybe it doesn't matter?

2nd question is:

What if I want a 1-heat range colder plug for "track use/sustained high speed". What do I get? Would it be this?

NGK RE10B-T trailing
NGK RE8C-L leading or RE8A-L (depending on answer to above)
They don't exist when I search at spark plugs.com. Does NGK MAKE a cooler plug for us? And if yes what's the part number?

or

if I (should I) want to use Denso (is this a good plug? or not - anyone used them?) that is listed at spark plugs.com as it is the only colder plug available?

Maybe this info once answered should be put in the frequently asked questions or somewhere easily found. Thanks.

Edit: corrected leading and trailing mixup thanks Brice-RX8 - see what I mean I'm so lol

 

Remember that the latest TSB changed the leading plugs again, don't have the paperwork to quote the part number.

 

I think you got a little confused, the -T is trailing and the -L is leading. You seem to have them backwards in your explanations.

 

Found one answer "<the RE7C-L> This plug is improved over the RE7A-L as the shell has been notched to reduce fouling and improve cold starting.

 

I have a NGK 9 for leading and NGK 10 for trailing.

I have taken it out today (11000km after install - 4 track day, nanny driving around town), and compare with the stock (similar track days and nanna driving).

It is what it looks like when I taken out and put it side by side of my OEM old plugs


Wei, my machanics clean it very nicely

 

Still a bit hard to read the pics... but it does look like the 7 range is 'cleaner looking' than the 9, yes or what do you think? Are you indicating the OEMs over the colder plugs?

 

Well I would say it collect the same deposit on colder plugs in half the distance; but there is less wear and less used.

So we decided to clean the colder plugs - although the colder plugs will collect it back again in 10months/10000km.

The trailing plugs are even harder to tell. That is why I only took the leading plug's pic.

BTW I had a lot of hesitation (misfire) at high rpm - that is what prompted me looking at the plug at RP's advice.

I know it is going to collect back, but there is no other sign that colder plug is fouling.

Let me find the link of picture illustration. hang on...

 

There it is ....

http://www.centuryperformance.com/spark2.asp

Look under ash deposit.

It said and it makes sense "these are light-brownish deposits that are encrusted to the ground and/or center electrode(s). This situation is caused by oil and/or fuel additives. This condition can cause misfires".

Our engine has oil in the chamber - naturally for the apex seals - I think it is "natural" to have this plug problem.

At least it is not looking like denotated, overheated or oil fouled.

Am I interpretting this correctly. RG? RP?

 

I never thought about this.
I'm already changing my wheels at the track... doing the plugs would just be a few extra minutes.

Excellent Idea.
D*MN thats dedication. I get upset just having to drive more than an hour.

-hS

 

Haha... the Australian RX-8 Nationals is in Goulburn NSW - it is in the other state from Melbourne. But people drive 2 days from Queensland (up north) last year. So I think it is just get together (45 cars last year) and have fun on the race track. Wakefield is better for RX-8 than any other track I have tried in Victoria (my state).

Changing plugs on the track? It is kind of difficult. You see the plug is so low down, although you can get to it by jacking the car up and take the left front wheel off. You have to get under the car and apply torque to get them out, put new ones in and put the plug lead head back on ------ harder work than driving 20 laps in a row.

I will rather pay someone to do it for me. And people stop telling me that it is not hard to change - theory yes. Practically --- bloody hell no.

 

Unless you have a car jack the size of Canada itself in your trunk like dannobre has

 

I changed my plugs before... it wasn't so bad. BTW, torque is no problem for some...
*FLEXES* RAWRRR!!! (jk jk).

I have a low-profile aluminum floor-jack that is pretty light, and fits in the trunk. The problem is fitting the race wheels in the car. This is where having other friends, who race and have extra room in their cars, helps a lot

 

Yeah, its actually not as hard as I thought it would be.

 

Everybody running the new leading plug yet? I have them in for about 500 miles now.

 

I offered that hotter plug during a recall service. I decided not if I want high rev sustaining drive ie track. Hotter plug were for rough starting - with an battery and starter motor upgrade which I had.

 

I went in to get my battery, starter, plugs changed this week.

Because of this thread, i decided to take the new plugs eventhough they were 7 and 9. I plan on having a second set of all 9s for track days. Hopefully this works out well.

Now that i think about it. Since im only using these plugs for about one day a month and the whole time its in very heavy duty driving periods... maybe i should get 9/10 for the track. Hmmm??? something to think about.

-hS

 

The new plugs are 6 and 9

 

Correct. It is to avoid any rough starting. Because there is take longer to build up the ash????

 

hmmm.. that sucks. Are you sure about this?

EDIT: I guess your right... Its on page 14 of the service order,
http://www.finishlineperformance.com...4-05-1448e.pdf

-hS

 

If you read the TSB carefully you will find that the NGK RE6C-L spark plugs are only recommende for those who have continuing problems with cold start fuel flooding.
For normal and spirited driving you should be using NGK RE7C-L.They have also been modified with the 4 radial slots.

 

I didn't even know RE7C-L was an option. I'll have to pick up a set of these.

-hS