It is a known fact that the rotary operate at a quite a high temperature and guys in the 7 club that they are changing their plug every 5000 miles. I have heard a lot of comments (especially from Gomez) about the Mazda’s schedule plug change at 60000km being too late.

Here is the evidence:
My plugs after 23500km.

Leading plugs


Trailing plugs



The leading plugs are a lot more dusky and have carbon deposit on them.
They don’t like the ones can be cleaned and reused.

Compare with others... mine is actually not that bad :o

20K miles (MazdaManiac)
https://www.rx8club.com/attachment.p...chmentid=43296

6.5k miles
https://www.rx8club.com/attachment.p...chmentid=43358

15K miles (PoLak)
Flooded plugs 30K miles
https://www.rx8club.com/attachment.p...chmentid=37422

More discussion
https://www.rx8club.com/series-i-tech-garage-22/plugs-after-20k-miles-55005/

 

Thanks Taka, very interesting post. Your plugs definitely look OK.
Re MazdaManiac, doesn't he run a turbo? Did he take that frightening picture after or before the modification?

I'll definitely won't wait 60000 km to change my plugs without going into RX7 extremes (5000 miles).

Fabrice

 

I wonder if those plugs are too cold...

 

Mmm dont u guys use like HR 11 or something like that?

 

I've enhanced the photos to make them a bit easier to see... the leading plugs were a bit dark on my calibrated monitor...

Leading:


Trailing:


Cheers

sco

 

Thanks sco.

I will remember to bring the plug for you guys to see in the National and ask if we should get Mazda to change the plug sooner than 60000km...

I went to track 5 times, but mainly the car is used to do weekend run on the Monash Fwy between Berwick and Balwyn (50km) with the baby inside. I drived like a nanny. I change rotary oil frequency and no flooding.

Fabrice,

I agree the plug looks like usual wear and tear. The trailing plugs are still good, but last time I see the same condition as the leading plug is in my Honda VTEC engine after 60000km not 23000km. Surpise of the premature aging that is all.

That was the plug before MazdaManiac went into turbo.

xxup, FunkyR,

We cannot go hotter than what we have now. Otherwise, there will be too much misfire at high rpm that you will never see 9000rpm.

In fact, I have gone even colder after reading what people write in the r-3.com (you see rotary router in Japan). They all gone for what Fujita Engineering is suggesting and changing it every 10000km

For Australian condition, especially it is your daily drive, I suspect you just need stock rating (NGK 7 trailing and 9 leading) plugs and change it every 30-40K km or sooner if you think the engine is smooth... coz since I changed the plug, the car went EXcellent.....ly

 

I believe the trailing is NGK 9 and the leading is 7.

 

yes... Yes.... Yes.... you don't have to pick on me LOL

You know what I meant :D

L-7 T-9

T always > L

Now I am L-9 T-10 . I might have to change it much earlier next time.

 

Interesting shots Taka.

60,000k is apparently not all that long for platinum plugs in a regular engine, but I had expected to see a few "Inspect spark plugs" instructions in the service charts along the way.

Apart from checking the condition of the plugs, it can actually become quite difficult to remove ones that have been untouched for a long period of time. Many years ago I rashly offered to service the car of a young girl in the same block of flats (yes, driven by lust no doubt...). The plugs were seized in so tightly that one actually sheered off flush with the cylinder head! i.e the metal, not the ceramic part.

When I went upstairs to break the bad news she was clad in a see through string top, with nothing underneath... By the time I'd removed the cylinder head, taken it into work and removed the remnant of the plug and fixed it all up, the moment was lost... Next time we spoke she was dressed neck to knee ... and it took me weeks to get the money for the plugs and gaskets, etc... Moral: Don't leave your plugs too long, and don't let your d*ck talk you into working on other people's cars! :D

In both our other cars it's suggested that the plugs are checked pretty regularly - certainly well before new ones are recommended.

I've not had experience with rotary engines (or platinum plugs) before, but I tend to regard all service charts as a basic recommendation rather than being set in concrete.

I've always checked plugs fairly regularly, cleaned and re-gapped, and then just replaced them when I thought it was called for, regardless of time or distance. So from force of habit I'll probably be doing the same with the 8.

 

I think that is a smart thing to do. Maybe I should jack the car up every now and then and take the plug out - at least the leading plugs.

Ehhh... we have iridium plugs

:o

Oh... nice story 3 paragraphs before

 

Whoops! :o

I know even LESS about Iridium plugs! :D


My experience was all with piston engines, and before the computer controlled era. Memo to self: check facts before posting. :p

 

I found this description:

"There are two spark plugs for each of the two rotor chambers. Those plugs have an iridium center electrode and platinum-tipped side (ground) electrode."

So it looks like they have platinum and iridium??

Does anybody know more about these plugs? Are there just iridium ones, just platinum, plus combinations? Or are they more or less the same thing?

EDIT: As far as I can tell, from a quick search, the designation "platinum" or "iridium" refers to the composition of the centre electrode, or the tip of it. So various combinations of centre electrode and ground electrode can be found, but the centre one is the one that gives the plug its name. Is that right?

 

Taka I didn't flood my plugs at 30k I had to replace them because one had a crack in
the ceramic insulation heres a Copy of the orignal post:
"This is my Trailing Plug on my rear rotor, RE9B T, only one i could reach without taking off the wheel.

Looks pretty good incomparison to some 8 owners, this is a shot of one at 30k (he flooded): https://www.rx8club.com/attachment.p...achmentid=37422
Here's another 8 owners at 6.5k: https://www.rx8club.com/attachment.p...achmentid=43358

Anyway I do a ton of short distance driving, my car hardly warms up on the 5min drive to school usually do a cold shut down before I turn off (3k for 10secs).
Occasionally I'll drive the car REALLY hard on a long trip to clean out that carbon buildup and I drive it up to the redline least once everytime I take it out. BTW 7500 on Castol Part-Synthetic, 7500 on regular dealer oil.

Anyway here it is right out of the motor, btw is there anything i can substitute for dielectric grease its midnight."

My plugs looked awsome for 15k

 

Mark

The trailing plug does look very good.

The worry is the leading plug... many people have leading plug replaced by warranty here in Australia, especially after complaining of cold starts.

 

Not in my case the one with cracked insulation was coincidently the worst one, heres pics of the ones that weren't.