Sparkplugs for our engine has always been a sore spot for me. The dang ngk's just cost to dang much---even at $80 a set ----Jeez ---come on!!! And they do not last long. My understanding is that iridiums were orginally made to get that 100K engine without a tune up for regular cars. It actually has a low electrial conductivity but it does wear very well.
The flat top old style plugs just dont run as well for me ---i have tried them and I did not like them. Yes they were correctly sized and washered.

Has ANYONE tried anything else? I am looking at some Brisk silver wire types and would get some right now but they only have a 19 mm reach and I really dont know how far the non protruded tip goes into the combustion chamber? They are only about 10 bucks apiece. Nology also has some silver sparkplugs with the same specs. they also have a 25 mm reach plug that maybe could be shimmed?.
Hell-- i would take copper also if i can find any that fit.
Size is a 14 mm thread, reach is 21 for the Leading and 19 for the trailing, and a hex(really not important for us) is a 13/16 and yes I do want a resistor type. Non protruding tip is also needed?
OD

Sparkplugs for our engine has always been a sore spot for me. The dang ngk's just cost to dang much---even at $80 a set ----Jeez ---come on!!! And they do not last long. My understanding is that iridiums were orginally made to get that 100K engine without a tune up for regular cars. It actually has a low electrial conductivity but it does wear very well.
The flat top old style plugs just dont run as well for me ---i have tried them and I did not like them. Yes they were correctly sized and washered.

Has ANYONE tried anything else? I am looking at some Brisk silver wire types and would get some right now but they only have a 19 mm reach and I really dont know how far the non protruded tip goes into the combustion chamber? They are only about 10 bucks apiece. Nology also has some silver sparkplugs with the same specs. they also have a 25 mm reach plug that maybe could be shimmed?.
Hell-- i would take copper also if i can find any that fit.
Size is a 14 mm thread, reach is 21 for the Leading and 19 for the trailing, and a hex(really not important for us) is a 13/16 and yes I do want a resistor type. Non protruding tip is also needed?
OD

What is your goal? Are you seeking a better plug or a cheaper plug?

Paul.

I too have wondered what makes them so expensive. My main issue is if they are worth the huge expense (for spark plug I mean) or if they are just poking us because they are specific to our engine.

What is your goal? Are you seeking a better plug or a cheaper plug?

Paul.

I'm thinking best bang, longevity for the buck.

Stockers in the trailing, RX-7 trailing plugs in Platinum for the leading.

Runs perfectly.

If it doesn't run correctly in your application, you have something else going on.

i havent tried that combination. The flat top plugs ran ok but just seemed to not have as much gas milage or low end grunt. (this was before i was running the twin fire). Just felt different. I do have short drives at times.
I am running now the one step colder Denso's for both leading and training.
They work fine. I just know that once a year I usually need to change the plugs.
I, like MM, really dont trust the itty bitty grounding strap on the ngks as i do regap them.
Also since I am fi and dont have the ability to redo the coils dwell., i run the twin fire on the oem coils. (which some tell me doesnt do a dang thing and others tell me it does?)
Now I am not having any problems with my system but if I can get a better conductive plug for a cheaper price, that has a stronger grounding strap, and comes in much wider hot/cold heat ranges then I should go for it?
I am thinking about trying the Brisk silver plug with the 19mm reach and running without a washer,but i really need to see the plugs tip protrusion before I try this?
They do make one that has the correct thread, heat range and has a 19mm reach. It has a non protruding tip and a tapered seat.
What do yall think? Paul?
OD
It would be nice to have a track set of plugs and a street set. If fact its beyound nice---its needed?

Once a year isn't so bad.
I change mine every couple of months. FI destroys the center electrode.

I do worry about the protruding electrode on the trailing - I did lose a motor to a mystery solid object intrusion and was never able to verify that it wasn't the plug (it definitely wasn't a seal).

The 19mm depth thing should not be underestimated.
Some people that have "investigated" the plug depth issue have not taken into account that "shoulder" depth isn't the issue, rather the "bowl" at the face of the housing isn't square.
A seemingly proper depth plug at 21mm will smash into this bowl and distort the housing.

Gremlins are not a stranger here either. Loosing a motor like that sucks--really sucks.
Yep-- I know about the bowl requirements on the trailing-- i plan on running oem there--like you and keeping them fresh. If I can find a something a little more sturdy and compatable Ok then, but i am looking at the leading 1st. Not ignoring the trailing as really that plug is more susceptable to detonation?
I can get a cheap plug with the same measuements and features to check the tip protrusion , seat etc
Another project:)
OD
OD.

I wonder if I lugged an old rotor housing into Autozone if they would let me try every plug in it. What is teh heat range for the stock plugs anyway.

a) Why is this in the S2 forum? Last I knew you had an S1.

b) An $80 annual plug change when you're running a supercharger on an engine that was originally NA doesn't strike me as extreme. Just be glad you're not running the NGK rotary racing plugs that are 2x+ what the OE plugs are, though that's probably what you should be using on a tracked FI rotary application. I suspect this is where Paul was going.

i hit the wrong button when i posted the thread- i am a idiot.
I have seen those $70 plugs but i dont think i am extreme enough to justify those.
My redline is a self imposed 7.5K and temps are good. The w/m also helps with the charge temps---so basically all i need is a little colder plug and i do ok.
My point, is that there are very few choices out there and the ones available (excluding the flatheads) are expensive.
The $80 bucks a year is for a regular set of rx8 plugs--mine are just a little more.
I much rather pay $50 for a set.
OD

Lol, I'm an idiot too so we're in good company

you probably fart away more than that difference over a year :dunno:

LOL!
Dang choked on my spaghetti!
OD

has anyone ran the trailing RE9B in the leading with the washer removed?
OD

Some people that have "investigated" the plug depth issue have not taken into account that "shoulder" depth isn't the issue, rather the "bowl" at the face of the housing isn't square.


"some people" did realise that . LOL

Anyhoo , I use the very cheap BUR9EQPs all around and like MM says the tips erode very quickly .
However I have recently realised that the trailing plugs don't do this , so when I replace the plugs I'll do the the leading only the first time then both the second time etc etc .

Denso!

I found two members that claim they're good. One tracked.

Made several inquiries. Butt know one has really posted a good thread on their use.

Feel free to do a search..

I had to send PM's to get confirmation that Denso's work good.

Have you tired this?

For competition, the NGK R6725-10.5 or 11.0 make a couple of more horsepower, but are too cold for street use except in boosted engines (where they perform very well). Gaps on these plugs should be approximately .032" to .035".

Have you tired this?

For competition, the NGK R6725-10.5 or 11.0 make a couple of more horsepower, but are too cold for street use except in boosted engines (where they perform very well). Gaps on these plugs should be approximately .032" to .035".


These were what I was referring to earlier. Not as expensive as I had remembered, also available 11.5

NGK R6725-105 Racing plugs. Recommended for all rotary engines used in racing applications. Use with thinner spark plug washer to move flash point closer and increase power, 0000-10-9101. NGK recommends that you start your vehicle and bring up to operating temperature with stock heat range plugs, then switch to the racing plugs.

Good info.
Currently i am running the denso's the IRLO1- 31's and 34"s.
They have done well--installed them in september/09.
I am now looking hard at a silver Brisk but approaching cautiously
I need to look at the ones you mentioned.
Headed toward Road Atlanta in March and expected to be turning sub 1:45 times
I have decided to have dedicated plugs and coils for track events--just like my old days in drag racing :)

80 a year is 6.66 cents a month....

That is nothing.

Like don't eat out once a month at fast food (if you do at all)

I don't see the big deal

Dont bash the OP, he has legitimate points. $80 for Spark plugs is ridiculous.

If your not going to look outside the box why have a forum at all?

An Automatic Rx8 owner shit talking......you fail.

80 a year is 6.66 cents a month....

That is nothing.

Like don't eat out once a month at fast food (if you do at all)

I don't see the big deal

6.66 cents a month.. dude.

so we ended up talking him into buying more expensive plugs :lol:

the price isn't ridiculous, they're unique for a rotary, it's just one of several concessions you have to make for owning one


.

Good advice from all and i appreciate it.
Dont know ---I like choices?
Currently --unless I go with the flattops- no one around here stocks a plug I can use.
Our plugs are way overpriced--guess it has to do with volume?

Plan at this time is to get the new coils and a set of R 6725, for track use.
Still undecided about the street,
Searching.......

Do Moderators do ANYTHING!!???..can these threads be put in the Correct Series 1 SUB FORUM..Please..

yea I screwed up and dont know how to move the thread

team you are right--i am laughing at myself. Seems like it always cost me more money for some reason.
But I am trying to find a good decent plug thats cheap.
i may have found a traiing plug for under 10 bucks. The 21.5 mm reach on the leading is a little harder to deal with.
Its a LOT of stuff out there to weed through.
OD

yea I screwed up and dont know how to move the thread

team you are right--i am laughing at myself. Seems like it always cost me more money for some reason.
But I am trying to find a good decent plug thats cheap.
i may have found a traiing plug for under 10 bucks. The 21.5 mm reach on the leading is a little harder to deal with.
Its a LOT of stuff out there to weed through.
OD

Denny,
Sorry man, I was not (well I hope) I did not insult you, I was in a grumpy mood this morning.:scratchhe

I thought like many the S2 sub-forums were are a good idea, but if those who volunteer and control the forum don't move threads then this one will become crap (IMO), and defeats the purpose of having it....perhaps that is what some are hoping for...perhaps if this does not work there could be a mandatory vehicle "type" incorporated in user's Avatar info that must be included in user details before you can post...like a small colored box that says S1 or S2.
That way for those who don't have a sig, contributors don't need to ask what car they are talking about or own??...I dunno!

ON Spark Plugs...from what I know in the past Denny the original NGK plugs have always been the best for rotaries...yep they are expensive, try living here around $300 plus for a set.
A Mazda Dealer here pays $42.80 Each Cost per plug! 'Genuine' from Mazda Australia!!

rest easy mate-no problems here.
I am really trying to figure out what makes rotary plugs so special, others make a oblique or side point electrodes/straps--so what is so special?
Heck even some of the racing plugs are not iridium. Iridium last a long time but there are better performance metals out there.
Search continues.
OD

i spoke with Brisk who displayed some interest in developing a rotary engine plug---we shall see--in the meantime i am experimenting in making my own.
OD

Heck even some of the racing plugs are not iridium. Iridium last a long time but there are better performance metals out there.

Race parts and street, or even performance, parts are two vastly different contexts.
Which metals might you have in mind?

Its expensive because its not mass produce.

Nycaps--Iridium plugs can be had for $8 for other makes.
other than the size there is nothin special about these plugs. I think we are getting ripped off.

Ray
copper itself is a better conductor
Silver is the best.

After fitting many many ngk plugs into old rotor housings (make sure yall CLEAN your spark plug holes)--i have found that all spark plugs of the same make are not identical.

What do yall think about running the leading without a washer--has anyone looked?
OD

What do yall think about running the leading without a washer--has anyone looked?
OD

for what ends ?

Ray
copper itself is a better conductor
Silver is the best.

There is far more to spark plug design than electrical conductivity. Spark plugs and ignition coils tend to be designed to work with each other, too, but Mazda (apparently) overlooked something when designing the RX-8 ignition system.

I never had any problem with it, but did run different spark wires :dunno:

for what ends ?

In general, the closer the firing point to the rotor the more power output

see the earlier quoted note from Mazda Motorsports regarding the NGK racing plugs, but you need a seal so other than using the thinner part number listed earlier I wouldn't drop it out entirely

exactly team. thanks.
With the stock washer the grounding strap/bar and electrode are imho to recessed from the combustion chamber. I havent measured it yet, but I will, just to give others an idea of what I have seen.
Mazda probably designed it this way to keep anyone from accidently not placing a washer on the plug and then having the plug end hitting the apex seal as it goes by?

A thinner washer would place the plug end closer to the chamber and in therory improve the effectiveness of the spark?

It also seems to me also, that some grounding stap modifications could improve things just a bit.

Maybe with getting the plug end closer-- indexing may become more important?

It surprises me that the thread end of the NGK plugs are not universal to the placement of the grounding strap. In other words the leading plugs, after being torqued, will have the grounding strap/bar facing in different directions that varies from plug to plug.
I am speaking of the oem plugs ---I havent really looked at the racing/colder plugs ---yet. But I will.
I wonder if a silicone sealer substitute for a washer?
It would be better to have a 5/8 hex head versus a 13/16 also?

It also surprises me that people are not cleaning the old anti seaze off of the the sparkplug hole area and it is also getting in the "recessed" area at the end.
This restricts the plugs of being properly inserted. It will torque out before it reaches full insertion dept.

It is easy to see the advantage of the flat top plugs (especially without a washer) in regard of getting the spark closer to the intake charge. It sure would be great if they could last longer. But for a track day dedicated set of leading sprak plugs ---this may be the way to go. They are cheap and plentiful.
These is interesting.

Silicone sealer, srsly? :hahano:

Hay.... come on..... he had a few Jack Daniels.

Nope --no JD's but a couple shots of Moonshine (home brewed and damn good) will do the same thing:).
My mind "wanders" some and I have to go get it and bring it back.