BTW - I just looked up the specs on the Mazda plug RE7AL and RE9BT and they have a gap of .048!!!!! That is a gap typical of a N/A car. You couldnt pay me to gap my plugs with a .048. Also, the Denso plugs have a 19mm reach for Trailing and 21mm reach for Leading with the Iridium and non Iridium. The only problem I have with using those plugs is the gap.

For your power range I would rather use the BR9EIX plugs, they have a 19mm reach, are Iridium, and come with a .024 gap which in my opinion is MUCH better for a forced inducted rotary.

Here is a link to the RX8 plugs....
http://www.sparkplugs.com/results_ap...1&AAIA=1416844

Here is a link to the BR9EIX plugs
http://www.sparkplugs.com/results_cross.asp?pid=br9eix

Also....check out the price difference haha. Those "rotary specific" plugs cost a FORTUNE compared to the others. I can pick up BR9EIX plugs from AutoZone for about $5 each, at $20 a set that wouldnt even buy one plug of the rx8 Iridiums.

Good luck with whatever you decide to do
Stephen

 

Stephen - the Mazda plugs are gappable...as stated in the first post, Rick gapped his plugs to about 0.02.

*edit*

Actually wait...I just realized that Rick never actually mentioned which RX-8 plug he was using...now that I see that he was able to gap the plug and from looking at the picture on the sparkplugs.com website of the NGK iridium plug, which looks ungappable, maybe he was using the Denso plugs! I'll check and confirm...

Sorry for the quick reply Stephen...

 

Stephen,

Why do you say the gap is too big? According to my research you want the biggest gap that your ignition system can handle. The bigger the gap the bigger the spark kernel size. Naturally if you go to big, the voltage required exceeds what our coils can handle and they will fail prematurely along with power loss. Voltage requirements are increased with forced induction applications and higher compression ratio engines. However plug design can lower the required voltage. For example a thinner tip (such as with iridium) can lower the required voltage.

I can't hazard a guess about how big of a gap we can use given our coils and these various plugs but I also wouldn't use blanket statements about the gap without knowing all of the facts. Can you support your statements with some facts? Perhaps we can look at the coils used in the Rx-8 to see what their output is compared to our coils.

FYI the standard NGK BUR9EQ plugs have a gap of over 1 mm, which is equivalent to a 0.048" gap so if you ever used standard plugs you actually paid to use a plug gapped at that amount. I currently use plugs with a gap of over 3mm, which is around a 0.11" gap. These plugs have a unique design though so are not comparable.

 

Oh wait...yes the stock NGKs are gappable. I think the picture is a little off, but there is a little wire that goes towards the electrode from the ground circle.

 

Just for everyone who doesn't know already, you will need a thin-wall socket to install the NGK BR7EIX / BR9EIX plugs, as they were not designed for use with a rotary engine. Mazdatrix has these available, there is a photo and brief explanation near the bottom of this page: http://www.mazdatrix.com/toolmisc.htm

-s-

 

the larger the gap the harder its going to be on your ignition system, especially when you start to turn up the boost and make more power. Your not going to get any gains from running a .04+ gap, your just going to open yourself up to being suseptable to spark blow out and ignition issues.

But go a head and try them. All I said is I wouldn't ever run a gap like that. I'll stick with the tried and true that I know works flawless and let you guys put your engines on the line to experiment with something thats not going to have any hp benifits.

The only high hp cars I've even see run a gap like that were N/A cars. Most forced induction cars that make any power typically run a smaller gap. It makes perfect sense that they would run a gap like that on a low hp N/A rotary.....but I wouldnt try it on my car. There is nothing to gain and everything to loose.

Stephen

 

Stephen, I thought you are a Trailplug user? You make mention of running the trailing plugs alot throughout this post. Just curious??

 

Here you go....

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): http://www.rx8club.com/attachment.ph...chmentid=37422
Here's another 8 owners at 6.5k: http://www.rx8club.com/attachment.ph...chmentid=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.

 

Well looks like i had to buy new plugs anyway, the ceramic insulation on my rear rotor leading plug has a hairline crack in it.

Don't know how long its been this way but I'm pretty sure I didn't do it while i was taking it out, the others were fine, although I'm worried i aggravated the problem, so new plugs it is.

There is a design difference/update on these plugs even though they are the "same" as stock, the washer place behind the thread is about 1.5mm's thicker so less of the plug is getting closer to the combustion changer.

 

No.... those are "crush washers." They are designed to crush and seal when the spark plug is installed.

 

Suppose the ones I removed from the car look smaller since they were already "crushed"?

 

Bingo!

 

Here are some more pics of the plugs that weren't cracked.

 

after all this I ended up going with the Denso IRE01-27, which is equivalent to the NGK heat range 9, according to Denso

the RX-8 trailing plugs are too short, I compared them at the dealer....the lead plugs are the correct reach (why NGK lists the reach for the RX-8 plugs as a different value compared to the RX-7 plugs is beyond me!) but I decided the 7s are too hot for my car and I don't want to run thin wall IX motorcycle plugs that you need a special wrench to remove/install

if the Densos last 20k miles and perform well over that service interval they're worth the $35 imo....we'll see

 

Good luck with those. I believe the RE8A-L leading plugs are attainable. They are listed on the international NGK site. http://www.ngk.de/Home.en.0.html

dis1

 

cool....if you find a source for them let us know

 

reading this thread made me decice to change my plugs since its been there for a year now and 25,000 miles of spirited driving. But before I do so I have some questions. Let me get this straight, the higher the number, the colder the spark. Thats why we have a 9 in the trailing for our 7's. From what I have gathered from this thread when ppl talk about "9 all around" they meant like putting a BUR9EQP on all all four sockets. BTW I have a intake, down pipe, cat back, lightened flywheel. power FC(untuned), some lightened pulley, act strret/strip clutch w/ HD pressure plate and magnacor plugs. On the same note how often do you guys change your plug wires?

 

A "cold" plug does not mean that the spark is "colder" or "less lightening-y" than a "hot" plug.

"Hot" engines need "cold" plugs. If a plug is too cold, crap builds up on it instead of burning off. It can foul, which means it stops firing, or at least doesn't fire very well because of all the crap built up on it. If the plug is too hot, it might wear out too fast or maybe even cause pre-ignition. If this doesn't make sense yet, seek more information on google, or any auto repair manual ("how to read plugs", etc.).

-Max

 

lots of good info here: http://www.autolite.com/tech/index.html

I'd say change your ignition wires every 20-30k miles. They're cheap to replace, less than $40 for the set.

-s-

 

Maybe it was already mentioned but I didn't see it n the thread. Denso has FD-specific Iridium Racing Sparkplugs, gap of 0.028, part numbers:

1RE01-27 (Leading)
1RE01-31 (Trailing)

about $35 ea

 

I picked up the Denso IRE01-27s, which are equivalent to NGK "9" heat range plugs

the 31s are equivalent to an NGK 10 or 11, which is too cold for most street applications imo, unless you have about 400+ hp

 

how do you know the heat range equivalencies?

RX-8 uses L-7 and T-9 heat ranges same as the FD and the specified denso are L-27 and T-31 which I'd say is the equivalent to the 7 and 9.

There are also colder RX-8 denso plugs L-31 and T-34

Anybody has the heat range comparisons??

 

I called the Denso Tech Line (888) 963-3676

NGK Tech Line (877) 473-6767

NGK Denso
8 - 24
9 - 27
10 - 31
11 - 34

 

can you use the RX8 plugs in the T2 motor?

 

So...in conclusion resurrecting this seriously dead thread. RE9B-T's good/safe for FD's? or RE7C-L's? haha