Has anyone tried the oem Rx-8 plugs in their FC?

They are advertised as iridium but retail for only $20, as opposed to the $40 one's sold for the fc?

Are there anyfirment issues? what are the heat rages on these?

Here's a link to them:

http://www.partsamerica.com/ProductL...or=Spark+Plugs

 

Fourty bucks for spark plugs? Where are you getting them? I pay like $27 bucks for a set at Pep Boys.

Heck, a fast online search for them turned up this: http://www.ngk.com/results_cross.asp?pid=BUR7EQ

 

its 40(actually around 37) for the iridium ones which are supposed to last 2 to 3 times longer than the platinums.

 

Both are wrong.

The '8s plugs are $20 each for Iridium plugs at sparkplugs.com

The 8 uses NGK RE7CL for the leading and the RE9BT for the trailing.

These should not be confused with the standard rotary engine spark plugs, the BUR7EQ or BUR7EQP as neither of those are Iridium plugs.

And as far as using them, the gap on the RE7CL and RE9BT is .048, which is radically too big for the stock FC coils and ignition system. The plugs need to be re-gapped down to .035 for systems using CDIs and .032 for stock systems.

There is no real performance gain, using Iridium plugs in a Rotary other than life of the plug.

And this has been covered quite a few times, you may wish to search next time.

 

Hey what did I say wrong? and I did do a quick search

but good looking on the plug gap info... I'll keep that in mind if I try them...

in your experience is it true that the iridiums last 2 to 3 times as long as the platinums(which are supposed to last longer than the stockers)?

so if the rx-8 iridium plugs are only $20... then they actually start to become cost effective versus the strock or even the platinum rx-7 NGK's... and for half the price of the rx-7 iridiums.

 

Yeah that depends on how fast your car wears them out. Combustion chamber pressure plays a big role there. Most guys here foul them out before wearing them out though.

B10EGV's $5 a pop a the local parts store... run those if you want to save money. You can run high boost on them too.

Josh

 

Sorry, your link was not valid for me (it is based off of zip code) so I ignored it.

yeah, I have played around with a lot of plugs for the FC. If life is an issue (as the BUR7EQ is worn out at 10K miles with the stock FC ignition system) then go ahead and replace them. I get the BUR7EQP's for around $4 so cost is not really an issue.

The only advantage I found (as they at best might give you an extra 1 or 2 HP at peak) is the wear when using a CDI system. When using a CDI system, the standard BUR7EQ was gone by 5K miles, and a BUR7EQP only lasts about 7K to 10K miles. This is where using the RE7CL has an advantage.

But in an every day driver with the stock system, there is no real advantage unless you want to only change your plugs once every 30K miles instead of every 10K miles.

 

B10EGV's ? what brand it that?

 

yeah I do not recommend those at all.

They are small engine/ Moped/snowmobile plugs, and just because you are running them 3 steps too cold, does not make up for their heat rejection issues.

And then using the B10EGV's (much like the BR10EIX) tends to lend to low speed fouling in cold weather too...

So you really have two strikes against you using the moped plug.

Then that they are Gold/Palladium (which although gold is a great conductor, it is very very very soft) which makes it the third strike.

 

by a CDI system you mean an MSD type box right?

So Icemark... what do you think about regapping the rx-8 iridium plgs? at $20 is that a better option than the rx-7 ngk platinums for 8 a piece?

 

Yes, an ignition multi-spark amplifier like a Mallory, Jacobs or MSD.

 

which of those would you recommend for the rx-7? I know the msd only lets off multiple spark until about a 3k rpm thresehold... does any of the other boxes go higher? or is the combustion event too quick past that point for it to be effective anyway?

 

I believe the combustion time is to quick to let off multiple sparks any faster then 3000-3500. I think I read that some where once upon a time.

 

I use the BR10EIX plugs, but I run 20psi. Don't use them unless you have to, the car won't idle as well or get as good of gas mileage. They aren't for a regular street FC, the stock BR9EQ are fine for at least 350rwhp.

 

You sound really lost...

You don't need the multi-spark after 3kRPM.
The reason there is a multi-spark on a CDI ignition system is to combat the inherent short duration spark - firing a multi-spark at lower RPMS aids in combustion.
At higher RPM's, YOU DON'T NEED IT.
This is why it's turned off.
Like you said, each "combustion event" shortens in duration as RPM's increase, and a single, short-duration spark is enough.

I sell NGK BUR9EQ's for $5 a pop all day, so those iridiums are still not cost-effective at my pricing.
So unless those RX-8 spark plugs are outlasting the normal NGK's at over 4 times the mileage, you're still losing money.

-Ted

 

you say i'm lost and then virtually quote me verbatim? interesting

The reason I am interested in a CDI box that will discharge multiple spark at a higher RPM is because the combustion event for a rotory @ 3k rpm is longer than a piston engine @3k rpm... It is long enough that it could benefit from multiple spark discharge all the way to 4k rpm and possibly 4.5k rpm. I understand that is what the trailing spark plug is for but I wouldn't mind more if I could get it.

 

I'd like to see you prove that statement?


-Ted

 

I thought that was pretty common knowledge since every chamber fires every 1 time around while every piston fires every 2 times around(at least for a 4 stroke).

Read up on it here:
http://en.wikipedia.org/wiki/Wankel_engine

specifically at the end of the advantages section...

speaking of... has any one seen any of the direct injected rotories that mazda has claimed they have made?

 

ok a quick question then...

S5 turbo engine
S4 intakes
S4 stock turbo
large FMIC
720cc secondary
550cc primary
open exhaust
10psi (roughly)
Large street port
exhaust port
stock ECU
SAFC piggy back


curently I am running the stock 7/9's

what do u guys think I shoudl run for efficiency, better burn, maybe a cooler plug etc..

Thx for any info!

 

most people would run four of the stock 9's

 

Spooledupracing,

You are probably just fine with the stock ones. I ran all 9's up until the boost went over 15 lbs. At 20lbs I'm running Denso Iridium 10.5's (IRE01-32's) and stock 9's in the trailing. The price of $35 each sucks. Those BR10EGV's Mark dislikes have worked well for me too though. I probably change my plugs every 2k, however the car isn't a d/d. Fwiw if you have a good ignition, they DON'T foul out at low rpm/idle. They will get carbon build up if you don't put your foot in it very much, but so does every other spark plug in a rotary.

Here is a site where a guy did testing of many different rotary plugs in his FD:
http://www.silverbulletrx7.com/plugs/index.html

Check out the article Denso wrote on rotary spark plug designs:
http://www.silverbulletrx7.com/plugs/Rotary.doc

Josh

 

what is the gain in using all 9's

 

So your justification of using the term "longer" is due to the fact it's 1 versus 2?


-Ted

 

No Josh, if the system is tuned correctly, and the temp of the spark plug is correct for the driving style the sparkplugs will not carbon foul. Perhaps you are not understanding what is meant by fouling?

Carbon build up and/or wet plugs are fouled.

A correct temp range spark plug for the engine will not build up carbon and will not foul.

Trying to make up for tuning issues with the wrong temp spark plug, will lead to fouling and carbon build up.

That is why I think that the BR10EGV and BR10EIX are not great choices for a street driven vehicle.

If you read the article that you posted from silver bullet, you will see when he got the right temp range plug, he didn't have fouling, however on a lot of the colder plugs he tested, he had the wrong temp and had major carbon fouling.

If you have additional boost, using '9s in the leading spot extends spark plug life, and reduces the possibility of detionation due to a hot plug.

but again may be too cold in an unmodified motor in a street use (driving style and conditions will limit the effectiveness).

 

CDI systems usually do not multi-spark at mid to high RPM, but rather only at sub 3000 rpm conditions.

At above 4000, almost all of them only provide a slightly "hotter" more intense single event spark. On a FC the only advantage at all of using a CDI system is if you spend a major amount of time above 6000 RPM (as the stock amplifier system starts breaking up around 6500 RPM) or have a ton of boost (that tends to blow out the spark at high boost).

But don't expect any low end increases or mileage increases... that won't happen. The minor high end (6500-7000 RPM) HP increases are only from a slightly more stable spark.