B9EGV or BUR9EQP??
 

Are there any obvious or subtle advantages to report on running the EGV over the BUR??

Pros for BnEGV plugs:
adjustable spark gap
non resisitor gives a hotter spark but still no EMF interferance
cheaper
recommended by a few reliable rotory tuners

Cons:
reqiures a thin wall socket or modified rotor housing

B10EGV's all the way around

i've come to be a firm believer in the BnEGV-type plugs to the point where i won't use anything else. granted, my applications have all been normal aspiration thus far, but i plan to use it in my turbo whenever i put it together.

the hotter spark has proven invaluable to me.

EGV all the way, never looking back.

Cheaper, More avialable heat ranges, whats not to love
www.sparkplugs.com

Thank you all....

The NGK “EGV” plug provides a number of different heat ranges*: 8.0, 9.0,
10.0 and 11.0. However, the reach of the “EGV” plug is not as long as that
of the racing plugs or the stock plugs. This shorter “reach” means that its flash-front
is not as close to the combustion chamber, and therefore may cost horse-power.
It also leaves some threads in the spark plug hole exposed, where
carbon can build up, resulting in possible detonation. Installation and removal
of these plugs on 1981 and later engines requires use of a special thin-wall
spark plug socket because of a protrusion that restricts the installation of the
wrong type of plug.

how does carbon build up on some threads cause detonation?

The plug is about an 1/8 shoter than the OEM. It not the sparkplug threads but the housing itself where the carbon will build. I was going to run these, but decided against. After seeing for myself how much shorter they actually are I can spare the extra 3 bucks a plug.

What about denso iridium?

Been running them for 3 years and have yet to see that.
Where are you getting 11 range plugs for $7?

Iw31?
 

Has anyone tried Denso IW31 plugs? They have the .4 mm iridium center electrode with a tapered U-grove ground electrode. Should be better than the .6 mm center and non-U-groove of the BR10eix. It's also a resistor plug so no problems with interference. It's about $19 so it's more than the BR10eix and similar projected nose plugs but it's a lot less than the $30+ of the iridium side gap plugs normally sold for 7s. You'll still have the issue with socket clearance but it looks like it's got possibilities and even advantages otherwise. Any experience and/or comments?

http://sparkplugs.com/results_cross....11EGV&x=46&y=5 these are only 5 bucks too. I would emagine that if carbon build up was that big a deal you could just put a standard sized sparkplug in every once in a while to clean out the carbone on those threads? I've been thinking about getting these plugs as the race 11.5 plugs are 120 bucks for the set and the b11egv's are only .5 hotter than the race plugs.

Carbon build up can become a heat riser. The carbon pieces hold heat that can auto ignite the mixture. Strictly speaking this would be pre-ignition and not detonation. However, pre-ignition can lead to detonation.

gotcha. so by just installing some stock plugs every once in a while should clean any carbon build up correct? Also not sure if I'll go with those gold plugs. THey sound good but after reading the differance between gold, platinum and iridium (gold being the lesser by a huge margin) I think I'll go with the expensive plugs.

It depends on how much power you want to make....

Stock 9's in the leading and 10.5 in the trailing is what I run around with at 21 lbs boost and anything higher I just stick NGK Racing 10.5's all the way around

I have made 544 whp at 25 lbs boost with stock 9's all the way around and it was fine on C16

So basically, if you are making under these numbers or boost, then 9's all way around is all you need. Reason to run colder plug in the trailing is under some circumstances it can act like a glow plug and pre-ignite.

Stock plugs are NOT that expensive considering how much everything else costs on a RX7, considering I pay 25 dollars a plug for the NGK racing 10.5's

So if the leading is doing a majority of the firing why put the colder plugs in the trailing? I've never really understude that. For sure I'm going to be running race gas and alky injection on a t70 and hbp so I'm expecting some big hp number at 25+ psi.

That's exactly what Steve Kan told me and that's why I put the 10's in the leading and 9's in the trailing. Also don't forget that the exposure of the plug lead is less on the trailing; look at the holes.

As the rotor comes around, if its already hot enough, the FIRST plug exposed to the combustion mixture is the trailing plug, now if its hot enough, that plug can act sorta like a glow plug and pre-ignite the mixture before the leading even fires, if you are running alot of boost and with it comes heat=compression, sort of acting like diesleing.
Thats the way I understand it, but regardless, I ran 10.5's all the way around on the 610 whp run. Ernie I believe runs 11.5's in leading and 10.5's in trailing, or 11.5's all way around.

Here's a great article at NGK about plugs, heat ranges, etc:

http://www.ngksparkplugs.com/techinf...000&country=US

Dont worry about the scare cries of carbon on threads, its a falicy !

I just tore down my own personal FD motor with 60k+miles on it running always B10EGV's and there is no such build up on inner threads, there is more build up on plug outer bodies (on any type you car to mention) and also on rotor faces before there is any noticable on threads in rotor housings ;)

The reason the carbon builds up in the first place is because the temperature is too low for the carbon to be consumed or start self cleaning (burning) for this reason you will always develope carbon (NORMAL AMOUNTS) on any non rubbing surface in any engine, this is because the thermal layers as they approach the walls in the enigne are very very low compared to combustion. Its a NON ISSUE, & the only time it becomes an issue is when you have vast quantities of the shit *carbon* building up due to extremley poor tuning on part throttle and low load situations which will quickly clog up the motor this THICK layer of carbon over extends past the boundry layer and can get hot and casue detonation. I have NEVER see this is a decently tuned rotary. BTW running 10.X:1 @ WOT and high power does not carbon up engines either ! its only poor tuning at idle, cruise etc that does this.

Now the reason trailing plugs always need to be hotter is becasue they are not cooled by passing fuel mixture (prior to ignition) anywhere near as much as the leading plug, they have a very small transfer hole because you cant make it any larer as too much compressio would bleed past the apex seal before full compression point as a result of this small tranfer hole alot more heat is retained in this section and the plug runs much hotter than the leading plug which is always cooled more via more exposure to a fresh non fired charge. This is why you dont have to use CDI on trailing plugs regardless almost of power since this plug is never under as much duress as the leading which will always be the one to foul first.

The heat is so much more that you will see the plug body will always show carbon self cleaning colour (tan brown) on trailing V's charcole black on leading plugs if you use same heat range in both holes.

I only use same heat range for inventory and also cycling plugs from one position to the other B10EGV's are perfect for a high power water injected car, Have used B11EGV's too and on some vehicles trim eitherway by 0.5 in heat range to get idea spark plug. have been using B*EGV's since 1995 with total sucsess. bought a set of *racing plugs once* and never again will I be ripped that hard, they are a total waste of money unless your going to do te LeMans 24hr in your unleaded fueled NA 4 rotor. And they are totaly inapropriate for leaded racing fuel as the platinum reacts badly with any lead content, its also a little known fact that platinum casues a catalytic reaction with methanol to keep its self glowing !!!! (this is why glow plugs are made from platinum) so there are multiple reasons to not use platinum electrode plugs.

B*EGV all the way ;)

I think you meant to say the reason the trailing plug is always colder heat range, not hotter...
the stock leadings from the factory are heat range of 7's which is a hotter range plug, the trailings are 9's which are colder....NGK plugs=the higher the number, the colder the heat range of plug :)

Never had an issue with using the NGK racing plugs in drag racing applications, they have worked fine in Mine, ernies, Ari, dan Schetcher, Ray wilsons, on c16, and Demetrios and Ken Sheepers all used the racing plugs in their methanol burning cars.

Again everyone has their differences in how they do things, doesnt mean they are wrong, just some have had better luck a certain way then others.

yes one word slip up in multi paragraph reply by a non typist :)

trailing = hotter running plug location = needs a colder plug

Platinum is a non ideal element for methanol & leaded racing fuel, just becasue people use it for multiple seconds at a time does not mean its good nor what should be used ;)

When using these elements for both ground or even ground and centre you will always see massive build of deposits up V's using gold paladium or even copper, when most peoples *drag 1 million rwhp* engines only last a few dyno pulls or runs it becomes of irrelevance though :) facts are NGK rotary racing plugs were not designed to run on those fuels especialy methanol or any level of leaded gas regarding methanol its a known catalyst (go read theory of glow plugs & methanol).

Heat range is Heat range is Heat range, if you run hot enough to bow shitty apex seals or wear badly good ones then you hot, very hot and B11EGV's work every bit as good (infact better due to more chemicaly correct centre electrode) as the stupidly expensive full racing type that again was only ever created for a certain application on unleaded petrol.

alot of these guys engines are lasting anywhere from 40 to I've heard some lasting as long as 80 passes.

Aren't the b11egv's gold paladium?

NGK BR9EIX (Iridium)
 

I tried these all around and the motor revved and idled smoother but they simply can't stand the rotary's heat under racing conditions.
On two occasions while doing numerous highway pulls I had my knock sensor go nuts with very high knock levels and after checking everything on the motor....one leading BR9EIX plug was the culprit, half of the porcelain insulator tip was gone !!!!!!
2nd time I went straight to the plugs and same deal. This time the motor had a slight drop in vacuum possibly from scratches but a year later it still runs strong.
With the BUR9EQs all around I never had this happen.

JD