zxrazorxz

as the title says why would people put these plugs in all the plug holes instead of using the leading and trailing plugs? (BUR9EQP is a trailing plug by the way)... what benefits/ negative effects?..

matt

Rotors R Cool

It just a slightly colder setup. For light to moderate street mods. Usually up to around 450rwhp. Really the ideal would be 10.5 race plugs for things over 400rwhp. However, when street driven, the race plug will carbon up quickly and they also cost around $35 each.

zxrazorxz

ohhh ok.. so there just trailing plugs that you use all around.. i live in canada and i talked to ngk and they said i could have the stock stuff or race plugs at 11 in the heat index

Rotors R Cool

11 would be pretty cold. Hotter plugs clean themselves better. But too hot may cause pre-ignition. The higher the number, the faster the plug will dissipate heat.

I make 400rwhp and I have a pair of 10.5 ngk race plugs. When I ran them, they lasted about 5000 miles before the car started miss-firing like crazy. It's just that when your on the street you can't really floor it all the time, therefore the colder plugs won't get hot enough to clean themselves.

I just run 9 all the way around for the street and put the race plugs on when I head to the track.

Just to add. The spark plug holes inside the engine are different sizes. I've been told the reason the trailing plugs are 2 steps colder is because the trailing holes are smaller. So they get hotter. I can't confirm that's totally true, however it makes sense to me.

tnn

iTrader: (3)

hey Rotors R Cool,

quick question: what is the part number for 10.5 ngk that you're talking about? is it B10EGV?

Rotors R Cool

Do a google search for: part number R6725-105

I don't know why but I can't find it on NGK's website. I only find the distributors.

zxrazorxz

the reason why you cant find them is becasue its in the race section im pretty sure heres the link
http://www.ngksparkplugs.com/product...g.asp?mode=nml

click on the product list

matt

j9fd3s

iTrader: (3)

the 9 is the heat range of the spark plug. in NGK lower numbers are hotter, so the stock 7 L is hotter than the stock 9 trailings.

when you make more power, you generate more heat, and you need a spark plug that can carry more heat away, and runs colder.

when a spark plug is too hot it can ignite the incoming air fuel mixture BEFORE the spark plug, preignition.

in a rotary the trailing plug is the first one that sees the fresh mixture, so it actually makes more sense to run 9L and 10.5 or 11 trailings

zxrazorxz

so say i was going to run about 18 psi on a stock motor but ported uim and the supporting mods ( fuel, turbo , ic etc.. ) would it be safe with a tune? im just about to throw her on the dyno after my vehicle inspection and i want to actually drive the car :P

Rotors R Cool

On the left is my cleaned up 10.5 Racing Plug and on the right is my uncleaned 9 Plug with 10k on it. Notice the Racing Plug has one ark point and the factory 9 Plug has 4 ark points. The Racing Plug makes for a way more powerful, accurate, and consistent burn.

tnn

iTrader: (3)

thanks.

wow they are expensive. some says B10EGV is same standard but much cheaper:
https://www.rx7club.com/single-turbo-rx-7s-23/ngk-r6725-105-spark-plugs-54080/

j9fd3s

iTrader: (3)

i wouldn't run 18psi without cold plugs....

Rotors R Cool

How much power will you be making? The boost level really doesn't matter. The more heat you make, the more the air in the motor expands, the more power you make. Therefore, heat range has to do with the amount of power you make.

Get the car tuned on the plugs you will run. Once tuned, you can put in a colder plug for special occasions but you can't put in a hotter plug.

zxrazorxz

well i ment with the 9's in place sorry to confuse :P

zxrazorxz

im shooting for 430-to 480rwhp and im thinking with 9's it would be ok at 18-20 psi.. i'll get a list of my supporting mods

Rotors R Cool

As far as boost is concerned it is more complex than just psi. The more psi the turbo makes, the hotter the air gets. However, the better the intercooler or chemical intercooler works, the colder the air will get before reaching the motor. It all depends on the temp of the air once it enters the chamber and the temp that the combustion reaches.

Rotors R Cool

Ok the 9's should be fine for short pulls at that power. However, if you do any extended boosting or road racing you MUST get a set of 10.5's.

Come to think of it, tuning on the dyno might be a little too much boosting without cooling periods. Idk, I'm not a total expert but to error on the side of caution, if you cross 450 I would really consider the 10.5's.

A little fun info: Steve Kan was telling me that he gained 30rwhp just from going to racing plugs on his E85 car. E85 burns colder so he got away with running 9's at 520rwhp. He's now at 550rwhp with the 30hp bump. I believe that his gain is not to do with the heat range but rather the 1 ark point instead of the factory 4 points.

zxrazorxz

motor- stock ports, ported uim, emissions removed
greddy: t88-33D, ti manifold, type r wastegate, type rs bov, m spec intercooler, pulley kit
walbro 255 lph fuel pump, ss lines, russell fittings, kg parts fuel rails, 850 cc primarys, 1600cc secondarys
aeromotive fpr border racing japan burnout ti exhaust koyo n flow rad
brains: apexi power fc + datalogit, aem wideband, hks evc 6 boost controller+ turbo timer, knight sports 300+ hood

zxrazorxz

motor- stock ports, ported uim, emissions removed
greddy: t88-33D, ti manifold, type r wastegate, type rs bov, m spec intercooler, pulley kit
walbro 255 lph fuel pump, ss lines, russell fittings, kg parts fuel rails, 850 cc primarys, 1600cc secondarys
aeromotive fpr border racing japan burnout ti exhaust koyo n flow rad
brains: apexi power fc + datalogit, aem wideband, hks evc 6 boost controller+ turbo timer, knight sports 300+ hood
prosport boost gauge

sorry for posting twice, the only reason why im asking is becasue the 9's are readily available but the higher ones i would have to order from the states and it could take up to 2 weeks or more to come.. which is retarded..

Rotors R Cool

Well you are in Canada right? So I assume your intercooler works pretty well. You should be ok with the 9's.

zxrazorxz

lol i am in canada.. but it still gets quite hot :P toda it was 36 degress celcius.. which is prett hot.. :P maybe not as hot as in cali.. but its more like a humid hot becasue i live near the ocean

oo7arkman

iTrader: (2)

This is much better confirmed by howard coleman, but I am pretty sure you would be just fine if you want to run all 9's with the addition of a water/methanol injection system. Without that, I would run 10.5's all around with that whp goal. Better safe than sorry with preignition on the rotary. Heat is definately the ememy...

zxrazorxz

definately i totally agree that heat is the enemy.. thats why i am doing the inner fender liner mod and im getting a scoote style hood

GoodfellaFD3S

iTrader: (213)

Heat inside the engine is pretty different from heat inside the engine bay.

If you plan to run 18 psi on a regular basis, if it was my car I'd be running colder racing plugs. If you don't want to spend the money on the expensive NGK ones consider the B10egv's or B10eix's.

People are giving you some good advice in this thread, it's up to you if you want to listen to it

zxrazorxz

thanks guys i'll do the 10s, and well .. heat inside the engine bay is a little different then engine heat i know that but i was refering to let the heat escape the engine bay for my intercooler and my rad would work better.. so technically if your able to cool the engine bay your actually cooling intake temps and coolant temps. so we are talking about the same thing goodfella :P... to a point anyway.
( your talking more about the combustion period i know)

thanks for all the input everyone