Spark Plugs, yes I know this is the 1 millionth thread please humor me I did a search

[keirnna]

I've been trying to fugure out which copper plugs will work in the SR20DET after a little research and guessing I came up wth these: NGK # BKR7ES-11

I ordered twelve since I plan on changing them every other oil change, or possibly every oil change. I posted originally on club240.com, but it seems that forum is only for decorations. This thread would also make a good sticky. Here is some good spark plug information I had sitting around:

I also had no choice but to go with Iridium Plugs on my STi, because as of now NGK only makes about two plugs for the STi. The stock Iridium plugs, and one stage colder iridium plugs.

Here is some good info I pulled off NASIOC:

Here are some of the thermal conductivities of some commonly used metals (Watts / centimeter*Kelvin) :
Zinc == 1.16
Aluminum == 2.37
Copper == 4.01
Steel == 0.70 - 0.82
Platinum == 0.716
Iridium == 1.47
You can easily see why Copper is the metal of choice for the core of the spark plug. It's just about the best thermal conductor on earth. Occasionally, you still find plugs with an aluminum core - stay away!


So, what we want is the sharpest tip possible such that it does not melt the electrode nor does it stay so hot as to cause pre-ignition. Let's break it down:

Bare Copper
They have a low melting temperature and the tips will vaporize away - they have a very wide tip so each little bit that disappears will not change the gap size greatly, but they still must be inspected often to make sure there is sufficient electrode material left. They are great for very hot running engines which must avoid pre-ignition at all costs since the wide tip will not stay hot(high boost forced induction and nitrous engines come to mind).

Platinum
Platinum plugs are usually constructed similar to copper plugs except that they have a thin coating of Platinum sputtered onto the electrode tips, about 0.010" thick (a human hair is about 0.005" thick). Because of the high melting point of Platinum, the tips can be made significantly sharper without fear of the gap changing shape. But the copper core is still sufficient to whisk the heat away fairly quickly. These are great all-around plugs, particularly for use on NA engines, and they should last a very long time. Very high heat engines should probably not use them because the sharper tips may not conduct enough heat away to prevent pre-ignition under adverse conditions.

Iridium
This is the new guy on the block. They are much like platinum plugs just with iridium in place of the platinum. Because of the extremely high melting point of iridium, they can have very sharp tips without risk of melting and they should last a very long time. These would be best for high-rpm NA engines where the sharpest tip is needed for the best spark, but there is little danger of pre-ignition.

Strange electrode geometries
For the most part - don't buy it. Splitfire (one of the originators) is undergoing all kinds of lawsuits for false claims. I won't go into detail here, but if you think about the Gauss' law thing (sharp points vs. brass balls) you really can't get any better a spark than between just two sharp points, and you're also increasing the shrouding of the spark with more or bigger electrodes.

An exception to this is retracted gap plugs ("surface-fire"), which are a lifesaver if you have severe detonation or plug-piston clearance problems, but they take a very powerful ignition to spark (no sharp points!) and they don't often get a good clean burn going.

Other tips
** Disregard any BS about the electrical difference of the metals - as I stated in my previous post, the micro-ohm difference in 0.010" of Copper vs. Iridium means exactly squat when there is a huge air gap equivalent to tens of mega-ohms of resistance right there in series with it.

Here's my question: I've been told before that Iridium Plugs can me "blown" out by high boost aplications, and that copper work much better for high boost engines. Can the spark actually be blown out or hindered by the high boost, and would changing to copper plugs yield more performance, or a safer running car? I asked NGK about this, and they said go with Iridium every time, I however feel that since Iridium plugs cost about 300% more than copper NGK may just be out to make a buck. NGK said that all of the car's they sponsor run Iridiums, and may of them are turbo charged cars. I am sure with the right tuning most plugs will work fine, but that doesn't mean that the car will achieve it's max HP/TQ. That is what I am looking for, while having a safley tuned engine.

So do you guys think I was right getting coppers or should I have maintained the status quo with Iridiums?

[TheSparo]

from what i have learned, the coppers will yield better performance/driveablilty, but last a shorter amount of time, whereas the iridiums will last longer, but won't give the better spark...
i run coppers myself...

[srpowered240sx]

i have run iridiums a heat range colder since day one. i switched to coppers for a few days while i was troubleshooting a problem and didnt feel any difference. just watch your gap on your iridiums. it also kinda depends on what fuel octane and boost levels you run.

[keirnna]

That is exactly what I have been told, and thought. Since it is super easy to change plugs in the SR20, I will use the coppers. Where my NGK part #'s correct?

[keirnna]

What gap should the copper plugs have? .44 is what the KA24DE plugs would be gapped to.

[srpowered240sx]

Originally Posted by keirnna

That is exactly what I have been told, and thought. Since it is super easy to change plugs in the SR20, I will use the coppers. Where my NGK part #'s correct?

"after a little research and guessing I came up wth these: NGK # BKR7ES-11"

not really, a stock heat would be bkr5e-11. but i rock a 6 heat range. a 7 i think would be too cold unless you run a ton of boost. i would use a ngk number bkr6eix11 (or stocking number 3764) for iridiums, or like you said you are gonna do for the standard v powers, go to the store and get a set of #2756 plugs, (ngk number bkr6e-11)

on a side note, when the car is still not completely warmed up, i do smell some unburnt gas from time to time, but as soon it warms up completely, it is gone. i think it has a lot to do with no cat.

[srpowered240sx]

oh yeah, and stock boost, .040 gap should be fine, but any higher go with .035 gap IMO

[jedi_car_fan]

^^^ I thought 6s were stock in the jdm rwd SR20det ? and the G35 with the SR20 etc has stock heat range 5 ?

Anyhow... I tried running 5s "from the G35" and she didnt like it... I run a BKR6.

[srpowered240sx]

you may be right, i was always under the impression it was 5's. i never checked the stock ones, i just used the 6's right out of the gate.

[keirnna]

Originally Posted by srpowered240sx

"after a little research and guessing I came up wth these: NGK # BKR7ES-11"

not really, a stock heat would be bkr5e-11. but i rock a 6 heat range. a 7 i think would be too cold unless you run a ton of boost. i would use a ngk number bkr6eix11 (or stocking number 3764) for iridiums, or like you said you are gonna do for the standard v powers, go to the store and get a set of #2756 plugs, (ngk number bkr6e-11)

on a side note, when the car is still not completely warmed up, i do smell some unburnt gas from time to time, but as soon it warms up completely, it is gone. i think it has a lot to do with no cat.

Yeah actually really. If you read my post I am going with coppers. Those are the correct copper plugs. I don't want V-power, or Iridium. The BKR5ES-11's are the stock plug for the KA24DE, an N/A car. If NGK heat range 6 came stock in the SR20DET I think NGK 7's should be good. I'm new to these boards, but not stupid. This is not my first turbo car.

Now on the gapping. You cannot change the gap more than .08 without moving the electrodes out of their most efficient zone. So plugs that come .44 are not recommended to be moved to .35. Can any one be sure what the propper gapping is? Are there any translated manuals or anything? I just want to make sure that my gapping and everything is correct. Guessing is not a game I like to play. Thanks for all of the help guys !

[evilimport]

Originally Posted by keirnna

NGK # BKR7ES-11

These are what I run and they are gapped to .28 with zero driveability issues. I've put several thousand miles on them like this... no probs whatsoever.