Spark Plugs

[Dzaster]

Well I figure since we are a tuning community, we might want to have at least one thread devoted to discussing spark plugs. So here we are.:D

I've been doing some research on spark plugs and the different types, appropriate plug type, etc. etc.

I have been running NGK BKR6EIX-11's(NGK heat range 6, iridium type, gapping of .044") for some time now. However, I came across some writeups that may have suggested a use of a cooler plug based on my assessment of my current plugs condition and my engines setup.
http://i525.photobucket.com/albums/cc340/dzaster96799/Tuning/IMG_2510.jpg

I took that yesterday after a 1-2-3 gear pull to 6000rpm--which is all I wish to take my motor consistenly, when so desired to push it. However, my mistake is that I allowed the car to run while on the decel--when, I believe, I should be cutting the motor after running out 3rd gear. So I think this may be an inaccurate condition to make any conclusions about that pull.

Anyways, I went out and picked up some NGK BKR7E's(NGK 7 cooler heat range, copper type, and ungapped). This brings me to the next part of the plug discussion. I am going to be gapping them to a smaller gapping than previously had with the BKR6EIX's. I'm thinking of going with .035 based on my application--higher compression(9.2:1) for forced induction(FI), methanol/water injection, and of course the turbo charged factor. I'm not even sure that the methanal/water injection has any impact on spark plugs.:confused:


Here are a couple sites I've referenced-not that either is Bible in its content, but mainly for the images/diagrams in each.

Lexus Toyota Spark Plugs (http://74.125.155.132/search?q=cache:x1HbQF08RO0J:www.lextreme.com/sparkplug.html+4agze+colder+spark+plug&cd=9&hl=en&ct=clnk&gl=us&client=opera)

and

Spark Plugs (http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html)

[Turbineguy]

I run one step colder from stock and have been for a good while. That plug tells me your running hot. That's usually how plugs look from running a little lean. White and ashy. They should be a nice toasty brown color with little to no deposits. I think the colder plugs will help out but you may need to adjust your timing a little since the colder plugs pull more heat from the combustion chamber. Also might try adding a little more fuel or add some water/meth flow just to see how it works. Do one thing at a time though. Run the colder plugs at the same gap and then check them. Then the tighter gap and check them. So on and so forth to eliminate one thing at a time.

[Dzaster]

Okay so they need to be gapped, I guess i will stick to the .044" of the originals. I never had any backfire with those--except when letting off the gas and occasionally getting the pop, but I trust that's from the rich mixture.

So then your from your observation, the things are lean and so you don't think that the fact that I don't just cut the motor after running out 3rd really conceals much of the intended 1-2-3 gear pull?

[Turbineguy]

Okay so they need to be gapped, I guess i will stick to the .044" of the originals. I never had any backfire with those--except when letting off the gas and occasionally getting the pop, but I trust that's from the rich mixture.

So then your from your observation, the things are lean and so you don't think that the fact that I don't just cut the motor after running out 3rd really conceals much of the intended 1-2-3 gear pull?

If your running a vent to atmosphere BOV then it's pretty common to get a pop and occasionally a little fireball from the exhaust when running a MAF based system. The reason is that all the air going in has fuel metered for it but when you let off the throttle some of that air vents out and you get a rich spike. The other issue with this is that the ECU see's this spike and pulls a bunch of fuel to correct for it right about the time you get back in the throttle and you get lean tip-in hesitation. Some cars are worse than others about it. Subies are horrible with VTA BOV issues and no one who has a clue runs one unless they just like the noise.

As far as the plugs go you can do some checks under various conditions to see what they look like. They may show rich during cruise and lean under WOT or some other condition. Do some more pulls with a shut off to see and also some normal driving. Water/meth injection will affect how the plugs look most definitely. It has a tendancy to steam clean the plugs, intake valves and piston tops to varying degrees based on how much you inject, what your mix is and type of engine.

[Dzaster]

Does that popping for for MAP sensor types. I have MAP sensor system and my BOV does not recirculate, although it could. I'll have to see where it cycles back too and perhaps give it a whirl. It doesn't happen too often, I know it did it constantly when I had overkill sized injectors. Much much better now though.

I installed them as is, I tried to index them, but only managed to get two. However, my motor the plug drops dead center of teh combustion chamber so not sure if it will even do much. figure I'd try.

As for the meth/water injection, I kinda thought it might change the appearence. Like to see if I can find some pics of spark plugs with a good tune on meth/water injection.

[Turbineguy]

Does that popping for for MAP sensor types. I have MAP sensor system and my BOV does not recirculate, although it could. I'll have to see where it cycles back too and perhaps give it a whirl. It doesn't happen too often, I know it did it constantly when I had overkill sized injectors. Much much better now though.

I installed them as is, I tried to index them, but only managed to get two. However, my motor the plug drops dead center of teh combustion chamber so not sure if it will even do much. figure I'd try.

As for the meth/water injection, I kinda thought it might change the appearence. Like to see if I can find some pics of spark plugs with a good tune on meth/water injection.

MAP sensor setups are typically fine with a VTA BOV since the air is vented prior to any measurement. In actuallity the air isn't even measured directly anyhow. Do all the plugs look the same or is there a difference between them?

[Dzaster]

They all look like that one pretty much. The new one is in, kinda notice the difference in power--prolly being copper(not iridium), colder, and since I had to gap it, I just gapped it to .036". I only went to run some errands in town so no real pulls nor did I bring tools to assess the plugs. I plan to cap these to the prvious .044" in a bit here and then go put gas and do a couple pulls/datalogs/spark plug assessments.

[Turbineguy]

They all look like that one pretty much. The new one is in, kinda notice the difference in power--prolly being copper(not iridium), colder, and since I had to gap it, I just gapped it to .036". I only went to run some errands in town so no real pulls nor did I bring tools to assess the plugs. I plan to cap these to the prvious .044" in a bit here and then go put gas and do a couple pulls/datalogs/spark plug assessments.

Copper plugs work very well but require pretty frequent change out due to lack of errosion resistance. They conduct much better than all the iridium or other types. The iridium and other types of wonder metals are used because of their hardness under high heat conditions but they don't actually conduct as well and some require a tighter gap than the same plugs with copper electrodes.

[Dzaster]

So I took them out and gapped them to .044". It was misfiring so I just turned around and came home. Gonna regap smaller and smaller until it stops misfiring. At least I know at .036" it ran fine.

So I'm thinking the difference in heat ranges(new copper ones being colder), is enough to cause misfire desipite the same gapping.

[Speedtek]

hey, i am a new member here..
however you should gap your plugs even smaller you can go down to 0.5mm which is 0.020"

I think you are misfiring because of your plug gap??

[Turbineguy]

hey, i am a new member here..
however you should gap your plugs even smaller you can go down to 0.5mm which is 0.020"

I think you are misfiring because of your plug gap??

The gap needs to be as big as possible without causing a misfire. The wider gap allows a hotter spark and results in better throttle response and low/midrange torque.