im going to get some new ngk plugs.. wanting the 2step colder ones but seem to only find online? can u buy them at like autozone or advanced? anyone know? and what should i gap them at? my mods are in my sig. thanks guys for any help

 

NGK bkr8e , i dunno i got my 7e from advance

 

Advance, NAPA, and O'Reilly's are the places that usually have em. I'm getting mine from O'Reilly's for like $1.70 apiece.

 

2 step colder plugs may not be the best for everyday driving. Actually, they are probably unnecessary unless you are spraying ALL the time. I would say 1 step colder will probably be fine.

Gaps are tricky, not every car is going to be exactly the same. The idea is to get the gap as wide as possible without getting spark blowout. The only way to know what gap your car likes best is trial and error. With a 2.8 and nitrous... I would probably try .035 and see how that feels.

 

I have gone to NAPA and they've always had the BKR7E's (one step colder).

Why do you want two step colder? Any special application we should be aware of?

 

thanks for the imput guys i didnt know their was that big of a difference between the 1 step and the 2 step.. ill be going with the 1 step

 

For every step colder you go with a spark plug you are reducing the combustion chamber temps by 75 - 100C. Optimal heat range for the combustion chamber is between 500 - 850C. The best thing to do would be to go 1 range colder then log the car to see if you get any knock at high load and high RPM. If you see any knock at high RPM while spraying then you can go another step colder. Driving around on plugs that are too cold will foul the plugs out pretty quickly though.

 

awesome great info thanks a lot

 

If I get the brk7e plugs on a stock motor, would that hurt anything ?

 

Will it "hurt" anything, probably not in the way of physical damage... well at least not in the short term.

Here is the problem with dropping spark plug heat range on a stock car, especially a dialy driver. Lets say on a stock cobalt ss/sc with the stock spark plug size during daily driving your combustion temps sit about 600C. This allows the car to burn the fuel as efficiently as possible, helping you to get the best fuel mileage as well as keeping carbon from building up. At high load you will be about 725C which is right in the perfect range. Now, we put a step colder plug in the car. The combustion chamber temps drop to 520C (which is the low end of the "optimal" range) and the car starts to not burn fuel as efficiently. At high load you will be about 625C which is still ok but starting to get toward the low end of the heat range. You could very well start to see a drop in fuel mileage as well as carbon build up on the spark plugs and in the cylinder itself. It will cause the plugs to foul quicker and over an extended period time you could see some nasty carbon build up.

If you drop pulley sizes your high load combustion chambers become a big factor. With a 2.9" pulley you are looking at a 75C rise in tempurature under load. That would put your combustion chamber temps at 800C under load which is starting to get very close to the upper limit. Once you throw a colder plug in you bring the high load combustion chamber temps back to 720C. Of course this does cause the daily driving temps to drop down to 520C so you have to run the car hard at least every once in a while just to help keep carbon build up down. Guys with lots of mods and pushing high boost may even need to go two steps colder to keep their high load combustion chamber temps down, but again that would take your "daily driving" temps to close to 440C, which can really start to cause heavy carbon buildup and have a big impact on fuel mileage. Really to get the best performance and fuel mileage you would need to swap spark plugs out depending on how you are driving, but that would be a pain in the ass so a happy medium is used.

 

You just outlined what I was fearing about swapping stages in plugs and modding our car in general - as you drop pullies, dropping the spark plug temperatures becomes necessary because it combines with the other heat created and can cause knock. However, in doing so you shift the whole range down, which includes your daily driving, thus accelerating carbon buildup.

I wonder since you're not in boost 90% of the time if it would be a good idea to have a daily driving tune with less high end timing and run stock temp plugs then just pull those for the colder ones and add the timing when you go to the track. For $8 I'm kinda curious if it'll add mileage and decrease carbon buildup since I only go to the track once in a great while.

 

That would of course be the ideal situation. The problem is that people don't want to swap plugs out all the time because they are inherently lazy and want to just put it in and leave it as long as possible... (me included).

You could easily leave the same tune on the car and just stay away from WOT during daily driving. Then all you would have to do is swap plugs at the track and you are already good to go. Of course, having seperate DD and track tunes is not always a bad idea.

 

The idea behind the separate tune is so you have the option to floor it without risking detonation on the street (for you kids who have ricer problems). You'll make less power but obviously that's more favorable than having to buy new pistons. Like you said, that only really works for people who own HPTuners. I think I may try that just for ***** and giggles to see if I get any results.

I just noticed you're gapped at .039, how's that working out for ya? I've been toying with different gaps recently and am wondering what the upper limit for blowout really is. Most people tend to gap by a set interval (.035 or .040) instead of the numbers inbetween.

Cheers.

 

For my car, the .039 works well. If I go lower it still works just fine, but I usually change the plugs out at every oil change. After about 6K miles the gap is uaually around .040~.041 and it still runs ok but starts to get rough up top if the gap gets more than .041. I could gap smaller and leave the plugs in alittle longer, but they are so easy to change that I would rather just gap them at .039 and change them every 6K or so. One of these days I may try going back to iridiums, but I would like to get the car tuned a little more on the copper plugs then do some playing with the iridiums to see if I get any knock with them compared to the coppers. I may get around to playing with them this summer sometime.

 

I had mine in for about 12k gapped at .035 before I started getting a little bit of misfires in the daily driving range. Swapped them out and it seems to have gone away, but I also upped my gap to .037 to see if it would help the random idle misfires my car seems to throw. This is the other reason I'm somewhat interested in trying the hotter plugs.

 

Here for a newb question;

So, what would be a good gap to run NGK BKR7E's on my Stage 2 DD? I'm going through all my regular maintenance this weekend, and this has been on my mind for a while.

Thanks in advance

 

If you are going to run BKR7E on a stage 2 (no reason you can't run BKR6E or BKR6EIX on a stage 2) I would run the gap at .040. No reason to close the gap on a stage 2 unless it is giving you problems.

 

Agreed. Keep in mind in the box they usually run around .030 so ALWAYS check your gap.

 

Awesome guys, thanks for the help.

What reasons would you say to use BKR6's have over the 7's?

 

Because.....

...since I didn't want to retype everything. Stage 2, especially a DD, is more than likely not going to see enough of an increase in combustion chamber temps to go to a colder plug. I ran BKR6EIX and BKR6E in my car when it was stage 2 and it ran great.