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What spark plugs are you using and how are they working out? Any recommendations for someone looking to install new spark plugs? Is there a suitable upgraded or better performing spark plug to go with? I have read that for BMW's, the best way to go is with factory ones, could this be true?
 

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Discussion Starter #4
Thank you for confirming my suspicions :D
 

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I've been running NGK-BKR7EIX, these are Iridium & one step colder than stock. Based on the setup of my motor & the way I run it, these plugs work great for me. Having said that, if your motor is closer to stock & and your not taxing it constantly; go with stock plugs in a stock heat range.


http://www.amazon.com/NGK-BKR7EIX-Iridium-Spark-Plug/dp/B000GZAUX6
This one is one step colder.

http://www.amazon.com/NGK-BKR6EIX-Iridium-Spark-Plug/dp/B000BYDA8E
This one is "stock" heat range.

Good luck.
 

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I've been running NGK-BKR7EIX, these are Iridium & one step colder than stock. Based on the setup of my motor & the way I run it, these plugs work great for me. Having said that, if your motor is closer to stock & and your not taxing it constantly; go with stock plugs in a stock heat range.


http://www.amazon.com/NGK-BKR7EIX-Iridium-Spark-Plug/dp/B000GZAUX6
This one is one step colder.

http://www.amazon.com/NGK-BKR6EIX-Iridium-Spark-Plug/dp/B000BYDA8E
This one is "stock" heat range.

Good luck.

Does this mean that the stock plugs, or even a version 1 step colder (eg, the BKR7EQUP), gave you problems? Are the Iridiums quantifiably better or have you just had good luck with them?
 

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Does this mean that the stock plugs, or even a version 1 step colder (eg, the BKR7EQUP), gave you problems? Are the Iridiums quantifiably better or have you just had good luck with them?

I never had any problems with stock plugs. But I only had my Bimmer for 6 months & less than 1K miles at the time of my performance build.

Quantifiable: no. I just have had good luck with them. I can't remember if Adam was using them at the time, but I know "ritos530i" was using them with his turbo setup, he recommended them to me. A few other forum members running F/I were successfully use this plug, that's why I adopted it.

When I finally get my nitrous installed I'll run the NGK BRK8EIX, 2 steps colder.
 

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when running catless, aa tune & cai snorkel intake(dinan) should i run stock or one colder?
tia
 

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I'm running the Denso IXU24 plugs. They're Iridium and have a heat range of "8" - stock heat range for the M3. I chose Denso because over at M3forum I couldn't find anyone who was dissatisfied with the Densos, while there were a couple people who apparently didn't like the NGKs. Prices were more or less the same, so I decided to try out the Densos. They have a finer tip electrode compared to the NGK Iridium plugs, so there's theoretically a small advantage there. My gut feeling is either would've been fine.
You're running one heat range colder than stock. Why? What advantage do you feel the Iridiums offer over the stock Platinums (BKR6EQUP)?
FWIW, the OEM Bosch plugs also have a heat range of 7. NGK's marketing literature seems to indicate that the Iridium plugs are superior to the laser platinums. Since the Iridiums tend to be cheaper, and are supposed to be better, I can't see the harm in switching to Iridiums. Most of the newer BMWs have switched to NGK Iridium plugs anyway
 

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I'm running the Denso IXU24 plugs. They're Iridium and have a heat range of "8" - stock heat range for the M3. I chose Denso because over at M3forum I couldn't find anyone who was dissatisfied with the Densos, while there were a couple people who apparently didn't like the NGKs. Prices were more or less the same, so I decided to try out the Densos. They have a finer tip electrode compared to the NGK Iridium plugs, so there's theoretically a small advantage there. My gut feeling is either would've been fine.


FWIW, the OEM Bosch plugs also have a heat range of 7. NGK's marketing literature seems to indicate that the Iridium plugs are superior to the laser platinums. Since the Iridiums tend to be cheaper, and are supposed to be better, I can't see the harm in switching to Iridiums. Most of the newer BMWs have switched to NGK Iridium plugs anyway
The finer tip of the Denso, theoretically, is slightly better for "performance" but worse for longevity. Manufacturer heat range numbers can't be compared as companies have their own numbering schemes (for some brands a larger number indicates a hotter plug and for others it means cooler). Based on how BMW spec'd them, the Bosch 7 is probably pretty darn close to the NGK 6.

http://www.ngk.com/charglossary.asp?kw=Heat+range

Marketing, gut feeling, speculation, etc don't mean much. Yes, there are numerous options that will work without causing problems. Different plugs won't gain you any power or fuel economy, so as long as they're not too hot and leading to detonation/pre-ignition issues or too cold leading to fouling it really comes down to longevity. This is why when someone states that they use a non-stock plug, I'm curious as to whether there was a reason or if they just tried it and it worked. Most people fall into the category of "I tried it and it didn't seem to cause a problem." We already know that in a stock M54 with the recommended stock plugs that the plugs are good for roughly 100k so I guess I find it hard to believe that other options are "better" or that their is any real rationale for shopping around. Perhaps other plugs are a little cheaper but I typically pay less than $7 per plug for the NGKs so I don't see where there are any real significant cost savings to be had.
 

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Here's what I have noticed:
The BMW NGK plugs and the NGK plugs break off the side electrodes after about 3 races on them. At that point I tried some Bosch plugs and they haven't broke one off yet. You have to remember, I'm running this thing flat out for up to 6 hours at a time. I'm pretty much an isolated case.

As for plugs, this is not 1965. Cars have 4 side electrodes just so they can go 100K miles and still pass emissions. Cars used to need a plug replacement every 10K. We all have a complex ECU that can adjust timing and fuel quantity. Plug heat range is not as critical as it was when you had a carb and a points distributor. Plus we have a coil pack on each plug, so we don't have to rely on a mass of plug wires, a rotor and a single coil trying to fire all of those plugs. Plus we are not running that dreaded leaded fuel anymore.

Spark plug marketing is what drives the sale of replacement plugs. Usually, people will believe they feel a difference when they put in a new set of plugs. There are times that is true because if you are like my brother in law who drive his Taurus 165K miles on the original plugs, a new set made the car start and run like a champ.
 

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The finer tip of the Denso, theoretically, is slightly better for "performance" but worse for longevity. Manufacturer heat range numbers can't be compared as companies have their own numbering schemes (for some brands a larger number indicates a hotter plug and for others it means cooler). Based on how BMW spec'd them, the Bosch 7 is probably pretty darn close to the NGK 6.

http://www.ngk.com/charglossary.asp?kw=Heat+range

Marketing, gut feeling, speculation, etc don't mean much. Yes, there are numerous options that will work without causing problems. Different plugs won't gain you any power or fuel economy, so as long as they're not too hot and leading to detonation/pre-ignition issues or too cold leading to fouling it really comes down to longevity. This is why when someone states that they use a non-stock plug, I'm curious as to whether there was a reason or if they just tried it and it worked. Most people fall into the category of "I tried it and it didn't seem to cause a problem." We already know that in a stock M54 with the recommended stock plugs that the plugs are good for roughly 100k so I guess I find it hard to believe that other options are "better" or that their is any real rationale for shopping around. Perhaps other plugs are a little cheaper but I typically pay less than $7 per plug for the NGKs so I don't see where there are any real significant cost savings to be had.
As you mentioned, the difference between spark plugs comes down to longevity (and I guess price). All other specifications being equal, an iridium plug should last longer than a platinum plug. It tolerates extreme temperatures better than platinum, and it withstands arc-erosion better than pretty much anything else out there. In most cases, Iridium plugs are a bit more expensive than other types of plugs, but that's not the case for the M54; seems the BKR6EIX tend to run ~$2/plug cheaper compared to the EQUP plugs. Since they should perform at least equally as well, last longer, and cost less it seems like a no-brainer to take the EIX plugs. Some people question whether or not the stock plugs can last 100k miles; the iridiums are more likely to make it that far.

I changed my plugs because according to BMW's service schedule, my plugs were a bit overdue. Honestly, the main reason I didn't buy the OEM plugs is because they are surprisingly difficult to acquire, and can be quite expensive ($13/plug aftermarket and more like $30/plug at the dealer). The Denso Iridiums (which I read are very popular amongst M3 owners) were cheaper ($8/plug iirc). I did consider the NGK Iridium plugs, but the Densos were more widely used in the community for whatever reason, so I decided to stick with what's tried and tested.

Also, there may be something to mrshelley's electrodes breaking off. The E39 M5 is known to see an unusual amount of electrodes breaking off, and those came with the NGK BKR6EQUP plugs.
 

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I used denso iridium in my titan and they were crap. No power gain and worse mpg. Went back to a new set of ngk and loved them. Will put ngk in my 330 when i change em.
 

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For what it's worth I have changed A LOT of spark plugs in my line of work, I have noticed that on most of the M54 engines there is a definite clean patch that develops on the intake side of the spark plug and just a few degrees back. This is an obvious firing line or burn line where the flame seems more obvious.
With the plugs I run and recommend being the NGK BKR6EK they have a 1.5K ohm internal resistance vs. the BKR6EQUP that has a 4.5K ohm internal resistance. Our motors have fairly high compression and letting the spark out quicker once you have achieved arc-over is from what I gather supposed to be better.
So with the BKR6EK plugs only having 2 ground electrodes I line them up inline with the engine to ensure that the flame is not blocked by a ground electrode.
 
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