[Rumbloki]

Has anyone experimented with different spark plugs or seen a comparison using the S55?

[M2C_OZ]

If tuned it's recommended to use ngk 97506 gapped at either .018 / .020 / .022

[F87source]

Originally Posted by M2C_OZ

If tuned it's recommended to use ngk 97506 gapped at either .018 / .020 / .022

No absolutely not, this is a huge misconception in the tuning community and can actually lead misfiring issues due to incomplete combustion.

Stock plug heat range works fine for stock and tuned power levels up to 700WHP, stock gap seems fine for 400 range as per s55's (only gap down when you start to misfire). The only point where you will want to go to a colder plug (keep in mind the s55 and m2 n55 plug is already colder than the standard n55 plug and 2 steps colder than an n54 plug iirc) is when you start experiencing misfires from a plug being blown out and confirmed by data logs and read the plug and it is deemed necessary to go to a colder plug.


So in my opinion stay with the stock plug and stock gap, this way you not only save your money as a stock bosch plug is $6/per plug at FCP but you will also save yourself a headache diagnosing misfiring and stutters.



Here is a quote from Justin at twisted tuning: "Just recommending someone go to a one or two step colder plug because of a changed tune is not best practice. Poor combustion and misfires can occur.
The stock heat range in the N55 is fine to 700whp or so. One step colder than N54 stock. And the same heat range as nissan GTR stock plugs. GTRs run the stock heat range to 800whp or so.
The old recommendation of one step colder per 100whp is also not accurate. I mention this because ive seen it spewed on a lot of these groups. By that recommendation people would be looking for 6 step colder plugs in some cars.
Also, which is a slightly different topic (has nothing to do with your post) but people need to stop immediately recommending .018 plug gaps just because a car is tuned.
Ideally you want the largest gap possible for a setup that promotes complete combustion without blowout (failure of the spark to jump the gap).
Long story short.... proper spark plug recommendation should come from reading the plugs for a specific setup. Not a blanket recommendation from something you’ve seen people do.
IE- my A90 supra for instance. I’ve seen some tuners already recommended colder plugs or gapped down plugs for immediate process after tuning. Well, my car... stock plugs, stock gap. At over 700whp and 720wtq and reading the plugs show no issues. And the car has not skipped a beat or misfired at all."

[Higgs Boson]

The other issue is that you need to run a plug that suits the majority of your driving. Just because a car has 800 hp doesn't mean it needs colder plugs if you're driving it to work and grocery store and occasionally punching it. You'll just foul the plugs all the time.

Run a street temp plug, if you want to track your high hp car and keep the RPMs high and get it all hot, swap plugs for the track.

[SEAT TIME RULES]

Pro Tuning Freaks recommends the NGK 97506 spark plugs gapped at 0.022-0.023, for the S55 motor when running their Stg2 OTS.

I'm running those and my car runs great with my Custom Jordan tune...

[F87source]

Originally Posted by SEAT TIME RULES

Pro Tuning Freaks recommends the NGK 97506 spark plugs gapped at 0.022-0.023, for the S55 motor when running their Stg2 OTS.

I'm running those and my car runs great with my Custom Jordan tune...

ZM2 has some weird stuttering issues last year that I helped him diagnose and it turned out to be plug gap related. But his engine is an n55 also running bm3 stage 2+.

So just blindly recommending people to run a tighter gap for no reason is imo stupid advice. People should instead read their plugs and look at their logs to see if a colder plug or tighter gap is warranted instead of following the "pack".

[SEAT TIME RULES]

Yeah I agree.....

I've heard conflicting thoughts on plug gaps on the S55 tuned.

Here's what BM3 says:

When tuning your BMW N20, N55, S55, N63TU, S63TU it is recommended to go with 1-step colder spark plugs. We've found the NGK SILZKBR8D8S (97506) in the picture attached working great when gapped to appropriate spec. If you'll be running less than 30psi of boost we suggest a 0.022-0.023" gap. We've gone to 0.018" on some cars with 30+psi but in most cases that isn't needed and will cause rough idle in some cases. In most cases though we just go with the 0.022-0.023" gap and call it a day.

[Rumbloki]

Thanks, guys. I'll add checking plugs to my routine maintenance.

[F87source]

Note I need to clarify something, while the stock plug heat range may be good up to 700 whp, the gap may need to be tightened as power and thus boost levels increase to prevent the spark from being blown out. This shouldn't be a huge factor until you are deep into the 500whp range, and you will be able to tell by misfires.

These issues can be solved by tightening the gap or even better, a higher powered coil kit which can help facilitate larger gaps, because you want the gap to be as big as possible without blowing out.

[TopJimmy]

Just watch out with changing coil packs on the S55. The OEM Delphi coils are best. Aftermarket are lower quality, including BavAuto and IP. I tried and found out...

[F87source]

Originally Posted by TopJimmy

Just watch out with changing coil packs on the S55. The OEM Delphi coils are best. Aftermarket are lower quality, including BavAuto and IP. I tried and found out...

+1

[BMW DIY Guy]

Originally Posted by F87source

Note I need to clarify something, while the stock plug heat range may be good up to 700 whp, the gap may need to be tightened as power and thus boost levels increase to prevent the spark from being blown out. This shouldn't be a huge factor until you are deep into the 500whp range, and you will be able to tell by misfires.

These issues can be solved by tightening the gap or even better, a higher powered coil kit which can help facilitate larger gaps, because you want the gap to be as big as possible without blowing out.

Can you share any specifics on plugs, gap and possible coils? I just jumped to stage 2, 503rwp (yesterday) and am experiencing knock.

Simple 5min drive to the grocery store and could feel something different today. Pulled logs and pretty consistent knock from 1900 to 2500 rpk, though can show at higher rpm.

I can easily flash back to the stock CS or C map, but my immediate thought was plugs. I have 19k miles on and don't know if the plugs have been changed previously.

thank you for the insight and any thoughts

[F87source]

Originally Posted by BMW DIY Guy

Can you share any specifics on plugs, gap and possible coils? I just jumped to stage 2, 503rwp (yesterday) and am experiencing knock.

Simple 5min drive to the grocery store and could feel something different today. Pulled logs and pretty consistent knock from 1900 to 2500 rpk, though can show at higher rpm.

I can easily flash back to the stock CS or C map, but my immediate thought was plugs. I have 19k miles on and don't know if the plugs have been changed previously.

thank you for the insight and any thoughts

Ok so you have 2 real options for spark plugs:

1) The OEM bosch plugs which are totally fine to use in high power level situations, and their heat range is also fine up to 700 whp. Now the part number is Bosch ZR5TPP330A (the A version iirc is the updated one that doesn't crack there was TSB on this).

With Bosch plugs the 3rd digit is the heat range so this has a bosch heat range of 5 which is equal to NGK's heat range of 7.

2) NGK 97506 the ngk heat range of this plug is 8 which is equal to a bosch heat range of 4. This plug is 1 step colder than the m2 n55/s55 stock plugs and 2 steps colder than the stock n54 plug.


With plugs like I said earlier no need to go colder for no reason as it can lead to bad combustion, but that doesn't seem to be an issue on these cars so it is your choice which option you want. For me I am happy with the stock plugs and they are also 1/4 the price of an NGK so i'm also saving money in the process. But do not let money savings prevent you from doing what is right for your car, if your car calls for it go for what it needs - but since I don't see many high 600whp-700 whp m2's there really is no need for it (it's like buying botique oils for no reason). Also remember to read your plugs when you change them to see if you do need to go colder, that is always the key to moving heat ranges, the 700 whp number is just a guide line it is always best to read your logs and plugs to determine if you need to switch - just like you would with a used oil analysis.




For gap start with the stock 0.028" gap and move your way down until the misfires stop. If you go too small you will get incomplete combustion and misfires and rough idles. Too big and your spark will blow out and the same misfires will occur at high boost conditions. Generally speaking mid 400 whp you won't have an issue with stock gap as that is where the m4 gts and m2cs are running. But since you are at 500 whp and with old plugs this could be a sign you need to get new plugs (tuned cars should get it ever 20k miles or less, and every 4 years as per bmw).



If you gap gets too ridiculously small like smaller than 0.022" then you probably should get upgraded coils. For the S55 there are no offerings yet (because of the air to water intercooler) - but this will change when nexyus makes the B58 coil conversion for the S55. This will be the best offering yet because the B58 coils make more power than the precision racewerks kit with less dwell, more spark duration, all while heating up the IGBT on the ecu less meaning better life time for that component. So wait on that kit.

But honestly you can get coils on a stock car too if you want, it just depends on if you want to spend money for no reason or not. Personally I would consider getting coils at a spark gap of 0.024" or less, but if you really don't want to spend alot of cash on a coil upgrade you can push it to 0.022 or less or whenever decreasing your gap sizes just don't cut it anymore and you keep misfiring no matter what. Remember our delphi coils are already more powerful than the stock n54 coils and those guys run upgraded eldor coils (same power output as our delphis so don't waste your money switching to those) for super high power builds so there really isn't a huge need to upgrade coils prematurely.


So let me sumarize this last part because it was likely convoluted because I like to ramble:

1) If you have money to burn upgrade coils even on a stock car - why not. (If you have alot of money consider giving me some lol JK donate it to charity or something, or save it for the future I am ok).

2) If you really want to optimize your ignition setup and rather spend money here over an exhaust, colored engine cover or whatever, (a really good idea compared to the former) upgrade when your gap size gets to 0.024" or smaller.

3) This one over rides all of the above, when you begin to continue to gap down but it doesn't solve your misfires at high rpm. Or your small gap size at high rpm works fine but low rpm it starts to stumble you should get upgraded coils so you can run a bigger gap at all times.


Hope this helps, and you probably should change out your plugs soon. On a used car I normally do all the belts, fluids, plugs, filters, brake fluid and pads even if not required.

[F87source]

Originally Posted by BMW DIY Guy

Can you share any specifics on plugs, gap and possible coils? I just jumped to stage 2, 503rwp (yesterday) and am experiencing knock.

Simple 5min drive to the grocery store and could feel something different today. Pulled logs and pretty consistent knock from 1900 to 2500 rpk, though can show at higher rpm.

I can easily flash back to the stock CS or C map, but my immediate thought was plugs. I have 19k miles on and don't know if the plugs have been changed previously.

thank you for the insight and any thoughts

Oh yeah i forgot to answer the second part of your question.

Ok what were you doing during that 5 minute drive? WOT? Have you had your logs read to make sure the tune wasn't too agressive for your fuel quality?

It is hard to say what it could be without looking at logs, it may be plugs (mostly likely to cause misfires not knocking) or it could just be standard knock. It is unlikely to be plugs though if it is occuring even during conditions without high boost.


But my previous post was just to answer what your options are for plugs, gap, and coil. We still do not know what is causing your issues. For now run a stock map to avoid engine damage.

[BMW DIY Guy]

Originally Posted by F87source

Oh yeah i forgot to answer the second part of your question.

Ok what were you doing during that 5 minute drive? WOT? Have you had your logs read to make sure the tune wasn't too agressive for your fuel quality?

It is hard to say what it could be without looking at logs, it may be plugs (mostly likely to cause misfires not knocking) or it could just be standard knock. It is unlikely to be plugs though if it is occuring even during conditions without high boost.


But my previous post was just to answer what your options are for plugs, gap, and coil. We still do not know what is causing your issues. For now run a stock map to avoid engine damage.

Stellar info and lots to digest.. I am reading up now and likely will get a set of the Bosch on the way regardless.

All LOW RPM and with very consistent knock at 19xx rpm to around 22xx rpm.. the dyno pass logs show a few (one or two total across multiple logs) knock at HIGH rpm (7k) but very little.

This right now is super consistent at low rpms in that low 2k range. I pulled 9 logs yesterday, all low RPM, very gentle driving in traffic. (going to the store) and 6 of them show knock, 3 in a row do not. These are all OTS S2 maps.

Here is a perfect example:

https://www.bootmod3.net/log?id=6065...0b4308c75b6f89

Two logs after that I have 3 in a row that are completely clean..

Also for more info: Backtracking logs from the CS map, I find knock though less. I only have a single log from stock C, and it shows a single knock.

[F87source]

Originally Posted by BMW DIY Guy

Stellar info and lots to digest.. I am reading up now and likely will get a set of the Bosch on the way regardless.

All LOW RPM and with very consistent knock at 19xx rpm to around 22xx rpm.. the dyno pass logs show a few (one or two total across multiple logs) knock at HIGH rpm (7k) but very little.

This right now is super consistent at low rpms in that low 2k range. I pulled 9 logs yesterday, all low RPM, very gentle driving in traffic. (going to the store) and 6 of them show knock, 3 in a row do not. These are all OTS S2 maps.

Here is a perfect example:

https://www.bootmod3.net/log?id=6065...0b4308c75b6f89

Two logs after that I have 3 in a row that are completely clean..

Also for more info: Backtracking logs from the CS map, I find knock though less. I only have a single log from stock C, and it shows a single knock.

Seems like feed back knock which does occur and should be benign (especially at low load conditions like where yours is happening), but here is the thing these logs are pretty useless (low rpm part throttle logs don't tell us much in regards to if you OTS map is too agressive or not). You need to do a 3rd or 4th gear WOT pull from 2000 - 2500 rpm to redline and if you can shift into the next gear for a couple thousand rpms, make sure traction control is off or else you will get timing pulls and throttle body closures from it kicking in.





Also just a few random things to note, what fuel octane are you running and what kind of mods this will help when looking at your tune?


Also just for curiosity what are your ambient temps and what driving mode (this changes thermostat functioning but the intercooler should be running no matter what because colder iats means more efficiency)? Because I noticed your iat's are 42C (that is when timing is generally pulled but I don't think this is what is causing your knock event - again you need to upload a proper log to really determine what is going on) which is quite high for this time of the year in Washington, especially when going at 70+ km/h and on an S55 with an air to water intercooler (my n55 m2 for reference with a stock intercooler at 15C ambients only pulls mid 30C iats at most even at low speeds).



Overall I recommend getting a WOT log and sending it to bm3 for review.

[BMW DIY Guy]

Originally Posted by F87source

Seems like feed back knock which does occur and should be benign (especially at low load conditions like where yours is happening), but here is the thing these logs are pretty useless (low rpm part throttle logs don't tell us much in regards to if you OTS map is too agressive or not). You need to do a 3rd or 4th gear WOT pull from 2000 - 2500 rpm to redline and if you can shift into the next gear for a couple thousand rpms, make sure traction control is off or else you will get timing pulls and throttle body closures from it kicking in.





Also just a few random things to note, what fuel octane are you running and what kind of mods this will help when looking at your tune?


Also just for curiosity what are your ambient temps and what driving mode (this changes thermostat functioning but the intercooler should be running no matter what because colder iats means more efficiency)? Because I noticed your iat's are 42C (that is when timing is generally pulled but I don't think this is what is causing your knock event - again you need to upload a proper log to really determine what is going on) which is quite high for this time of the year in Washington, especially when going at 70+ km/h and on an S55 with an air to water intercooler (my n55 m2 for reference with a stock intercooler at 15C ambients only pulls mid 30C iats at most even at low speeds).



Overall I recommend getting a WOT log and sending it to bm3 for review.

good info and just rolled it all up for PTF. 8)

[AlpsRider]

Originally Posted by BMW DIY Guy

Can you share any specifics on plugs, gap and possible coils? I just jumped to stage 2, 503rwp (yesterday) and am experiencing knock.

Simple 5min drive to the grocery store and could feel something different today. Pulled logs and pretty consistent knock from 1900 to 2500 rpk, though can show at higher rpm.

I can easily flash back to the stock CS or C map, but my immediate thought was plugs. I have 19k miles on and don't know if the plugs have been changed previously.

thank you for the insight and any thoughts

If you are stuck with low octane fuel then Stage 2 tune could be pushing boost too high. You could run a few gallons of 100 octane in a tank and see what happens.

[smurchill]

Originally Posted by F87source

Ok so you have 2 real options for spark plugs:

1) The OEM bosch plugs which are totally fine to use in high power level situations, and their heat range is also fine up to 700 whp. Now the part number is Bosch ZR5TPP330A (the A version iirc is the updated one that doesn't crack there was TSB on this).

With Bosch plugs the 3rd digit is the heat range so this has a bosch heat range of 5 which is equal to NGK's heat range of 7.

2) NGK 97506 the ngk heat range of this plug is 8 which is equal to a bosch heat range of 4. This plug is 1 step colder than the m2 n55/s55 stock plugs and 2 steps colder than the stock n54 plug.


With plugs like I said earlier no need to go colder for no reason as it can lead to bad combustion, but that doesn't seem to be an issue on these cars so it is your choice which option you want. For me I am happy with the stock plugs and they are also 1/4 the price of an NGK so i'm also saving money in the process. But do not let money savings prevent you from doing what is right for your car, if your car calls for it go for what it needs - but since I don't see many high 600whp-700 whp m2's there really is no need for it (it's like buying botique oils for no reason). Also remember to read your plugs when you change them to see if you do need to go colder, that is always the key to moving heat ranges, the 700 whp number is just a guide line it is always best to read your logs and plugs to determine if you need to switch - just like you would with a used oil analysis.




For gap start with the stock 0.028" gap and move your way down until the misfires stop. If you go too small you will get incomplete combustion and misfires and rough idles. Too big and your spark will blow out and the same misfires will occur at high boost conditions. Generally speaking mid 400 whp you won't have an issue with stock gap as that is where the m4 gts and m2cs are running. But since you are at 500 whp and with old plugs this could be a sign you need to get new plugs (tuned cars should get it ever 20k miles or less, and every 4 years as per bmw).



If you gap gets too ridiculously small like smaller than 0.022" then you probably should get upgraded coils. For the S55 there are no offerings yet (because of the air to water intercooler) - but this will change when nexyus makes the B58 coil conversion for the S55. This will be the best offering yet because the B58 coils make more power than the precision racewerks kit with less dwell, more spark duration, all while heating up the IGBT on the ecu less meaning better life time for that component. So wait on that kit.

But honestly you can get coils on a stock car too if you want, it just depends on if you want to spend money for no reason or not. Personally I would consider getting coils at a spark gap of 0.024" or less, but if you really don't want to spend alot of cash on a coil upgrade you can push it to 0.022 or less or whenever decreasing your gap sizes just don't cut it anymore and you keep misfiring no matter what. Remember our delphi coils are already more powerful than the stock n54 coils and those guys run upgraded eldor coils (same power output as our delphis so don't waste your money switching to those) for super high power builds so there really isn't a huge need to upgrade coils prematurely.


So let me sumarize this last part because it was likely convoluted because I like to ramble:

1) If you have money to burn upgrade coils even on a stock car - why not. (If you have alot of money consider giving me some lol JK donate it to charity or something, or save it for the future I am ok).

2) If you really want to optimize your ignition setup and rather spend money here over an exhaust, colored engine cover or whatever, (a really good idea compared to the former) upgrade when your gap size gets to 0.024" or smaller.

3) This one over rides all of the above, when you begin to continue to gap down but it doesn't solve your misfires at high rpm. Or your small gap size at high rpm works fine but low rpm it starts to stumble you should get upgraded coils so you can run a bigger gap at all times.


Hope this helps, and you probably should change out your plugs soon. On a used car I normally do all the belts, fluids, plugs, filters.

Thanks for this info and write up. I was curious about something: those plugs you listed are like $7 a piece, while the genuine OEM (BMW part# 12120039634) are like $25 a piece and the Bosch OE part I found (12120039634KT2) is almost as expensive as OEM as I figured they were just a non-branded equivalent. Are the Bosch ZR5TPP330A gapped to 0.028" really all I need for a stock car for the routine maintenance I was planning? If so, do you know the difference between those two Bosch parts?

[F87source]

Originally Posted by smurchill

Thanks for this info and write up. I was curious about something: those plugs you listed are like $7 a piece, while the genuine OEM (BMW part# 12120039634) are like $25 a piece and the Bosch OE part I found (12120039634KT2) is almost as expensive as OEM as I figured they were just a non-branded equivalent. Are the Bosch ZR5TPP330A gapped to 0.028" really all I need for a stock car for the routine maintenance I was planning? If so, do you know the difference between those two Bosch parts?

Yup for a stock car just buy those plugs and drop them in and you're good. No need to gap it because that 330A Bosch plug is pregapped to 0.028".


No clue about that other Bosch part number but if you buy the bmw ///M plug for the m2 it has the same 330A part number from Bosch as what you'd buy from Bosch, the only difference is the lack of the ///M logo. Same thing with oil filters, the OEM bmw one has the exact same part number as the Mann hu8011z the only difference is the lack of the ///M logo.

But you can Google for a picture of the OEM bmw M2 plug and you can look, it's the same as the Bosch 330a plug.

[F87source]

Originally Posted by smurchill

Thanks for this info and write up. I was curious about something: those plugs you listed are like $7 a piece, while the genuine OEM (BMW part# 12120039634) are like $25 a piece and the Bosch OE part I found (12120039634KT2) is almost as expensive as OEM as I figured they were just a non-branded equivalent. Are the Bosch ZR5TPP330A gapped to 0.028" really all I need for a stock car for the routine maintenance I was planning? If so, do you know the difference between those two Bosch parts?

Here's the real oem link with the genuine bmw part number: https://www.realoem.com/bmw/enUS/par...&q=12120039634


RB ZMR5TPP330 this is the partnumber, the only variation is the presence of M after the Z which designates the ///M logo iirc.


Also make sure you get the 330A variant, the 330 variant had ceramics that were proned to cracking and the 3330A version rectified this issue and it is no longer and issue at all. BMW has a TSB regarding this as well.

[smurchill]

Originally Posted by F87source

Here's the real oem link with the genuine bmw part number: https://www.realoem.com/bmw/enUS/par...&q=12120039634


RB ZMR5TPP330 this is the partnumber, the only variation is the presence of M after the Z which designates the ///M logo iirc.


Also make sure you get the 330A variant, the 330 variant had ceramics that were proned to cracking and the 3330A version rectified this issue and it is no longer and issue at all. BMW has a TSB regarding this as well.

Awesome, thanks for the info! Pretty amazing how much that ///M logo costs lol.

Another quick question while I have you, I was searching around for the E18 inverted torx bolts that fasten the strut brace and I think I finally found them as part #2 (07147270121) here: https://www.realoem.com/bmw/enUS/sho...diagId=51_8381

Are all 4 torqued to 56Nm + 90 degrees? I have also seen some people say the brace doesn't need to be removed to access the plugs, but it seems like it would be easier. Trying to find torque specs without newTIS is kind of a pain, although I suppose I could just pay the $30, but it's the principle of the thing!