[Unklejoe]

Hello,

I'm trying to figure out which spark plugs to buy for my N55. I'd like to get one heat range colder than stock.

Many N54 people run the NGK 5992 which is one heat ranger colder than the stock N54 plug, but basically equal to the stock N55 plug. (The NGK 7 heat range is equal to the Bosch 5 heat range).

The DILKAR8A8 plug for the GTR seems like it would fit, and is an 8 heat range, which equals a Bosch 4 heat range. This ends up being one step colder than the stock N55 plug.

I found a thread somewhere else where people have reported success with this plug, but I'm looking for more feedback before I drop $20 per plug.

Jake

[JETmn]

I know I have seen posts of people running the N20 plug, but I have no first hand experience. Might want to do some research on that. It was pretty recent.

[Unklejoe]

Originally Posted by JETmn

I know I have seen posts of people running the N20 plug, but I have no first hand experience. Might want to do some research on that. It was pretty recent.

Yep.

The N20 plugs and the GTR plugs are both NGK Iridiums of the same physical dimensions and heat range. The only difference between the two I can tell is that the GTR plugs have little point on the ground strap. Maybe the N20 ones do as well; I can't tell.

I'll probably get the N20 plugs since they were designed for a direct injected engine, but it probably doesn't make a difference. They're both like $18 each lol

[M.a.r.k.u.s]

Originally Posted by Unklejoe

Yep.

The N20 plugs and the GTR plugs are both NGK Iridiums of the same physical dimensions and heat range. The only difference between the two I can tell is that the GTR plugs have little point on the ground strap. Maybe the N20 ones do as well; I can't tell.

I'll probably get the N20 plugs since they were designed for a direct injected engine, but it probably doesn't make a difference. They're both like $18 each lol

$13.17 on amazon right now for the ngk 96987

[stari335]

Run the PTF spec-ed plugs and never look back. BMW N20 motor flex fuel plug gapped to 0.018". They must've custom tuned 100s if not 1000s of N55s all over at this point and that's what they seem to be recommending to everyone out there these days.

[BKBMW335I]

Originally Posted by stari335

Run the PTF spec-ed plugs and never look back. BMW N20 motor flex fuel plug gapped to 0.018". They must've custom tuned 100s if not 1000s of N55s all over at this point and that's what they seem to be recommending to everyone out there these days.

Do you have the plug model number?

[tke344]

Originally Posted by stari335

Run the PTF spec-ed plugs and never look back. BMW N20 motor flex fuel plug gapped to 0.018". They must've custom tuned 100s if not 1000s of N55s all over at this point and that's what they seem to be recommending to everyone out there these days.

Wow, that's a really tight gap, any issues with idle? Maybe it's different because they're colder.

I'm running the NGK 5992s at .025 but I think the consensus is they aren't actually a step colder than stock. Maybe I'll give the N20 plugs a try in the spring.

[Unklejoe]

Originally Posted by BKBMW335I

Do you have the plug model number?

ZKBR8C8S is the number for the N20 plugs, which are one step colder than the stock N55 plugs and two steps colder than the stock N54 plugs.

Originally Posted by tke344

Wow, that's a really tight gap, any issues with idle? Maybe it's different because they're colder.

I'm running the NGK 5992s at .025 but I think the consensus is they aren't actually a step colder than stock. Maybe I'll give the N20 plugs a try in the spring.

Yeah, the 5992s are the same heat range as the N55 stock plugs, but they're one step colder than the stock N54 plugs.

The N20 plugs are one step colder than stock N55 and therefore two steps colder then stock N54 plugs.

N20 plugs will be my next plugs.

However, some guys on another website have been running the GTR plugs with great success.

I know PTF is very competent (they've been tuning my car for over a year), but it never hurts to explore new options.

The reason I decided on the N20 plugs is mainly because of PTF's proven success with them and the fact that they're designed for a motor that probably has a very similar head to the N55 (direct injection, etc). I'd like to try to GTR plugs but it's such a pain in the ass to change plugs on this car that I don't feel like it. I'd rather go with what works and be done with it.

Plus, they seem like they're basically the same design. The only difference I can see is the little tip on the ground electrode on the GTR plugs.

[BKBMW335I]

Originally Posted by Unklejoe

ZKBR8C8S is the number for the N20 plugs, which are one step colder than the stock N55 plugs and two steps colder than the stock N54 plugs.



Yeah, the 5992s are the same heat range as the N55 stock plugs, but they're one step colder than the stock N54 plugs.

The N20 plugs are one step colder than stock N55 and therefore two steps colder then stock N54 plugs.

N20 plugs will be my next plugs.

However, some guys on another website have been running the GTR plugs with great success.

I know PTF is very competent (they've been tuning my car for over a year), but it never hurts to explore new options.

The reason I decided on the N20 plugs is mainly because of PTF's proven success with them and the fact that they're designed for a motor that probably has a very similar head to the N55 (direct injection, etc). I'd like to try to GTR plugs but it's such a pain in the ass to change plugs on this car that I don't feel like it. I'd rather go with what works and be done with it.

Plus, they seem like they're basically the same design. The only difference I can see is the little tip on the ground electrode on the GTR plugs.

Since I'm so new to BMWs I was wonder how difficult/hard is it to change the plugs on the 335i?

[olivojoe]

Originally Posted by BKBMW335I

Since I'm so new to BMWs I was wonder how difficult/hard is it to change the plugs on the 335i?

Very easy. You'll spend more time pulling all of the s*&^ off the top of the engine to get to the coils (Intake, cosmetic covers, cowl, strut braces, etc.) than you will spend changing the plugs.



A few suggestions:

Obviously start with a cold engine for two reasons, burn hazard and expansion of the threads can cause improper/over tightening.

Gap the plugs down properly to the required gap (otherwise you'll be pulling them out again and doing it later, trust me you'll misfire)

Use a little anti seize on the plug threads, makes life easier later since we have to change plugs so often due to being tuned.

EDIT: Also, use a torque wrench! I have heard too many horror stories of broken plugs or over tightened plugs causing massive headaches down the line. Nothing particular for these cars, but just auto maintenance in general.



There are a few good DIY's here on the forum and youtube, I suggest watching one all the way through before you decide to tackle it.

[BKBMW335I]

Originally Posted by olivojoe

Very easy. You'll spend more time pulling all of the s*&^ off the top of the engine to get to the coils (Intake, cosmetic covers, cowl, strut braces, etc.) than you will spend changing the plugs.



A few suggestions:

Obviously start with a cold engine for two reasons, burn hazard and expansion of the threads can cause improper/over tightening.

Gap the plugs down properly to the required gap (otherwise you'll be pulling them out again and doing it later, trust me you'll misfire)

Use a little anti seize on the plug threads, makes life easier later since we have to change plugs so often due to being tuned.

EDIT: Also, use a torque wrench! I have heard too many horror stories of broken plugs or over tightened plugs causing massive headaches down the line. Nothing particular for these cars, but just auto maintenance in general.



There are a few good DIY's here on the forum and youtube, I suggest watching one all the way through before you decide to tackle it.

Thanks for all the advice, I will take up this project once I get my new plugs in.

[M.a.r.k.u.s]

Originally Posted by Unklejoe

ZKBR8C8S is the number for the N20 plugs, which are one step colder than the stock N55 plugs and two steps colder than the stock N54 plugs.

That is what ECS tuning has but looking at different sites (rockauto, autozone, amazon, etc.) they have different ones depending on what year 328i I select. I'm not sure if the N20 has changed at some point but it either comes up with a NGK 96987 or NGK 97506. No idea what the difference is and why there is a difference.

Anyone know the answer to this?

[Unklejoe]

Okay, I found some new info.

There are actually 5 plugs listed for the N20.

NGK SILZKBR8B8S (BMW# 12120038704)
NGK SILZKBR8C8S (BMW# 12120038896)
NGK SILZKBR8D8S (BMW# 12120039664)
NGK SILZKBR8E8S (BMW# 12120040573)
NGK SILZKBR9F8S (BMW# 12120042724)


Info:

NGK SILZKBR8B8S

This was the first N20 plug. It has been discontinued. One heat ranger colder than stock N55. Two colder than stock N54. It was replaced as per this TSB:

"As of March 2012 vehicle production, a new spark plug is being introduced in all models with the N20 engine. Its designation is NGK SILZKBR8C8S, BMW P/N 12 12 0 038 896. The new spark plug doubles the original replacement interval to 60,000 miles or every 4th engine oil service, instead of 30,000 miles/every 2nd engine oil service. The previous spark plug had the designation NGK SILZKBR8B8S. It has been discontinued."


NGK SILZKBR8C8S

Second N20 plug. One heat ranger colder than stock N55. Two colder than stock N54. This plug is what PTF recommends, but it has been discontinued. RealOEM lists the NGK SILZKBR8D8S as the replacement.


NGK SILZKBR8D8S

Current listed plug for the N20. One heat ranger colder than stock N55. Two colder than stock N54. This replaced the NGK SILZKBR8C8S listed above.


NGK SILZKBR8E8S

Current listed plug for N20's produced up to early 2015. One heat ranger colder than stock N55. Two colder than stock N54. Even though the revision is "E", it would appear that the "D" plug listed above is currently the latest recommended plug for the N20 as of today. The brand new N20 LCI motors call for the "D" plug. Maybe BMW made another revision after the "D" plug but then changed their mind and stuck with the "D" plug? IDK


NGK SILZKBR9F8S

This plug is interesting. First of all, I'm not positive that this is the correct NGK plug number. I found this info on a website that wasn't very clear. However, this plug is listed for all N20's that are "flex fuel" compatible...AKA E85. If this NGK number is correct, it would indicate that this plug is TWO steps colder than the stock N55 plug and THREE steps colder than the stock N54 plug. Maybe there's a reason for the colder plugs on motors designed to use E85?


CONCLUSION

The latest NORMAL N20 plug is the NGK SILZKBR8D8S (BMW# 12120039664). It's one step colder than the stock N55 plug and two steps colder than the stock N54 plug.

However, there's a potential new plug that was designed for flex fuel N20 motors called the NGK SILZKBR9F8S (BMW# 12120042724). This plug is two steps colder than the N55 plugs (if the NGK number is correct). I would have originally said that two steps colder is too much, but BMW seems to think that the colder plug was necessary for E85 cars, so maybe it could be advantageous to N55s as well. Someone should buy one of these so we can figure out the actual NGK number. Not it. This plug seems VERY hard to find.

[Unklejoe]

Another reassuring fact is that the F25 X3 20i lists the NGK SILZKBR8D8S and Bosch ZR5TPP33S as both being suitable replacements. This means that the stock N55 plug and the NGK N20 plug are compatible, with the only difference being the heat range, according to BMW at least.

[weehe126]

Great work. I'm pretty sure that range 9 plug number is wrong. However, I am pretty sure the only flex fuel BMWs are in Brazil, so would make sense that it is hard for us to find info on.

[M.a.r.k.u.s]

Aliexpress has these for $45.99 for a 4 pack with free shipping, just fyi.

http://www.aliexpress.com/snapshot/7...73031668808389

[Cory S]

Originally Posted by olivojoe

Obviously start with a cold engine for two reasons, burn hazard and expansion of the threads can cause improper/over tightening.

Actually, having a slightly warm (not hot) cylinder head is best. A cooled down aluminum head, will tightly grip the Nickel coated steel plug threads more.

Usually, a 1-1.5 hour cooldown seems to give best results.

[Unklejoe]

Originally Posted by Cory S

Actually, having a slightly warm (not hot) cylinder head is best. A cooled down aluminum head, will tightly grip the Nickel coated steel plug threads more.

Usually, a 1-1.5 hour cooldown seems to give best results.

Interesting. Is this the general consensus? I'd hate to break a plug trying to remove it.

[Cory S]

Originally Posted by Unklejoe

Interesting. Is this the general consensus? I'd hate to break a plug trying to remove it.

All my cars (performance, and commuter) have had aluminum heads for almost 20 years, and I always changed plugs with a slightly warm cylinder head. Always super easy to crack loose and spin freely out.

[olivojoe]

Originally Posted by Cory S

Actually, having a slightly warm (not hot) cylinder head is best. A cooled down aluminum head, will tightly grip the Nickel coated steel plug threads more.

Usually, a 1-1.5 hour cooldown seems to give best results.

Interesting point, I have always told the two metals should be relatively close in temperature when torqueing as to not develop any non-uniform stress. Probably far more relevant at very high temperatures or very high amounts of torque. But what you say does make sense.

[stari335]

PTF actually recommend the regular N20 plug for the non E85 cars and the flex fuel N20 plug for E85 blend cars and all of them gapped down to 0.018". I always listen to my tuner. They deal with this crap every single day.

[Unklejoe]

Originally Posted by stari335

PTF actually recommend the regular N20 plug for the non E85 cars and the flex fuel N20 plug for E85 blend cars and all of them gapped down to 0.018". I always listen to my tuner. They deal with this crap every single day.

Where is this reccomendation? I can't find it anywhere. I've heard that they reccomend the regular N20 plug, as do I, but this is the first I'm hearing of them talking about the flex fuel N20 plug. If you have a link, please provide it. My _assumption_ is that the reason they reccomend the flex fuel plugs for E85 cars is because cars running E85 mixtures tend to make more power and could benefit from a colder plug. It's probably not necessary to go two steps colder on a pump gas car, so the regular N20 plug will do. If there's some other reason, I'd love to know. Has anyone on these forums ever used the flex fuel plugs? What is the NGK part number?


Also, not trying to come at you directly, but what's the deal with the "just do what so-and-so says and don't ask any questions" mentality on these forums? The whole purpose of a technical forum is to discover and share information, but it seems like any time there's a real technical discussion, someone chimes in with "just do what the tuner says."

Some of us like to learn the reasoning behind things rather than blindly following the word of others, regardless of how reuptable they are.

It's not that I don't trust PTF (quite the opposite actually, as they've tuned my car and have produced great results). I'm just naturally curious and I consider myself more than capable of understanding the technical details behind the reasoning.

It's not like I even disagree with their reccomendation...

I'm sure you didn't mean this, but your comment comes off as kind of condescending; almost as if I'm a fool for questioning their decision.

Not to go on a massive rant here, but for what it's worth, I've also tuned a few cars in my day. Not as many as PTF, but I know my way around an EFI system. The projects I work on are usually unique, because I feel that learning is 90% of the fun.

Some of the more unique cars that I've tuned include:

- LQ4 (LS2) swapped Mustang with a BW 84mm turbo, running on a Megasquirt3. It made 798 whp on a bone stock bottom end with straight 93 octane (no meth, no race gas, no E85, etc...). So far, the best time was 8.8X at 160. This is pretty common these days, but still unique in the grand scheme of things.

- Turbo H6 EZ30 swapped STi (one of the ~3 in the country). Also running on a Megasquirt3 standalone. I'm not aware of anyone else running this particular combo.

- Turbo 2JZGE Swapped Mustang. Currently in progress. Expecting to go high 10's (or bust in the process). This will also run a MS3 standalone.

- 2002 VQ35DE Turbo Maxima. 374whp on 7 psi with a 58mm turbo and a stock motor. This was tuned on a Greddy E-Manage Ultimate piggy back. I was also the first person to run Mustang GT500 injectors in a VQ35DE and the first to run an EU in a Maxima. The car had over 100,000 miles on this setup until I sold it.

- 1992 Automatic swapped Galant VR4 with a Holset HX40 pro wheel. Tuned on DSMLink; 32 PSI on E85. I was also one of the very few people who swapped an auto into a GVR4.

I've also tuned a bunch of common setups, including a couple of JRSC supercharged SIs, an EVOX, 3000GT VR4, etc. This isn't my job (I'm actually a programmer), but rather something I do for fun.

I opted to have PTF tune my BMW because I didn't feel comfortable learning the intricacies of the platform on my own car, and I knew that they had experience. I'm sure I could have done it myself, but I don't want to do 100 pulls while knocking to learn the limits of the motor. If this was a cheaper car, then maybe.

My point is that I hate when people try to discourage exploration and independent thought.