trustz

Hi,

I just got a 16 GTs and wondering for those you have an ECU tune, what is the part number for your one-step colder spark plug? My tuner wants me to replace the stock spark plug and a new O2 sensor.

Thanks in advance.

AndrewFerg

I'm eager to hear the answers. It seems to me that if your tuner is sophisticated enough to know that a colder spark would be beneficial, they'd also tell you what plug to buy. I can ask my tuner but it may not be applicable to what you've had done.

Acta_Non_Verba

So, some points to make on tuning theory - The 4.0L Hot V platform has some range on turbo pressures. This is the primary source of more HP/TQ for the aftermarket tuners. Stage one tunes usually only take a couple of tenths bar increase to produce about 50/60 extra hp. But, by doing so, they're also increasing cylinder pressures and temperatures.

When they go stage two, they're increasing boost pressure even more, and subsequently are likely needing to retard some timing too to keep cylinder pressures/temps in control. I'm saying it this way BC each tune house views its tune strategy as intellectual property and are not revealing what they do, but having tuned cars for over ten years now, there aren't any places they can go that's some big secret that has gotten past the rest of us. So, I'm pretty sure I can tell where your tuner is coming from.

Back to cylinder pressures, any amount of forced induction greatly increases cylinder pressures, and subsequently cylinder temperatures. If the tune strategy takes you up and away from factory specs, then the factory engineered spark plug range is also going to likely fall out of its useful high heat range. A spark plug used in a tune that has significantly more cylinder temps and pressures, begins to fail at the maximum pressures and temps and begins to contribute to spontaneous combustion (could even be pre-ignition, but that would be rare). Spontaneous combustion (commonly known as knock) is kryptonite to the engine and performance. Every tuner's job is to "beat down" spark knock. The ECU will do it if the tuner doesn't. but that would be a bad tune in any tuner's (or engineer's) eyes. We call those tuners "tooners" and, yes, they're out there.

When a tuner wants to go to a colder plug it's telling me that he's maxing out the timing as far as it can go with the increased boost, and with a colder plug he can hold a degree or two of timing in PE that he'd have to sacrifice with the hotter, factory heat range and get rid of some sporadic knock. Every good tuner deals with this. I've done a few NA converted engines to FI and routinely go two ranges colder on plugs with even modest 6 to 8 psi boost.

So back to the question about spark plugs. Plug manufacturers all use their own numbering systems to determine heat range. Some go up in #s for colder plugs, some go down in #s for cold range. I'll show two of the most common plugs below and how their numbering differs. So, bottom line, you need to know what plug you want to use and what's in your car, then you can pick the plug number you need to go one range colder. BTW, I think the GT series is using Bosch with a heat range 6, but not absolutely sure. If that's the case, Bosch goes down in #s for colder, so you want a 5.

Here is a typical Bosch range (not the actual plug in the GT, just a Bosch example)


With Bosch, they change the number in the middle of the part # to change heat range. So, if you had a Bosch FR6DC plug and wanted to do one step colder, it would be a FR5DC.

If NGK, they go in the opposite direction.


Here if your plug number is BKR6E-11, moving to a BKR7E-11 would give you one step colder plug.

One final comment on spark plug ranges - on the other end of the spectrum, cold starting - As the plug gets colder and colder in heat range (away from the factory spec) cold starts get choppier and choppier. So there aren't any concerns here, if you switched to a colder than factory plug and you live in Anchorage and you got up one January morning and the car was hard to start, idled terribly, and took forever to even out, then that is a consequence of going to a colder plug, but for the most part, one step colder isn't going to be dramatic on the cold start, especially if you live somewhere like I do, where the worst the cold start is going to be is about 30*/40*F.

Sorry for the length here.

EDIT:

Here is one more graphic I found that better shows a few plug manufacturers and how their numbering systems denote hot and cold ranges:

AndrewFerg

Acta_Non_Verba - seriously awesome response. Thanks for sharing your expertise. I'm new to tuning so this is greatly appreciated.

dlefty

Call @PTG Premier Tuning Group, they sell 1-range colder plugs for AMG GT platform of Cars.
If they are out i have a couple sets “in stock”.

trustz

I PM you, please check.

dlefty

Roger that!

foooo

I must be an idiot... I found these 2 spark plug part numbers for my '16 GTS

NGK - SILZKFR8F7S
Bosch - 96347

What's the part number for either of these that would be one colder?

Thanks,
Foo

Acta_Non_Verba

On the NGK the heat range of that plug is 8, so a colder plug would be SILZKFR9F7S

The Bosch number 96347 is a stock number, not the actual plug number.

The challenge on this engine being very low production, is finding a spark plug manufacturer that makes the plug type in different heat ranges. I haven't looked, but likely NGK doesn't even produce a SILZKFR9F7S because there would be no volume market for it.

For this engine there is very little. I know of one obscure Japanese plug maker that does plugs for a lot of ricers, that claims to have a cold plug for this engine, but I don't like the company so no recommendation.

I've had similar challenges with my Bentley W12 engine. There are plugs for the NA version used in VAG cars, but as soon as it is turbocharged there is only one plug for it by NGK but NGK doesn't even distribute the plug commercially, so I have to buy it from an obscure Euro dealer at $20 a plug.

dlefty

Assuming you are talking about the 3-letter company from Japan for the plugs of which you speak 😁
If so, that 1-range colder plug has been being used for a couple/few years now in many C63 and GT M177/178 Cars with much success that have tune+downpipes at a minimum. The bigger turbo crowd especially have logged many cars and miles with that plug and are happy.
Not to mention, fairly confident a plug brand you like makes them for them anyway.

Stenzel-Germany

Hi,

My personal experiences with spark plugs:
Mainly M112 / M113 AMG engine versions with double ignition, so change 60 - 120 spark plugs per year.

When you buy original MB spark plugs, there are different manufacturers. (e.g. Bosch)

If you buy original "AMG" spark plugs, they are always NGK (Iridium) spark plugs.

Only buy NGK spark plugs according to MB specifications.
Platinum for NA engines and Iridium for supercharged engines.

Spark plugs last almost forever today. (Manufacturer change intervals up to 50k mls)
Better electrode material, stronger multiple ignition sparks, and the main reason, no more lead in the gasoline.

Customer vehicle: Engine M112 supercharged with over 100k mls and the 1st spark plugs. That was NGK iridium.
If the electrode gap had been corrected slightly, another 50k mls would have been in it. LOL.

Question:
Before correcting the heat value of the spark plug, the spark plug pattern should not be consulted first?

Best regards

Stenzel

Acta_Non_Verba

Hi Stenzel,

I interpret your question to say - Should you examine the plug tip before considering changing to a different heat range? Is that correct?

Assuming so, when I am tuning and going in the direction of more cylinder pressures and temperatures (as in increasing boost, or converting NA to boost), with everything remaining the same, I know I will have a timing correction, and a fueling correction (to help cool hotter cylinders too, besides just AFR).

Without examining the spark plug tip, if I know I have a spark plug that accepts the current cylinder temps, then if I increase cylinder temps it is very likely the current plug will be out of its maximum heat range. When a spark plug exceeds its capacity to shed heat on every cycle, then it starts to become like a glow plug. If the spark plug works like a glow plug then it will contribute to spontaneous combustion, and sometimes, even worse, create pre-ignition. I assume I will deal with this without need to look at the tip because I increased cyl temps. And, for the most part, the tip on a plug too hot for the present conditions doesn't tell me much anyway.

When I tune going higher in cylinder pressures and temps, I rely on data logs. With actual real-time data I can get a more holistic look of everything operating together and where the weaknesses lie. I expect when I increase boost, that present timing will be too high, fueling will be on the lean side, and with these parameters at extremes of their limits, spontaneous combustion can occur.

When I see spontaneous combustion I first get fueling corrected, then timing, then back to a fueling finer adjustment. So, one of the next steps - I can assume the plug is out of heat range, I will go to the next colder plug, then go back to see if I can increase timing again to get maximum performance from the existing conditions. The spark plug change alone can sometimes make a 3* or 4* increase in timing in PE.

Here is a DL from an engine I was tuning doing what I described above, increasing boost. Look at all the parameters circled in white. You can see I was WOT but losing timing BC the ECU saw knock (the red jagged data at the center of the graph). I changed this tune to a one step colder plug and lost most of the knock without needing to recorrect timing, so the plug was too hot for the newer conditions I created.

Stenzel-Germany

Hi Acta,


Yes, I meant that and that to change the heat value also needs a reason. Just on suspicion doesn't make sense.

Thank you for your knowledgeable answer. That is well established and understandable.

It can be a trade-off between maximum performance and suitability for everyday use.


I like twin ignitions. The good old days .. LOL


Best regards

Stenzel

foooo

Yep, broke the internet with that one

foooo

Hi, please tell me the part number for this mystery plug

dlefty

Just call/email the company I reference above. I know they have a bunch on hand right now.

anwar_hamoude

Champion Double Platinum Plug Number KEC4PYPBF-1 Spark Plug

• Heat Range: 4

Champion 4 is NGK 9


**Unfortunately** these Champion plugs have 14mm thread and are matched according to Champion website.



Searching NGK website I found...

NGK 93253 R2556G-9 Racing Plug

I inquired with NGK to find out if these or another one step colder plug works, and also if ignition coils need to be swapped for these plugs.

If I get a response I'll update.

.

G. P

Last night I got a promotion email from Weistec Engineering about their Laser Iridium spark plug for the M178, claiming to run One Step Colder. I found it interesting since I was looking for one for the last year but could not find any. The AMG GT are relatively rare, and spark plugs manufacturers reluctant to produce variation of similar spark plugs.

The OEM spark plugs seems to be NGK SILZKFR8F7S. Weistec offers the NGK SILZKBR8D8S as a One-Step-Colder plugs.

Looking at both NGK plug specs, I came across some differences: Weistec NGK offered plugs run resistance of 5000 Ohms while the OEM runs 1000 Ohms. Also, the Heat Rate of both are:8, so there is really no “One-Step-Colder” scenario here.

I went back to Weistec’s tech support and they advise me that if I re-gap the plugs from the pre-gap size of 0.028mm to 0.022-0.024mm I will get the “One-Step-Cooler” scenario they advertised.

I don’t know much about spark plugs, so I will appreciate some advice regarding the accuracy of their statement. Will re-gapping a plug to a narrower space is the same as running cooler? Hence, I can advance the ignition timing back a bit, to stay farther then the timing retard limit? And have additions boost level available if necessary?

dlefty

That is CRAP advice from them, the entire point of a colder plug is to reduce heat on modified or increased boost pressure cars, gapping will NOT simulate this. And frankly, you want the widest gap possible (within spec) that isn't a victim of spark blow out. IF in proper heat range on a modified car, and seeing some blowout from boost, that's when you tighten the gap, NOT to "simulate" a colder range.....just horrible advice since that has ZERO to do with reducing temps.

Just refer to my post above from the other year, PTG has the real 1-range colder plugs, if wanting fast, I have a set I can sell you as I bought a bunch.

dlefty

And now that I took a deep breath after my jaw hit the ground from that "simulated colder range" nonsense......

Keep in mind that the factory plug in these cars are really darn good, and often times will work more than adequately for the level of modification most here do. Now that's different when you get into bigger housing turbos, additional fueling, big boost, modifications that are getting more extreme, etc.....

On my past GTS I owned which was simply an ECU tune and downpipes for power modifications, I simply changed to new factory plugs 12 months after the initial tune, to check them out and just in general good practice.....then got into the habit of changing every 2 years as it allowed me to look at them and keep fresh plugs on a lightly modded car, never had a need for colder plugs on that car.

G. P

Thanks, this is really good info.
I have couple on tune maps that I use on the track. One of which, is running a 26PSI boost using 93 Octane. This obviously generate a lot of heat. Shy of going to 100 octane or adding WMI, do you think a cooler plugs will help here?

dlefty

Yes, for track use fighting heat is important and tuned with track use can see benefits here in fighting heat.

G. P

after additional communication with Weistec, it turn out that they were under the assumption that the OEM plugs of the M178 motor in running heat rating higher then 8 and therefore the NGK plugs they offer are colder. I’m not sure if the are backing out of their story, but one thing for sure is that they do not have colder plugs for the GT series. I hope they will remove the M178 from their plug webpage.

LTHL VPR

So, what is the recommended plug if you want to do a 1 range colder. I've seen HKS recommendations but they claim there are no plugs for a GT.
Anyone with first hand knowledge and a reasonable deal?

G. P

i think we are back to square one. HSK 50003-M45HL seems to fit the GT, but there is no info about its Heat Rating.