Changing Type of Spark Plug Lower Engine Temp?

[KRAM36]

I've always used Bosch FGR-6-KQE spark plugs. I decided to try some NGK 94279 FR6AHX-S Ruthenium HX plugs because of people always commenting on the Bosch plugs having a prong break off on them, although I have not had that issue, but I thought I would ease my mind on it and go with the NKG plugs.

Plus with the mods done to my car and not knowing if the engine is running lean or rich (she eats a lot of gas though) along with NGK's claims on this plug, I figured why not try them out. I also only run Ethanol-free gas in my car.

NGK Ruthenium HX is designed for newer engines which demand high ignitability. Double Fine Electrode (DFE) design promotes spark energy concentration and ignites a wider range of air-fuel ratios, offering improved performance in rich or lean engine conditions.

With the Bosch plugs my cars temp gauge was always around 185° to 186°, even during the winter time. Last week I changed to the NGK plugs. I have gone for many drives since installing them, some pretty spirited and just normal driving and my temp gauge just barley cracks past the 180° mark now.

Is it possible that the type of plug you use can affect the engine temp like this?

[JFP in PA]

Originally Posted by KRAM36

I've always used Bosch FGR-6-KQE spark plugs. I decided to try some NGK 94279 FR6AHX-S Ruthenium HX plugs because of people always commenting on the Bosch plugs having a prong break off on them, although I have not had that issue, but I thought I would ease my mind on it and go with the NKG plugs.

Plus with the mods done to my car and not knowing if the engine is running lean or rich (she eats a lot of gas though) along with NGK's claims on this plug, I figured why not try them out. I also only run Ethanol-free gas in my car.



With the Bosch plugs my cars temp gauge was always around 185° to 186°, even during the winter time. Last week I changed to the NGK plugs. I have gone for many drives since installing them, some pretty spirited and just normal driving and my temp gauge just barley cracks past the 180° mark now.

Is it possible that the type of plug you use can affect the engine temp like this?

Heat range of spark plugs refers to the rate at which the firing tip of the plug transfers heat to the cooling jacket of the cylinder head. "Cooler" plugs transfer it faster, "hot" plugs transfer it slower. This keeps the spark plug temperature high, which allows the plug to self clean and prevent fouling.

The heat range of a given plug should have little to no impact on the car's stead state coolant temperature, that is controlled by the thermostat.

[KRAM36]

Originally Posted by JFP in PA

Heat range of spark plugs refers to the rate at which the firing tip of the plug transfers heat to the cooling jacket of the cylinder head. "Cooler" plugs transfer it faster, "hot" plugs transfer it slower. This keeps the spark plug temperature high, which allows the plug to self clean and prevent fouling.

The heat range of a given plug should have little to no impact on the car's stead state coolant temperature, that is controlled by the thermostat.

Yes, I understand the heat range of spark plugs. That's why I didn't mention the heat range in my post, but thanks for the info. The difference is in the plug's design, the Bosch plugs have 4 prongs and the NGK has only one prong and the electrode is made of different material at the tip.

Maybe my NGK plugs made a deal with my thermostat? j/k

Or maybe the thermostat has given up and is sticking open all the time now, just happened at the same time I decided to change my plugs?

I really want to get to the bottom of this, as it's much warmer outside now and my car is running cooler since the plug change. I DD my Boxster, even during the winter it would hit 185° on the highway.

[Racer Boy]

Whatever the heat range of your spark plugs, they have no affect on the water temperature of your engine.

[KRAM36]

Originally Posted by Racer Boy

Whatever the heat range of your spark plugs, they have no affect on the water temperature of your engine.

Why is the heat range even being mentioned? Both plugs have the same heat range. It's the physical difference in the plugs that I am referring to.

Now, from what I feel, the engine is running smoother. It appears to me that the NKG plugs are doing a better job at igniting the air/fuel mixture and doing it at a more proper time. This is allowing a more complete burn and the timing at which it's doing it at is allowing the more of the combustion to escape the cylinder when the exhaust valve open, which allows more heat to escape the engine.

We are not talking a huge difference here, probably around 4° cooler.

[Quadcammer]

placebo...

[Topless]

Originally Posted by Quadcammer

placebo...

^^ +1

Zero science to support a lower water temp by changing to NGK plugs.

[KRAM36]

Originally Posted by Topless

^^ +1

Zero science to support a lower water temp by changing to NGK plugs.

Pretty sure I laid out some science on why this could be the case, but go ahead and ignore it. Maybe you could have offered information that rebutted it.

[Starter986]

Originally Posted by KRAM36

Pretty sure I laid out some science on why this could be the case, but go ahead and ignore it. Maybe you could have offered information that rebutted it.

+1



The message you have entered is too short. Please lengthen your message to at least 10 characters. fu

[JFP in PA]

Originally Posted by KRAM36

Pretty sure I laid out some science on why this could be the case, but go ahead and ignore it. Maybe you could have offered information that rebutted it.

If changing the spark plug resulted in more efficiently burning the fuel/air charge, it would generate more heat, not less...………...

[KRAM36]

Originally Posted by JFP in PA

If changing the spark plug resulted in more efficiently burning the fuel/air charge, it would generate more heat, not less...………...

Not if they ignited at the improper time or should I say a more optimal time. Plus a cleaner full burn would allow the combustion to escape the cylinder more efficiently, thus allowing the heat to escape more efficiently.

[KRAM36]

Originally Posted by Quadcammer

placebo...

Placebo makes my engine run cooler? Interesting, then human brain has some amazing powers.

[Quadcammer]

uh no. The type of plug is not changing the timing of the spark. Whatever you're quoting is marketing wank. Not to mention, a modern fuel injected car like the 986 very accurately controls the a/f ratio, so this WIDE RANGE would be between about 12.8 and 14.7, which pretty much any plain jane copper plug can ignite all day for 40k miles, especially at our given compression ratio.

Lets start with how are you measuring these temperatures so accurately?

[KRAM36]

Originally Posted by Quadcammer

uh no. The type of plug is not changing the timing of the spark. Whatever you're quoting is marketing wank. Not to mention, a modern fuel injected car like the 986 very accurately controls the a/f ratio, so this WIDE RANGE would be between about 12.8 and 14.7, which pretty much any plain jane copper plug can ignite all day for 40k miles, especially at our given compression ratio.

Lets start with how are you measuring these temperatures so accurately?

Oh yes the spark can happen faster and with more intensity depending on the what the spark plug is made out of. Have you never watched any videos of different spark plugs sparking? I thought this was pretty common knowledge for gear heads. Go watch some videos on the 4 prong type plugs, they seems to have some latency in their sparking action to them.

If you read my first post, you would know how the measurement was done. By the gauge in the cluster. Now if I had know this was going to happen, I would have logged the temps with my Durametric, it just turned out to be a unexpected surprise.

[maytag]

Originally Posted by KRAM36

Oh yes the spark can happen faster and with more intensity depending on the what the spark plug is made out of. Have you never watched any videos of different spark plugs sparking? I thought this was pretty common knowledge for gear heads. Go watch some videos on the 4 prong type plugs, they seems to have some latency in their sparking action to them.

How old are you?
Waaaay bank in the old days, when we used to have to tune ignition curves with weights and springs, it was important to monitor your flame front; ie, get it moving faster. We'd also maximize the quench area for this very same reason. This was particularly important when cylinder pressures were very high (boosted) or when RPM's were very high (10k rpm and up). So yes, in those days, knowing your spark plugs really well was vital. But only in those very extreme situations.

With today's adaptable/ learning ECU's controlling spark and fuel, based on actual readings from sensors means that you can pretty much slap any old plug in there and you'll see negligible differences, other than longevity of the plug itself. (Again, until you start taking about the extremes)

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[KRAM36]

Originally Posted by thstone

Ok, here's twelve to get us started...

Air temp
Humidity
Pressure
Percentage of cloud cover
Throttle position over the past 5-30 minutes
Load over the past 5-30 mins
Length of time at idle over the past 5-30 mins
Length of time at various speeds over the past 5-30 mins
Fans cycling on or off
Inaccuracy of the temp sending unit
Inaccuracy/inconsistency of visually sighting the temp gauge
Amount of other traffic

My Boxster is my daily driver and it's the only vehicle I have owned since 2013. I know this car like the back of my hand. I can feel when something is out of order. That being said, as noted the previous temp was between 185° to 186° (these temps are under normal driver conditions. Spirited driving would raise the temp more or sitting still for a long period the temp would go up), even in the Winter time and it's been this way as long as I have owned this car. I have experienced every variation you noted in the last week, except for the temp gauge inaccuracy other then Porsche's calibration, which I understand the gauge always reads lower then the actual temp and I don't have inaccuracy/inconsistency of visually sighting the temp gauge needle with over 6 years of ownership with the car being my DD and the only vehicle I have owned in over 6 years. The only thing different in the last week than previous weeks is the change of spark plugs and we are now in warmer weather.

It's been a week now since the plugs have been changed. I have done city driving short runs, highway driving for over an hour. I have experienced every situation in the last week, air temp changes, was very humid yesterday as it rained and went to 71° with Sunshine. Actually turned on the home A/C unit because of it. I have the four stalk column with the OBC turned on, so I can see the outside temps. I've always been puzzled why this car would still run as warm in the Winter time as it does.

Originally Posted by maytag

How old are you?
Waaaay bank in the old days, when we used to have to tune ignition curves with weights and springs, it was important to monitor your flame front; ie, get it moving faster. We'd also maximize the quench area for this very same reason. This was particularly important when cylinder pressures were very high (boosted) or when RPM's were very high (10k rpm and up). So yes, in those days, knowing your spark plugs really well was vital. But only in those very extreme situations.

With today's adaptable/ learning ECU's controlling spark and fuel, based on actual readings from sensors means that you can pretty much slap any old plug in there and you'll see negligible differences, other than longevity of the plug itself. (Again, until you start taking about the extremes)

I'm 51 and I have owned a very wide range of vehicles, all of them except one were fuel injected. I understand the ECU can advance and retard timing and adjust the fuel flow, however, the ECU can not control how quick the spark plug will fire over another plug, electricity follows the path of least resistance, the ECU can not control that and the intensity of spark you will get out of the spark plug do to the materials the spark plug is made out of and can not be changed by the ECU. No, even with today's computer controlled cars, you can't just stick any old spark plug into the engine and expect the engine to operate exactly the same. That's a very stupid statement.

My car ran great with the Bosch plugs and the car still runs great with the NGK plugs. The one thing I am seeing is the temp difference, while not huge, it's a pleasant surprise to see the lower temp. I watch my car like a hawk and I notice everything, even a slight change in the temp gauge needle position.

[maytag]

Originally Posted by KRAM36

I'm 51 and I have owned a very wide range of vehicles, all of them except one were fuel injected. I understand the ECU can advance and retard timing and adjust the fuel flow, however, the ECU can not control how quick the spark plug will fire over another plug, electricity follows the path of least resistance, the ECU can not control that and the intensity of spark you will get out of the spark plug do to the materials the spark plug is made out of and can not be changed by the ECU. No, even with today's computer controlled cars, you can't just stick any old spark plug into the engine and expect the engine to operate exactly the same. That's a very stupid statement.

Hey there, friend: you can call me stupid all ya like.... but YOU are the one making a fool of yourself here.

The ecu doesn't HAVE to control "the intensity", as you call it. All the ecu has to do is measure (with the o2 sensor) how close to stoichiometry the burn is, and then adjust from there, as necessary.

You're sure arguing a lot, for a guy who doesn't understand the subject matter.

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[Quadcammer]

Cool, no biggie.

Now as to your coolant temps, i cant offer any explanation why plugs would cause this temp decrease.

[thstone]

The problem is that there are far too many other variables that you can't keep constant in order to say that the spark plug change was the cause for such a small change in temp as shown on the gauge cluster. Even if you had Durametric data, there are still far too many variables in play.

That is why people are saying "placebo" - they don't mean that you're not seeing a difference on the temp gauge, instead they are saying that it is highly likely NOT the spark plugs and much more likely one or more other variables that can affect the reported coolant temp.

[KRAM36]

Originally Posted by thstone

The problem is that there are far too many other variables that you can't keep constant in order to say that the spark plug change was the cause for such a small change in temp as shown on the gauge cluster. Even if you had Durametric data, there are still far too many variables in play.

That is why people are saying "placebo" - they don't mean that you're not seeing a difference on the temp gauge, instead they are saying that it is highly likely NOT the spark plugs and much more likely one or more other variables that can affect the reported coolant temp.

What other variables could be involved? I changed the plugs, the temp went down slightly, yet it's much warmer outside now.

Did my thermostat decide to stick open or partially open at the same time I changed my plugs?

I've been thinking about getting one of those lower temp thermostats for years. I've heard pros and cons of running the lower temp stat. I'm not even going to think about it now that my car is at the temp where it should be at.