BEST NGK SPARK PLUG FOR MY CAR?
07-29-2010, 06:26 PM
#31
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Join Date: Apr 2004
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07-29-2010, 07:33 PM
#32
Drifting
Thread Starter
The way I understand it is that the expensive plugs, made out of more exotic metals, last longer.
The NGKs that we use wear much faster, are cheaper, but ironically the coppers are what we need to conduct the spark in our high pressure combustion chambers.
One of those examples where more expensive is not necessarily better.
The NGKs that we use wear much faster, are cheaper, but ironically the coppers are what we need to conduct the spark in our high pressure combustion chambers.
One of those examples where more expensive is not necessarily better.
07-29-2010, 10:26 PM
#33
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http://www.ngk.de/Spark_plugs_with_m...rou.653.0.html
http://www.ngk.com/sparkplug411.asp?...-ground&mfid=1
they do make ngk plugs with 2, 3, or 4 electrodes for a longer wear/service life. they are available in copper as well as platinum and iridium.
they do last a little longer with multiple electrodes
http://www.ngk.com/sparkplug411.asp?...-ground&mfid=1
they do make ngk plugs with 2, 3, or 4 electrodes for a longer wear/service life. they are available in copper as well as platinum and iridium.
they do last a little longer with multiple electrodes
07-29-2010, 11:36 PM
#34
Three Wheelin'
I agree with TurboTommy as well - of all the research I did the expensive platinum's and what not were NOT ideal for our cars. Stick with copper's. I use the 7ES's in my car and love them. They idle great (noticeably better than the Bosch's), particularly at start up and burn nice in my 15PSI on 93 octane setup. I gap at .26.
07-30-2010, 08:56 AM
#35
Nordschleife Master
I don't know were to start but a few points I would like to make.
1.Regardless of plug tip material on over the counter spark plugs the core material will be copper.
2. How a heat range is determined given to me from NGK website.
http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml
Surface area and/or length of the insulator nose
Thermal conductivity of the insulator, center electrode, etc.
Structure of the center electrode such as a copper core, etc.
Relative position of the insulator tip to the end of the shell (projection)
3. Now, for some information.
There is a reason the factory decided to put 911 turbo owners through the pain of reducing the service interval from 60,000mi on your standard model 911 to just 30,000mi on a turbo. The reason for the change is the factory decided it better to switch to a copper tipped spark plug for the turbo 911.
Why did they make this decision?
Copper has the best Electrical Performance and the best Thermal Performance.
What do I mean?
10-ga wire Resistance Ohms/ft
Copper = 0.000999
Iridium = 0.00306
Platinum = 0.00579
Obviously, this only effects the "Tip" as all cores are copper. However, there is another important factor to resistance and that is size.
Wire Gauge Resistance per foot of Copper (Same theory of larger is less resistance applies to all metals)
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480
28 .0764
So, in a simple answer copper tips are the largest and just like in wire this means the least amount of electrical resistance and as a result more voltage at the tip to fire to ground. Also, with a copper plug there is no metal type transition that also hurts electrical conduction.
We know that there is going to be less voltage drop from resistance from tip to tip of a spark plug (not counting ground strap!) If we use copper and since we know this and then we know that the resistance goes up as we start to produce more power. This makes it harder for the plug voltage to overcome the air gap resistance and fire to the ground strap (Closing the circuit). So if we run non-copper tip plugs we have less voltage to make this jump. If the flow is not enough on these non-copper plugs to jump onto the ground strap you misfire. So that leaves us with 2 possible solutions. We make the air gap resistance less by reducing the plug gap allowing us to not misfire or you switch to copper plugs.
Now, You might be wondering why don't I just reduce my gap? Well, doing so will result in a power loss for a few reasons. A stronger spark will help start flame propagation meaning that the stronger it starts the less timing you need to put in to maximize the engines performance. Timing is the only other way to maximize propagation with the ignition system. However, since flame front speed is linked to cylinder pressure (along with things like AFR) as you increase pressure you also increase flame speed. So a strong spark in a way acts like advancing the timing but without the drawbacks.
Now, that I covered the electrical aspect of the plug its time to talk about the more important thermal aspect.
As I had mentioned Copper has the best heat properties of all the metals in question.
Thermal Conductivity
Btu / (hr - ft -°F)
Copper = 231
Iridium = 85
Platinum = 41.36
This means that copper can conduct heat at much higher levels then Iridium or Platinum but more important for our spark plugs. As mentioned earlier type of tip is a factor in determining a spark plugs heat range but the largest factor is the insulator. However, not all things are equal in this case because heat ranges are not determined by dynamic testing but static testing. Sadly, engines are dynamic when it comes to thermal environment. Since you have the heat of combustion and the cooling of an intake charge etc.
This is another reason to use copper because copper is the best in a dynamic environment since it will be able to transfer heat away from the tip into the core faster. The problem is that sometimes a colder iridium or platinum spark plug cannot move heat away from the tip fast enough. It does not have the physical size or metal properties to allow for such a quick transfer to occur. Since the plug is unable to move the heat into the body of the plug quick enough The plug can become super heated at the tip can cause detonation (even colder plugs).
5. The final point about sparkplugs is that your 944 Turbo has a terrible ignition system from the factory and as boost increases your going to need to drop down your gap significantly. It is impossible on some sparkplugs such as iridiums to adjust this gap without damaging the tiny electrode.
Now, for obvious reason you can understand why I wouldn't use one of these Iridium plugs or Platinum plugs in your high performance 944 turbo.
-Your Pal
Fishey
1.Regardless of plug tip material on over the counter spark plugs the core material will be copper.
2. How a heat range is determined given to me from NGK website.
http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml
Surface area and/or length of the insulator nose
Thermal conductivity of the insulator, center electrode, etc.
Structure of the center electrode such as a copper core, etc.
Relative position of the insulator tip to the end of the shell (projection)
3. Now, for some information.
There is a reason the factory decided to put 911 turbo owners through the pain of reducing the service interval from 60,000mi on your standard model 911 to just 30,000mi on a turbo. The reason for the change is the factory decided it better to switch to a copper tipped spark plug for the turbo 911.
Why did they make this decision?
Copper has the best Electrical Performance and the best Thermal Performance.
What do I mean?
10-ga wire Resistance Ohms/ft
Copper = 0.000999
Iridium = 0.00306
Platinum = 0.00579
Obviously, this only effects the "Tip" as all cores are copper. However, there is another important factor to resistance and that is size.
Wire Gauge Resistance per foot of Copper (Same theory of larger is less resistance applies to all metals)
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480
28 .0764
So, in a simple answer copper tips are the largest and just like in wire this means the least amount of electrical resistance and as a result more voltage at the tip to fire to ground. Also, with a copper plug there is no metal type transition that also hurts electrical conduction.
We know that there is going to be less voltage drop from resistance from tip to tip of a spark plug (not counting ground strap!) If we use copper and since we know this and then we know that the resistance goes up as we start to produce more power. This makes it harder for the plug voltage to overcome the air gap resistance and fire to the ground strap (Closing the circuit). So if we run non-copper tip plugs we have less voltage to make this jump. If the flow is not enough on these non-copper plugs to jump onto the ground strap you misfire. So that leaves us with 2 possible solutions. We make the air gap resistance less by reducing the plug gap allowing us to not misfire or you switch to copper plugs.
Now, You might be wondering why don't I just reduce my gap? Well, doing so will result in a power loss for a few reasons. A stronger spark will help start flame propagation meaning that the stronger it starts the less timing you need to put in to maximize the engines performance. Timing is the only other way to maximize propagation with the ignition system. However, since flame front speed is linked to cylinder pressure (along with things like AFR) as you increase pressure you also increase flame speed. So a strong spark in a way acts like advancing the timing but without the drawbacks.
Now, that I covered the electrical aspect of the plug its time to talk about the more important thermal aspect.
As I had mentioned Copper has the best heat properties of all the metals in question.
Thermal Conductivity
Btu / (hr - ft -°F)
Copper = 231
Iridium = 85
Platinum = 41.36
This means that copper can conduct heat at much higher levels then Iridium or Platinum but more important for our spark plugs. As mentioned earlier type of tip is a factor in determining a spark plugs heat range but the largest factor is the insulator. However, not all things are equal in this case because heat ranges are not determined by dynamic testing but static testing. Sadly, engines are dynamic when it comes to thermal environment. Since you have the heat of combustion and the cooling of an intake charge etc.
This is another reason to use copper because copper is the best in a dynamic environment since it will be able to transfer heat away from the tip into the core faster. The problem is that sometimes a colder iridium or platinum spark plug cannot move heat away from the tip fast enough. It does not have the physical size or metal properties to allow for such a quick transfer to occur. Since the plug is unable to move the heat into the body of the plug quick enough The plug can become super heated at the tip can cause detonation (even colder plugs).
5. The final point about sparkplugs is that your 944 Turbo has a terrible ignition system from the factory and as boost increases your going to need to drop down your gap significantly. It is impossible on some sparkplugs such as iridiums to adjust this gap without damaging the tiny electrode.
Now, for obvious reason you can understand why I wouldn't use one of these Iridium plugs or Platinum plugs in your high performance 944 turbo.
-Your Pal
Fishey
07-30-2010, 09:36 AM
#36
On a friend's 2.5 (TO4, Sybele EMS, 18psi) we did a back to back comparison of the NGK against the Denso on the dyno. Even after trying different plug gaps, the engine kept misfiring under boost with the NGK. It didn't with the Denso. Same heat range btw. The NGK were brand new, unused, the Denso weren't even new.
07-30-2010, 02:09 PM
#37
Rennlist Member
Fishey;
nice piece of info
But, I don't know if I agree with #5 (terrible factory ignition). From looking into it and from my resources, I understand the the stock ignition is more than adequate; it just needs to be replaced from time to time.
But, this might be the chance for someone else (that's in the know) to chime in on the stock ignition performance.
nice piece of info
But, I don't know if I agree with #5 (terrible factory ignition). From looking into it and from my resources, I understand the the stock ignition is more than adequate; it just needs to be replaced from time to time.
But, this might be the chance for someone else (that's in the know) to chime in on the stock ignition performance.
07-30-2010, 06:12 PM
#38
Addict
Lifetime Rennlist
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I don't know were to start but a few points I would like to make.
1.Regardless of plug tip material on over the counter spark plugs the core material will be copper.
2. How a heat range is determined given to me from NGK website.
http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml
Surface area and/or length of the insulator nose
Thermal conductivity of the insulator, center electrode, etc.
Structure of the center electrode such as a copper core, etc.
Relative position of the insulator tip to the end of the shell (projection)
3. Now, for some information.
There is a reason the factory decided to put 911 turbo owners through the pain of reducing the service interval from 60,000mi on your standard model 911 to just 30,000mi on a turbo. The reason for the change is the factory decided it better to switch to a copper tipped spark plug for the turbo 911.
Why did they make this decision?
Copper has the best Electrical Performance and the best Thermal Performance.
What do I mean?
10-ga wire Resistance Ohms/ft
Copper = 0.000999
Iridium = 0.00306
Platinum = 0.00579
Obviously, this only effects the "Tip" as all cores are copper. However, there is another important factor to resistance and that is size.
Wire Gauge Resistance per foot of Copper (Same theory of larger is less resistance applies to all metals)
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480
28 .0764
So, in a simple answer copper tips are the largest and just like in wire this means the least amount of electrical resistance and as a result more voltage at the tip to fire to ground. Also, with a copper plug there is no metal type transition that also hurts electrical conduction.
We know that there is going to be less voltage drop from resistance from tip to tip of a spark plug (not counting ground strap!) If we use copper and since we know this and then we know that the resistance goes up as we start to produce more power. This makes it harder for the plug voltage to overcome the air gap resistance and fire to the ground strap (Closing the circuit). So if we run non-copper tip plugs we have less voltage to make this jump. If the flow is not enough on these non-copper plugs to jump onto the ground strap you misfire. So that leaves us with 2 possible solutions. We make the air gap resistance less by reducing the plug gap allowing us to not misfire or you switch to copper plugs.
Now, You might be wondering why don't I just reduce my gap? Well, doing so will result in a power loss for a few reasons. A stronger spark will help start flame propagation meaning that the stronger it starts the less timing you need to put in to maximize the engines performance. Timing is the only other way to maximize propagation with the ignition system. However, since flame front speed is linked to cylinder pressure (along with things like AFR) as you increase pressure you also increase flame speed. So a strong spark in a way acts like advancing the timing but without the drawbacks.
Now, that I covered the electrical aspect of the plug its time to talk about the more important thermal aspect.
As I had mentioned Copper has the best heat properties of all the metals in question.
Thermal Conductivity
Btu / (hr - ft -°F)
Copper = 231
Iridium = 85
Platinum = 41.36
This means that copper can conduct heat at much higher levels then Iridium or Platinum but more important for our spark plugs. As mentioned earlier type of tip is a factor in determining a spark plugs heat range but the largest factor is the insulator. However, not all things are equal in this case because heat ranges are not determined by dynamic testing but static testing. Sadly, engines are dynamic when it comes to thermal environment. Since you have the heat of combustion and the cooling of an intake charge etc.
This is another reason to use copper because copper is the best in a dynamic environment since it will be able to transfer heat away from the tip into the core faster. The problem is that sometimes a colder iridium or platinum spark plug cannot move heat away from the tip fast enough. It does not have the physical size or metal properties to allow for such a quick transfer to occur. Since the plug is unable to move the heat into the body of the plug quick enough The plug can become super heated at the tip can cause detonation (even colder plugs).
5. The final point about sparkplugs is that your 944 Turbo has a terrible ignition system from the factory and as boost increases your going to need to drop down your gap significantly. It is impossible on some sparkplugs such as iridiums to adjust this gap without damaging the tiny electrode.
Now, for obvious reason you can understand why I wouldn't use one of these Iridium plugs or Platinum plugs in your high performance 944 turbo.
-Your Pal
Fishey
1.Regardless of plug tip material on over the counter spark plugs the core material will be copper.
2. How a heat range is determined given to me from NGK website.
http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml
Surface area and/or length of the insulator nose
Thermal conductivity of the insulator, center electrode, etc.
Structure of the center electrode such as a copper core, etc.
Relative position of the insulator tip to the end of the shell (projection)
3. Now, for some information.
There is a reason the factory decided to put 911 turbo owners through the pain of reducing the service interval from 60,000mi on your standard model 911 to just 30,000mi on a turbo. The reason for the change is the factory decided it better to switch to a copper tipped spark plug for the turbo 911.
Why did they make this decision?
Copper has the best Electrical Performance and the best Thermal Performance.
What do I mean?
10-ga wire Resistance Ohms/ft
Copper = 0.000999
Iridium = 0.00306
Platinum = 0.00579
Obviously, this only effects the "Tip" as all cores are copper. However, there is another important factor to resistance and that is size.
Wire Gauge Resistance per foot of Copper (Same theory of larger is less resistance applies to all metals)
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480
28 .0764
So, in a simple answer copper tips are the largest and just like in wire this means the least amount of electrical resistance and as a result more voltage at the tip to fire to ground. Also, with a copper plug there is no metal type transition that also hurts electrical conduction.
We know that there is going to be less voltage drop from resistance from tip to tip of a spark plug (not counting ground strap!) If we use copper and since we know this and then we know that the resistance goes up as we start to produce more power. This makes it harder for the plug voltage to overcome the air gap resistance and fire to the ground strap (Closing the circuit). So if we run non-copper tip plugs we have less voltage to make this jump. If the flow is not enough on these non-copper plugs to jump onto the ground strap you misfire. So that leaves us with 2 possible solutions. We make the air gap resistance less by reducing the plug gap allowing us to not misfire or you switch to copper plugs.
Now, You might be wondering why don't I just reduce my gap? Well, doing so will result in a power loss for a few reasons. A stronger spark will help start flame propagation meaning that the stronger it starts the less timing you need to put in to maximize the engines performance. Timing is the only other way to maximize propagation with the ignition system. However, since flame front speed is linked to cylinder pressure (along with things like AFR) as you increase pressure you also increase flame speed. So a strong spark in a way acts like advancing the timing but without the drawbacks.
Now, that I covered the electrical aspect of the plug its time to talk about the more important thermal aspect.
As I had mentioned Copper has the best heat properties of all the metals in question.
Thermal Conductivity
Btu / (hr - ft -°F)
Copper = 231
Iridium = 85
Platinum = 41.36
This means that copper can conduct heat at much higher levels then Iridium or Platinum but more important for our spark plugs. As mentioned earlier type of tip is a factor in determining a spark plugs heat range but the largest factor is the insulator. However, not all things are equal in this case because heat ranges are not determined by dynamic testing but static testing. Sadly, engines are dynamic when it comes to thermal environment. Since you have the heat of combustion and the cooling of an intake charge etc.
This is another reason to use copper because copper is the best in a dynamic environment since it will be able to transfer heat away from the tip into the core faster. The problem is that sometimes a colder iridium or platinum spark plug cannot move heat away from the tip fast enough. It does not have the physical size or metal properties to allow for such a quick transfer to occur. Since the plug is unable to move the heat into the body of the plug quick enough The plug can become super heated at the tip can cause detonation (even colder plugs).
5. The final point about sparkplugs is that your 944 Turbo has a terrible ignition system from the factory and as boost increases your going to need to drop down your gap significantly. It is impossible on some sparkplugs such as iridiums to adjust this gap without damaging the tiny electrode.
Now, for obvious reason you can understand why I wouldn't use one of these Iridium plugs or Platinum plugs in your high performance 944 turbo.
-Your Pal
Fishey
07-30-2010, 07:06 PM
#39
Drifting
Thread Starter
I don't know were to start but a few points I would like to make.
1.Regardless of plug tip material on over the counter spark plugs the core material will be copper.
2. How a heat range is determined given to me from NGK website.
http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml
Surface area and/or length of the insulator nose
Thermal conductivity of the insulator, center electrode, etc.
Structure of the center electrode such as a copper core, etc.
Relative position of the insulator tip to the end of the shell (projection)
3. Now, for some information.
There is a reason the factory decided to put 911 turbo owners through the pain of reducing the service interval from 60,000mi on your standard model 911 to just 30,000mi on a turbo. The reason for the change is the factory decided it better to switch to a copper tipped spark plug for the turbo 911.
Why did they make this decision?
Copper has the best Electrical Performance and the best Thermal Performance.
What do I mean?
10-ga wire Resistance Ohms/ft
Copper = 0.000999
Iridium = 0.00306
Platinum = 0.00579
Obviously, this only effects the "Tip" as all cores are copper. However, there is another important factor to resistance and that is size.
Wire Gauge Resistance per foot of Copper (Same theory of larger is less resistance applies to all metals)
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480
28 .0764
So, in a simple answer copper tips are the largest and just like in wire this means the least amount of electrical resistance and as a result more voltage at the tip to fire to ground. Also, with a copper plug there is no metal type transition that also hurts electrical conduction.
We know that there is going to be less voltage drop from resistance from tip to tip of a spark plug (not counting ground strap!) If we use copper and since we know this and then we know that the resistance goes up as we start to produce more power. This makes it harder for the plug voltage to overcome the air gap resistance and fire to the ground strap (Closing the circuit). So if we run non-copper tip plugs we have less voltage to make this jump. If the flow is not enough on these non-copper plugs to jump onto the ground strap you misfire. So that leaves us with 2 possible solutions. We make the air gap resistance less by reducing the plug gap allowing us to not misfire or you switch to copper plugs.
Now, You might be wondering why don't I just reduce my gap? Well, doing so will result in a power loss for a few reasons. A stronger spark will help start flame propagation meaning that the stronger it starts the less timing you need to put in to maximize the engines performance. Timing is the only other way to maximize propagation with the ignition system. However, since flame front speed is linked to cylinder pressure (along with things like AFR) as you increase pressure you also increase flame speed. So a strong spark in a way acts like advancing the timing but without the drawbacks.
Now, that I covered the electrical aspect of the plug its time to talk about the more important thermal aspect.
As I had mentioned Copper has the best heat properties of all the metals in question.
Thermal Conductivity
Btu / (hr - ft -°F)
Copper = 231
Iridium = 85
Platinum = 41.36
This means that copper can conduct heat at much higher levels then Iridium or Platinum but more important for our spark plugs. As mentioned earlier type of tip is a factor in determining a spark plugs heat range but the largest factor is the insulator. However, not all things are equal in this case because heat ranges are not determined by dynamic testing but static testing. Sadly, engines are dynamic when it comes to thermal environment. Since you have the heat of combustion and the cooling of an intake charge etc.
This is another reason to use copper because copper is the best in a dynamic environment since it will be able to transfer heat away from the tip into the core faster. The problem is that sometimes a colder iridium or platinum spark plug cannot move heat away from the tip fast enough. It does not have the physical size or metal properties to allow for such a quick transfer to occur. Since the plug is unable to move the heat into the body of the plug quick enough The plug can become super heated at the tip can cause detonation (even colder plugs).
5. The final point about sparkplugs is that your 944 Turbo has a terrible ignition system from the factory and as boost increases your going to need to drop down your gap significantly. It is impossible on some sparkplugs such as iridiums to adjust this gap without damaging the tiny electrode.
Now, for obvious reason you can understand why I wouldn't use one of these Iridium plugs or Platinum plugs in your high performance 944 turbo.
-Your Pal
Fishey
1.Regardless of plug tip material on over the counter spark plugs the core material will be copper.
2. How a heat range is determined given to me from NGK website.
http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml
Surface area and/or length of the insulator nose
Thermal conductivity of the insulator, center electrode, etc.
Structure of the center electrode such as a copper core, etc.
Relative position of the insulator tip to the end of the shell (projection)
3. Now, for some information.
There is a reason the factory decided to put 911 turbo owners through the pain of reducing the service interval from 60,000mi on your standard model 911 to just 30,000mi on a turbo. The reason for the change is the factory decided it better to switch to a copper tipped spark plug for the turbo 911.
Why did they make this decision?
Copper has the best Electrical Performance and the best Thermal Performance.
What do I mean?
10-ga wire Resistance Ohms/ft
Copper = 0.000999
Iridium = 0.00306
Platinum = 0.00579
Obviously, this only effects the "Tip" as all cores are copper. However, there is another important factor to resistance and that is size.
Wire Gauge Resistance per foot of Copper (Same theory of larger is less resistance applies to all metals)
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480
28 .0764
So, in a simple answer copper tips are the largest and just like in wire this means the least amount of electrical resistance and as a result more voltage at the tip to fire to ground. Also, with a copper plug there is no metal type transition that also hurts electrical conduction.
We know that there is going to be less voltage drop from resistance from tip to tip of a spark plug (not counting ground strap!) If we use copper and since we know this and then we know that the resistance goes up as we start to produce more power. This makes it harder for the plug voltage to overcome the air gap resistance and fire to the ground strap (Closing the circuit). So if we run non-copper tip plugs we have less voltage to make this jump. If the flow is not enough on these non-copper plugs to jump onto the ground strap you misfire. So that leaves us with 2 possible solutions. We make the air gap resistance less by reducing the plug gap allowing us to not misfire or you switch to copper plugs.
Now, You might be wondering why don't I just reduce my gap? Well, doing so will result in a power loss for a few reasons. A stronger spark will help start flame propagation meaning that the stronger it starts the less timing you need to put in to maximize the engines performance. Timing is the only other way to maximize propagation with the ignition system. However, since flame front speed is linked to cylinder pressure (along with things like AFR) as you increase pressure you also increase flame speed. So a strong spark in a way acts like advancing the timing but without the drawbacks.
Now, that I covered the electrical aspect of the plug its time to talk about the more important thermal aspect.
As I had mentioned Copper has the best heat properties of all the metals in question.
Thermal Conductivity
Btu / (hr - ft -°F)
Copper = 231
Iridium = 85
Platinum = 41.36
This means that copper can conduct heat at much higher levels then Iridium or Platinum but more important for our spark plugs. As mentioned earlier type of tip is a factor in determining a spark plugs heat range but the largest factor is the insulator. However, not all things are equal in this case because heat ranges are not determined by dynamic testing but static testing. Sadly, engines are dynamic when it comes to thermal environment. Since you have the heat of combustion and the cooling of an intake charge etc.
This is another reason to use copper because copper is the best in a dynamic environment since it will be able to transfer heat away from the tip into the core faster. The problem is that sometimes a colder iridium or platinum spark plug cannot move heat away from the tip fast enough. It does not have the physical size or metal properties to allow for such a quick transfer to occur. Since the plug is unable to move the heat into the body of the plug quick enough The plug can become super heated at the tip can cause detonation (even colder plugs).
5. The final point about sparkplugs is that your 944 Turbo has a terrible ignition system from the factory and as boost increases your going to need to drop down your gap significantly. It is impossible on some sparkplugs such as iridiums to adjust this gap without damaging the tiny electrode.
Now, for obvious reason you can understand why I wouldn't use one of these Iridium plugs or Platinum plugs in your high performance 944 turbo.
-Your Pal
Fishey
07-31-2010, 05:08 PM
#40
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