spark plug question for rotax 503

The function of a spark plug is to regulate the temperature in the combustion chamber and has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system.

Hello Fritz,

I went to the link you provided from Autolite and I was not able to understand how it said that the function of a spark plug is to regulate the temperature in the combustion chamber and has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system.

I would be grateful if you would post the source of your information related to the function of a spark plug regulating the temperature in the combustion chamber and how it has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system so I can become less ignorant.

Thank you, Vance
 
That was also my understanding. The inverted engines required plugs more resistant to oil fouling. Where's Dennis Fetters when you need him? :noidea:
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I have posted on this matter several times, so if anyone wants to know more, just search it.

It is not a matter of using a different plug. It's a matter of not running your engine EGT's too low. In cruse, you need to run your EGT's no cooler than 950F. 1050F is perfect. This way there is not a buildup of carbon, or excess oil at shutdown.

Also, always run the oil injector, and set it correctly. If you mix, then after shutdown the fuel will evaporate and leave excess oil behind.
 
I have posted on this matter several times, so if anyone wants to know more, just search it.

It is not a matter of using a different plug. It's a matter of not running your engine EGT's too low. In cruse, you need to run your EGT's no cooler than 950F. 1050F is perfect. This way there is not a buildup of carbon, or excess oil at shutdown.

Also, always run the oil injector, and set it correctly. If you mix, then after shutdown the fuel will evaporate and leave excess oil behind.

Dennis, I tried to do the search, but couldn't find what I thought I remembered. I did remember that you probably had more experience with inverted Rotax engines than most of us. I apologize if I have inconvienced you. Thanks for the clarification anyway.
 
Dennis, I tried to do the search, but couldn't find what I thought I remembered. I did remember that you probably had more experience with inverted Rotax engines than most of us. I apologize if I have inconvienced you. Thanks for the clarification anyway.

I didn't mean it was an inconvenience to answer. I only meant that I had discussed the topic in more detail before, and rather do so again, it would only be a matter of looking at some of my old posts, for those that would be interested.
 
Hello Fritz,

I went to the link you provided from Autolite and I was not able to understand how it said that the function of a spark plug is to regulate the temperature in the combustion chamber and has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system.

I would be grateful if you would post the source of your information related to the function of a spark plug regulating the temperature in the combustion chamber and how it has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system so I can become less ignorant.

Thank you, Vance

Yeah, me too! Fritz, it would be most interesting to see how you reverse the known laws of thermodynamics.

Us Ignoramuses are anxiously awaiting your enlightenment!:rolleyes:
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Thanks to all for the excellent feed back and all have a good holiday.
 
I have posted on this matter several times, so if anyone wants to know more, just search it.

It is not a matter of using a different plug. It's a matter of not running your engine EGT's too low. In cruse, you need to run your EGT's no cooler than 950F. 1050F is perfect. This way there is not a buildup of carbon, or excess oil at shutdown.

Also, always run the oil injector, and set it correctly. If you mix, then after shutdown the fuel will evaporate and leave excess oil behind.


There seems to be a lot of mystery and misinformation about using exhaust gas temperatures to tune engines. Claims by many EGT gauge manufacturers about it being the best way to tune an engine must be qualified. The BEST way to tune an engine is on an engine dyno- PERIOD. What EGT is good for is a reference for where the engine made maximum torque at wide open throttle. Once removed from the dyno, a similar air/fuel ratio can be established at a later date by dialing in the mixture to achieve the target EGT. It is really the AFR that is important, not the EGT
 
Nice thing is you can remove them and wipe them off, and they look like new.
Just make sure you don't use a wire brush, you will deposit metal from the brush to the elctrode, causing the spark to track down to earth. If you observe a spark in a spark plug cleaning machine under pressure, you'll see that the spark jumps from the edge of the electrode, thats why it wears itself round, then the spark has to travel in an arc to the centre. requiring a higher voltage. so if you take an old plug and file the electrode flat it will take less voltage, stopping any misfires. Also bend the ground to be as parrallel to the centre electrode as possible. Thats why these plugs with the thin electrode fires better for longer. With the right heat range, it shouldn't matter what plug you use.
 
There seems to be a lot of mystery and misinformation about using exhaust gas temperatures to tune engines. Claims by many EGT gauge manufacturers about it being the best way to tune an engine must be qualified. The BEST way to tune an engine is on an engine dyno- PERIOD. What EGT is good for is a reference for where the engine made maximum torque at wide open throttle. Once removed from the dyno, a similar air/fuel ratio can be established at a later date by dialing in the mixture to achieve the target EGT. It is really the AFR that is important, not the EGT

No mystery about it. Use the stock plugs that Rotax says, install your EGT sensors at the proper distance from the piston face, use proper calibrated EGT's and guage and don't run them to low or too high.

We don't "tune" engines. Rotax tunes the engines. We just "Use" the engine and stay within the Rotax parameters. People that like to experiment with getting the most power out of an engine is something else, and has it's place, but not in general aviation. We want reliability more than max power.
 
Hello Fritz,

I went to the link you provided from Autolite and I was not able to understand how it said that the function of a spark plug is to regulate the temperature in the combustion chamber and has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system.

I would be grateful if you would post the source of your information related to the function of a spark plug regulating the temperature in the combustion chamber and how it has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system so I can become less ignorant.

Thank you, Vance


The basic understanding of a spark plug is that it must perform two primary functions.

1. To Ignite the Air/Fuel Mixture

2. To REMOVE the heat out of the combustion chamber

Spark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of voltage must be supplied by the ignition system to cause the spark to jump across the spark plug gap, thus creating what is called Electrical Performance.

Additionally, the temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called Thermal Performance, and is determined by the heat range of the spark plug.

It is important to understand that spark plugs CANNOT create heat, only remove it. The spark plug works as a heat exchanger, pulling unwanted thermal energy away from the combustion chamber and transferring the heat into the engine's cooling system. The Heat Range is described as the spark plug's ability to dissipate heat. The rate of heat exchange is determined by: http://www.centuryperformance.com/spark-plug-tech-spg-26.html
 
No mystery about it. Use the stock plugs that Rotax says, install your EGT sensors at the proper distance from the piston face, use proper calibrated EGT's and guage and don't run them to low or too high.

We don't "tune" engines. Rotax tunes the engines. We just "Use" the engine and stay within the Rotax parameters. People that like to experiment with getting the most power out of an engine is something else, and has it's place, but not in general aviation. We want reliability more than max power.

No mystery about it. Use the stock plugs that Rotax says, install your EGT sensors at the proper distance from the piston face, use proper calibrated EGT's and guage and don't run them to low or too high.

Isn’t that called tuning?

We don't "tune" engines. Rotax tunes the engines. We just "Use" the engine and stay within the Rotax parameters. People that like to experiment with getting the most power out of an engine is something else, and has it's place, but not in general aviation. We want reliability more than max power.

In my opinion replacing the OM spark plug for a superior one dost not detract from reliability nor it would change Rotax parameters in any way, and is not 'experimenting' trying to get most of the engine by have it properly tuned.
 

It is important to understand that spark plugs CANNOT create heat, only remove it. The spark plug works as a heat exchanger, pulling unwanted thermal energy away from the combustion chamber and transferring the heat into the engine's cooling system. The rate of heat exchange is determined by: http://www.centuryperformance.com/spark-plug-tech-spg-26.html


Thank you Fritz,

That is a very interesting opinion.

How does the heat get from the spark plug to the cooling system?

How much unwanted thermal energy can a spark pull away from the combustion chamber and transfer into the engine’s cooling system?

Thank you, Vance
 
Thank you Fritz,

That is a very interesting opinion.

How does the heat get from the spark plug to the cooling system?

How much unwanted thermal energy can a spark pull away from the combustion chamber and transfer into the engine’s cooling system?

Thank you, Vance

How does the heat get from the spark plug to the cooling system?

That is a very complex question and the answer most probably will develop confusion to those not familiar with the complexity of a spark plug, but in addition to firing a spark, is to remove heat from the combustion chamber, this is accomplished by channelling the heat through the insulator material and metal housing, from there, the heat is transferred to the cylinder head where the engine cooling system can go to work

How much unwanted thermal energy can a spark pull away from the combustion chamber and transfer into the engine’s cooling system?

That depends on the selected heat range of the spark plug
 
No mystery about it. Use the stock plugs that Rotax says, install your EGT sensors at the proper distance from the piston face, use proper calibrated EGT's and guage and don't run them to low or too high.

Isn’t that called tuning?

We don't "tune" engines. Rotax tunes the engines. We just "Use" the engine and stay within the Rotax parameters. People that like to experiment with getting the most power out of an engine is something else, and has it's place, but not in general aviation. We want reliability more than max power.

In my opinion replacing the OM spark plug for a superior one dost not detract from reliability nor it would change Rotax parameters in any way, and is not 'experimenting' trying to get most of the engine by have it properly tuned.
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oooooook.


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Yeah, me too! Fritz, it would be most interesting to see how you reverse the known laws of thermodynamics.

Us Ignoramuses are anxiously awaiting your enlightenment!:rolleyes:
.

I would not use ‘Us Ignoramuses’ but rather your ignorance believing I would try to reverse laws of thermodynamics. If in doubt next time, I am always ready to provide an answer for your enlightenment!
 
I would not use ‘Us Ignoramuses’ but rather your ignorance believing I would try to reverse laws of thermodynamics. If in doubt next time, I am always ready to provide an answer for your enlightenment!

I'm still waiting for you to explain how the spark plug cools that recessed area in the cylinder head commonly known as the combustion chamber. That would require reversing the laws of thermodynamics. Heat conducts from high to low.
 
I'm still waiting for you to explain how the spark plug cools that recessed area in the cylinder head commonly known as the combustion chamber. That would require reversing the laws of thermodynamics. Heat conducts from high to low.

see post 192
 
The function of a spark plug is to regulate the temperature in the combustion chamber and has the ability to remove/ maintain the heat produced by the combustion process and does take away the excess heat from the cylinder head and it will transfer it to the cooling system.

Is this the one you are refering to?
 
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