Sparkplug question
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Cargo Master
Joined: May 2002
Posts: 3,271
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From: Gulf Coast, FL
Sparkplug question
I have heard of plugs referenced by a "hotter plug" or "colder plug". I believe they are refering to the operating temperature of the plug. Am I correct??
Can someone please help me understand this??
Can someone please help me understand this??
Sit. Stay.
Joined: Oct 2001
Posts: 18,308
Likes: 20
From: Washington State
Yes, you are correct.
Sparkplugs come in varying heat ranges. This way a plug can be matched to the type of use the engine will be receiving.
For low speed, short hop and extended highway driving, the plug's electrodes must stay hot enough to burn away carbon deposits, so a hot plug is needed.
For high speed racing at high rpm, a hot plug can glow like a diesel glowplug causing pre-ignition and detonation. To prevent this a cold heat range plug is needed. But in low speed driving, a cold plug can become fouled with carbon.
A plug's heat range is determined by the length of the insulator of the center electrode.
If the porcelain insulator is short, it is a cold plug. A cold plug's short center electrode has a short path to conduct heat out of the electrode.
If it is long and extends deeply into the steel shell of the plug, it is a hot plug.
A hotter plug has a longer path and dissipates heat more slowly.
Factory sparkplugs typically split the difference and are usually equipped with a plug that split the heat range right "down the middle".
Sparkplugs come in varying heat ranges. This way a plug can be matched to the type of use the engine will be receiving.
For low speed, short hop and extended highway driving, the plug's electrodes must stay hot enough to burn away carbon deposits, so a hot plug is needed.
For high speed racing at high rpm, a hot plug can glow like a diesel glowplug causing pre-ignition and detonation. To prevent this a cold heat range plug is needed. But in low speed driving, a cold plug can become fouled with carbon.
A plug's heat range is determined by the length of the insulator of the center electrode.
If the porcelain insulator is short, it is a cold plug. A cold plug's short center electrode has a short path to conduct heat out of the electrode.
If it is long and extends deeply into the steel shell of the plug, it is a hot plug.
A hotter plug has a longer path and dissipates heat more slowly.
Factory sparkplugs typically split the difference and are usually equipped with a plug that split the heat range right "down the middle".
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