What Heat Range Spark Plug Should I Use?

While setting spark plugs in your vehicle, just determining the quality and size is not enough. To keep its efficiency throughout, you need to consider the heat range of them as well, depending on your vehicle’s engine modification.

Or else, too hot (a low degree of heat dispersal) or too cold (high degree of heat dispersal) range than your engine’s requirement can deteriorate the spark plugs’ functioning.

What Heat Range Spark Plug Should I Use

People often get confused while choosing the right heat range; hence, we have brought a brief article about this.

Some Common Discussion About Heat Range of Spark Plug

Spark plug too cold symptoms

Spark Plug Too Cold Symptoms

If your spark plugs’ heat range is too cold, you might face engine fouling and misfiring symptoms. The engine will start too slow with cold spark plugs. Carbon deposits will build up more as the plugs miss self-cleaning when the temperature is too cold around.

Therefore, the heat range tip temperature should be at least 500-degrees Celcius to avoid too cold plugs.

Too hot spark plug symptoms

Hot Spark Plug Symptoms

On the other hand, if your spark plug’s heat range is too hot, which is more than 850-degrees C, then the engine can suffer from detonation, power loss, or pre-ignition.

Moreover, the spark plugs will overheat with too hot heat range, create white blisters on the insulator tip, melt the electrodes, and do not!

Spark plug temperature and vehicle speed

Spark Plug Temperature And Vehicle Speed

A spark plug only functions completely and fully when its center electrode temperature is between 500°C and 850°C. Too heat makes your engine experience detonation, pre-ignition, or power loss.

Spark plug heat range 6 vs 7

The law : colder the higher the number, hotter the lower the number.

BKR6E-11 (heat range 6), a colder plug would # BKR7E-11 (heat range 7) source:ngk

Spark plug heat range chart

Spark Plug Heat Range Chart

Heat ranges differ from brand to brand. Whatever the brand of spark plug you choose, make sure you consult with your sales representative to know about your required heat range keeping in mind your vehicle’s basic info and any additional modifications you have inputted.

Chevy 350 spark plug heat range

The best spark plug considered for Chevy 350 is NGK, ACDelco platinum, copper or iridium, and Bosch double iridium. So, from this, you can guess that chevy 350’s preferred spark plug heat range is between 500-800 degrees C. Check spark plug wires for chevy 350 with headers.

NGK spark plug chart

Here’s a chart of NGK spark plugs, from which you can see the heat range in the middle. As the range increases, the plugs get hotter. The chart also contains all the full forms of the indicators, shell size, and GAP to help you figure them out easily.

NGK spark plug chart

Source: NGK Spark Plug Numbering System By NGK

AC spark plug heat range chart

ACDelco makes all the premium-quality spark plugs that serve your engine to the next level. Each of them is made from materials like iridium, platinum, or chrome-allow, as shown in the chart. So, they have different heat ranges. You can know more about ACDelco’s spark plugs from here. ACDELCO Spark Plug Heat Range Chart by ACDELCO.

AC spark plug heat range chart

Source: Wrench Monkey Webpage


People Also Asked

#1. What happens if you use a hotter spark plug?

Hotter spark plugs cause overheating and cause the electrodes to melt. Also, it can lead to pre-ignition to your engine and make it damage permanently. Lastly, they leave white blisters on the insulator tip causing inefficiency.

An average spark plug should have a maximum temperature of 600-800-degrees C depending on the engine type.

#2. Are the hot or cold spark plugs better?

Both the types are suitable for two different reasons. For high RPM engines that produce high operating temperature, cold spark plugs are better. Whereas, for low RPM engines with a low operating temp, hot plugs prove to serve better. As a result, the temperature balances out with the engine’s temperature for self-cleaning and preventing overheating.

#3. What is the heat range of NGK Spark Plugs?

Heat range for NGK Spark Plugs is 500 degrees C to 800 degrees C. Do select the heat range with great care for optimal thermal performance, or else your vehicle will face serious problems.

#4. What controls the spark plug heat range?

The insulator nose’s length controls the spark plug range, as it transfers the heat to the spark plugs’ metal shells. Then it is transferred to the cylinder head and eventually to the coolant passage, and the radiator cools it down.

It means the longer the nose, the hotter the spark plugs will be, and tips will remain hot for long, vice-versa.

#5. Does spark plug heat range affect performance?

Of course, it does. Choosing the right heat range offers the right thermal energy to perform at its optimum level. Too cold spark plugs prevent the spark plugs’ self-cleaning, allowing carbon buildup. Whereas, too cold spark plugs damage the engine and its power by pre-igniting.

#6. Do Iridium plugs burn hotter?

Iridium spark plugs are very long-lasting that do not need frequent replacement and improve your engine’s performance more than any other ones. They have less heat-conducting capacity than copper, so they don’t burn hotter. Also, another reason they are long-lasting is that they don’t overheat frequently.

Source: Denso Webpage