Colder spark plugs

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beretta777
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Colder spark plugs

Postby beretta777 » Thu May 30, 2013 8:47 pm

Is anyone running colder plugs im running a beretta dirt racing with a 3100 with 3400 top end going to get it tuned. the guy doing the tuning said to try and find a colder plug so we can jump the timing more cause the car gets really hot after and during the race and wanna make sure I can start it when its hot. So if anyone knows of part number or plugs to get any info would be nice thanks.



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Re: Colder spark plugs

Postby heavywoody » Thu May 30, 2013 8:48 pm

Colder plugs don't normally do anything unless you're either spraying or boosted. But I could be wrong.


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Re: Colder spark plugs

Postby Slinky » Thu May 30, 2013 9:45 pm

I believe Woody is correct no matter how hot your engine gets Or how hard you be going to a colder plug won't help it stay colder, I run .030 or .035 In my engine but it is boosted, You should just run stock which are .040 or .045 I believe


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Re: Colder spark plugs

Postby Rettax3 » Fri May 31, 2013 3:06 am

I don't know... My old Honda 750 (it is a motorcycle, but was normally-aspirated and liquid-cooled with aluminum heads) was a totally different animal with colder plugs -easier hot-starts because the plug wasn't so hot the fuel probably pre-ignited on the hotter plugs during the low RPMs of cranking and it even ran a little cooler -that bike uses Resistor plugs though, so running a colder plug for me probably advanced the timing by a degree or two, since electrical resistance changes with temperature, and at 10.5:1 compression, it is temperamental to say the least.

ngksparkplugs.com has a great article on this, and they seem to offer a better temperatur range than many other manufacturers for a given size of plug. I love NGK plugs, I would recommend looking into them to see if they offer what you are looking for.


1989 Super Charged 3800 Series II (First)Six-Speed Conversion GTU
1990 Turbo 3.4 Five-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 Five-Speed Indy GTi (Rebuild Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 3400 Top-End Auto OD Z-26

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Re: Colder spark plugs

Postby Slinky » Fri May 31, 2013 7:14 am

I think colder plugs main usage are in boosted engines because of their shorter arc length, the boost actually will blow out a stock spark plug arc in aome cases so a shorted gapped plug is needed


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Re: Colder spark plugs

Postby 3X00-Modified » Fri May 31, 2013 8:04 am

Don't confuse temp and gap, two different things. Rather than try to explain it in my own words it's easier to use the spark plug tech stuff they have on their websites to explain the heat range.
NGK Spark Plugs Heat Rating

The spark plug heat range has no relationship to the electrical energy transferred through the spark plug. The heat range of a spark plug is the range in which the plug works well thermally. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type.

Heat rating and heat flow path of NGK Spark Plugs

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Some basic structural factors affecting the heat range of a spark plug are:

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)
The major structural difference affecting the heat rating is the length of the insulator nose. A hot type spark plug has a longer insulator nose. The insulator nose of a hotter spark plug has a longer distance between the firing tip of the insulator, and the point where insulator meets the metal shell. Therefore, the path for the dissipation of heat from the insulator nose to the cylinder head is longer and the firing end stays hotter. The insulator nose of a hotter spark plug also has a greater surface area that is exposed to more of the ignited gases and is easily heated to higher temperatures. A colder spark plug functions in an opposite manner.

The heat range must be carefully selected for proper spark plug thermal performance. If the heat range is not optimal, then serious trouble can be the result. The optimal firing end temperature is approximately between 500°C (932°F) and 800°C (1472°F). The two most common causes of spark plug problems are carbon fouling (< 450°C) and overheating (> 800°C).

http://www.youtube.com/watch?feature=player_embedded&v=LbR75wq9nmM

Causes of Carbon Fouling:

Continuous low speed driving and/or short trips
Spark plug heat range too cold
Air-fuel mixture too rich
Reduced compression and oil usage due to worn piston rings / cylinder walls
Over-retarded ignition timing
Ignition system deterioration

Pre-delivery fouling

Carbon fouling occurs when the spark plug firing end does not reach the self-cleaning temperature of approximately 450°C (842°F). Carbon deposits will begin to burn off from the insulator nose when the self-cleaning temperature is reached. When the heat range is too cold for the engine speed, the firing end temperature will stay below 450°C and carbon deposits will accumulate on the insulator nose. This is called carbon fouling. When enough carbon accumulates, the spark will travel the path of least resistance over the insulator nose to the metal shell instead of jumping across the gap. This usually results in a misfire and further fouling.

If the selected spark plug heat range is too cold, the spark plug may begin to foul when the engine speed is low or when operating in cold conditions with rich air-fuel mixtures. In some cases, the insulator nose can usually be cleaned by operating the engine at higher speeds in order to reach the self-cleaning temperature. If the spark plug has completely fouled, and the engine will not operate correctly, the spark plug may need to be cleaned / replaced and the fouling cause identified.

Causes of Overheating:

Spark plug heat range too hot
Insufficient tightening torque and/or no gasket
Over-advanced ignition timing
Fuel octane rating too low (knock is present)
Excessively lean air-fuel mixture
Excessive combustion chamber deposits
Continuous driving under excessively heavy load
Insufficient engine cooling or lubrication
The most serious result of selecting a heat range that is too hot is overheating. Overheating will cause the electrodes to wear quickly and can lead to pre-ignition. Pre-ignition occurs when the air-fuel mixture is ignited by a hot object/area in the combustion chamber before the timed spark event occurs. When the spark plug firing end (tip) temperature exceeds 800°C, pre-ignition originating from the overheated insulator ceramic can occur. Pre-ignition will dramatically raise the cylinder temperature and pressure and can cause serious and expensive engine damage. When inspecting a spark plug that has experienced overheating or pre-ignition, blistering on the ceramic insulator and/or melted electrodes can sometimes be found.

As a general guideline, among identical spark plug types, the difference in tip temperature from one heat range to the next is approximately 70°C to 100°C.



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Re: Colder spark plugs

Postby Slinky » Fri May 31, 2013 12:06 pm

Nice Jon!!


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Rettax3
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Re: Colder spark plugs

Postby Rettax3 » Fri May 31, 2013 4:10 pm

That is exactly the NGK site I saw. Thanks for copying that over for us , Jon.


1989 Super Charged 3800 Series II (First)Six-Speed Conversion GTU
1990 Turbo 3.4 Five-Speed T-Type
1990 4.0L 4-Cam 32-Valve V-8 Five-Speed Indy GTi (Rebuild Project)
1990 Stock(!) 3.1 MPFI Auto Indy
1995 3400 Top-End Auto OD Z-26


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