spark plugs

[02MeanStreak]

What type of spark plugs are you using in your mean streak? I have the stock ones, but I was curious if anyone was using hotter plugs?

[Ericthejet]

FYI and my manual has no provisions for differnet spark plug heat ranges.

A spark plug's heat range has no relationship on the actual voltage transferred through the spark plug. Rather, the heat range is a measure of the spark plug's ability to remove heat from the combustion chamber. The heat range measurement is determined by several factors:

The length of the ceramic center insulator nose
The insulator nose's ability to absorb and transfer combustion heat
The material composition of the insulator
The material composition of the center electrode
The longer the insulator nose gives you a larger surface area exposed to combustion gasses and heat is dissipated slowly. This also means the firing end heats up more quickly. We are talking about exposed ceramic length, not extended tip length.

In identical spark plugs, the differences from one heat range to the next is the ability to remove approximately 70°C to 100°C from the combustion chamber. A projected style spark plug firing temperature is increased by 10°C to 20°C.
The colder type plug removes heat more quickly, and will reduce the chance of pre-ignition/detonation and burn-out of the firing end. (Engine temperatures can affect the spark plug's operating temperature, but not the spark plug's heat range).

Influences on Spark Plug Temp and Performance:

Below is a list of possible external influences on a spark plug's operating temperatures. The following symptoms or conditions may have an affect on the actual temperature of the spark plug. The spark plug cannot create these conditions, but it must be able to deal with all the levels of heat, otherwise performance will suffer and engine damage can occur:

Air/Fuel Mixtures seriously affect engine performance and spark plug temps.

Rich air/fuel mixtures cause tip temperature to drop, causing fouling and poor drivability.
Lean air/fuel mixtures cause plug tip and cylinder temperatures to increase resulting in pre-ignition, detonation, and possibly serious spark plug and internal engine damage.
It is important to read spark plugs many times during the tuning process to achieve optimum air/fuel mixture. Computer-controlled engine applications do a pretty good job of this with the various sensors that report back to the ECM.
Higher Compression Ratios and Forced Induction will elevate spark plug tip and in-cylinder temperatures.

Compression can be increased by performing any one of the following modifications:
a) reducing combustion chamber volume (i.e.: domed pistons, smaller chamber heads, milling heads, etc.)
b) adding forced induction (Nitrous, Turbocharging, Supercharging)
c) camshaft change
As compression increases, a colder heat range plug is required, as well as higher octane fuel and paying careful attention to ignition timing and air/fuel ratios are also necessary.
Advanced Ignition Timing: Advancing timing by 10° causes plug temperature to increase by approximately 70°C to 100°C.

Engine Speed and Load: Increases in firing-end temperatures and are proportional to engine speed and load. When traveling at a constant high rate of speed, or carrying/pushing very heavy loads, a colder heat range spark plug should be installed.

The heavier your vehicle or greater the amount of work the engine sees (racing applications, construction trucks, vans, RVs & Motorhomes, etc.), the more critical this becomes.

Ambient Air Temperature:

As air temperature falls, air density volume increases, resulting in leaner air/fuel mixtures. This creates higher cylinder pressures and temperatures that causes an an increase in the spark plug's tip temperature. Fuel delivery should be increased.
As temperature increases, air density decreases, as does intake volume, and fuel delivery should be decreased.


Humidity: As humidity increases, air volume decreases. The result is lower combustion pressures and temperatures, causing a decrease in the spark plug's temperature and a reduction in available power. Air/Fuel mixture should be leaner, depending on ambient air temperature.

Barometric Pressure and Altitude:

Affects the spark plug's temperature
The higher the altitude, the lower the cylinder pressure becomes. As the cylinder temperature decreases, so does the tip temperature.
Many tuners attempt to "chase" tuning by changing spark plug heat ranges.
The real answer is to play with the jetting or air/fuel mixtures in an effort to put more air back in the engine.

[Phatboy]

Originally Posted by Ericthejet

The colder type plug removes heat more quickly, and will reduce the chance of pre-ignition/detonation and burn-out of the firing end.

I've heard of people running a slightly colder plug for the above reason.

[Frankt07]

ok guys
im at about 6K on the clock and was thinking maybe its about time to replace the plugs. i would like to go with NGK or Denso iridiums, but cant find a place that has em. while i was at the auto parts the other day, i noticed they carry Bosch platinums in single, dual, and quad tips. has anyone used any plugs other than the NGK's?

and Deron, i aint puttin no dadgum AC Delco in my machine either

[Rocsmeanie]

hmm, maybe I should change my plugs. I have 18k km which is about 11000 miles and still have the original plugs in.

[cudaosix]

Originally Posted by Frankt07

ok guys
im at about 6K on the clock and was thinking maybe its about time to replace the plugs. i would like to go with NGK or Denso iridiums, but cant find a place that has em. while i was at the auto parts the other day, i noticed they carry Bosch platinums in single, dual, and quad tips. has anyone used any plugs other than the NGK's?

and Deron, i aint puttin no dadgum AC Delco in my machine either

Frank thats strange that you cant find NGK plugs. I buy NGK BP8ES plugs at a Discount auto parts. Is it that you cant find a specific NGK your looking for? Bro I think you should be able to get a whole lot more then 6K out of your plugs.

[Frankt07]

Originally Posted by cudaosix

Frank thats strange that you cant find NGK plugs. I buy NGK BP8ES plugs at a Discount auto parts. Is it that you cant find a specific NGK your looking for? Bro I think you should be able to get a whole lot more then 6K out of your plugs.

i really havent checked. i was looking online. i wqs also looking to go with high performance plugs too. i have heard the iridiums are awesome

you goin to fudds tonight?

[Xlr8n]

frank- FWIW, most 'high performance' plugs have been shown to provide no benefit in performance or longevity in otherwise stock engine applications. I'd just go with the manufacturer recommended plugs.

[Frankt07]

hw about them dual or quad tipped plugs. they supposedly have a better spark due to the extra material for the spark to hit

[cudaosix]

Frank I think your better off with NGK then a plug that claims to produce better spark for whatever reason. I dont think it makes much of a difference other then in your wallet. NGK is inexpensive and should last several thousand miles.

[bluestringer]

Originally Posted by Frankt07

ok guys
im at about 6K on the clock and was thinking maybe its about time to replace the plugs. i would like to go with NGK or Denso iridiums, but cant find a place that has em. while i was at the auto parts the other day, i noticed they carry Bosch platinums in single, dual, and quad tips. has anyone used any plugs other than the NGK's?

and Deron, i aint puttin no dadgum AC Delco in my machine either

Stock plugs should last around 30,000. If you go with iridiums, you will never have to change them again.

[kingofwings]

I changed to NGK Iriduim DPR8-EIX-9 (colder then stock) last year. Picked them up at Advance Auto for $7.00 each. I'd absolutely recommend this to any Meanie/Marauder owner. About 10,000 miles on them.... look great. Worth the $30.00 experiment.