My MCS currenlty has 44K on it. I bought it used last year so I have not pulled the spark plugs yet to see how they look. The mini is running fine, I was just doing some preventive maintenance before I go on a road trip end of June and into July.

I have changed or checked many fluids, but now I am considering the plugs.

My mini is mostly stock except for a CAI, should I stick with the stock plugs or...?

My Haynes manual lists NGK plugs.

Advice appreciated

Laters Kelly

 

This thread was just posted in the mods section a day or two ago- it should give you some good info about getting colder (new) plugs on a nearly stock car.

https://www.northamericanmotoring.co...d.php?t=102799

 

Thanks MINIFVR, for the link. Wouldn't you know I only searched for spark plugs, I guess I am learning to try a variety of terms when I search....

 

No prob. Hope that helps.

 

I just did it not a big deal to do, the one odd thing I found was the coil had rust on the back 2 posts. Not sure if its due to the way they face letting water run in? Just seemed odd and the fronts look like new. FYI I went with the NGKs stock temp but I don't have any modsin my case.

 

Waste of money to "upgrade" the plugs on a stock car. Stock plugs are fine....

 

I changed mine at about 80k. I just wanted to do a complete tune up. I went with the colder plugs, but not on purpose. I realized it when I received them. They do work great...just like stock. I went with the iridium because I think they will last longer since it is a harder metal. I do plan on doing some mods in the near future though.

I think 44k may be a little to soon to change them if it is running fine. I think the wires would go before the plugs.

 

Sounding like a complete newb here, but in terms of the chemical reaction, combustion or whatnot, what exactly is the difference between colder plugs and 'regular' plugs?

 

Here is a good read and it should answer all of your questions....

http://www.carcraft.com/techarticles/spark_plugs_tips/

 

Bottomline.
If you have a stock MINI then use stock plugs, get them from the dealership or equivalent source. They come pre-gapped.
Plugs get dirty or fouled over time. Stock plugs work for stock MINIs and for modded ones as well.

For those that have installed reduced Supercharger Pulleys, spark plugs (often Irridium) are installed with one setting colder (IK-22) with slightly better results but you can still run stock plugs and most of us won't be able to really appreciate that much difference.

Beru plugs are less costly than IK-22 and come in stock or colder as well.
http://www.outmotoring.com/mini-coop...er_spark_plugs

See
http://www.centuryperformance.com/spark.asp
Quote:
Spark Plug Heat range-
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.

The insulator nose length is the distance from the firing tip of the insulator to the point where the insulator meets the metal shell. Since the insulator tip is the hottest part of the spark plug, the tip temperature is a primary factor in pre-ignition and fouling. No matter what the plugs are installed in, be it a lawnmower, a boat, your daily driver or your race car, the spark plug tip temperature must remain between 450°C to 850°C. If the tip temperature is lower than 450°C, the insulator area surrounding the center electrode will not be hot enough to deter fouling and carbon deposit build-ups, thus causing misfires. If the tip temperature exceeds 850°C, the spark plug will overheat which can cause the ceramic around the the center electrode to blister as well as the electrodes will begin to melt. This may lead to pre-ignition/detonation and expensive engine damage. (see the plug pictures that are part of this article)

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 firing end appearance also depends on the spark plug tip temperature. There are three basic diagnostic criteria for spark plugs: good, fouled, and overheated. The borderline between the fouling and optimum operating regions (450°C) is called the spark plug self-cleaning temperature. This is the temperature point where the accumulated carbon and combustion deposits are burned off automatically.

Bearing in mind that the insulator nose length is a determining factor in the heat range of a spark plug, the longer the insulator nose, the less heat is absorbed, and the further the heat must travel into the cylinder head water journals. This means that the plug has a higher internal temperature, and is said to be a "Hot" plug. A hot spark plug maintains a higher internal operating temperature to burn off oil and carbon deposits, and has no relationship to spark quality or intensity.

Conversely, a "Cold" spark plug has a shorter insulator nose and absorbs more combustion chamber heat. This heat travels a shorter distance, and allows the plug to operate at a lower internal temperature. A colder heat range can be necessary when an engine is modified for performance, subjected to heavy loads, or it is run at high RPMs for significant periods of time. The higher cylinder pressures developed by high compression, large camshafts, blowers and nitrous oxide, not to mention the RPM ranges we run our engines at while racing, make colder plugs mandatory to eliminate plug overheating and engine damage. 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).

Also-
Influences on Spark Plug Temperatures 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...etc.), the more critical this becomes.

---------------
To check your plugs just remove them and inspect for fouling.
If they are OK you can reuse them or you can replace or upgrade them.

Reading plugs-
http://www.strappe.com/plugs.html

IK-20 for stock heat setting and IK-22 for one step colder-
http://www.outmotoring.com/mini-coop...ark-plugs.html