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• Designed to outlast other performance plugs on the track or on the street
• Unique insulator design improves spark isolation
• Superior design for high performance engines
• Iridium - 40% higher melting point than nickel plugs
• Lower voltage Requirements for longer coil life

MSD Spark Plugs are durable enough to withstand the rigors of performance operation using high output ignitions.
 

With over four decades of experience in engineering and manufacturing high output ignition systems, MSD Performance proudly offers High Performance Iridium spark plugs! Whether you’re on the street, trail or track, MSD has a performance plug that will fire up your engine.
 

Compare The Facts

What makes MSD’s Iridium plugs a cut above the competition? Besides our race winning experience of firing 330 mph top fuel cars, the endurance of 500 mile stock car racing and the brutal expectations of off-road racing, our new spark plugs are designed to perform from the inside out. PERIOD
 

MSD’s spark plugs are engineered to improve the efficiency of the combustion process to create the most power possible combined with increased durability. The center tip of the plug is made from iridium to promote the best spark and increase resilience. A proprietary ceramic material enhances the dielectric strength of the plug housing forcing the spark, even under extreme cylinder pressures, to jump across the plug gap to the ground electrode. This electrode is machined to expose more spark to the incoming gases to promote the most effective combustion event possible.

MSD Plug Style Code

I = Iridium
R = Resistor
5 = Heat Range
Y = Projected Tip
L = Extended Procected Tip
 

The term "spark plug heat range" can be misleading. Mny think that it has something to do with a hotter spark and it does NOT. The heat range of a spark plug is its ability to transfer heat from the combustion chamber to the cylinder head. The heat transfer pulls heat out of the cumbustion chamber and at the same time awaw from te spark plug tip. This is most commonly done by changing the contact area of the porcelain insulator nose to the shell during manufacturing. A visual comparison of the two extremed make this very clear, looking at the colder plug you can see where the porclain meets the shell and on the hotter plug the point where the porcelain meets the shell is further down inside.

As a general rule of thumb use the coldest plug possible without fouling at low speed or idle. The use of too hot a plug may cause severe engine damage. The guideline for the differende in tip temperature from each heat range to the next is 70°C to 100°C. 

Considerations in choosing the heat ranges:
If an engine is normally operated at low speeds or at low temperatures then, a hotter heat range may be required to keep the spark plug from fouling. If the engine is modified, operates at high RPM, under heavy loads or at high temperature then, a colder heat range spark plug will be necessary to helt prevent detonating or pre-igniting.

All engine modifications which increase cylinder preassure typically increase cumbusted temperatures, and therefore, increasing these temperatures will require a colder heat range. So, if you think you need a higher octane fuel to keep the engine from pinging, you will probably need a colder plug as well.

It is important to follow the cylinder head manufacturers recommended torque specification for the spark plugs. It is also a good practice to put a small amount of anti-seize compound on the treads, but be sure that it does NOT insulate the spark plug from the cylinder head.