Wednesday, February 17, 2010

Inside the Fiat 500: Spark Plugs...


Inside the MultiAir combustion chamber

The days of throwing a set of Champion spark plugs in and forgetting about them is long gone. The Fiat 500 uses the latest engine technology available so it's fitting that the plugs it uses are cutting edge. Fiat has partnered with NGK to use their latest design offerings.

For the 1.2 L 8V Fiat 500, Fiat is installing NGK ZKR7A-10 spark plugs as exclusive OE fitment. NGK has developed this 12mm diameter plug specifically for Fiat�s FIRE EVO and PDA engine families. It is a nickel alloy plug with 5mm protrusion and 1mm gap setting.


Fiat 500 1.2L and 1.4L NGK spark plugs



For the 1.4 L 16V version of the Fiat 500, NGK�s DCPR7E-N-10 has been selected as Original Equipment. This 12mm spark plug has been developed specifically for the FIRE MPI engine family. It is also a nickel alloy plug with a gap setting of 1mm.

One of the reasons Fiat chose the DCPR7E-N-10 plug is because its small diameter makes for easier installation in multi-valve small displacement engines. Another reason is its good ignition quality without requiring the costs of precious metal and its robust ground electrode design.

Fiat 500 Abarth



Fiat 500 Abarth Assetto Corse



The high performance Fiat 500 Abarth's engine was developed at Fiat Powertrain Technology (FPT) under the Chief of Petrol Engine Development, Paolo Martinelli's leadership. A noted engineer, Martinelli previously was head of Scuderia Ferrari's Engine Department from 1994 to 2006 and was responsible for developing the Ferrari V10 Formula One engines that won 6 constructor championships.

For the 1.4L 16V Turbo engine, FPT had NGK develop a high performance spark plug called the IKR9F8. This plug is exclusive to the 1.4L 16V Turbo and is the only plug recommended for it.


Fiat 500 MultiAir spark plugs and Lambda sensors



The IKR9F8 is a double precious metal spark plug. The tip of its centre electrode is extremely thin and made of Iridium. It dramatically reduces the required ignition voltage and guarantees an optimal spread of the flame front within the combustion chamber. In addition, the IKR9F8 contains a platinum ground electrode. Because both the precious metals, iridium and platinum, are extremely resistant to spark erosion, this plug ensures the highest degree of ignition relaibility and resistance to misfiring.

Additionally, the IKR9F8 requires less space than standard spark plugs. This is due to an unusually long thread of 19mm combined with a compact diameter of only 12 mm. The benefit of this is it allows for the designing of larger cooling passages within the cylinder head which is an important consideration in a high performance Turbo engine.

More than just Spark Plugs

NGK is the world�s largest manufacturer of Lambda (O2 sensors) under the NTK brand name. Fiat has chosen NGK/NTK lambda sensors (o2 sensors) for all Fiat 500's equiped with MultiAir. In the normally aspirated version of the 1.4L 16V MultiAir engine and the 1.4L 16V MultiAir Turbo engine used in the 500 Abarth, Fiat has specified a wide band oxygen sensor- ZFAS-U2 - to provide the high accuracy Air/Fuel metering necessary when controlling not only the quantity of fuel injected but also the air flow rate, ensuring an optimised Air/Fuel ratio.

This wide band oxygen sensor was selected because of its very fast light-off time, quick signal response and high degree of accuracy, together with its resilience against water splash. NTK�s OZAS-S2 binary Lambda sensor has been selected for the downstream catalyst monitoring function.


Photos courtesy Fiat Group Press, NGK
with help from NGK, de

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