Porsche Turbo Spark Plugs

Tuned Porsche 997 Turbo and shorter spark plug life

We all know that a modified 997 Turbo has a shorter plug life than stock one; however a modified car has a more efficient combustion cycle. Porsche states that the Spark plugs should be replaced every 40,000 km, however a more realistic time period should be between 20,000 and 30,000km. This is especially true when driving more aggresively on a continued basis. One method to increase the life of the plugs for tunes that take advantage of the sport mode button, would be to reduce the amount of hours you run the car in sport mode. Generaly tuners mirror the engine management maps, to that of the factory settings, for the "normal mode", hence spark plug life, due to ECU tuning is only affected once in Sport mode.

All this said, efficiency is determined by more than just power. Optimizing the variables will determine a better efficiency. One could have a tuned 997 Turbo that chewing through spark plugs at a much faster rate (and cylinder component life), because it has higher IAT's which in turn reduces the ability to optimize the other variables. A tuned car with such optimized variables will be more efficient over stock.

Life expectancy of spark plugs

The life expectancy of the plug and cylinder components can be reduced by the level and type of stress being placed upon them. Naturally the greater the power output of the cylinder the greater the need for all variables to be optimized to get the best reliability and longevity of the associated components. That doesn't mean that an engine can't make extra power if all the variables aren't optimized for highest efficiency, however this does have a dramatic impact on expected life of the components in question.

Spark plugs in a tuned engine will never last as long as one in a stock (OEM Tuned) engine but it comes down to the variables that ultimately dictate just how much shorter the plugs like will become.

Spark charge, how rich/lean it runs under full load, etc. have a dramatic effect on spark plug life. But one would argue that any modified Porsche that is putting out significantly more power than stock has a higher volumetric efficiency which would lead to a reduction in spark plug life.

ECU Tuning and Spark Plug life, Internal combustion temperatures

Combustion temps are primarily a function of the amount of air and fuel that combusts and less so on the temp of the air/fuel prior to combustion. The Greater the charge density the more thermal energy is produced and thus power. So if power is the culprit in reducing a plug's life then a more efficient IC (Internal Combustion) would facilitate that.

Time to replace Spark Plugs? The Symptoms:

If your engine has a hard-to-correct missfire, it may need a new set of spark plugs. This generally becomes apparent in or around 3500rpm when under heavy throttle in third gear (or higher gears) in the 997 Turbo. The car tends to start to jerk, feels like the fuel is being cut, and in more extreme cases the Check engine light starts to flash, there after stays on permenantly or comes off after lifting off of the throttle. In extreme cases there is a dramatic loss of power through out the rev range and the car feels less smooth.

High performance plugs, for tuned Porsche 997 Turbos

The following High performance plugs, for tuned 997 Turbos are recommended:

Best reccomended plugs are the: PK20PR-P8 Denso. Close the gap to .025" for higherboost levels.
The NGK equivalent of stock number 2667 of BKR7EIX is also recomended and used in many of the high horse power Porsche 997 Turbos. The Denso also works well.
Ruf apparently run the "Beru Ultra 14 FR-6-LDU" plugs on their 550 Rturbo.
Stock OEM for the 997 Turbo being the Bosch FR6DPP332 spark plugs.

For Turbo's running under 650hp (crank), OEM plugs may be used and life expectancy would be the same as that of the Denso and Beru mentioned above. Once you start venturing into the higher horse power applications it would be recommended to change up to the "one stage colder" plugs (mentioned above) as replacement to the Bosch OEM plugs.

Increasing the life of your spark plugs

Proactive measures such that increasing the size and volume of the intercoolers to cool the fuel air mixture down is definately a good place to start to increase the life span of the plugs.

Combustion temps are primarily a direct result of the combustion process which occurs from introducing fuel, air, spark and timing to the cylinder. The cooler the IAT (Intake Air Temperature) charge to the cylinder the more power can be made from the denser air charge which on its own allows the introduction of greater and more efficient variables (air, fuel, timing).

However, the cylinder components will inevitably last longer if subjected to a cooler intake charge vs a hot IAT charge. And it all becomes a viscous cycle in the sense that the higher the combustion temps the hotter the exhaust temps become and as the exhaust gas passes through the turbine the heat transfer to the compressor becomes greater. If the plugs are to last longer they need to be in a better environment and none better than a cooler intake temperatures that bring about a more efficient combustion cycle.

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