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Originally Posted by my89_928gt
Hmmm, why not platimum?
I whent down to my local shop(reputable) and they sold me Bosch Platinum 4 spark plugs.
I have not put them on yet.
The only time I ever heard of not useing platinum plugs was in a heavly boosted engine. I also, thought they were platinum from the factory as cooper plugs will not last to 90,000 miles witch is when I understand they are to be changed.
Am I wrong??
Richard
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Hi,
I believe that the newer Boxsters use a different plug than the early non-egas models. These have double contacts as opposed to 4 of them. More isn't necessarilty better as you effectively divide the Spark Energy from the coil resulting in a less energetic spark. This is a trade-off over the single Annode Plugs which may be oriented the wrong way when properly Torqued for proper FlameFront Travel (Racers and HotRodders often use spacers to insure the Spark is oriented in the proper place relative to the Piston Face).
I have heard from 2 different Porsche Techs that they have seen engine damage from the Platinum Tips coming loose and rattling around in the cylinders. One mentioned a TSB cautioning their use, although I have never seen it and don't have the TSB #.
Platinum tips offer
Nothing in terms of added performance. Their strength is that they last longer. Personally, I believe this is a false economy - to save a few bucks on Spark Plugs. For the non-egas engines at least, Porsche specs a Cu (Copper) Cathode (Center Electrode).
There is perhaps no other Maintenance you can perform on a Porsche which is as cheap and easy as changing the Plugs. Changing the plugs more regularly (I install a fresh set every season - mine's a seasonal car) insures that the insulators are not cracked and allows me to see the condition of the ECU/Fuel System by reading the Plugs. Many slight malfunctions can be accomodated by the ECU, such as a slight lean condition, or Spark arcing, which will be otherwise unnoticable.
Also, an AfterMarket Plug must have the proper Heat Rating. It is a common misconception that this Heat Rating relates to the car's ignition, that a hotter spark is produced using a Hotter Plug. In fact, this rating is a measure of how much heat the plug removes from the cylinder (ever notice how they're similar to a Heat Sink?) to be carried away by the Coolant flowing through the Head. This is a function of the length of the Ceramic Insulator (a longer one is termed a Cooler Plug (because it can carry away less heat) and vice-versa). Each Heat Range Value for a plug approximate it's ability to remove between 70°C - 100°C of Heat. In addition to carrying away the proper amount of heat, the correct Heat Range insures that the Plug operates at it's predesigned
Self-Cleaning Temperature which prevents it from fouling due to combustion deposits condensing on it.
Longer lasting Plugs were concieved for those driving everyday vehicles, non-enthusiasts who didn't, or couldn't do their own maintenance. My suggestion is to replace every 10k mi., such as when Changing the Oil. Many will disagree, but considering the ease and minimal cost of changing them, it certainly won't hurt, but may in fact help for the reasons I've already described.
One final caution - Plug Gapping. Even though many Plugs now come pre-gapped, Manufacturing Tolerances and the possible abuse in Transportation and Distribution warrant checking them prior to installation. They are notoriously off. The 12 Plugs I just recently purchased were improperly gapped in 4 instances. That's more than 30% error rate.
Happy Motoring!...Jim'99