|
A bit of 2 stroke history.
In the old days of 2 stroke and points, plugs had a real hard time. At low power settings, the plug electrodes did not get hot enough to burn off the oil/carbon on the electrode. Lawn mowers/bikes ran great. Next time you tryed to start it, nothing. The problem with points is that the spark rise time was slow. So slow that as the voltage rose, it would leak down through the carbon on the electrode and never jump the gap. Now take your neighbour that ran his mower full taps. Ie hot plugs. He never had a problem starting as his plugs were hot enough to burn off the carbon. The correct electrode/porcelain should look white to about 1/3 of its length. Ask any 2 stroke racer and he will tell you.
Now roll on the CDI - Capacitive discharge ignition. The rise time of the spark is very very high. So high that it will relieve its energy where ever it can. Down the electrode carbon as well as the spark gap so now the old fowled plug will still fire and in most cases the motor will run. Once it warms up the situation gets better.
I had a mini may years ago (a real one) and I made a CDI for it. One misty morning I started it and while running I heard this loud Clac Calc. I opened the bonnet. Due to the heavy mist the plugs were wet. No problem for this CDI , it had a nice fat blue spark running down the outside of the plug while the car was still idling perfectly.
TCI Transistor assisted ignition is a bit between the 2. Not sure what Porsche uses.
In most cases a good thrashing of the motor will burn of the carbon and return the plugs to normal.
PS if you always tootle around in your car, you need a hotter plug, if racing a colder one.
The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine, normally between 500 and 800 °C (932 and 1,472 °F).
The heat range of the plug helps keep the tip at the correct temperature and burn of the carbon.
|