pa23driver,
PA23...that's an Aztec or Apache, right? I flew a Cessna 337 Skymaster for 20 years. Enjoyed every minute of it.
I guess we should start by defining performance. As you go from the standard coil to the Ultimate coil, the coil voltage goes from about 37,000 to 82,000. By comparison, the stock points coil produces 10,000 on a good day when it was new, so you will get more than three times that voltage just with the standard coil.
Higher voltage results in several advantages:
1. 37,000 volts at 14.5 battery volts will still produce 20,000 volts when starting. Faster starts and less wear and tear on the starter, battery and alternator.
2. All of these coils produce a longer spark duration than the stock coil. Longer duration means more of the mixture is exposed to the spark, resulting in a larger "kernel" of initial flame that will ignite more of the mixture, resulting in greater efficiency, more power and better gas mileage.
3. The Ultimate coil with it's 82,000 volts means that you can increase the plug gap which also exposes more of the mixture to the spark to produce a bigger "kernel" of initial flame.
4. Higher voltage means more current in the spark across the gap. More current means a hotter spark. Hotter spark ignites more of the mixture, for more efficiency.
5. Higher voltage and more current also means that the spark can burn through fouling for a faster start and smoother idling.
Basically, the mixture going into the cylinder from the carb is not a perfect mixture. It consists of some air molecules, some fuel molecules and a few of each that just happen to be close enough together to form a true mixture with the ideal ratio of fuel and air, so the larger and hotter and longer lasting the spark, the more likely that more of the mixture will be ignited to form a "kernel" of flame that goes on to ignite the rest of the mixture charge.
Are you going to feel a surge of power with a 82,000 volt coil? You will if the rest of the engine is in great condition. The spark by itself cannot produce power.
Here is a table of some test runs I did with my stock '81/H to show the increased gas mileage with various coils and spark plugs. Gas mileage is a measure of the efficiency of the engine. Greater efficiency equates to more power, all things being equal:
You can also see the increased mileage with the installation of the Iridium spark plugs. The 6903 coil is the Ultimate coil.
These tests were done on a 60 mile round trip route over mostly highway roads with few stops at a steady 55 MPH, returning to the same gas pump each time for fillup and for accuracy of gas used.