Ben is right. Look for the cause. The octane booster is just a poor bandage. Cleaning the carbon out is a good place to start, reference the steam cleaning.
You will be much happier fixing the problem instead of doctoring it forever.

Ping knock is a result of too high of a combustion chamber temp. It occours over 2500 deg F. It also creates NOX, more harmfull than CO. There can also be hot spots in the cylinders that cause fuel to light in the wrong place, and makes the flame front from the plug collide with the flame from the hot spot.

These can be caused by carbon, timing, improper EGR (The whole purpose of on EGR is to stop this but can make it worse in some conditions), and high temp in general. If the thermostat is operating too high, the fan is not moving enough air, etc, the engine will run hot and ping.

Ocatane is actually the resistance to burning. High octane fuel burns colder and slower than low octane. The cooler burn drops the cylinder temp.
But the slower, longer burn produces more heat. Don't confuse heat temp with volume. Higher temp does not necessarly produce more heat.

Try heating you house with a cutting torch, very high temp but not enough heat, won't happen. Try cutting steel with your furnace, a lot of heat but not enough temp, won't happen.

The greater quanity of heat warms the air in the cylinder more.

When the spark stops, and the fuel and oxygen are consumed the cylinder is only about 20 to 25 degrees after top dead center. At this point there is no more compustion pressure. So what pushes the piston down?

Not only did we put fuel and oxygen in the cylinder, there is a lot of air. Only 21% is O2. The other 79% has been super heated from the heat of combustion. The super heated air expandes and pushes the piston down.

By high octane burning for a longer period of time it super heats the air more, causing more expansion, causing more power. Heat is your friend, temp is not necessarly good.

Some engines won't run on high octane. The burn is too cold to completely light the fuel. They need the higher temp to do this. Many, not all, new computer cars at this way. High octane will make these cars run worse.

Long answer to a short question.

Look for the cause. Is something worn, set wrong, dirty, or is the engine built that way?

|UPDATED|5/28/2004 7:10:50 AM (AZT)|/UPDATED|

thanks for the detailed explanation ken..

one question I have on this subject that isnt really vette related..

I had an 88 t-bird turbo coupe (which was overall the best car I ever owned)...

it had a fuel octane switch on the dash... for 87 or 92

what exactly did this switch change...

ie did it just advance the timing or something more complex??

It was mostly a timing adjustment. But because the timing affects idle and emissions, the idle and fuel control was varied slightly. Selecting the lower octane did cut power, but should have helped fuel mileage, but only a very small amount. The biggest advantage was spending less on gas. The higher octane selection did make it run better.

Many computer cars, have a knock sensor. When knock is detected the computer retards the timing 2 degrees. If it still knocks, 2 more degrees retarted. When it quits knocking, it advanced 1 degree. Still no knock another 1 degree advance. Some of the newest ones have two knock sensors, and can retard timing per cylinder knocking, instead of all of them. When they have knock sensors they do not need the switch. But many of these use low octane normally, and often high octane won't help them.

The new Vette and several high end new ones have dual knock sensors, run on high octane, but can run low octane and adjust automatically without the switch.

|UPDATED|5/28/2004 6:15:32 PM (AZT)|/UPDATED|