In understanding the answer to this question you will understand why it is so important to get your car set up correctly to take advantage of all these nice expensive modifications you have just fitted to your car. There are 3 main ingredients to a powerful engine. AIR, FUEL, and SPARK. Making your engine more powerful involves trying to squeeze as much air as possible inside your combustion chamber, then trying to add as much fuel as you can to it and ignite them to produce the power.

Obviously this is over simplified but you do get the idea. Most people concentrate on modifications that allow more air to enter the combustion chamber. Like exhausts, turbos, air filter, cams, valves, etc. but they only way you are going to take advantage of these modifications is by supplying your engine with the correct amount of fuel to make power out of it.

Detting (also called pinking or pinging) in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug, but burns too quickly, combusting completely before the optimum moment during the compression phase of the four-stroke cycle. The resulting shockwave collides with the rising piston, creating a characteristic metallic "tinkling" sound.

The fuel is normally ignited slightly before the point of maximum compression to allow a small time for the flame front of the burning fuel to expand throughout the mixture, so that maximum pressure occurs at the point of maximum compression. It is only when this flame front arrives too early, for whatever reason, that the knocking effect occurs. If allowed to persist, knocking can cause vibration and damage to engine parts.

Knocking can typically be prevented by:

• The use of higher octane Octane is an organic chemical, specifically an alkane, with formula C8H18 (8 carbon alkene). It is the major constituent of petrol.
• Reduction, or retardation of spark plug ignition. Correct ignition timing is essential for optimum engine performance and efficiency.
• The use of water injection.

Modern automotive engines have sensors that can detect knock and delay the spark plug firing to prevent it, allowing cars to safely use fuel of lower octane ratings, with the consequence of reduced power and efficiency. Knocking is a different phenomenon from pre-ignition, which occurs when the air-fuel mixture in the cylinder ignites before the spark plug fires.

Pre-ignition is caused by heat buildup in engine components or overheating of the air-fuel mixture during compression, and cannot be prevented by delaying spark plug firing. As such, if pre-ignition is allowed to continue for any length of time, severe engine damage can result.

Your engine can run lean (out of fuel) and for a turbo charged engine that is not good news. Running lean will cause loss of power, but also will cause heat! Heat in turn will cause the engine to detonate and ultimately you will end up with a broken engine and a costly repair bill.

On the other hand cranking the fuel pressure up, or adding bigger fuel pump and injectors to get more fuel at the top end on standard ECU although may sound like an easy fix, will also have problems of it is own. Running too rich (too much fuel) will cause bore wash, thinning of the oil and ultimately engine failure again. Why else would you need to get your engine properly mapped?

Variations of fuel octane will also play a big factor on how your engine will respond to modifications. As well as some of these Japanese imports have got their ecu mapped for Japanese fuel this is 101octane. Unfortunately we don't get more than 98octane in this country. Running the car for prolonged periods of time with the wrong fuel will cause the engine to detonate itself to death. One of the main reasons of engine failure on some Japanese imports when they first arrived to the UK.