What is detonation in simple speak?
When the air fuel mixture in the engine goes bang before it should do.
What! Please explain...
Detonation is quite a complex subject and this article only suggests explanations in basic simple speak! A basic and brief part of an engine cycle...
|Piston goes down||Piston goes down|
|Air is taken into the engine||Air is taken into the engine|
|Piston starts it's upwards journey||Piston starts it's upwards journey|
|Fuel and air goes bang prematurely|
|Piston reaches top of cylinder - ish||Piston may not reach top of cylinder!|
|Spark plug "sparks" and ignites fuel||Spark plug fires - may ignite remaining fuel|
|Fuel and air goes bang||Last bit of fuel and air may go bang|
|Piston goes down||Piston may go down|
|Car surges forwards||Car sort of goes forwards/may blow up|
|Normal engine sound||Tinkling / crap engine sound|
What causes the fuel/air mixture to ignite before it is supposed to?
This can be a variety of things:
|Air sent to cylinders too hot||
|Hot spots in the cylinder||
|Lack of fuel/lean mixture||
|Incorrect grade of spark plug||
|Poor quality fuel||
How do I overcome these?
To set your ignition timing click here
To reduce the air intake temperatures click here
Turbo inefficient - have a look at an upgraded turbo.
Hot spots in the cylinder - overhaul head and remove carbon deposits/sharp edges around valve seats is the definitive cure. To "help" remove these deposits - run Redex, Optimax and Water Injection. WI will have the added benefit of cooling the intake air temperature dramatically.
Lack of fuel - upgrade fuel pump, run larger injectors, fit a fuel pressure regulator, get the car setup by a professional, get an upgraded ECU or ECU add on e.g. Dastek, Apexi S-AFC, MoTec, Haltech, Autronic - have a look here
Run colder grade spark plugs. For an explanation click here
Poor fuel - put your hand in your pocket and buy super unleaded. Optimax is the highest rated RON petrol in the UK.
What happens if I get detonation?
Detonation can damage your cylinder head, piston, piston rings, con rods and bearings. Avoid detonation it's expensive.
How do I know if I get it?
You should be able to hear a "metallic tinkling sound" from the engine. Often referred to as men with tiny hammers! You should also notice a decrease in engine output power, as the ECU retards the ignition timing. The ECU takes in a signal from the knock sensor to determine when the engine is knocking i.e. detonating. Click here for pictures of the knock sensor.
What should I do if I get detonation?
Don't drive wildly i.e. loads of boost, loads of acceleration.
If your car is standard suggestions are:
If you've turned up your boost: