15-June-09

Combustion chamber

Posted under Technical

      The unwanted explosion in the combustion chamber, also called detonation, appears frequent to the cars that use a pre-ignition fuel. This anomaly of the combustion chamber that reefers to the burning of the fuel true a explosion is the fault of a abscess that is formed in the combustion chamber. When the mixture of air and gasoline is lighten by the spark in the head of the piston, the power that must result from this burn is stopped by the unburned fuel in the combustion chamber and in result the combustion chamber give the ignition to the mixture formed in the head of the piston before the spark does. The result that the fuel in the head of the pistons is not ignited by the spark and it is by the detonation process.

      The detonation can cause to the burning process to cede just before the optimal moment before it can reach the fourth burning cycle. Then you will be able to hear a very sharp noise like two metals heating each other, and a tremendous pressure is applied to the combustion chamber and to the exhaust system. Problems can appear to the pistons, cylinders and to the sparks when detonation takes place.

      The good part is that we can keep the detonation process away from our car by following a few easy steps:

1. You can use a gasoline that has a bigger octane number, because the octane number of the gasoline measure also the risk of apparition of the detonation, the higher the octane number is the smallest chance for the detonation to appear. The most of the engines are running on a gasoline that has the octane number of 87. But for the engines that have a bigger compression over 9 to 1 the ones with superchargers and turbochargers or the ones that accumulate carbon you will have to use a gasoline of 89 in the octane number section or bigger.

2. If the right fuel is not near you, always consider about some additives that increase the octane number. You can use substances like MMT, isooctane and other agents that increase the octane number of the fuel.

3. The recycle of the gases that came from the exhaust system it is called EGR. This system has the amazing capability of re-filtering the gases from the exhaust and eliminates the nitrous oxides from the exhaust pipes. This thing helps in the cooling of the gasoline that enters the combustion chamber and preventing the detonation. This is the reason that the exhaust system must be maintained clean because if appears a problem to the system the gasoline that enters the engine will reach a bigger temperature and will favorites the detention.

4. The engines with a compression of 9 to 1 are beaten because the 10.5 to 1 appears, and that engine requires an octane number bigger then 93 and even with this type of fuel the detonation is imminent and some special measure needs to be taken.

5. You can increase the number of injectors so you will give more air to the engine and stopping the detonation to appear.

6. If you can eliminate the heat from the combustion chamber before ignition you will also eliminate detonation.

7. You can apply a correction process before ignition. For some cars this is a simple task because they come whit such systems from the factory. If you don’t have this option you must know a little bit of the electrical part of the car and to modify the current from the induction coil to be faster.

8. You can mount spark with faster ignition.

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