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Taming Detonation
Detonation or pre ignition occurs when the air/fuel mixture ignites before the piston reaches top dead center. On a turbo charged engine this is the first and last sign of bad things to come. Detonation can turn a daily driver engine into scrap very quickly. This article will cover a few easy ways to prevent detonation from happening.
There are several easy modifications that you can do that will help prevent engine detonation. Some of these are more easily accomplished than others but they all address the same problem. The idiom, "A ounce of prevention is worth a pound of cure" holds true with detonation. It's better to take steps that reduce the chances of detonation before it sets in.
Increase the octane rating of your fuel
Low octane fuel tends to burn too rapidly for proper combustion to take place, increasing the octane rating allows for a longer burn. Many people have used toluene, which has an octane rating of 110, to increase the octane rating of their fuel. This can easily be done with the following equation.
[ (gal x octane) + (gal x octane)] / total number of gallons.
[(5gal x 92oct) + (3gal x 110oct)] / 8 = 98.75 octane
Do not exceed 20% toluene.
Use a colder spark plug
In a turbo application the standard spark plugs tend to retain too much heat from the combustion chamber. This increased heat can ignite the air/fuel mixture before the spark plug fires. Premature combustion can create tremendous forces on the piston if it occurs before the piston has reached top dead center.
Lower your engine's intake temperature
Lowering the engine's intake temperature increases the density of the air and reduces the temperature of the air/fuel charge. Many turbo systems that I have seen draw air from the engine bay which increasing the load on the intercooler. Creating a cold air induction for your turbo setup that draws air from the wheel well can dramatically decrease the turbo's inlet temperature. This is a quick and cheap way to increase your engine's power potential without buying a larger intercooler.
Combustion chamber carbon buildup
Carbon buildup can produce hot spots inside the combustion chamber. This has a tendency to ignite the air/fuel mixture before the spark plug fires.
Decrease engine coolant temperature
Pulling heat out of the combustion chamber can reduce detonation. Using products like water wetter, purple ice, 40 below, etc. will all help lower the surface temperature of the coolant. These products allow the coolant mixture to contact the metal longer providing superior heat dissipation over standard coolants. Additionally, you may want to consider an aftermarket fan, which provides increased cooling capacities in a smaller package.
Use a catch can
The PCV system routes oil fumes from the valve cover back into the intake. This contaminates the incoming air/fuel charge with hot oily fumes, which greatly increase the chance of detonation. In a turbo car this can be disaster. One of the first steps you should do is incorporate a catch can into your system. A catch can will condense the oily fumes into the can before they can reenter the intake.
Causes:
Low octane fuel ((high octane fuel, octane booster
A colder spark plug
Exhaust Gas Recuriculation EGR
Carbon buildup in the combustion chamber (water injection, cabon cleaning fuel additive)
Hot intake temperatures (cold air intake, larger intercooler)
Decrease engine temp (water wet, increase cooling capacity, aftermarket fan
Positive crankcase ventilation PCV (catch can, oil air separator)
Too much spark advance timing (retard timing)
Detonation or pre ignition occurs when the air/fuel mixture ignites before the piston reaches top dead center. On a turbo charged engine this is the first and last sign of bad things to come. Detonation can turn a daily driver engine into scrap very quickly. This article will cover a few easy ways to prevent detonation from happening.
There are several easy modifications that you can do that will help prevent engine detonation. Some of these are more easily accomplished than others but they all address the same problem. The idiom, "A ounce of prevention is worth a pound of cure" holds true with detonation. It's better to take steps that reduce the chances of detonation before it sets in.
Increase the octane rating of your fuel
Low octane fuel tends to burn too rapidly for proper combustion to take place, increasing the octane rating allows for a longer burn. Many people have used toluene, which has an octane rating of 110, to increase the octane rating of their fuel. This can easily be done with the following equation.
[ (gal x octane) + (gal x octane)] / total number of gallons.
[(5gal x 92oct) + (3gal x 110oct)] / 8 = 98.75 octane
Do not exceed 20% toluene.
Use a colder spark plug
In a turbo application the standard spark plugs tend to retain too much heat from the combustion chamber. This increased heat can ignite the air/fuel mixture before the spark plug fires. Premature combustion can create tremendous forces on the piston if it occurs before the piston has reached top dead center.
Lower your engine's intake temperature
Lowering the engine's intake temperature increases the density of the air and reduces the temperature of the air/fuel charge. Many turbo systems that I have seen draw air from the engine bay which increasing the load on the intercooler. Creating a cold air induction for your turbo setup that draws air from the wheel well can dramatically decrease the turbo's inlet temperature. This is a quick and cheap way to increase your engine's power potential without buying a larger intercooler.
Combustion chamber carbon buildup
Carbon buildup can produce hot spots inside the combustion chamber. This has a tendency to ignite the air/fuel mixture before the spark plug fires.
Decrease engine coolant temperature
Pulling heat out of the combustion chamber can reduce detonation. Using products like water wetter, purple ice, 40 below, etc. will all help lower the surface temperature of the coolant. These products allow the coolant mixture to contact the metal longer providing superior heat dissipation over standard coolants. Additionally, you may want to consider an aftermarket fan, which provides increased cooling capacities in a smaller package.
Use a catch can
The PCV system routes oil fumes from the valve cover back into the intake. This contaminates the incoming air/fuel charge with hot oily fumes, which greatly increase the chance of detonation. In a turbo car this can be disaster. One of the first steps you should do is incorporate a catch can into your system. A catch can will condense the oily fumes into the can before they can reenter the intake.
Causes:
Low octane fuel ((high octane fuel, octane booster
A colder spark plug
Exhaust Gas Recuriculation EGR
Carbon buildup in the combustion chamber (water injection, cabon cleaning fuel additive)
Hot intake temperatures (cold air intake, larger intercooler)
Decrease engine temp (water wet, increase cooling capacity, aftermarket fan
Positive crankcase ventilation PCV (catch can, oil air separator)
Too much spark advance timing (retard timing)