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Old 10-13-2012, 10:29 AM   #37
shamrock 05
Scooby Guru
Member#: 120057
Join Date: Jul 2006
Chapter/Region: MWSOC
Location: *outskirts of motor city*
2018 WRX (base) 6spd


^^^^^^"Blow-by occurs when the explosion that occurs in your engine’s combustion chamber causes fuel, air and moisture to be forced past the rings into the crankcase. Your engine’s rings must maintain an excellent fit in order to contain the pressure.

The causes of blow-by: wear, soot and deposits

As rings and cylinder liners wear away they are less capable of maintaining this seal. Consequently as a car ages the amount of blow-by that occurs can increase.
Soot and deposits left over from incomplete combustion that collect on the rings can also inhibit their seal worsening blow-by.

The effects of blow-by: loss of horsepower and oil contamination and dilution

Blow-by inhibits performance because it results in a loss of compression. When the expanding gases slip past the rings they cannot as effectively push the piston down and make the vehicle go. As a result the car will have less horsepower. This also results in a loss of fuel economy.

When the fuel, air and moisture slip into the crankcase they contaminate and dilute the oil in the crankcase.

Among the many gasses in your compression chamber are unburned fuel, moisture, sulfur dioxide and soot. Once these gasses slip into your crankcase they can dilute into your engine causing great damage.

The detergents and Molybdenum Disulfide work together to clean the soot and deposits off of your rings allowing them to better seal the combustion chamber.

The Moly fills the crevices in the cylinder walls providing a better seal"

So by that definition..... if you have blowby you will have a lower compression. A new car should not have low compression.......however these 2.5L do have ring issues.
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