Part I
An intercooler should be considered an integral part of any good turbo kit. While it may not be necessary for a low boost application, I would still highly recommend it. The two main considerations when selecting a properly sized intercooler is of coarse it's effeciency and the pressure loss between the intercooler inlet and outlet.
One of the most obvious characteristics of a good intercooler is how well it cools the intake air. This characteristic is generally represented by the intercooler's effeciency, and naturally the more effecient the intercooler there better it is.
The pressure drop across the intercooler should also be considered. I would highly recommend that the pressure loss be minimized to at least 2 psi or less. Now, why is this pressure loss bad? Lets say you want to run 15 psi of boost, and your intercooler has a pressure lose of 3 psi. So you set your boost controller for 15psi and you only get 12 psi of boost at the intake manifold. You still want to run 15 psi, so you have to set the boost controller to 18 psi to get 15 psi at the manifold. Sounds simple to simply bump the boost up, but you have two problems with this. First of all, you have effectively increased the air charge temperature coming from the compressor and two you have increased the exhaust manifold pressure (backpressure). Though your intercooler may be more efficient than one with a lesser pressure drop, the above intercooler now has to cool the aircharge from a higher temperature, so in effect you could have a less efficient intercooler with a 1 psi pressure loss that could cool the intake charge to a cooler temperature than the 3 psi loss intercooler, because you would only have to set the boost controller at 16 psi to get you 15 psi of boost, which would have reduced the compressor outlet air temperature from the 18 psi setting. Similarily, with the lower 16 psi boost setting the wastegatewill be open more, relieving exhaust manifold pressure, and reducing the exhaust temperature, which would effectively reduce combustion chamber temperatures and chances of detonation, etc, etc. Its almost like a viscious cycle once you really start to thing about it. So the bottom line is to try and reduce pressure loses in the intake track between the compressor and combustion chamber.
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An intercooler should be considered an integral part of any good turbo kit. While it may not be necessary for a low boost application, I would still highly recommend it. The two main considerations when selecting a properly sized intercooler is of coarse it's effeciency and the pressure loss between the intercooler inlet and outlet.
One of the most obvious characteristics of a good intercooler is how well it cools the intake air. This characteristic is generally represented by the intercooler's effeciency, and naturally the more effecient the intercooler there better it is.
The pressure drop across the intercooler should also be considered. I would highly recommend that the pressure loss be minimized to at least 2 psi or less. Now, why is this pressure loss bad? Lets say you want to run 15 psi of boost, and your intercooler has a pressure lose of 3 psi. So you set your boost controller for 15psi and you only get 12 psi of boost at the intake manifold. You still want to run 15 psi, so you have to set the boost controller to 18 psi to get 15 psi at the manifold. Sounds simple to simply bump the boost up, but you have two problems with this. First of all, you have effectively increased the air charge temperature coming from the compressor and two you have increased the exhaust manifold pressure (backpressure). Though your intercooler may be more efficient than one with a lesser pressure drop, the above intercooler now has to cool the aircharge from a higher temperature, so in effect you could have a less efficient intercooler with a 1 psi pressure loss that could cool the intake charge to a cooler temperature than the 3 psi loss intercooler, because you would only have to set the boost controller at 16 psi to get you 15 psi of boost, which would have reduced the compressor outlet air temperature from the 18 psi setting. Similarily, with the lower 16 psi boost setting the wastegatewill be open more, relieving exhaust manifold pressure, and reducing the exhaust temperature, which would effectively reduce combustion chamber temperatures and chances of detonation, etc, etc. Its almost like a viscious cycle once you really start to thing about it. So the bottom line is to try and reduce pressure loses in the intake track between the compressor and combustion chamber.
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