John S

adiabatic or not.

Jim Torongo

job of retaining pressure but at the expense of cooling. No you don't what a drop in pressure but you get it anyway to some degree. JIM

NJ-Eric

inevitable, but the manifold pressure is maintained by the ECU isn't it, regardless of whatever pressure drops occur upstream in the intercooler plumbing? In other words, whatever is going on in the intercooler plumbing, the manifold pressure is what is maintained and controlled by the ECU and wastegate. Is this correct?

-EJS

Bob

Think of an intercooler as an air-to-air radiator.

The intake air is compressed by the turbocharger, and in the process becomes hotter. The air is then directed through an air-to-air radiator (the intercooler) which uses the relatively lower temperature air in the engine compartment to remove heat from the turbocharged air in the TT's intake system. The cooler air becomes more dense (assuming constant pressure) and can now effectively support the combustion of a greater amount of fuel than non-compressed air.

The engine's air mass sensor detects the density and temperature of the turbocharged, intercooled air and provides that data to the ECU. In turn, the ECU evaluates the throttle position (idle, moderate accelleration, hard accelleration) and determines the proper amount of gasoline to be injected by the fuel system.

Because the air in the TTs intake system has more oxygen molecules relative to a non-turbocharged intake system, it can support the use of more gasoline per combustion cycle and produce more power.

The dual intercooler setup on the 225hp TT (along with the larger K04 turbocharger) stuffs even more oxygen into the intake system and allows the combustion of a greater amount of fuel, which results in greater horsepower output.

Jim T

it expands- this expation is what causes the pressure drop. Some intercoolers have a bigger pressure drop than others; what everyone wants is a small pressure drop with maximum cooling. Thats tricky because they work at cross purposes. JIM

evan

Thanks Bob! Very helpful info for a Turbo Newbie like me.

mne

really was a great explanation Bob. Ya done good!

NJ-Eric

am I remembering thermal physics/physical chemistry/carnot cycles correctly?

-EJS

Bob

Let's invite Boyle and Avogadro to join in.

Jim Torongo

Eric, we need to draw the line somewhere, thou I'm not sure where.