I have been following this thread on intercooler's and I will add a couple if
things.
It goes without saying that the turbo, compresses air, and when you compress air
you get heat.
I have an early maintenance manual for my 914. In the section on the turbo, it
addresses the issue of the temperature probe that is installed in the "air box"
It is there to measure the inlet air temperature in the air box just before
the air goes to the carb's. The onset of detonation occurs at approximately 165
degrees F. air box temperature, on the 914 ,due to the compression ratio of
9 to 1. When the temperature probe registers
165 degrees F a command is then sent to the servo to open the wastgate, which
lowers the temperature going into the air box, which prevents detonation... You
normally will only get this high temp on take off with full boost and 5800 RPM
on a very hot day.
The intercooler simply lowers the inlet air temperature to a point where
detonation
does not occur. Here in Florida, in the summer time its very easy to reach
the 165 degrees temperature, on take off with full boost, without an
intercooler.
I feel that of you exceed the 5 minute limit, then you will be thermal stressing
the engine..
Jim Brown
Robert Borger wrote:
>
> Gary,
>
> As the others have said, additional power is available due to a cooler, denser
charge of air. But there is another reason to add an intercooler. That hot,
compressed volume of air that comes out of the turbocharger is prone to cause
detonation. By cooling the air, you greatly reduce the chances for detonation
which is always a problem with turbocharged or supercharged engines. This
is the reason I chose to add the intercooler.
>
> I have been told that by adding an intercooler, the 5 minute limit on max
> power
is no longer necessary. That limit was imposed to ensure the engine never
went into detonation. With the intercooler, one can use full power
continuously.
Please understand that this is hearsay information and I have not proven
or tested it. Perhaps others more experienced in the area can comment.
>
> Good building and great flying,
> Bob Borger
>
>
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