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Group A Turbos

BNR

By BNR,
in Engines & Forced Induction

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rev210 Grand Master

rev210

Posted
Posted
Rev210,

With the group A turbos you need to be aware that the relatively low efficiency of the compressor will give you a higher inlet temperature to you intercooler - ie have a think about the cooler.

If you use 25lb/min airflow & a pressure ratio of 2 as an example the temperature at the intercooler inlet will be almost ten degrees higher when using the group A turbos than when using the N1 turbos.

Have a look at the attached graph.  It is a log of temperatures from my mates RX-7 when he is giving the thing a bootfull.

Blue is at the air filter

Pink is after the turbo

yellow is after the intercooler

cyan (Aqua) is at the throttle body

Note that the cooler is a cheap chinese type, but nonetheless has an efficiency of 71%

Note also the effects of heat soak.

at the end of the run there is an idle period.  Note way the air filter temps rise when the car is sitting still, eg at the start of a hillclimb.  This is the downside of having pod filters with no external air feed.

Interesting.

I appreciate what you are saying. Unlike most people who bolt these straight in I have upgraded the camshafts which enable higher airflow reducing the boost requirements of the turbos to make the same power.

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