At 550 horsepower the stock turbo is done. Are some tuners able to squeeze more out of it? Yes, by putting it on kill. In this episode, Gale takes It to the limit to explain variable geometry, why the turbine is so important, and how to know when it’s in a choke.

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0:00 Intro
0:20 Why this it’s out to lunch
3:10 Birth of the iDash
4:00 Geometry of Borg Warner turbo
6:45 Analyzing vein position
10:10 Compressor pressure ratio
12:00 Testing at 2,000 RPM
15:55 This is how you kill

Why it’s out to lunch

The turbine drive pressure is higher than the boost outlet pressure from the compressor, which corks in the heat and exhaust energy and chokes the turbine.

Birth of the iDash

People tune up their Duramax engines without knowing how close they are to blowing the thing up because they don’t have the proper instrumentation. This notion led Gale to invent the iDash, so tuners would have all the data they would need to safely tune their engines.


Turbo Geometry


Compressor pressure ratio

Testing at 2,000 RPM

This is how you kill a turbo

On episode four of Killing a Duramax….