Momentum Worx is the PREMIER supplier of Heavy Duty Diesel Truck Turbos & Manifolds.

Specializing in CAT, CUMMINS, & DETROIT

MERCH: https://momentumworx.com/mmwxapparel/

Boost pressure is only 1 parameter of many! While it is great to have a some parameter to zero in on, boost pressure only paints part of the picture of how a turbo is performing and interacting with the engine.

This video gives an overview of other metrics involved with turbos and how these metrics affect overall performance.

30 PSI is not 30 PSI watch the video to find out more :)


Compressor Maps: Pressure Ratio, Mass Flow Rate, Surge, Choke, Efficiency Island

Pressure ratio Absolute outlet pressure divided by the Absolute inlet pressure. The gauge in your vehicle measures the pressure above atmospheric pressure (So if you are making 12PSI, its actually 12PSI + atmospheric pressure). Absolute pressure at sea level is 14.7, this will decrease as elevation increases.

Mass Flow Rate The physical mass of air flowing over a given time period. Often expressed as lb/min (pounds per minute), or CFM (cubic feet per minute)
How to determine desired flow rate: To generalize, gasoline engines will generate 9.510.5 horsepower at the flywheel for each lb/min of airflow. If your target peak horsepower is 400 Hp will require 40 lb/min. This is NOT perfect science, just a rough guestimation.

Surge Line The left hand boundary of the compressor map. This area is plagued by flow instability, the turbo will flutter or bark. This is because the pressure is far beyond the flow capability at that time and the air is forced back through the turbo charger instead of into the engine. This can happen when:
The throttle plate is quickly closed when you let of the accelerated and there is pressure in the air piping but no where for it to escape to. This is where BOVs and MAP groves comes into play.
The motor physically cannot consume anymore air at this operation level
Choke Line The right hand limit of the compressor map. The turbo is no longer efficient in this area. Shaft speed will be beyond its mechanical limits and the amount of heat generated will decrease overall performance.
Efficiency Islands Specific segments on the maps that represent points which the compressor is most efficient. The smallest island near the center of the map is the highest or peak efficiency island. Each larger ring is less efficient then the one that proceeds it. .