Looking at the Lbs per Minute line on the turbo map link, I provided, you will see that a larger engine will have more mass flow per revolution of the engine. If you have more mass flow, you will be farther away from the "surge line" for any given Turbo map you are looking at. Surge is a major issue on smaller engines at street part throttle conditions (with large turbos). The small engine does not have enough mass flow for the turbo to stay on the right side of the Surge line.
Speaking of the Surge Line. The left most vertical line on the turbo map is called the surge line BUT the surge line area is actually a larger area. Think of the Berlin Wall in Germany where the Russians planted mines a hundred yards before the actual wall. The turbo might actually go into surge the next line to the right on that given turbo as the mapping process is not perfect. It is done on a test stand and test stands are not engines in vehicles. Just like computer simulations are not real drag cars going down the track.
More on turbos later. Please provide questions and I will try and answer them or search for links to the answers on the web that are easy to understand.
Tom Vaught
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"Engineers do stuff for reasons" Tom Vaught
Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
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