Compressor surge in pre-compressor injection

[JohnA]

Has anybody else experienced this?

During pre-comp injection, as the compressor map is shifted to the right and upwards we move the choke line further away so we can extend the useful range of our turbo. Which is nice.

However we also move the surge line, which is not so nice.
I cannot tell if the surge line moves rightwards proportionately to the choke line - may it moves quicker, thereby narrowing our useable range in the compressor map.

I'm thinking that it might also have to do with the effective narrowing of clearances at the compressor tips - something that would increase efficiency but potentially aggravate surge.

This might be one of the 'gotchas' of this technique (hey, what did we expect - a free lunch? :wink: )