Originally Posted by
Chip
I disagree that running a turbo at a point in its compressor map where it is LESS efficient is a good thing TBH
obviously i didnt explain my view correctly,
my understanding was that most turbos are efficient at low rpm's and decrease as speed and pressure ratio's increase, as below
its peak efficiency island starts at 0.5 bar of boost, granted its less efficient below that as the turbo's low rpm make's it less able to hold a compressed charge efficiently.
as the case is the same in these...
T66
GT35
2 bar on the GT3582 above drops its efficiency by 2% under the efficiency at 1 bar, not a great deal i agree but its still decreasing.
chaffe---Its not all about max bhp, its about usable bhp. 400bhp with a big turbo at 1 bar is not as good as 400bhp with a decent sized turbo at 2 bar, they both peak at similar revs (as that is down to the engine VE) but the one with the smaller tubo will make more power from lower down and for longer.
I agree that choosing a larger turbo to reduce boost for a givern power is not always correct, what im suggesting is that the rest of the engine should be made as efficient as possible with porting to the head etc etc, so that the same turbo as before produces the same power just at a lower point in the graph to before..
correct me if im way of the mark?