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Posted for "George Braly" <gwbraly@gami.com>:
Rob,
How is it determined ??? By carefully instrumenting up one of these engines with internal cylinder pressure transducers and watching the internal cylinder pressures in real time as one changes the fuel flow.
Please don't ignore what I am telling you. 0.55 for a BSFC is actually too low even for a normally aspirated engine. TCM does that on their IO-550s and it is one of the things that causes them a lot of warranty problems.
But doing it on a boosted version of that engine is crazy.
An IO-540 300 Hp Lycoming will have a typical max power BSFC up near 0.6.
A 350Hp TIO Lycoming engine uses a BSFC in the 0.68 to 0.70 range. You should too.
The boosted engines need a heck of a lot more fuel to control the burn times of the fuel/air charge to keep from over pressuring the cylinder. Regards, George
a BSFC = 0.55. ... needs to be up around .70 to .72
ok, so how is the .7 BSFC determined?
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