Just some thoughts....
Dynamite, keep in mind the 3500 lb rating for the 731-20 engine on the Lear 40, at SL ISA conditions, is for an N1 of 85% or so. Maximum cruise N1 is normally 100% N1. So to compare thrust at altitude with SL thrust involves more than just pressure and mach differences, but N1 also.
Flyboyike, if the CF34 produces 40% of it’s SL rated thrust at 35,000 feet, that’s quite an engine. Somehow I think that figure should be closer to 25% as a guess, perhaps less.
Rigpiggy, not sure what the “b” stands for in “bsfc”. The term I’m used to is TSFC as in “Thrust specific fuel consumption”. That is, lbs of fuel burned, per lb of thrust produced, per hour.
BelArgUSA, I’m not sure fuel flow is linear with thrust as altitude changes, so your calculation may give a ballpark figure only. TSFC of .378 sounds too good to be true for cruise altitudes, perhaps it’s SL only. In high altitude cruise, .58 is about as low as you go.
XP Morten, For this graph to be of any help, one need to know what “efficiency” means. I’m quite sure it does not mean TSFC.
Hawk