Hi
Bravo73,
According to Lycoming, the HIO-360G1A in the 300CBi produces the same amount of power as the HO-360C1A fitted to the 300CB. If you look at the respective POH's for the helicopters, you will see the same performance charts - the only difference is that the CBi does not have a "mixture leaned" page.
I have never flown a CBi with more than 450 hours on it, and I have never flown a CB with less than 1,800 hours on it, so I cannot make a subjective comparison. Our CBi certainly performs better than our CB, but it weighs 100 lbs less, and is three years and 1400 hours newer.
Aircraft FI systems are not like current automotive FI systems, they are like FI systems fitted to cars in the 1960's - continuous flow, no electronics, and in the CBi, metering via a mechanical mass-airflow system. An aircraft like the Enstrom 280 or the 300C has pilot-controlled mixture which is set using EGT as a gauge.
You are likely to get better performance out of a FI engine, as the fuel metering is usually more precise - however, I suspect that similarly equipped and equally fresh, a
properly leaned CB would perform very close to a CBi (even at sea level, the CB is usually running a bit too rich - try the leaning procedure from the POH some time). The R22 would benefit from the FI system fitted to the CBi, as currently there is no leaning procedure for the R22, nor is it fitted with a vernier knob - once you are operating above 3,000' MSL, that O-360 is definitely running rich with the mixture knob fully in.
Remember that the bottom line on engine power is the amount of fuel the engine can burn at the optimum fuel/air ratio. As long as the induction system is capable of flowing air freely, and the fuel system is capable of fully atomizing the proper amount of fuel, it doesn't matter how it gets to the cylinders.
It's easier to efficiently get the optimum mixture to all the cylinders with FI, so it's easier to get the engine to deliver its rated power. However, all other things being equal, you are talking about a relatively small gain. Since the R22 already has "too much" engine power, it would only gain a little performance at high MSL altitudes - which could also be realized by fittting it with a proper mixture control and devising a leaning procedure.
However, for a training helicopter, the FI in the CBi is a great safety feature - it only takes one actual case of carb ice to make anyone a believer!
