On May 27, 2007, at 4:43 PM, Craig Berland wrote:
Paul Tackabury wrote:
A repeat question--I was probably a bit too obtuse with the first try: We have at lease two configs of TSIO-550s out there (7.5 and 8.5 CR) and many interpretations of LIV(P)s. If they are run at the same fuel flow LOP then to the first order they are making the same horsepower. If their airspeed indicator/pitot static systems are reasonably accurate then a comparison of indicated airspeed should give an idea of relative efficiency and how the breed is evolving. So if we operate our TCM dollar eaters at 17.5 gph LOP as Walter suggests is typical on some airframes, then what sort of KIAS are we seeing? Mine was 211 KIAS before paint and as I stated I am hoping for an increase of about 4 knots after paint. I hope to have the reassembly complete this coming week and will share the results.
Paul, I hope you get some detailed answers to your question of speed, however the answers are somewhat suspect as some folks compensate for temperature and others use a standard airspeed gage. I do want to point out that a 8.5 C/R will make slightly more power if all other variables are held constant. The higher compression ratio is slightly more efficient. The higher ratio is not a freebie as you need to be somewhat more concerned about higher cylinder pressures and detonation. What FL are you seeing 211 kts?
Craig Berland