Mogas and LASAR
Mike.
At the time I was ready to sell the Arrow, my fuel consumption averaged 9gph with LASAR. before average was 10 to 11. At altitude with LASAR as low as 8 gph, and crusing at published top speed (LASAR did in fact increase the cruise speed, in part due to the C/S prop)
In any case fuel consumption averaged near 20% less with LASAR.
According to Unison, due to certification the FAA deemed that only 100LL was to be used.
Not this boy. The engine at the time was rebuilt (not overhauled) and had some 500 hrs. It was to specifications and balancing the rotating masses was also included when rebuilt.
Had to try Mogas. Engine is IO360B1E, 180HP.
At 3000'MSL in north Florida normal cruise settings were 24/24 and 142 kts.
EGT 1380. FF 9.4 . Right tank was dry and 5 gal of 93 oct mogas. left tank full of 100LL
To save gas, take off and reaching cruise alt, was done with 100ll. Once the engine settled. fuel tanks was switched over to mogas.
EGTs dropped, and had to lean to go back to 1380. FF down to 8.7, and no change in speed. The real eye opener was, the smooth engine running even smoother. Switching back top 100LL. EGT rose and had to add fuel, and back to 9.4. Silky smoothness gone. It was done initwo legs of 75nm, and 2 on board, and switches lasting 5 to 10 min.
In each case when switching to mogas, fuel flow dropped while no changes in performance, and a smoother running engine.
In all my years with engine, I had never expected such results. My passenger was a friend, with lots of jet time and a CFII. Joe was just as amazed as I was.
My RV10 is outfittted with LASAR and I will use mogas. Love experimentals.
FYI, I also operate with a friend a Searey amphib, that uses a Rotax 912S as used on the RV12. It specifies mogas. The use of 100LL requires changing oil on a 3:1 basis. We used 100LL on the 'Rey, on a return trip from a fly in. Rick used enough to get us back home. At cruise speeds, the Rotax refused to remain it's stable self. When we arrived home, I had to check the plugs. They were covered with a silvery coating. Concerned, Rick wanted to replace the plugs. I did not agree, and parsomony took over.
Filled back with mogas, and the engine got back to normal.
Rick also owns a 182, but no LASAR (not approved with Contis). The 182 has a mogas STC (87 oct). With mogas fuel consumption is lower as is oil consumption. The spark plugs love the stuff. The 182s engine is 200 hrs from TBO and loves oil.
TT
RV10 N968TP