I have a carburated 550 in a 56 skylane, (tx skyways) and thinking of upgrading my other skylane but the fear of disappearing 100ll in the next 8-10 years is a real concern. I really love the extra little bit the 550 offers over the other 520 and -50 conversions but the option of putting mogas in the lower compression cylinders has me considering the -50 conversion.

Does anyone know if it would be a option to retrofit and derate 550 with low compression cylinders if it was necessary due to 100ll availabilityissues? I would not mind so much to spend $10/$12 k in a few years on cylinder replacement rather than a complete downgrade and have to convert to a new -50 conversion should 100ll disappear.

skydiveoc wrote:I have a carburated 550 in a 56 skylane, (tx skyways) and thinking of upgrading my other skylane but the fear of disappearing 100ll in the next 8-10 years is a real concern. I really love the extra little bit the 550 offers over the other 520 and -50 conversions but the option of putting mogas in the lower compression cylinders has me considering the -50 conversion.

Does anyone know if it would be a option to retrofit and derate 550 with low compression cylinders if it was necessary due to 100ll availabilityissues? I would not mind so much to spend $10/$12 k in a few years on cylinder replacement rather than a complete downgrade and have to convert to a new -50 conversion should 100ll disappear.

There will certainly be a suitable substitute for 100LL when the LL is removed, clean plugs no lead deposits, look forward to the day. Is it realistic to think that all aircraft requiring 100LL will be grounded in the future?

No, they'll just discontinue the $6/gallon 100LL & start selling the $10/gal 100UL (or whatever). No problem at all. What's the power difference between the Ponk O-520 (aka +50) & the O-550? As I recall, a factory IO-520 is rated at 300 for takeoff, 285 continuous and the IO-550 is 300 continuous?

And to think we have over 100 octane unleaded being made 12 miles from my house today. They use it in Brazil as well as the Tea South Dakota guys in their RV-3's. Definitely no clinkers on the spark plugs. Oh, and it's priced about 40 cents a gallon less than regular unleaded gasoline.