How will big radials and V12 do with new unleaded AvGas ?

[CAPFlyer]

Lead also reduces detonation, which is not something you want in an aero engine. Ever.
I believe this is one of the hurdles they are trying to clear with the unleaded fuel.

The *ONLY* reason for TEL is to increase Octane. Octane is a rating that, in essence, describes how "hard" you can compress the fuel before it pre-detonates (i.e. knocks). The higher the octane, the higher compression ratio that can be used. The lubrication properties were a "bonus", but again - that's in car engines. In aero engines, there is so little TEL left after combustion that it doesn't provide any appreciable lubrication. Hence (again) why most aero engines have always used hardened valves and seats. Not only that, but the hardened valves and seats last longer overall, allowing for more TBO, something that's very important in our application.

[Dave Hadfield]

No good with O-Rings, and blisters paint.

https://www.avweb.com/aviation-news/cal ... 1762301G5A

[AG pilot]

[CAPFlyer]

For those TL:DR -

1) This *ONLY* affects Nitrile O-Rings. Those are the cheapest O-rings you can use in a 100LL fuel system. Any natural rubber or silicone rings will be dissolved by 100LL or 100UL. It does not affect Vitron or Silicone O-Rings as the aromatics in the 100UL are non-corrosive to Silicone.

2) The paint issue is a non-issue. Have you ever seen a slow leak of 100LL on an airplane and what it does to the paint? Yep - it blisters it too, especially if it was applied over sub-standard primer.

Also, GAMI has responded to the article and stated (as was noted in the article itself) that the STC specifies that only Vitron or Silicone-based O-Rings should be used. So this is a well known issue and has a stated fix already.