I didn’t know Aspen caused issues… What exactly was the problem?
When we (the FIA, when i was part of it) introduced 100% 2nd gen bio fuel in 2023, single supplied by P1, the “only” issues we had found were some rubber components’ sensitivity in the sense that they engorged over time (mainly intake gaskets of some manufacturers on float chamber carburators like the Dellorto). With membrane carbs, the small complications came from the membrane themselves drying out and having to be changed slightly more often than with standard fossil fuel.
Apart from that, the fuel itself runs richer than standard, and makes considerable more power across the entire powerband. Close to an additional hp at peak, from what i have been told. Moreover, it has a very high resistance against detonation.
The fuel is more sensitive to changes in atmospheric humidity and temperature, which makes carburation throughout the day more complicated than ussual, but this is why factory teams exist…