Fuel/compression/timing

[850cc racer]

Hi Guys, i have a question regarding maximum compression/timing vs' Fuel used.

i know Maximum isn't a great word to use. maybe suggestable limit

Avgas is getting harder to obtain and im looking at switching to pump fuel.

the fuel i would be using is the same as the 94 available in the US,no ethanol, running at sea level

this is for a 2.0 Merc, on a light race hull.

if timing was set at 25, what would be the the suggestable maximum cranking compression?

thanks

[Jay Smith]

IMO 150-155 lbs cranking at sea level with 25 degrees timing would be safe with your 94 octane fuel..

Jay

[850cc racer]

Cheers Jay. the rating of the fuel over here is 98 octane however from what i have read the 94 fuel in usa is rated in AKI? and 98 RON (australian measurement) is equivelant

[Jay Smith]

I started to ask you if that was RON ... Then I'd feel safe at 170-175 cranking at sea level with 25 degrees timing.. 98 should support that just fine. I'm building a F1 motor going to AUS right now..

Jay

[850cc racer]

Hi Jay, thanks for the reply, i was thinking 98 octane should be okay, however wanted to be sure! the little 2.0 is starting to go really well and didnt want to "upset" it if 98 wasnt going to be okay

who's that one for? or cant say?


thanks
Rob

[Jay Smith]

First name is Simon , thats all I can say...

Jay