How high of compression can I run in a propane small block?
With 92 octane gasoline I feel comfortable with about 9.5:1 max.
Propane (I believe?) is about 110 octane, is 11.5:1 reasonable???

if it is 110 octane (thats damn high :eek: ) 11.5:1 would be fine, hell you could probably go 13:1. This would make up for lower BTU rating of propane comparared to gasoline

just an FYI and after a little research..... propane=92,000 btu and gasoline mid grade is 125,000 btu.

later,
riff

I just saw on Lance's tech page that propane is 110 octane-research, and 103 octane pump. Which rating to I compare to premium unleaded 92?? I'm thinking the 103 rating?

I was told by a propane dist. that the optimum comp. ratio was 13.5 to 1

I never verified it

Compare the pump ratings. :flipoff2:

Originally posted by Dennis
I was told by a propane dist. that the optimum comp. ratio was 13.5 to 1

I never verified it

I heard this last night too. I talked to a guy who converted his truck to propane......

if the pump rating is 103 I would think 11.5:1 would be a good compression ratio, expecially if your using a smaller cam for low end power. you could probably get away with 12-12.5:1 but I'm not sure, the only motors I've ever seen with that high compression ran really big cams that bleed off alot of cylinder pressure so detonation isnt a big deal at low-midrange

I also found an octane rating on a propane site= RON 100. I think that's the one on the pump:confused: (R+M)/2 or somthing like that:confused:
I'll probably use the lowest octane rating (100) and be conservative with the compression ratio because I will be running a short duration cam and lugging the motor. I just am unsure what that # is, 11:1-13.5:1:confused: It's not like I can add a bottle of octane boost to the propane tank if I screw up

Can you run a short duration cam (say stock) with 11.5 to 1 I have heard you can beening the way it burns:confused: