speyers
Well Known Member
I have been looking into the relationship between compression ratios and the ties to auto fuel. It appears as though older engines originally certified for 80 octane have lower compression ratios (6-7.5:1) versus the engines certified for 100 octane fuel. They usually come in around 8:5-10:1 on the compression ratios. I understand the logic of needing a higher octane fuel but it seems as though the cut-off range is in the 8-9:1 range. Wondering if anyone has experience with auto fuel in a 0-320 or 0-360 with a CR or 8.5:1.
Reading Lycoming SL1070, they are (of course) very much opposed to the use of auto fuel. However, due to the amount of lead in the fuel, engines that were originally certified for 80 octane now are getting 4X the amount of lead they were originally designed for (0.5ml vs 2ml). I just finished helping a friend ream his exhause guide and polish a valve because of a sticking valve on his A-65 engine. Granted this is the opposite end of the spectrum with a CR of only 6.3:1. The point is this, can I run my 0-320 or 0-320 with a CR of 8.5:1 that was originally certified for 91 octane on auto fuel and still be OK? It seems as though it is right on the border with regards to the comprestion ratio scale...
Oppinions or personal experiences welcome.
Reading Lycoming SL1070, they are (of course) very much opposed to the use of auto fuel. However, due to the amount of lead in the fuel, engines that were originally certified for 80 octane now are getting 4X the amount of lead they were originally designed for (0.5ml vs 2ml). I just finished helping a friend ream his exhause guide and polish a valve because of a sticking valve on his A-65 engine. Granted this is the opposite end of the spectrum with a CR of only 6.3:1. The point is this, can I run my 0-320 or 0-320 with a CR of 8.5:1 that was originally certified for 91 octane on auto fuel and still be OK? It seems as though it is right on the border with regards to the comprestion ratio scale...
Oppinions or personal experiences welcome.