Sorry typed that while drink'n. The final developed pressure verse being at sea level is reduced thus if you compared that against your sea level pressure the compression ratio in terms of pressure would appear to be reduced when it comes to fuel mixture even though the engine is still compressing the local atmospheric pressure the same amount, there is just a lower starting pressure to compress. So in the world of octane which higher levels are needed for retarding knocking of higher compression engines you inherently would need less octane if your ultimate pressure is reduced by atmospheric changes.
Assuming 0' of elevation is 14.7psi on a 10:1 engine would develop 147psi at sea level but at 5000' with a pressure of 12.2psi the engine would only have 122psi at the top of the stroke. Less octane is needed. Less power is also made. Less fuel is also used relatively but more throttle may be need to make up for the less power. Etc. I'll be feeling the whole situation out soon.
Makes sense.Good luck with the gas issue. You should not have a problem,there seemed to be plenty of it out there and not at a gouge price. It was interesting to see the 85% ethanol.I wonder how many cars out in the area where I saw it can use it.Or people just burning it anyway.Don't think it would be good for most engines.
Frank
Assuming 0' of elevation is 14.7psi on a 10:1 engine would develop 147psi at sea level but at 5000' with a pressure of 12.2psi the engine would only have 122psi at the top of the stroke. Less octane is needed. Less power is also made. Less fuel is also used relatively but more throttle may be need to make up for the less power. Etc. I'll be feeling the whole situation out soon.
Makes sense.Good luck with the gas issue. You should not have a problem,there seemed to be plenty of it out there and not at a gouge price. It was interesting to see the 85% ethanol.I wonder how many cars out in the area where I saw it can use it.Or people just burning it anyway.Don't think it would be good for most engines.
Frank
