Posting this here
from the Alberta Politics & Government Thread 2.0 since it was quite off-topic.
Quote:
Originally Posted by Johnny Makarov
I've had BMWs, Acuras and Lexus's that needed premium that I've just filled regular for the past 20 years and nothing happened. No engine pinging or anything.
Of course you need it for high end sports cars like lambos and ferraris. unless that was what Torquedog was filling up.
|
I'm going to make some assumptions here:
1. The BMW, Acura, and Lexus vehicles you were filling up weren't using forced induction (no turbo or supercharging).
2. The models you were driving were not the top-end performance variants.
3. You drove largely in areas with elevations similar to or higher than Calgary's.
Naturally-aspirated engines -- as a result of our higher elevations here -- do end up having a lower actual compression ratio as a result of the thinner atmosphere here. Because of the lower compression ratio, you can get away with using a lower grade fuel than required/recommended by the manufacturer in high altitudes. This is why you can find 85 octane fuel as the 'regular' in Colorado, for example, whereas we have 87 octane as the standard across Canada.
So yeah, it's not uncommon especially here to get away with using lower grade fuel with no ill-effects for regular applications, but anyone running a high performance application should probably avoid it just to be safe.
Supercharged engines also see a similar drop due to their belt-drive system being tied directly to RPM and not the boost itself, and thus are unable to accommodate for this change in atmospheric pressure. Turbocharged applications don't have this limitation as they're free-spinning compressors and will bleed off excessive PSI once the target boost is reached. A S/C'd car designed for 8 PSI at sea level won't reach peak boost in Calgary, but a turbo'd car will no matter what elevation you operate in.
Now that said, yeah I was filling a high-end sports car (Aston Martin), so I'm not going to try and save a few with cheaper fuel in a 7,500 RPM V8.
Quote:
Originally Posted by Faust
|
Yup, exactly the point I was making above; putting premium grade fuel in a car that doesn't require it won't give you any benefits, but
not using it for an engine that is designed for it (by way of compression ratio or forced induction) is detrimental to its expected factory performance.