Quote:
Originally Posted by chesterakl
The ONLY thing the higher octane is needed for is engine knock. High-performance engines are more sensitive to the octane level because they have higher compression ratios, so they tend to knock on lower octanes.
Plus, the computers in today's engines also detect knocking and will adjust the spark timing and other settings to control it.
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Higher octane fuel allows for higher compression engines. Higher compression engines are capable of getting more energy out of gasoline than are lower compression engines. At least at their thermodynamic limits. This is the ONLY reason that diesels get better mileage than gas cars.
So while there might not be any more energy in the fuel, you can access more of it.
Also, low octane fuel in a high compression engine can self ignite due to the compression. This is the cause of engine knocking. Adjusting the spark timing won't do jack for it. But, fuel mixtures can be adjusted to prevent it.
You can not get the full engine power off of low octane fuel.
Quote:
Originally Posted by chesterakl
There is also a claim by some people that they put premium in once in a while to "clean out the system". Most of the time, the detergents suppliers put into their fuels are the same in all grades.
So in reality, most cars on the road today need nothing more than the regular old 87 octane fuel.
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In my experience premium fuel has more detergents than regular. Now, does it matter? I don't know. I'm betting not, but still I think it's important to be accurate.
BTW, I'm looking forward to the results of the E30 testing. I had read the articles mentioning it as the sweet spot, and have been really curious about the results.
2005 Ford Escape Hybrid - Titanium Green, 4WD, Appearance Pkg, Leather, Nav System