Originally Posted by Superchips_Distributor

(Snip
By the way - on the subject of fuels & energy content - higher octane fuel does not automatically have "less energy." On the other hand, it is also false that higher octane premium fuels will always automatically have a *higher* energy content than "regular" fuels, as some assume (and as some oil companies have advertised/marketed) - more often than not, when there is a difference, it's usually in favor of the higher octane fuel. There is not any kind of "rule-of thumb" *either* way.

When dealing with *quality* fuels, the actual BTU content per gallon (or per lb.) of fuel usually does not vary much regardless of octane (in the 87-100 octane range, R+M/2). The actual energy content of gasoline is expressed by the oil company/refiner in terms of the number of BTU's per gallon - say, 110,000 BTU's per gallon, or 98,000 BTU's per gallon, etc. - and that is not "automatically" increased or decreased (all else being equal) based solely on the octane rating.

Another point that comes up from time to time regarding fuels & higher octanes is the burn rate - once ignited, the flame front propagates itself across the combustion chamber at roughly the same speed regardless of octane (again, when we're talking about fuels in the 87-100 octane range R+M/2), generally speaking - but getting it *LIT* - actually INITIATING the burn of the A/F mixture takes more time - both in real time and in degrees of crankshaft rotation, as octane rating goes up. This is *precisely* why it's generally considered close to a waste of money to use more octane than the motor is tuned for, more often than not - and I'd be the first to say not to bother using more octane than the motor is tuned for, I do agree with you on that, certainly. Using significantly more octane than the engine is tuned for will actually *reduce* power and fuel mileage, and can also cause MIL's, etc. just as the owners manuals for most of these vehicles mentions.

With higher octane, it's not just that we can make more power & mpg *if* we add timing - proper tuning dictates that we *must* add more timing to the motor to compensate for now much longer it takes to *initiate* the burn of the higher octane A/F mixture. The spark plug needs to get it's current with the piston further down the bore (BTDC) so that peak cylinder pressure still occurs with the piston the same approximate number of degrees *down* the bore (ATDC) - otherwise the engine doesn't make the power it should, and won't get the fuel economy it should, either - this is why most of these vehicles owners manuals specifically instructs *not* to use premium gas, as they are originally tuned for 87 octane from the factory.

In tuning, the BTU content ("energy") of the fuel makes every bit as much difference, if not more, than just it's octane rating. A low energy 93 octane fuel can be out-performed by a higher-energy 92 octane fuel, for example. Or take methanol-based fuels (far different from gasoline) - now they have a *very* high octane rating, but have only about 50%-70% of the BTU content per gallon of gasoline.

Just some quick general FYI...................

Originally Posted by BLYOTH

It is not the $$$ that I am worried about it is the enviroment. Do you know of any where that you can legally dump a gallon or two of pre-mix?