Date: Tue, 16 May 2006 22:19:45 -0400 From: Fred W <Malt_Houndnospamm-me-not*yahoo.com> Subject: Re: Regular gas in a 9.5?
Bob wrote: > On Sun, 14 May 2006 14:11:50 -0400, Fred W > <Malt_Houndnospamm-me-not*yahoo.com> wrote: > > >>Not necesarily. The energy contained in the fuel is the same. If the >>engine computer (ECU) retards the timing it is because the fuel is >>burning too fast (pinging) and the combustion is happening before TDC. >>If the ECU does a correct job of backing off the timing is could have no >>effect on mileage. > > > Backing off the timing is going to seriously reduce power on a > practical basis. > > Normally I would agree with you, that is if the fule octane was held constant. In other words, if the fuel burns at a constant rate (octane) then retarding the ignition would cause the fuel to not have enough time to complete combustion and you would lose energy. But if the reason the ignition is that the engine is pinging due to early combustion of the fast burning, low octane fuel, doesn't it make sense that the fuel will still be fully burned during the power stroke? -- -Fred W
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