10% Ethanol in Gas
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From: Steve Austin on 24 Dec 2007 12:11 Mike Romain wrote: > jim wrote: > >> Here's the problem: >> What your engine does or does not do above 3000 RPM has nothing to do >> with getting good gas mileage. > > If the top end is 3500 RPM, which is 'full throttle or the pedal to the > metal, then cruising at 2300 rpm needs about 3/4 of the throttle pedal. > > When the top end is 4500 rpm on the same engine, again that is pedal to > the metal, then cruising at 2300 rpm only needs about half throttle. > > This 25% difference in the gas pedal position 'sure' appears to > translate into a sweet 25% 'increase' in gas mileage. > > It has for me and over a half dozen others I have tuned up with the > emissions 'governor' gone. > > Why is this hard to understand? > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 'New' frame in the works for '08. Some Canadian Bush Trip and Build > Photos: http://mikeromainjeeptrips.shutterfly.com Better gas mileage comes from having the throttle opened more, not less. This is the main purpose for egr now. More throttle with more dead gas equals less pumping losses.
From: Mike Romain on 24 Dec 2007 12:40 Steve Austin wrote: > Mike Romain wrote: >> jim wrote: >> >>> Here's the problem: >>> What your engine does or does not do above 3000 RPM has nothing >>> to do >>> with getting good gas mileage. >> >> If the top end is 3500 RPM, which is 'full throttle or the pedal to >> the metal, then cruising at 2300 rpm needs about 3/4 of the throttle >> pedal. >> >> When the top end is 4500 rpm on the same engine, again that is pedal >> to the metal, then cruising at 2300 rpm only needs about half throttle. >> >> This 25% difference in the gas pedal position 'sure' appears to >> translate into a sweet 25% 'increase' in gas mileage. >> >> It has for me and over a half dozen others I have tuned up with the >> emissions 'governor' gone. >> >> Why is this hard to understand? >> >> Mike >> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 >> 'New' frame in the works for '08. Some Canadian Bush Trip and Build >> Photos: http://mikeromainjeeptrips.shutterfly.com > > Better gas mileage comes from having the throttle opened more, not less. > This is the main purpose for egr now. More throttle with more dead gas > equals less pumping losses. I have a carburetor engine... Mike
From: jim on 24 Dec 2007 15:03 Steve Austin wrote: > > Mike Romain wrote: > > jim wrote: > > > >> Here's the problem: > >> What your engine does or does not do above 3000 RPM has nothing to do > >> with getting good gas mileage. > > > > If the top end is 3500 RPM, which is 'full throttle or the pedal to the > > metal, then cruising at 2300 rpm needs about 3/4 of the throttle pedal. > > > > When the top end is 4500 rpm on the same engine, again that is pedal to > > the metal, then cruising at 2300 rpm only needs about half throttle. > > > > This 25% difference in the gas pedal position 'sure' appears to > > translate into a sweet 25% 'increase' in gas mileage. > > > > It has for me and over a half dozen others I have tuned up with the > > emissions 'governor' gone. > > > > Why is this hard to understand? > > > > Mike > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > > 'New' frame in the works for '08. Some Canadian Bush Trip and Build > > Photos: http://mikeromainjeeptrips.shutterfly.com > > Better gas mileage comes from having the throttle opened more, not less. So now we have one moronic theory to counter another. Having the throttle wider open will give you better mileage iff that is accomplished by putting in a smaller engine. Sure if you put in a smaller more efficient engine then you can run down the road at WOT and that will give you better fuel economy. But only an idiot would think that tuning your engine so that it requires wide open throttle to maintain the same speed rather than tuning it so that 1/2 throttle will give you that same power is going to increase your gas mileage. At least Mike has that part right. But that has nothing to do with ethanol or what he could be getting in fuel economy. If anybody still remembers ethanol and good gas mileage was the topic of discussion. The 258 is a long stroke engine with excellent low end power. So tuning it so that it doesn't run well at the engine rpm where it is designed to run most efficiently is not going to give you the best mileage even if it does give you better mileage than somebody else's sick engine. It is no big surprise that a bunch of stuff that was stuck on to a good engine to supposedly control emissions resulted in poor performance and bad fuel economy at whatever RPM. Remember this was AMC and they went out of business and there was a good reason for that. > This is the main purpose for egr now. The initial intent of EGR was to reduce NOX emissions. It was discovered that it also acted like an octane boost which does allow you to tune an engine with more advanced timing and leaner mixture which can translate into better fuel efficiency (but to some extent defeating the original intent). >More throttle with more dead gas equals less pumping losses. If you are going from point A to point B in a certain vehicle with a certain gear ratio and their are no losses due to things like the tires slipping then you will have exactly the same number of engine revolutions no matter how you plant your foot on the throttle. How is running more gas and air thru a fixed number of cycles going to improve the mileage? -jim
From: Steve Austin on 24 Dec 2007 17:43 jim wrote: > > Steve Austin wrote: >> Mike Romain wrote: >>> jim wrote: >>> >>>> Here's the problem: >>>> What your engine does or does not do above 3000 RPM has nothing to do >>>> with getting good gas mileage. >>> If the top end is 3500 RPM, which is 'full throttle or the pedal to the >>> metal, then cruising at 2300 rpm needs about 3/4 of the throttle pedal. >>> >>> When the top end is 4500 rpm on the same engine, again that is pedal to >>> the metal, then cruising at 2300 rpm only needs about half throttle. >>> >>> This 25% difference in the gas pedal position 'sure' appears to >>> translate into a sweet 25% 'increase' in gas mileage. >>> >>> It has for me and over a half dozen others I have tuned up with the >>> emissions 'governor' gone. >>> >>> Why is this hard to understand? >>> >>> Mike >>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 >>> 'New' frame in the works for '08. Some Canadian Bush Trip and Build >>> Photos: http://mikeromainjeeptrips.shutterfly.com >> Better gas mileage comes from having the throttle opened more, not less. > > So now we have one moronic theory to counter another. Having the throttle > wider open will give you better mileage iff that is accomplished by > putting in a smaller engine. Sure if you put in a smaller more efficient > engine then you can run down the road at WOT and that will give you better > fuel economy. > But only an idiot would think that tuning your engine so that it > requires wide open throttle to maintain the same speed rather than tuning > it so that 1/2 throttle will give you that same power is going to increase > your gas mileage. At least Mike has that part right. But that has nothing > to do with ethanol or what he could be getting in fuel economy. > > If anybody still remembers ethanol and good gas mileage was the topic of > discussion. The 258 is a long stroke engine with excellent low end power. > So tuning it so that it doesn't run well at the engine rpm where it is > designed to run most efficiently is not going to give you the best mileage > even if it does give you better mileage than somebody else's sick engine. > It is no big surprise that a bunch of stuff that was stuck on to a good > engine to supposedly control emissions resulted in poor performance and > bad fuel economy at whatever RPM. Remember this was AMC and they went out > of business and there was a good reason for that. > > > > > >> This is the main purpose for egr now. > > The initial intent of EGR was to reduce NOX emissions. It was discovered > that it also acted like an octane boost which does allow you to tune an > engine with more advanced timing and leaner mixture which can translate > into better fuel efficiency (but to some extent defeating the original > intent). > > > >> More throttle with more dead gas equals less pumping losses. > > If you are going from point A to point B in a certain vehicle with a > certain gear ratio and their are no losses due to things like the tires > slipping then you will have exactly the same number of engine revolutions > no matter how you plant your foot on the throttle. How is running more gas > and air thru a fixed number of cycles going to improve the mileage? > > -jim Same gas, same air. More dead gas. More throttle for same amount of good air. The otto engine is most efficient at wide open throttle. Those old economy runs where they got insane gas mileage were all done at full throttle.
From: jim on 24 Dec 2007 18:10
Steve Austin wrote: > > Same gas, same air. More dead gas. More throttle for same amount of > good air. The otto engine is most efficient at wide open throttle. > Those old economy runs where they got insane gas mileage were all done > at full throttle. sure but they engineered it with a tad bit more knowledge than 'we need to drive this thing at wide open throttle'. Since that little tiny bit of the knowledge seems to be the only part of the total knowledge you possess it is unlikely that you would ever be able to even come close to getting the type of fuel economy the average driver does. |