sutter@osu-eddie.UUCP (09/15/85)
From: sutter (Bob Sutterfield)
High-octane gasoline contains more energy per gallon than low-octane gas,
right? I mean, it accelerates better, hesitates less, and knocks very
little on Super Unleaded as compared to driving on Regular Unleaded. So a
gallon of it should drive my car further (more mpg) than would low-octane
gas, right? How much further? Enough further to offset the price
difference? What factors work into the equation? Do I need to be able to
change the mixture setting, compression, spark advance, or whatever, to make
a difference? Will the higher temperatures hurt my engine at all?
--
Human: Bob Sutterfield
Facilities Management Division
The Ohio State University Instruction & Research Computer Center
Workplace: Ohio Cooperative Extension Service, Computer Management Group
OCES VAX System Manager/Programmer (VMS)
Mail: ...cbosgd!osu-eddie!sutter.UUCP
or: sutter@ohio-state.CSNET
MaBell: (614) 422 - 9034wjh@bonnie.UUCP (Bill Hery) (09/16/85)
> High-octane gasoline contains more energy per gallon than low-octane gas, > right? I mean, it accelerates better, hesitates less, and knocks very > little on Super Unleaded as compared to driving on Regular Unleaded. So a > gallon of it should drive my car further (more mpg) than would low-octane > gas, right? How much further? Enough further to offset the price > difference? What factors work into the equation? Do I need to be able to > change the mixture setting, compression, spark advance, or whatever, to make > a difference? Will the higher temperatures hurt my engine at all? > High octane gasoline does NOT have more energy per gallon than regular-- it only has more anti-knocking additives per gallon. If your car does not knock on regular, high octane should not improve your gas mileage. (If your car knocks significantly on regular, it is not burning the gas efficiently, so high octane will improve mileage.) Several years ago, I thought as you do and tried an experiment with a new car (Plymoth Barracuda, 318 engine, 3 speed stick). For the first 4 or 5 thousand miles, I used regular, then switched to premium for another few thousand miles, then back to regular. I found no real increase in gas mileage with high octane.
gvcormack@watdaisy.UUCP (Gordon V. Cormack) (09/17/85)
> High-octane gasoline contains more energy per gallon than low-octane gas, > right? I mean, it accelerates better, hesitates less, and knocks very > little on Super Unleaded as compared to driving on Regular Unleaded. So a > gallon of it should drive my car further (more mpg) than would low-octane > gas, right? How much further? Enough further to offset the price > difference? What factors work into the equation? Do I need to be able to > change the mixture setting, compression, spark advance, or whatever, to make > a difference? Will the higher temperatures hurt my engine at all? > -- > Human: Bob Sutterfield > Facilities Management Division High octane gasoline will have no effect on an engine that runs correctly with lower octane gas. Every new-car owner's manual I have ever read makes this perfectly clear. If you are prepared to make engine mods, you can indeed get better performance from higher octane gas. The amount of power produced by your engine is roughly proportional to the compression ratio. If you switch from regular to premium, you may be able to use a compression ratio of, say, 10.5:1 instead of 9.0:1. This will give you more energy for the same amount of gas. Of less signigicance are some other changes that one may make. With higher octane gas, it is possible to run an engine slightly leaner without pinging, and it is sometimes possible to advance the ignition timing, which may improve performance. Buy the cheapest gas you can, so long as your engine does not knock. I don't think that any of the above mods, particularly timing and mixture, could possibly recoup the difference in cost. -- Gordon V. Cormack CS Department, University of Waterloo gvcormack@watdaisy.uucp gvcormack%watdaisy@waterloo.csnet
res@ihlpl.UUCP (Rich Strebendt @ AT&T Information Systems - Indian Hill West; formerly) (09/17/85)
> From: sutter (Bob Sutterfield) > > High-octane gasoline contains more energy per gallon than low-octane gas, > right? Wrong. The difference is in the ability of the gas to undergo compression without igniting. > I mean, it accelerates better, hesitates less, and knocks very > little on Super Unleaded as compared to driving on Regular Unleaded. So a > gallon of it should drive my car further (more mpg) than would low-octane > gas, right? Wrong. There should be very little, if any, difference in MPG. Rich Strebendt ...!ihnp4!iwsl6!res
goldman@ittvax.ATC.ITT.UUCP (Ken Goldman) (09/17/85)
> High-octane gasoline contains more energy per gallon than low-octane gas, > right? > should drive my car further (more mpg) than would low-octane > gas, right? How much further? Enough further to offset the price As I remember it, high octane gas only burns more slowly and is less likely to detonate from high temperature and pressure. It contains no extra energy, dispite the gas company ads. It's useful in high compression engines where the lower octane would ignite from the increase in pressure instead of waiting for the spark -> knocking. Also at times in modern engines which run hotter to decrease pollution. While high compression engines have better performance, it's the engine. Using higher octane gas gains you nothing.