premium gas
#5
bad. higher octane=slower burn.
slower burn on a boosted or super high compression engine is great because it prevents detonation.
slower burn on a low powered moderate compression engine like ours will simply cause an incomplete combustion cycle in the chamber leaving deposits on your plugs and valves, as well as causing your cat to filter even more unburnt fuel and shorten its life. Gas mileage debates still roar over this issue, but just run 87 unless you go with high comp pistons or boost/nitrous.
slower burn on a boosted or super high compression engine is great because it prevents detonation.
slower burn on a low powered moderate compression engine like ours will simply cause an incomplete combustion cycle in the chamber leaving deposits on your plugs and valves, as well as causing your cat to filter even more unburnt fuel and shorten its life. Gas mileage debates still roar over this issue, but just run 87 unless you go with high comp pistons or boost/nitrous.
#9
For what it's worth, the Fit ECU does run more ignition advance w/ premium fuel. Doesn't mean it makes financial sense to do so, though. Just means it probably isn't going to hurt your gas mileage any, and it *might* make some more power.
Anyone interested in all the data, search under my user name.
Anyone interested in all the data, search under my user name.
#12
Octane rating - Wikipedia, the free encyclopedia
HowStuffWorks "What does octane mean?"
#13
This is complete nonsense. The octane rating is a measure of a fuel's resistance to detonation. As long as it's unleaded, high octane fuel is neither good nor bad for a Fit's relatively low compression (10.4:1) engine, but it will lighten your wallet faster.
Octane rating - Wikipedia, the free encyclopedia
HowStuffWorks "What does octane mean?"
Octane rating - Wikipedia, the free encyclopedia
HowStuffWorks "What does octane mean?"
#14
higher octane keeps the engine clean.
#15
wikipedia is not a reputable source, nor is howstuffworks. Tell any tech you are using super premium unleaded in your stock or all motor tuned honda fit and they will laugh. All you are doing is spending money that doesnt need to be spent and it is also MARGINALLY detrimental to your engine. It doesn't create enough of a difference that most people would notice but the slower burning nature of high octane fuel causes the mixture in your combustion chamber to be richer and therefore leave more deposits behind on your plugs, valves, and clog your cat faster. The fit burns pretty lean from the factory to conserve fuel so the difference won't be as noticeable as it would on some other cars that burn closer to stoich, but there will still be a difference.
also the theory that higher octane gas cleans the engine is so far from the truth it isn't even funny. If you look on any fuel injector cleaner or fuel system cleaner etc you will see that they use a mixture of many things including diesel fuel (which has a much much LOWER octane rating than regular gas). This is because the hotter and faster burning nature of diesel mixed with the other detergents in the cleaners will burn off any excess deposits left over from the incomplete burn that even regular gas gives.
also the theory that higher octane gas cleans the engine is so far from the truth it isn't even funny. If you look on any fuel injector cleaner or fuel system cleaner etc you will see that they use a mixture of many things including diesel fuel (which has a much much LOWER octane rating than regular gas). This is because the hotter and faster burning nature of diesel mixed with the other detergents in the cleaners will burn off any excess deposits left over from the incomplete burn that even regular gas gives.
Last edited by 5speedwonder; 09-09-2009 at 03:31 PM.
#17
I did see an interesting post about how using the higher octane fuel causes the ecu to run more ignition advance, which in turn would cause the engine to run with more power and comparable burn rates as regular gas (depending on just how much ignition advance takes place).
I think I'm going to have to do some tests myself with my datalogger and wideband and see what kinds of results I get with regular vs premium. I only wish my local dyno shop hadn't closed down so we could have some solid numbers to run off of power wise. It would be interesting to see whether the ecu can advance ignition enough to actually make it worthwhile to run premium.
I think I'm going to have to do some tests myself with my datalogger and wideband and see what kinds of results I get with regular vs premium. I only wish my local dyno shop hadn't closed down so we could have some solid numbers to run off of power wise. It would be interesting to see whether the ecu can advance ignition enough to actually make it worthwhile to run premium.
#18
I think I'm going to have to do some tests myself with my datalogger and wideband and see what kinds of results I get with regular vs premium. I only wish my local dyno shop hadn't closed down so we could have some solid numbers to run off of power wise. It would be interesting to see whether the ecu can advance ignition enough to actually make it worthwhile to run premium.
Fuel economy testing for regular vs premium would be even more problematic. Someone who lives in Florida (relatively flat, with little climate variation) and drives the same route every day would be a good candidate, and even then I would want to see a month of fill-ups for each fuel before coming to any conclusions.
#19
It depends. For non-controversial information in STM (science, technology, medicine) Wikipedia has a good reputation. A definition of octane rating falls within this category. Wikipedia's reliability for soft disciplines, and for topical subjects is another matter entirely. Caveat lector.
I've been a librarian since 1972, so evaluating information sources is a major part of what I've been doing for nearly 40 years. A while ago I did a fairly extensive literature search, including both Medline and Wikipedia, for information on bupropion. The Wikipedia article provided the most comprehensive and best sourced (146 references as of 09/09/09) overview of anything I found.
I've been a librarian since 1972, so evaluating information sources is a major part of what I've been doing for nearly 40 years. A while ago I did a fairly extensive literature search, including both Medline and Wikipedia, for information on bupropion. The Wikipedia article provided the most comprehensive and best sourced (146 references as of 09/09/09) overview of anything I found.
Last edited by Selden; 09-09-2009 at 05:03 PM.
#20
wikipedia is not a reputable source, nor is howstuffworks. Tell any tech you are using super premium unleaded in your stock or all motor tuned honda fit and they will laugh. All you are doing is spending money that doesnt need to be spent and it is also MARGINALLY detrimental to your engine. It doesn't create enough of a difference that most people would notice but the slower burning nature of high octane fuel causes the mixture in your combustion chamber to be richer and therefore leave more deposits behind on your plugs, valves, and clog your cat faster. The fit burns pretty lean from the factory to conserve fuel so the difference won't be as noticeable as it would on some other cars that burn closer to stoich, but there will still be a difference.
also the theory that higher octane gas cleans the engine is so far from the truth it isn't even funny. If you look on any fuel injector cleaner or fuel system cleaner etc you will see that they use a mixture of many things including diesel fuel (which has a much much LOWER octane rating than regular gas). This is because the hotter and faster burning nature of diesel mixed with the other detergents in the cleaners will burn off any excess deposits left over from the incomplete burn that even regular gas gives.
also the theory that higher octane gas cleans the engine is so far from the truth it isn't even funny. If you look on any fuel injector cleaner or fuel system cleaner etc you will see that they use a mixture of many things including diesel fuel (which has a much much LOWER octane rating than regular gas). This is because the hotter and faster burning nature of diesel mixed with the other detergents in the cleaners will burn off any excess deposits left over from the incomplete burn that even regular gas gives.