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89 0ctane vs 87 octane... hi, i have a 2003 coupe ex. while looking at the fuel specifications for the car i realized that it recomends 89 octane, i have been using 87...does this really matter? will it effect the engine/performance if i continue to use 87 octane? thanks in advance, DC |
honestly, you can put 87 in it and it will most likely not effect performacnce. |
actually civics are rated for 87 |
Originally Posted by gearbox actually civics are rated for 87 |
i-4 light car, compression ratio im sure is low enough for 87 octane so ur perfectly fine |
1. always use what the manufacture recommends. 2. There has never been a civic (barring the Si's which generally use a completely different engine) that recommends 89 that I have ever seen, and I had an '03 EX. |
yeah as stated above...it should be in your manual to use 87 and above. My trialblazer has a 10.1:1 compression and it says to use 87 octane or above. |
use what the manual says, which is 87 |
higher the octane, the slow it burns. highly modded engines run high octane because you want the fuel to burn slower due to advance timing. you want to go low as possible without binging to get the most performance. i run 87 all the time. for daily driving and for track days without problems |
Originally Posted by usafstud higher the octane, the slow it burns. highly modded engines run high octane because you want the fuel to burn slower due to advance timing. you want to go low as possible without binging to get the most performance. i run 87 all the time. for daily driving and for track days without problems Well.... burning slower isn't really the reason. That is more myth, although it does technically burn slower, you or the engine will never notice, we are talking nano seconds difference in an engine that goes in micro seconds.... in other words the burn rate is essentially the same. The advantage to higher octane is that it doesn't combust as easy. So you can compress it and add more heat to it before it starts to blow up. That can be translated to higher compression ratio, more boost, or even more advanced ignition timing because lower octane’s will spontaneously combust under certain loads. By that I means the fuel will ignite on it's own without any help, so you could see if the fuel ignites to soon, you could have some problems. So low octane will blow up if you put to much heat, pressure or that stuff on it, will blow up to early (blowing up your engine at the same time), where as higher octane may not, hence keeping your engine in one piece. So your end result is correct, but the reasoning is wrong. |
Originally Posted by Jrfish007 Well.... burning slower isn't really the reason. That is more myth, although it does technically burn slower, you or the engine will never notice, we are talking nano seconds difference in an engine that goes in micro seconds.... in other words the burn rate is essentially the same. The advantage to higher octane is that it doesn't combust as easy. So you can compress it and add more heat to it before it starts to blow up. That can be translated to higher compression ratio, more boost, or even more advanced ignition timing because lower octane’s will spontaneously combust under certain loads. By that I means the fuel will ignite on it's own without any help, so you could see if the fuel ignites to soon, you could have some problems. So low octane will blow up if you put to much heat, pressure or that stuff on it, will blow up to early (blowing up your engine at the same time), where as higher octane may not, hence keeping your engine in one piece. So your end result is correct, but the reasoning is wrong. |
Yeah...let me add more... My chem prof. exlpained when i was in school...its the gas molecular strcuture that allows more compression using higher octane gas... think of it as long _._._._. for the higher octane....anyone taken chem should know this... When is this state, it is relatively easy to compress this long molecule to a certain point without changing the property until....knocking or detonation... its called premature ignition.. |
Originally Posted by Jrfish007 Well.... burning slower isn't really the reason. That is more myth, although it does technically burn slower, you or the engine will never notice, we are talking nano seconds difference in an engine that goes in micro seconds.... in other words the burn rate is essentially the same. The advantage to higher octane is that it doesn't combust as easy. So you can compress it and add more heat to it before it starts to blow up. That can be translated to higher compression ratio, more boost, or even more advanced ignition timing because lower octane’s will spontaneously combust under certain loads. By that I means the fuel will ignite on it's own without any help, so you could see if the fuel ignites to soon, you could have some problems. So low octane will blow up if you put to much heat, pressure or that stuff on it, will blow up to early (blowing up your engine at the same time), where as higher octane may not, hence keeping your engine in one piece. So your end result is correct, but the reasoning is wrong. There is no credence to the idea of different rates of burn for the different octane fuels. There is no correlation between octane (fuel grade) and the concept of slower or faster or hotter or cooler running of engines. Chevron supreme gasoline will not burn hotter than the other grades. Gasolines with oxygenates (ethanol or methyl tertiary butyl ether - MTBE) may burn hotter than those without oxygenates, but the octane has nothing to do with it. There are a number of text books on internal combustion engines. Two well known authors are J. B. Haywood (MIT) and E. F. Obert (Northwestern University). They both discuss flame speed. Flame speed in a spark-ignition engine is more controlled by the engine design and operating conditions than by fuel hydrocarbon composition. The design of the combustion chamber and inlet ports and how they affect turbulence is most important. A turbulent motion of the fuel-air mixture increases the speed of flame propagation by rapidly intermingling the burned and unburned portions of the flame front. Increasing engine speed increases turbulence and flame speed. Fuel-air ratio also is very important with the fastest flame speed occurring at slightly rich of the stoichiometric (chemically correct) air-fuel ratio. Fuel composition also can affect flame speed. The gaseous fuels, methane and propane, have higher flame speeds than gasoline. Methanol has a higher flame speed than the gaseous fuels. In gasoline, isooctane (a paraffin) is about 20% slower than benzene (an aromatic). Benzene has a similar flame speed to 1-hexene (an olefin). Flame speed does depend on composition. However, it is just not directly related to octane level, but, rather, on the compositional makeup of a particular fuel. Thus, there is no direct correlation between octane rating and flame speed. Octane rating is only a measure of resistance to knock, or delay before autoignition. From the above fuel discussion it is concluded that although the composition will vary between regular and premium gasoline the difference in flame speed is very small and no correlated with octane level. Further, the fuel composition effect is small compared to the engine design and operating factors |
Originally Posted by djc hi, i have a 2003 coupe ex. while looking at the fuel specifications for the car i realized that it recomends 89 octane, DC whered you get this info from? |
i read it off of some online site reviewing the 2003 civic coupe ex...but the more i think about it and the fact that none of you guys use it it's prolly a misprint? thanks for the info guys! |
yeah misprint. check your owner's manual. it says 87 |
i use 94 octane, is there any problem wit that? |
here we go with this shit again.....use 87 |
Originally Posted by jdm_veloz i use 94 octane, is there any problem wit that? |
i wasnt lookin for performance tho, i thot it might be better for the engine cuz it is a higher octane. plus just couple more bux more. |
it wont do anything for the engine, it was designed for 87 octane, so use 87 octane |
the manual did not say use 87, so itz not designed to use 87, just says " use octane 86 or higher" but wut your sayin is dat 94 acts the same as 87? |
yea cause our cars were designed for 87, thats what the ecu reads, my manual says use 87 octane and so does a lot of other peoples, idk whats up with yours tho |
Originally Posted by jdm_veloz the manual did not say use 87, so itz not designed to use 87, just says " use octane 86 or higher" but wut your sayin is dat 94 acts the same as 87? Yes, they act the same, so why spend more for the same? |
There's nothing wrong with using fuel with an octane rating that's higher than 87. Also keep in mind that a lot of companies put more additives in the higher-octane fuels, which will help keep your engine clean. Here in Ottawa, Ontario at least, Petro Canada puts a much better additive package in their 91 octane fuel than in the cheap stuff. |
Originally Posted by ironchef There's nothing wrong with using fuel with an octane rating that's higher than 87. Also keep in mind that a lot of companies put more additives in the higher-octane fuels, which will help keep your engine clean. Here in Ottawa, Ontario at least, Petro Canada puts a much better additive package in their 91 octane fuel than in the cheap stuff. I don't know about Canada, but for the US, it is FEDERAL LAW that all gas dispensed out of a single nozzel must have the same addatives in the same amounts. SO the only way they can put more addatives in higher octane is to have seperate pumps and nozzels for each grade, and that is becoming very rare to see. Besides, the so called addative make up around 0.01% of the gas, in other words you are not getting that much addative any way to do any good. Just food for thought. |
Really?!?! Then for you guys in the US there's really no point in going over 87. |
shell gas here has more additives in 93 gas than in 87/89. their gas is terrible anyway so it doesn't matter lol. |
i thought shell had good gas, i heard that BP is the best place to go for gas, its also really expensive, so is shell for some reason |
Originally Posted by ironchef Really?!?! Then for you guys in the US there's really no point in going over 87. Yeah, that's my point, there is no reason at all to put anything higher than what you need in your car, in the US anyway. |
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