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| Thread ID: 80495 | 2007-06-25 08:08:00 | 91 vs 95 octane petrol | george12 (7) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 562734 | 2007-06-25 21:35:00 | Most modern cars of the average variety use 91. My old 1966 Rover used 96 although what it really needed was 100. |
pctek (84) | ||
| 562735 | 2007-06-25 22:02:00 | In Japan, the standard is 98. Often the [older] cars are not re-tuned to suit NZ fuel (91, even 95). If you have a smaller car (1200 - 1800cc) you will not notice a lot of difference no matter what you put in. If, however your car is larger (2000 +cc) you will notice it will run smoother, and will also run cleaner and you should get slightly better economy. The difference between my old '92 Estima (2.4 supercharged) running on 91 and 95 was amazing. It was a lot quicker on 95, accelerated smoother from low revs, and got way better economy than running on 91. I think the nissan's and toyota's are the main ones that like the higher octanes, speaking from expreience.:cool: |
wratterus (105) | ||
| 562736 | 2007-06-25 23:05:00 | Now . . on to using a higher octane fuel in an engine that does not REQUIRE it . . . . DON'T DO IT!!!!! Allow me to emphasize that again: DON'T DO IT!!!! Putting fuel of higher octane into an engine that does not require it . . is damaging to so many other devices and in ways that may not seem obvious at first but are gonna bite you in the fleshy places later on . I'm no real expert but must agree with this comment . I thought it was well known and I am most surprised to find there are those who don't know . Lets repeat it again . Don't put 95 in your car if it is designed for 91 Tom |
Thomas01 (317) | ||
| 562737 | 2007-06-25 23:23:00 | Running your high performance car(evo, wrx etc) on 91 when it should run on 95/96 will in fact retard the timing producing less HP. Running your average car(corolla) on 95/96 when it is designed to run on 91 will only cost you at the pump with no performance increase. Top gear did a test on this very thing Yup. My wife put 91 in our WRX wagon and it produced less power and actually went through more gas than normal. |
jonboy (11457) | ||
| 562738 | 2007-06-26 00:13:00 | designed for 91? I put 91 into my corolla, but if I go read the manual, it says "Unleaded gasoline, Research Octane Number 91 or higher" um..wonder why they put that in manual, if timing can't be tuned automatically.. |
heni72847 (1166) | ||
| 562739 | 2007-06-26 00:47:00 | Since i bought my Toyota trueno in November ive been running 91 in it - until a few weeks ago where i got "harrassed" by a friend of mine and told me to run it on 95 octane - so i did - and what a change! the car is a lot more powerful and a hell of alot smoother - on 91 i would get 500km a tank - now on 95 i get around 600km a tank - its GREAT :D ive been told that since i was running 91 in it that the "knock sensor" saw that i was running low octane fuel and retarded the timing so everything ran ok - since ive switched it must have noticed and reset it so to work with the new fuel :D |
MAC_H8ER (5897) | ||
| 562740 | 2007-06-26 01:56:00 | The knock sensor is called the ESC sensor . That's lingo for "Electronic Spark Control" . . . . and it doesn't "see" anything . . it hears the destructive noise of pinging and octane knock and retards the timing in blocks of prearranged values . It's a little microphone mounted near the lower portion of the engine, nearest as it can be to the main bearings and crankshaft . On most US cars, those retard blocks of timing are five degrees each . Now . . smaller iron and older cars will respond very badly while running five or ten degrees retarded . If for some arcane reason your particular engine was set at a hellacious ten or fifteen degrees over-advanced, then it might help to add higher octane or really retard the timing a lot! . . . but that's so totally out of the realm of possibility that there has to be something else wrong with the computer and/or sensors in the system . Step one: ascertain if the vehicle REALLY is computer controlled . . . if it's fuel injected then it probably is . If it was built after (US standards here might NOT be up to yours though) 1973, then it has even a rudimentary form of emission controls that had impact on the performance and economy . After about 1992, things got a little better with better software, firmware and hardware in the vehicles, and they are pretty bullet-proof by now . Step two: Since the majority of vehicles have no adjustable timing because of new designs (no distributors (DIS)), crank and cam position detectors (CMP, CPS) , ESC, HO2S (both post- and pre-cat), BMAP, Baro, ADM and MAF devices if they are defective, they can take a serious amount off the top for performance and economy . But . . a big BUT here!!!---something's wrong if you have to use higher octane fuel in a vehicle that normally runs well on lower grades for everyone else . Step three: There should be a CEL (Check Engine Light) on the dashboard that is lit up solid red or orange telling you that something is wrong . If it's really bad . . the CEL flashes constantly . . that's a big no-no to operate an engine with that blinking! That blinking warning means that you are in imminent danger of burning your cat out or melting it off and dropping it into the bushes creating a fire hazard . . . . . a really big expense! Imagine that CEL as a BSOD for your car! It MUST come on right after you start the engine and as parity is achieved, it MUST go out in just under a minute . . . most go out at 10 to 15 seconds . . If it doesn't come on at start-up . . it's either broken, taped over, removed, painted black or someone disconnected it for reasons that might be criminal or illegal . Numbers concerning octane are vague and spurious according to the country and research system used to moderate these values . . . we have all our (US) vehicles (except Volvos) running on 87 Res/Ron octane, but that's R+M/2 values, and I don't know what NZ uses as base numbers . Our highest octane here (street-legal anyway) is 91 Res/Ron . Our fuel grades are 87, 89 and 91 . Thermodynamics are globally the same everywhere on earth, so I suspect either someone's got some really bad gas going there or the NZ gummernent is messing with youse guys . Typically, the new OBD-II systems can reset themselves in just under 200 miles . Some OBD-II readiness monitors are reset at start-up . . . others require a designated number of start-ups, cool down to a certain temperature and restart again . . all the while reading driving speeds, transmissions shifts and acceleration values to meet the standards to reset the adaptive values . Other "failures" need to be erased by a bi-directional scanner . . and pulling the battery cables off will not accomplish anything except extend the time required until the values are reset . Don't bother . |
SurferJoe46 (51) | ||
| 562741 | 2007-06-26 02:07:00 | I have to use 95 or better in my supercharged Calsis, because of pre-detonation with lower grade fuel. | SolMiester (139) | ||
| 562742 | 2007-06-26 06:46:00 | My method is to ask manufacturer on purchase of said vehicle. | Cicero (40) | ||
| 562743 | 2007-06-26 08:35:00 | Never mind... I have answered my own question by... reading the manual!!! :illogical many of you may ask... what is a manual? :confused: well it is a book detailing how to/specs/etc on a particular item... in this car my car manual :p You know it is amazing what you can find in a manual :D I am getting low on fuel... I might chuck in a tank of 95 and see what happens |
The_End_Of_Reality (334) | ||
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