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| Thread ID: 139508 | 2015-05-14 00:02:00 | 91 octane versus 95 - advice please | BBCmicro (15761) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 1400650 | 2015-05-14 12:14:00 | Generally 91 has a higher calorific content than 95 not the other way round as many people think.. 1 litre of petrol = 100% 1 litre of 91 = 20% additive & 80% hydrocarbon fuel 1 litre of 95 = 30% additive & 70% hydrocarbon fuel Therefore 91 contains more energy than 95. This is compensated for by allowing a higher compression ratio to be used with 95 which produces better high speed performance. Most cars made since 1980 have octane sensors which adjust the ignition timing and fuel/air ratio to suit. |
mzee (3324) | ||
| 1400651 | 2015-05-15 04:52:00 | just a bit about engines ecu adjusting ignition timing to suit the fuel, that only really works well on ecu's that are tuned for it. later model tend to be tuned to run on a wide range of fuels. however not all are and earlier ones certainly not. they all have knock sensors etc and will retard timing, but they are not necessarily tuned for that fuel. they will adapt to lesser fuels but not perfectly. so they will run on 91 but get best performance and economy on 95. catch is the wear. on a high km engine it may be down on compression enough that it runs best on 91 instead of 95. |
tweak'e (69) | ||
| 1400652 | 2015-05-15 06:23:00 | Probably more important is what grade of oil is used and does it actually get changed or just added too Using a oil that is suited to a slightly worn engine may reduce oil use If it says in the Handbook to use 95 as someone that does not know anything about 91 E10 may have adverse effects if used Have a 98 Maxima that states in the Handbook able to use 91 but was informed by Nissan NZ in a mail out to use 95 octane because 91 was not upto spec |
Lawrence (2987) | ||
| 1400653 | 2015-05-16 07:50:00 | 1 litre of petrol = 100% 1 litre of 91 = 20% additive & 80% hydrocarbon fuel 1 litre of 95 = 30% additive & 70% hydrocarbon fuel Therefore 91 contains more energy than 95. This is compensated for by allowing a higher compression ratio to be used with 95 which produces better high speed performance. Most cars made since 1980 have octane sensors which adjust the ignition timing and fuel/air ratio to suit. The additive is a hydrocarbon as well with a high octane rating to boost the rest of the mix. Therefore it contains energy as well so your argument seems to be unconvincing. You would need to know the relative energy content of the additive and the rest of the fuel. |
user (1404) | ||
| 1400654 | 2015-05-17 02:43:00 | Mitsi. Lancer 1998 SEi, sticker inside petrol cap cover recommends 95+, but have always used 91, no hesitation responses on acceleration. lurking. |
Lurking (218) | ||
| 1400655 | 2015-05-17 10:24:00 | My 2003 Mazda 6 2.3L is supposed to run ok on 91 but it didn't (pinked like mad under load) so I changed to Gull's ethanol-based 91 and it not only stopped the pinking, it also improved gas mileage. If I am going on a long journey I always top up with Gull Ethanol 95 as it runs even sweeter on that, and gas mileage takes another big leap. Like I mentioned some time back: Auckland to Palmerston North-return, in one day and without refueling: close to 1000km. Cheers Billy 8-{) |
Billy T (70) | ||
| 1400656 | 2015-05-17 12:23:00 | Hey Billy interesting to see that so i always wanted to know if Gull is any better since Gull has caused problem to a person i know , something in the engine became problem after fuel up . So as you it runs well , maybe i may try when i get car but i will have a good look since i like to have a browse before i buy something , reviews help me too . |
AppleFan (17097) | ||
| 1400657 | 2015-05-17 19:18:00 | My 2003 Mazda 6 2.3L is supposed to run ok on 91 but it didn't (pinked like mad under load) so I changed to Gull's ethanol-based 91 and it not only stopped the pinking, it also improved gas mileage. If I am going on a long journey I always top up with Gull Ethanol 95 as it runs even sweeter on that, and gas mileage takes another big leap.Like I mentioned some time back: Auckland to Palmerston North-return, in one day and without refueling: close to 1000km.CheersBilly 8-{)how big is your tank billy | plod (107) | ||
| 1400658 | 2015-05-17 22:52:00 | Most cars made since 1980 have octane sensors which adjust the ignition timing and fuel/air ratio to suit. since 1980 ? I doubt that :-) Maybe on the more expensive models. 3 out of my 4 last cars didnt have octane/knock sensors, nor a engine computor. All 4 were 1989-1991 . |
1101 (13337) | ||
| 1400659 | 2015-05-18 03:31:00 | ditto 1101's experiences as have found running 98 is actually cheaper although the cost per litre is higher initially....plus you get more power & cleaner burning etc.... Experience based on doing same route and mileage etc with all three fuels 91,95,98 Most cars will automatically adjust to the fuel used unless really old like this one.... |
Koenig Tiger (14621) | ||
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