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Thread: Does RON number impact fuel efficiency?

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    Default Does RON number impact fuel efficiency?

    The car's engine can take minimum RON91. So I should be able to use 92, 95 or 98 petrol. Has anyone done any studies which would give a better mileage or are they supposed to be the same?

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    Default Re: Does RON number impact fuel efficiency?

    dun think you use 98 got better mileage than 92 if you compare cents and dollars...

    but 98 sure give you more smoother and better acceleration than 92.
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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by Del_CtrlnoAlt View Post
    dun think you use 98 got better mileage than 92 if you compare cents and dollars...

    but 98 sure give you more smoother and better acceleration than 92.
    Is it supposed to be like that? I feel 98 kind of sluggish and 92 makes the car feel very light... But I've yet to see that translate into fuel efficiency.. That's why I asked... Maybe I need to pump back 98 and try again..

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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by lsisaxon View Post
    Is it supposed to be like that? I feel 98 kind of sluggish and 92 makes the car feel very light... But I've yet to see that translate into fuel efficiency.. That's why I asked... Maybe I need to pump back 98 and try again..
    Try V-Power... lol...

    if 92 more power... next time i try 92 liao, cheaper... no more 98...

    best is empty the whole tank flush it with 92 run it with 2 go of 92, then test 5 rounds.. then empty again, and follow same procedure for 98...

    let me know end result... btw, u peg it to fixed fuel cost lah...
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  5. #5

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by lsisaxon View Post
    The car's engine can take minimum RON91. So I should be able to use 92, 95 or 98 petrol. Has anyone done any studies which would give a better mileage or are they supposed to be the same?
    higher ron rated petrol just have better knock suppressing capabilities. tats all.

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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by lsisaxon View Post
    Is it supposed to be like that? I feel 98 kind of sluggish and 92 makes the car feel very light... But I've yet to see that translate into fuel efficiency.. That's why I asked... Maybe I need to pump back 98 and try again..
    Go for 95..more power(as compared to 98), save some money(as compared to 98) and not causing too much harm to the earth(as compared to 92)..
    to go for 92 a bit..extreme liao lah..unless u really on a tight budget..i ever saw one uncle pumping 92 for his jaguar..
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  7. #7

    Default Re: Does RON number impact fuel efficiency?

    I have watched 5th Gear show compared different 3 fuel on different 3 cars. The test result showed fuel consumption affect 1 car only and the rest are the same. So is depend on car engine.
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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by Del_CtrlnoAlt View Post
    Try V-Power... lol...

    if 92 more power... next time i try 92 liao, cheaper... no more 98...

    best is empty the whole tank flush it with 92 run it with 2 go of 92, then test 5 rounds.. then empty again, and follow same procedure for 98...

    let me know end result... btw, u peg it to fixed fuel cost lah...
    I thought since the number is the resistance to knock, the lower number should ignite more readily, so theoretically should be more powerful if the engine can take the RON right? I wanna see who has the same experience.. everyone else is saying that the higher number is better..

    Not practical for me to flush the tank leh.. To do that 5 rounds will take a long time.. I pump full each time I hit 1/4 tank, that's when I calculate the FC.

    Any engine expert here can shed some light?

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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by Del_CtrlnoAlt View Post
    dun think you use 98 got better mileage than 92 if you compare cents and dollars...

    but 98 sure give you more smoother and better acceleration than 92.
    not really true leh.. my engine cannot take 98, will have a loss of power, knocking and low idling, 95 for me only.
    92 will make it sluggish and slow to respond, but at the end of the day, i don't see significant FC difference.
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  10. #10

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by lsisaxon View Post
    I thought since the number is the resistance to knock, the lower number should ignite more readily, so theoretically should be more powerful if the engine can take the RON right? I wanna see who has the same experience.. everyone else is saying that the higher number is better..

    Not practical for me to flush the tank leh.. To do that 5 rounds will take a long time.. I pump full each time I hit 1/4 tank, that's when I calculate the FC.

    Any engine expert here can shed some light?
    the lower ron number means the petrol is more susceptible to pre ignition. which means for eg. when ur engine is working under a heavy load, the engine works at a higher temp than normal, the petrol will ignite from the high heat itself instead of from the spark plugs.

    this in term will result in damage to the engine.

  11. #11

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by blazer_workz View Post
    Go for 95..more power(as compared to 98), save some money(as compared to 98) and not causing too much harm to the earth(as compared to 92)..
    to go for 92 a bit..extreme liao lah..unless u really on a tight budget..i ever saw one uncle pumping 92 for his jaguar..
    I was with 95 for quite a while, but I changed to 92 (since my engine can take minimum of 91) at the wrong time because it was during the same time I changed job and my usual route changed, so I don't know if it's the new route or the fuel which slightly reduced the FC.

    I think I'll put back 95 for 2 more top ups and make an evaluation again.

    If you felt 95 has more power over 98, then it tallies with my observation that 98 is sluggish and 92 makes the car feels lighter. So it's not my imagination.

  12. #12

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by yanyewkay View Post
    not really true leh.. my engine cannot take 98, will have a loss of power, knocking and low idling, 95 for me only.
    92 will make it sluggish and slow to respond, but at the end of the day, i don't see significant FC difference.
    Wah.. what engine is that? I thought 98 is supposed to resist knocking better? Maybe the pump put the wrong fuel in that day you pumped 98?

    Hmm.. interesting that there is no FC advantage. If that's the case, then it means that I can stick to 92 for better $ economy?

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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by lsisaxon View Post
    I was with 95 for quite a while, but I changed to 92 (since my engine can take minimum of 91) at the wrong time because it was during the same time I changed job and my usual route changed, so I don't know if it's the new route or the fuel which slightly reduced the FC.

    I think I'll put back 95 for 2 more top ups and make an evaluation again.

    If you felt 95 has more power over 98, then it tallies with my observation that 98 is sluggish and 92 makes the car feels lighter. So it's not my imagination.
    many months back when the fuel prices keep rising..ST Life got one article comparing the fuel efficiency for the different RONs including VPower..the test is conducted by MotorImage..and the car used was an Impreaza TS..it shows very favourable results for Esso RON 95..
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    Default Re: Does RON number impact fuel efficiency?

    actually, i dunno much about the RON thingy...

    i only go to the petrol station, then i think...

    便宜没好货
    好货不便宜

    lol...
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    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by lsisaxon View Post
    Wah.. what engine is that? I thought 98 is supposed to resist knocking better? Maybe the pump put the wrong fuel in that day you pumped 98?

    Hmm.. interesting that there is no FC advantage. If that's the case, then it means that I can stick to 92 for better $ economy?
    NC23E
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    Default Re: Does RON number impact fuel efficiency?

    i've been pumping caltex techron95, but for recent 2 top ups, i pumped techron98, and can feel more power with 98. i'm going back to 95 to see any changes or not.


    Quote Originally Posted by lsisaxon View Post
    I was with 95 for quite a while, but I changed to 92 (since my engine can take minimum of 91) at the wrong time because it was during the same time I changed job and my usual route changed, so I don't know if it's the new route or the fuel which slightly reduced the FC.

    I think I'll put back 95 for 2 more top ups and make an evaluation again.

    If you felt 95 has more power over 98, then it tallies with my observation that 98 is sluggish and 92 makes the car feels lighter. So it's not my imagination.

  17. #17

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by yanyewkay View Post
    NC23E
    Motorcycle?
    It is rated for RON>91 also. Should not knock with 98...
    http://www.cb400sf.co.uk/specifications.html
    Last edited by lsisaxon; 21st January 2008 at 02:29 PM.

  18. #18

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by blazer_workz View Post
    many months back when the fuel prices keep rising..ST Life got one article comparing the fuel efficiency for the different RONs including VPower..the test is conducted by MotorImage..and the car used was an Impreaza TS..it shows very favourable results for Esso RON 95..
    I'm switching to Esso once I run out of my SPC petrol voucher.

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    Default Re: Does RON number impact fuel efficiency?

    Basically the RON or octane rating gives you an indication of the amount the fuel can be compressed before it spontaneously ignites - the lower the RON, the less compression it can take. Igniting from compression causes engine knocking - which can be quite bad for the engine.

    One of the ways of increasing engine power (while keeping engine volume the same) is to increase the compression ratio of the engine - doing so means that you have to use a higher RON fuel to avoid knocking. So generally more powerful engines of the same volume need a higher RON fuel.

    There doesn't seem to be any evidence that using a higher RON than what your engine was designed for gives you any added benefits that outway the extra cost.

  20. #20

    Default Re: Does RON number impact fuel efficiency?

    Quote Originally Posted by gooseberry View Post
    Basically the RON or octane rating gives you an indication of the amount the fuel can be compressed before it spontaneously ignites - the lower the RON, the less compression it can take. Igniting from compression causes engine knocking - which can be quite bad for the engine.

    One of the ways of increasing engine power (while keeping engine volume the same) is to increase the compression ratio of the engine - doing so means that you have to use a higher RON fuel to avoid knocking. So generally more powerful engines of the same volume need a higher RON fuel.

    There doesn't seem to be any evidence that using a higher RON than what your engine was designed for gives you any added benefits that outway the extra cost.
    Adding onto what gooseberry has said, ron is onli impt to ur car if ur car's ECU is programed to o/p the bhp/torque using the particular fuel. Meaning, traditionally high compression engines ie honda/suzuki 11.0:1 requires high octane petrol to prevent pinging or early detonation. Hence the higher the compression, the higher the oactane u may need. NA racing cars even require octane booster as they run insane levels of compression. The worse i knoe of, was a b18c type R which blew even running on v-power. The compression was above 12.5+:1.

    However, if u take a look at force induction engines, they may require high octane petrol despite their low compression. This is because some force induction engines are tuned to o/p power/torque @ a particular octane rating. This is why like megaweb mentioned, top gear's test showed the WRX to o/p the highest figures @ the highest octane petrol.

    This is also why japanese cars have two different models. JDM & export. Japan has one of the highest octance petrol available to consumers. Whereas the export models factor into consideration of the mass market out their. This is also why some of their performance breeds especially the WRX & type R, there's a difference between the JDM & export models in performance figures. They are tuned for different octane petrol.

    So conclusion is.. most of our cars do not need high octane petrol. For fuel economy, it may be due to easier combustion of low octance petrol (i'm not too sure abt this). As for performance, there is no difference unless ur ECU is tuned to perform at high octane petrol or u are driving a car with high compression engine. Any differences felt are usually in our mind unless its proven :P

    Dun forget, there are countries still running on ron 87, 91, & 95 being their highest.
    Last edited by tan131; 21st January 2008 at 03:59 PM.

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