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Thread: Mixing 91 with 95 together

  1. #31
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    Quote Originally Posted by malcy25 View Post
    Wrong. As you say right above that, it's a measure of it's ability to resist detonation. Octane is not a measure of energy value of the fuel. It just allows the engine and tuner/builder to do the things that create the power and not eat itself.
    He goes on to say "Disclaimer. Yes I know I'm massively over simplifying it and missing a bunch of information, but it's almost 1 am and I don't give a fuck.".

    I'd count this comment as a massive over simplification. I think we all agree the extra energy isn't "in" the fuel.
    Can I scream?

  2. #32
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    Quote Originally Posted by malcy25 View Post
    "If you ran 105 octane, you'd essentially be wasting your time, there would be no using the extra "bang" in the fuel." Wrong. As you say right above that, it's a measure of it's ability to resist detonation. Octane is not a measure of energy value of the fuel. It just allows the engine and tuner/builder to do the things that create the power and not eat itself. Things can get funky above 100 octane. The original SAE testing only could test to 100. Once you start looking at specialist fuels the range is massive and fining the right one can be fun, just looking at the, Sunoco, VP or Elf range makes my head explode, let alone the wallet....there's a whole world out there. The good old regular Avgas works fine in a lot of older bike situations where they have been leaned upon, but it is set for low rpm engines at high altitude. Modern high rpm engines don't like it and I've heard of guys with R1's and the like thinking they'll get a bonus, but actually get less power than PULP and shittier running.

    Octane boosters.....hmmm, I've had a play with those, including one that is arguably the best. I've heard of independent testing that could not detect an effect. I used tetraboost out of the UK which gave good results in a 98 unleaded in the UK (specific dyno testing and real world results, better than Avgas for total performance due to good octane AND high burn speed, more like an ELF) and shit result for me here. I suspect the octane booster was okay, but the underlying fuel was the let down. Pre-ignition anyone.....that cost me a lot of money.
    Intersting thing is Honda did a load of reaserch and proved high octane was actually irelevent at high revs.
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    also fuels also used to have a supercharger rating such as 100/110 Avgas.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  3. #33
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    Quote Originally Posted by Dave- View Post
    He goes on to say "Disclaimer. Yes I know I'm massively over simplifying it and missing a bunch of information, but it's almost 1 am and I don't give a fuck.".

    I'd count this comment as a massive over simplification. I think we all agree the extra energy isn't "in" the fuel.
    Precisely.

    1234567890.
    It’s diametrically opposed to the sanitised existence of the Lemmings around me in the Dilbert Cartoon hell I live in; it’s life at full volume, perfect colour with high resolution and 10,000 watts of amplification.

  4. #34
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    Quote Originally Posted by husaberg View Post
    Intersting thing is Honda did a load of reaserch and proved high octane was actually irelevent at high revs.
    Click image for larger version. 

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    also fuels also used to have a supercharger rating such as 100/110 Avgas.
    MSD ignitions spark multiple times under about 3,000 RPM. Then it's a single spark. The critical bit for engines is the bit before the torque and HP lines intersect. I'd write a full response on this, but no one would read it, and everyone would disagree anyhow, based on their backgrounds of huge engine building experience they don't have...

    As for the supercharger rating - it's a complex balance of the fuel, the type of blower (roots / centrifugal), carb'd or injected. If injected, then how big the intercooler is... etc etc...
    It’s diametrically opposed to the sanitised existence of the Lemmings around me in the Dilbert Cartoon hell I live in; it’s life at full volume, perfect colour with high resolution and 10,000 watts of amplification.

  5. #35
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    Quote Originally Posted by madbikeboy View Post
    MSD ignitions spark multiple times under about 3,000 RPM. Then it's a single spark. The critical bit for engines is the bit before the torque and HP lines intersect. I'd write a full response on this, but no one would read it, and everyone would disagree anyhow, based on their backgrounds of huge engine building experience they don't have...

    As for the supercharger rating - it's a complex balance of the fuel, the type of blower (roots / centrifugal), carb'd or injected. If injected, then how big the intercooler is... etc etc...
    https://i.imgflip.com/lti1z.jpg

    your so kewl.

  6. #36
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    Hate to spoil the party, but all the op asked was whether he could put 91 in a tank that had 95 in it.

    The answer is yes.

    Sent from somewhere using Tapatalk

  7. #37
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    Quote Originally Posted by Dave- View Post
    It's funny how people offered advice then admitted they couldn't follow your post.

    Just wait till they start asking about e85....
    I'm totally green with E85. I know a few hot rodders who have attempted to make power on it, but the really gifted work is the young guys with Japanese cars with lots of boost. I'm heading back to Aus in a very short amount of time, one of my mates is building a E85 Barra turbo set up in a '66 Mustang, he's going to be doing the tuning work on it around the middle of the year and I've asked to tag along during the dyno stage. White man's magic.
    It’s diametrically opposed to the sanitised existence of the Lemmings around me in the Dilbert Cartoon hell I live in; it’s life at full volume, perfect colour with high resolution and 10,000 watts of amplification.

  8. #38
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    Quote Originally Posted by madbikeboy View Post
    I'm totally green with E85. I know a few hot rodders who have attempted to make power on it, but the really gifted work is the young guys with Japanese cars with lots of boost. I'm heading back to Aus in a very short amount of time, one of my mates is building a E85 Barra turbo set up in a '66 Mustang, he's going to be doing the tuning work on it around the middle of the year and I've asked to tag along during the dyno stage. White man's magic.
    I've just converted my subaru hillclimb/track car to E85. It is great stuff for turbo engines. The tuner can pretty much advance the ignition timing as much as he wants without seeing detonation. They can generally get to the point when any further advance results in less torque (there's probably a good name for it) and then wind it back just a bit. When I got back into bikes I looked briefly at doing an E85 conversion but I don't think its worth while without a turbo.

  9. #39
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    Quote Originally Posted by mangere View Post
    They can generally get to the point when any further advance results in less torque (there's probably a good name for it)
    https://en.wikipedia.org/wiki/Maximum_brake_torque

    "Typically" 13-14 deg after TDC (so say -13 BTDC)

    Anyone interested in this guff ought to check out https://www.hpacademy.com/

    USD$99 for the tuning basics package ought to enlighten 99% of people to the basic principles of engine tuning.
    Can I scream?

  10. #40
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    Quote Originally Posted by husaberg View Post
    Intersting thing is Honda did a load of reaserch and proved high octane was actually irelevent at high revs.
    Click image for larger version. 

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    also fuels also used to have a supercharger rating such as 100/110 Avgas.
    Husa

    is 100/130 octane rating for avgas we get here (and for the old purple 115/145 as I am lead to believe, but we don't see that here anymore).

    I've survived on 100LL blue in Aussie at various times, but was glad to find some 100 Green this year, same as what we usually get here. In past years the 100LL "race fuel" we have received at various times might as well have been turps....

  11. #41
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    Quote Originally Posted by malcy25 View Post
    Husa

    is 100/130 octane rating for avgas we get here (and for the old purple 115/145 as I am lead to believe, but we don't see that here anymore).

    I've survived on 100LL blue in Aussie at various times, but was glad to find some 100 Green this year, same as what we usually get here. In past years the 100LL "race fuel" we have received at various times might as well have been turps....
    I'd have to check, it will be on the Mobil website etc i guess.
    I couldn't remember myself i was quoting of the cuff.
    How the ratings work is well covered in the Bell 2 stroke book.
    Pg 117 on
    http://iheartstella.com/resources/ma...nce-Tuning.pdf
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  12. #42
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    Quote Originally Posted by husaberg View Post
    I'd have to check, it will be on the Mobil website etc i guess.
    I couldn't remember myself i was quoting of the cuff.
    How the ratings work is well covered in the Bell 2 stroke book.
    Pg 117 on
    http://iheartstella.com/resources/ma...nce-Tuning.pdf
    I had a look at mobil came up empty
    Shell had this on their international website
    http://www.shell.com/business-custom...ook-2fuels.pdf
    Avgas 100 This was the standard high octane fuel for aviation piston engines and has a high lead content. There are two major specifications for Avgas 100. The ASTM D 910 and UK DEF STAN 91-90. These two specifications are essentially the same, but differ over antioxidant content, oxidation stability requirements and max lead content.
    Avgas 100 is dyed green and is now only produced in a few refineries in the world.
    Avgas 100LL This grade is the lower lead version of Avgas 100. Low lead is a relative term. There is still up to 0.56 g/litre of lead in Avgas 100LL. This grade is listed in the same specifications as Avgas 100, namely ASTM D 910 and UK DEF STAN 91-90.
    Avgas 100LL is dyed blue and is the main grade of Avgas used worldwide.
    Avgas 100VLL This grade is the very low lead version of Avgas 100LL, containing a maximum lead concentration of 0.45 g/litre. It is effectively a variant of Avgas 100LL with a restraint on the max lead content. It could be made available as an interim measure prior to the introduction of an unleaded high octane fuel, should it be necessary to address environmental concerns about leaded fuels. This grade is listed in ASTM D 910 and, other than the lower lead content, is constrained by the same specification requirements as Avgas 100LL. It therefore meets the same aircraft approvals and operating limitation requirements as Avgas 100LL meeting ASTM D910.
    Avgas 100VLL is dyed blue.
    AVIATION FUELS

    2.72.6
    Avgas UL82 This grade is intended to comply with the same aircraft approvals as the original motor gasoline (mogas) Supplementary Type Certificate (STC) approvals, but with better compositional and performance control. It is aimed at the low compression ratio engines which do not need the high octane of Avgas 100 and could be designed to run on unleaded fuel. Avgas UL82 is specified in ASTM D 6227. Unlike other Avgas specifications, ASTM D6227 allows the use of some non-hydrocarbon components used in mogas, such as ethers, but, unlike mogas specifications, alcohols are not permitted.
    Avgas UL82 is dyed purple.
    Avgas UL87 This is a relatively new grade added to ASTM D6227, driven by the need for some light sport engines to have a higher octane fuel than Avgas UL82.
    Avgas UL82 is dyed yellow.
    Avgas UL91 Compositionally this grade is somewhat comparable with Avgas 100LL but with a zero lead content, which results in a lower octane rating of 91MON. Avgas UL91 is specified in ASTM D7547. Avgas UL91 differs principally from both Avgas UL87 and UL82 not only in the higher octane rating, but in lower vapour pressure (49kPa max compared with 60kPa max in ASTM D6227) and that oxygenates such as ethers are not permitted. In common with all other current Avgas specifications, ASTM D7547 does not permit the use of alcohols such as ethanol.
    Avgas UL91 is dyed orange.
    History of Avgas Grades Avgas is gasoline fuel for reciprocating piston engined aircraft. As with all gasolines, avgas is very volatile and is extremely flammable at normal operating temperatures. Procedures and equipment for safe handling of this product must therefore be of the highest order.
    Avgas grades are defined primarily by their octane rating. Two ratings are applied to aviation gasolines (the lean mixture rating and the rich mixture rating) which results in a multiple numbering system e.g. Avgas 100/130 (in this case the lean mixture performance rating is 100 and the rich mixture rating is 130).
    In the past, there were many different grades of aviation gasoline in general use e.g. 80/87, 91/96, 100/130, 108/135 and 115/145. However, with decreasing demand these were rationalised down to one principle grade, Avgas 100/130. (To avoid confusion and to minimise errors in handling aviation gasoline, it is now common practice to designate the grade by just the lean mixture performance rating; thus Avgas 100/130 becomes Avgas 100).
    Some years ago, an additional grade was introduced to allow a common fuel to be used in engines originally designed for grades with lower lead contents as well as in those engines certified for higher lead contents. This grade is called Avgas 100LL, the LL standing for ‘low lead’.
    All equipment and facilities handling avgas are colour coded and display prominently the API markings denoting the actual grade carried. Currently, the two major grades in use internationally are Avgas 100LL and Avgas 100. To ease identification the fuels are dyed: Avgas 100LL is coloured blue, while Avgas 100 is coloured green.
    In 1999 a new Avgas grade UL82 (UL standing for unleaded) was introduced as a low octane grade suitable for low compression engines. It has a higher vapour pressure than conventional Avgas and can be manufactured from motor gasoline components, but, notably, the specification does not allow alcohols such as ethanol to be used. It is particularly applicable to those aircraft which have STCs to use automotive gasoline.
    An extension of this has been the grade Avgas UL87, which was created in response to the higher octane demand of some light sport engines; notably the turbocharged Rotax® engines. UL87 is otherwise similar to UL82, using similar components, but again expressly excluding alcohols.
    The relatively high vapour pressure of the ASTM D6227 specification makes UL82 and UL87 somewhat unsuitable for high altitude flight as engine failure from vapour lock can be an issue. In order to meet the demands from the military for an unleaded Avgas for use in high flying, unmanned aerial vehicles (UAVs), a new low vapour pressure UL91 grade was introduced, resulting in the requirement for a new specification, ASTM D7547. At the time of writing, this specification is approved for light sport engines, such as Rotax®, and is in the process of being considered for approval in a wider range of general aviation engines of low to mid-octane demand. However, it is clear that this will not be of high enough octane rating to be used safely in all general aviation engines and work continues in trying to find a true unleaded alternative to the almost ubiquitous Avgas 100LL.
    pretty sure just the first two apply to us.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  13. #43
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    Quote Originally Posted by mangere View Post
    I've just converted my subaru hillclimb/track car to E85. It is great stuff for turbo engines. The tuner can pretty much advance the ignition timing as much as he wants without seeing detonation. They can generally get to the point when any further advance results in less torque (there's probably a good name for it) and then wind it back just a bit. When I got back into bikes I looked briefly at doing an E85 conversion but I don't think its worth while without a turbo.
    What are you using as an ECU? Are you using a pair of maps for E85 and for 98?
    It’s diametrically opposed to the sanitised existence of the Lemmings around me in the Dilbert Cartoon hell I live in; it’s life at full volume, perfect colour with high resolution and 10,000 watts of amplification.

  14. #44
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    Quote Originally Posted by Dave- View Post
    https://en.wikipedia.org/wiki/Maximum_brake_torque

    "Typically" 13-14 deg after TDC (so say -13 BTDC)

    Anyone interested in this guff ought to check out https://www.hpacademy.com/

    USD$99 for the tuning basics package ought to enlighten 99% of people to the basic principles of engine tuning.
    Wow. That's neat. Wish there had of been this sort of resource available when I was a pup.
    It’s diametrically opposed to the sanitised existence of the Lemmings around me in the Dilbert Cartoon hell I live in; it’s life at full volume, perfect colour with high resolution and 10,000 watts of amplification.

  15. #45
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    Quote Originally Posted by Dave- View Post
    https://en.wikipedia.org/wiki/Maximum_brake_torque

    "Typically" 13-14 deg after TDC (so say -13 BTDC)

    Anyone interested in this guff ought to check out https://www.hpacademy.com/

    USD$99 for the tuning basics package ought to enlighten 99% of people to the basic principles of engine tuning.
    They should also read up about the famous Harley engine that powered Lucifiers Hammer.
    Click image for larger version. 

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    Then read up on FZ and FZR racing engines plus how much advance the 60's Honda GP bikes needed compared to a 70's Cosworth for the other end of the spectrum.
    Click image for larger version. 

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    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

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