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High octane fuel and the truth

Discussion in 'General' started by moose man, Mar 8, 2010.

  1. alex2_s

    alex2_s Member

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    Quote regarding VS V6 engine management system,

    "to achieve optimum engine efficiency, the ECU continually advances the ignition timing until detonation occurs. When detonation occurs, the ECU receieves a low voltage signal which is generated by one or both knock sensors and the ignition timing is instantly retarded".

    Would this not mean that the point in which detonation occurs would be later with 98 RON compared to 91 RON, alllowing more advance automatically?
     
  2. MasterOfReality

    MasterOfReality Miners go deeper

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    People are missing the point.

    On a stock car with a factory tune, and no knock sensor, using premium won't make any difference.
     
  3. ephect

    ephect Donating Member

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    i hardly think discussing is trashing your thread. all that most have asked is to show your workings and references. i can see your points but your points almost assume we all run carby engines with no technology in them.. remember the VS and up can advance timing not much but enough to benefit.
    you can take the the same model car, one will love premium the other no difference. there are soo many things your not taking into account, how the engine has been treated if the car is in bad need of maintenence..

    i dont need to run 95 or 98 but i like to think im treating my engine.

    ok i did said more fuel which isnt the correct word, but im sure you would have understood if you werent so focused on blindly hammering your point across.

    i qouted the below because you havent mentioned anything about them which all bring a valid augument to the table.

    ..

    this is true but the op didnt specify any details apart from you'll just waste your money, its all the same.. etc
    even a car roughly 15years old, straight from the factory, tune and knock sensors standard, can adjust to premium. obviously you wont see the full benefits compared to a worked donk but it will still be there.

    personnally i've run 95 and noticed little results economy wise, but yet run E10 (95) and i get another 100+ kms from a tank.. same conditions both times, depends on too many factors, and at the end of the day, your engines preference :)
     
  4. fabz

    fabz I Can Do Science Me

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    lol your telling me you get 200 extra kms because you switch fuel. I really dont think thats correct and i think you should check your data.
     
  5. wraith

    wraith Hand over the dog bikkies

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    Yeah I know it's weird. I have no clue what is going on. Come up to Mackay, pay for the fuel and I will gladly show you. I got from Mackay to Emerald on one tank with 98. Didn't make it half way on one tank with 95. I don't know I am no expert. As said before I have witness who will back up my claim.
     
  6. Super_Low 91

    Super_Low 91 ┌∩┐(◕_◕)┌∩┐

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    i will gladly verify the km's wraith used to drive my ass around all the time
     
  7. Calaber

    Calaber Nil Bastardo Carborundum

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    Okay, here's a question for you guys who maintain that using premium leads to a 3 or 4% improvement. Obviously, I'm only addressing those with standard V6's, not S/C ones or V8's.

    How does that translate in terms of driveability?

    Can you "feel" the difference in the way the engine runs? Are you able to detect improved performance ie accelleration?

    Wraith claims 50% improvement in fuel economy. I can't believe that, but what about the rest of you - has your economy improved?

    Do you continue to use premium because you believe it's better for your car or because you believe it is economical to do so?
     
  8. bloodyricho

    bloodyricho Bloody Richo

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    look it up they are a BMZB eprom in the cop V6 and some other in the V8's so "Mr I know everything type" check chips on memcals.com (go dr bob) and ask Green foam or Bob the damn memcals can be tuned for premium with real results and i am running one tune for E10 and one for Premium and can switch between the tunes on the fly. I get same economy out of both fuels but a shitload more power outa the premium on its tune.
     
    Last edited: Mar 10, 2010
  9. minux

    minux Infidel Bear

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    Hmm, i guess I am only imagining the 91 pinging its head off and not wanting to rev over 4k rpm without playing up. Damn that no difference premium.
     
  10. Nanos

    Nanos Not a Mod

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    guess my engine tuner is wrong when he said its tuned for premium.

    so the rules of higher octane and tuning is all wrong. i think the OP needs to walk into a good tuners workshop and tell them this.

    Think they will show you hundreds of dyno charts to prove otherwise.

    Also the LS1's have from factory in the standard tune low octane and high octane fuel maps. Therefore i beleive high octane fuel makes a difference.

    plus i never beleive whats written in book.
     
  11. minux

    minux Infidel Bear

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    Nanos, I never beleive anyone that says "trust me, i would show you proof but I am not allowed" :p
     
  12. Tsunamix

    Tsunamix Active Member

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    Ok Time to put a shoe in this one.

    Octane ratings come from a test rig that measures the point in a set test bed engine at which a particular fuel pre-ignites, in comparison to a standard mix of Iso-Octane and Heptane.

    91 RON Fuel pre-ignites at the same point as a mix of 91% Iso-Octane and 9% heptane.

    All engines from the factory are tuned initially to run on the lowest standard octane fuel available in the country of origin, be it 91 octane, 95, 98 or 2.2 . From their, specif models can be tune with different base fuels in mind, but all will have the ability to be run on the base fuel mixes, somehow. More often by reducing the amount of spark advance to limit pre-ignition.

    This very often means that each cars ECU has 2 spark maps. 1 for High octane fuels, and 1 for Standard.

    NO-WHERE has flame speed, or anything else been mentioned.

    It is interesting to note that Ethanol and methanol share a RON rating when pure of 129, and are frequently added to fuels as an octane booster.

    Changing from a 91 Octane fuel to a 98 Octane fuel can have no effect on the engine if the engine does not have a spark map to take advantage of this change.

    Other additives in the fuel may affect performance. However a 91 Octane fuel with the performance additives from the very best premium fuels will perform identically to a 98 Octane fuel with the same additives - unless the ECU has the Spark Map to take advantage of it.

    This spark map is commonly referred to as the Tune.

    Now listen up. this is where you people go wrong.

    The ENERGY VALUE of Heptane, per Kg is 44.592 Mj / Kg
    The ENERGY VALUE of Iso-Octane, per Kg is 44.374 Mj / Kg
    Click Here for Data

    The Total maximum energy liberation in burning 1kg of 91 Octane Reference fuel is 44.57238 MJ
    The Total maximum energy liberation in burning 1kg of 98 Octane Refernce fuel is 44.58764 MJ

    Since the average efficiency of the combustion engine is less than 20%, the difference between the 2 is
    0.003052 Mega Joules per Kg . 1 Kg = 1.34228 litres (745g / litre but varies brand and type to type).

    So for every Litre you burn, you have an additional .00227374 Mega Joules of energy to play with. This is cut big time by the efficiency of the internal cimbustion engine which is less than 20%.

    87 Octane Fuel has 44.4 Mj/Kg, Aviation Petrol (Not kerosene based jet fuel) has 46.8 Mj/Kg.
    Picking something like 45.2 as the 91 Octane energy value, by switching to 98 from 91 octane you have about .0002515% more liberated energy to play with (.00227374 / 9.04 - which is the 20% effeciency value of my guesstimated 45.2 MJ figure).

    So for all of those that travel additional miles or get better performance from 98 Ron without tuning for it ? I call scientific bullshit.

    Word of warning - Theres plenty of chance there are other factors involved than just octane rating. But since this discussion was all about octane ratings to start with....
     
  13. delcowizzid

    delcowizzid on holiday

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    well slower burn helps means you get more force on the pistons down stroke for longer increasing torque theres your fuel saving
     
  14. vn_v6

    vn_v6 Blumpkin

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    i dont know what you guys are on about but when i put premium in it idles ALOT smoother and its more responsive, there is a difference, and i do feel it when i put my foot down, especialy if i reset the computer after a full tank, argue with me, but in my car atleast, i can feel it
     
  15. BowTie

    BowTie Active Member

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    Why has the argument been narrowed down again to purely to octane ratings.

    The OP was adamant that there is NO BENEFIT WHATSOEVER.

    Why is it so hard for people to comprehend that the octane rating is not the only difference between the two types of fuels.
     
  16. Tsunamix

    Tsunamix Active Member

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    I dunno about slower burn Delco.

    Slower burn is often more complete for greater completion percentage of burn, but faster burns tend to liberate les sthermal waste during the burn. In the end it doesn't matter if it's slower or faster burn if the energy liberation difference between the 2 is identical.

    It's all about converting liquid and gas into a different rapidly expanding gas. The larger and more complete the conversion, the greater the force applied to the piston head.
     
  17. minux

    minux Infidel Bear

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    As I said earlier, who needs technical mump like Tsunamix copy and pasted.

    All I need to know is:

    Senator on 91, no skids on take off
    Senator on 98 smoky rear window on take off.

    All the proof I need that it does make a difference :p
     
  18. wraith

    wraith Hand over the dog bikkies

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    Pics or it never happened :whistling
     
  19. Tsunamix

    Tsunamix Active Member

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    Was no copy and paste. I calculated most of that sh*t myself :(
    Was questions I asked myself and thats how I found the answer.
     
  20. Nanos

    Nanos Not a Mod

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    i can only go my experiences.

    put 91 in the wagon and the engine will ping and most likely not last long at all.

    put 98 in the wagon and no ping and performance is back.

    like most have said pinging is directly related to octane rating. so therefore if i use a lower octane fuel i get less performance. higher octane = higher performance and also better km's/100.

    the OP did say standard engines. Wonder what his version of standard engine is??
     

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