Regular v premium

Discussion in 'Motorized Bicycle General Discussion' started by Henshooter, Feb 19, 2014.

  1. Davezilla

    Davezilla New Member

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    I'm glad people actually realize this... I've had countless arguements in other forums about putting in a lower octane fuel because it burns faster and puts out less emissions because of this... Octane is the fuel's resistance to burning, not the other way around like most people think. 87 octane will make more power and burn more completely hence the lower emissions output.
    Luckily here in San Antonio we're not in an emissions county, but there are some counties in Texas that we do have to check for emissions when we inspect the cars. I've been telling people for years that if they don't have all their emissions components intact, the car can still pass an emissions test by running the Lowest octane fuel available and retarding the ignition timing as much as possible, even to the point where the engine feels sluggish (set to lowset recommended setting if the inspectors check the timing during the test, go a little lower if they're not required to check timing) , then drive it straight to the test station, let them run the testing, then switch everything back after testing is done. On turbocharged or supercharged vehicles, these Must run high octane fuels so I tell them when driving with the low octane gas in it DO NOT boost and it'll run ok enough to get there and back.

    Posted something like that in one of the turbo forums I used to frequent and talk about starting a huge arguement from other members who didn't know against the few of us that do know...

    The whole octane thing is basically use what's needed, and only go higher if it's needed... Anything more than what's needed will cause performance to go down and just drain your wallet faster.
     
  2. maniac57

    maniac57 Old, Fat, and still faster than you

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    I no longer even respond to most octane or "premium" gas threads for that exact reason Davezilla. It's a hot button topic among noobs.
    Too many "experts" want to argue and claim "I picked up 10mph on premium!!" when experienced motorheads know better, and I tend to get annoyed easily.
    Glad to see SOMEONE knows better.
     
  3. maniac57

    maniac57 Old, Fat, and still faster than you

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    As a side note to your inspection thoughts, I used to mechanic for a taxi fleet up north and we had a specially built carb from an old school master mechanic we would use to pass emissions. It was jetted SO LEAN the exhaust manifolds would be glowing red hot within about 10 minutes run time.
    Never failed a test using that carb, even on motors so badly worn they were smoking like a bug fogger with normal carb. Bad valve seal, excessive blowby, didn't matter.
    We had to start the motor with ether due to the insane lean jetting, but once running, it WOULD pass.
     
  4. YesImLDS

    YesImLDS Member

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    If a vehicle is tuned for an octane it's best to stick to that octane unless you are hauling some sort of load. High octane resists burning compared to low octane, that's why you get more HP/Torque out of a high compression engine, because you are increasing the efficiency of the engine itself. Now in modern vehicles they pull timing and add timing as you go along. In my personal car it can run 87 octane, but from the factory they recommend 91 octane. Normally I would run 91 octane just because that's what it's suppose to have, but every once in a while I'll have to run 87 octane. Usually the gas mileage will drop just a hair just because of the power output not being the same and once I go back up to the 91 octane it will still stay about the same until the knock sensors realize that it can run higher timing without pre-ignition.

    Now onto the real stuff with these bikes it's best to just find out what actually works on the engines themselves before knocking and stick with that because less octane will cause harm on the engine and more octane won't burn as well as the stuff you are suppose to be running.
     
  5. YesImLDS

    YesImLDS Member

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    Now I will say that if you go to premium because it has no ethanol there could be performance gains due to the fact that the 10% of ethanol has less power in comparison to gasoline (20.9MJ/L compared to gasolines 32.4MJ/L according to wikipedia) despite the higher octane rating.
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    Personally I think anyone who is seriously looking for better power this hard is never going to be happy with a chinadoll.
    These engines are meant for cruising around all week at 15-25 mph.
    It takes a serious effort to make one fast, and if you don't already know about octane, you probably don't have the skills yet to get a fast AND reliable chinadoll. So you will end up badmouthing them and storming off in a huff.
    At least that's been my experience online...
    No offense intended or implied. I respect the need for speed, even when the noob is rabid and insane.
    I am.
     
  7. mapbike

    mapbike Active Member

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    lol...... this post is so true.....lol....dance1
     
  8. Davezilla

    Davezilla New Member

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    Amen to that... So true..
     
  9. Theon

    Theon New Member

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    Don't know about over there, but over here, they use ethanol to boost octane rating, so, it's not going to have thee same oomph as lower octane gas.
     
  10. Davezilla

    Davezilla New Member

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    They use up to 10% ethanol over here too, but the octane ratings are still the typical 87, 89, and the premium can be anywhere from 91 to 94 depending on region, but they use the ethanol more of a filler than an octane booster.

    Alcohol is different than gasoline in that it has a very high octane rating but it has about half the energy that gasoline has, and it does make more power once the engine is jetted right. Most people notice a very slight drop in performance tho because their vehicles were made before they decided to put 10% alcohol in all the fuels over here, and the newer vehicles that are designed for this mix tend to run about the same as or very slightly beter on the 10% blend with a slight drop in gas milage, but the gas milage is pretty much neglidgeable on most smaller vehicles.

    The people I get the most complaints from over here are the ones with high perfromance engines built back before all the fuel was mixed with alcohol, but jetting the carb up a size or even a half size, or doing an ecu remap to give it just a little more fuel under load will fix the issues.

    My biggest complaint about the alcohol in the fuel is that it doesn't keep nearly as long and the alcohol can absorb water so in a vehicle that has to sit for several months it can damage the fuel system or gum up a carb or set of injectors. Alcohol can also become very corrosive, but ethanol isn't nearly as bad as methanol in this situation, both for water absorption and corrosiveness, but both types of alcohols are bad for some plastic and rubber fuel components in older cars that weren't designed to run on this stuff.
     
  11. Theon

    Theon New Member

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    Living in the Tropics, where it's above 90 % humidity probably 1/2 the year, gets me a bit skeptical of fuels with higher ethanol content, I forgot to mention the water absorption thing. Cheers Dave.
    Your right about rejetting for alcohol, and I guess it could lead to a lean condition also on a Two stroke that was tuned for regular gas?
    In which case may seem like a little more power if you were originally running a little rich.
    Don't know how/why, but our fuels seem to have higher ratings than yours, but we pay 4 times? the price for it.
    Ethanol is also used as a 'filler' here, but I remember reading somewhere that our 'Premium' (95/98) is boosted with ethanol?
     

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