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    Thread: high octane!!!!

    1. Member
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      05-12-2012 07:21 AM #1
      I'm wondering what the highest level octane you can put into a stock 1.8l n.a. I am not worried about the lowest operating requirements. This is for a race fule unethenol premium blend. Calculating average by octane per gal. So if someone knows what I can put in it without blowing my engine that would be great. I have heard it can take 97 but I just want to double check. Thank you.

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      05-14-2012 11:51 AM #2
      if the engine is stock and NA, you aren't going to see big gains from high octane fuel either way. the biggest benefit to high octane fuel is seen when you have engines with extremely high compression, especially with forced induction. I know this doesn't answer your question, but why do you need to put super high octane fuel in anyways?
      2008 GTI 6spd 2 DR Tornado Red- APR Stage II+, koni coils, clutchmasters fx350 clutch (steel flywheel), APR subframe mount, SS brake lines, brake stiffening kit, shift linkage/ shifter bushings, 2DIN Panasonic head unit, Alpine R speakers, JL 5 channel amp

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    3. Member
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      05-18-2012 07:12 AM #3
      For one it cleans the **** out of ur engine. Two I am preparing for an amateur race were stock (for the most part) is a rule so any leg up I want

    4. Member oRANGEJULIUS's Avatar
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      05-19-2012 11:42 PM #4
      Higher octane fuel is not going to benefit you in itself. In reality, higher octane fuel burns slower so its not cleaning out your engine like you hope it would. Benefits are as described by other members above: Deck the head, gain a few compression points, and advance the timing a few degrees (or one or the other), now running the higher octane fuel will help curb pre detonation. The power was made by the modifications… the fuel made it possible. No other real reason to run anything over 93 at the pump.
      P.S Running digi or cis / e ? either way, stay away from e85 or any other high ethanol blends ( even aside from the obvious water absorption properties of ethanol, and turning your seals and fuel lines to goo) ethanol contains less energy per same quantity of gasoline , what this means is your fuel injection system is striving for a slightly rich value just off stoichiometric assuming your using gas. A high percentage of ethanol in your fuel tank will burn faster than gas, requiring more of it to stay at the same a/f. Unless you retune your fuel injection (digi, good luck there, cise is doable) you will run lean and potentially blow the motor.

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      05-20-2012 06:46 AM #5
      Octane does more than just help with pre detonation. Depending on the molecular chain makes a big difference on how it behaves when burning. Avgas, which a lot of people run in cars strong enuff to deal with it, puts out a good strong punch but is best at maintaining a steady rpm. Airplanes don't change there rpm drastically like a car does. So it does not burn at a rapid rate. Race gas on the other hand burns very rapid and is designed for fast rpm changes. It's also cleaner to burn then pump gas. That is why race cars don't use 93 octane but 110 or higher. The higher the octane # the harder the combustion force is, which helps to knock out deposits. Generally its also cleaner leaving fewer deposits behind. Fewer deposits mean the engine can function properly which means better hp and mpg. It all comes down to how the gas is designed to burn. If you use Avgas it will burn slow and stable. That can be a good thing if you are a plane or just want some bench mark dyno readings. Pump gas is a constant fluctuating mix of old and new gas. Not to mention the sediment and debris that is in there. Higher octane fule also burns hotter giving it more power and cleaning out your engine. That's why you beef up a engine before you try and run straight 110 octane. You will blow your engine apart.the heat softened up metal, and the power warps it leading to failure. If your engine some how lives long enuff that's when you thin and boil off fluids. I know how gasoline works. I just was wondering if someone knew how high of an octane a stock 1.8l na engine could handle. I can't really modify anything on the car but suspension and brakes. I can and know about adjusting the timing. Maybe no one on here knows so I will look else were. Sorry for my rant.

    6. Junior Member pamatt's Avatar
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      05-22-2012 11:36 PM #6
      If you want more power VP street blaze 100 will give you the most power without any negative side effects. We have run it in every thing from dirt bikes to big block chevys. Regular race fuel only gives you detonation protection and no added power. Street blaze will add power just by putting in your car. They are very different fuels. If you need more info about why pm me.

    7. Member Louie Mac's Avatar
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      06-24-2012 04:24 PM #7
      Fastest way around a track is skill, suspension, and brakes. Just worry about those man! Good luck in the race!
      Luke

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      08-09-2012 09:49 PM #8
      OP, we do a lot of testing with different fuels in our lab and the general result of a higher octane is just unnecessary amounts of carbon build up, higher octane resist combustion ("that is it"), beneficial to those with higher compression or advanced timing. I too ran the highest octane i could find before I was educated on the matter. You will probably benefit most from the lowest octane you can run without pre-ignition, I say this because with the proper octane you will be burning all (more) of the available HC content in the chamber resulting in less build up in the long run (extended performance).

      Also
      Quote Originally Posted by oRANGEJULIUS View Post
      now running the higher octane fuel will help curb pre detonation.
      Dont mean to nag but since I'm here I would like to say there is no such thing as "pre-detonation" its a common misconception, I hear it a lot.

      Pre-ignition is when the A/F mixture is ignited to soon. (before the plug fires) due to high compression, or the compression temps being too high.
      ( this usually leads to melt down, if nothing else of the plug electrode)

      Detonation is when the mixture has a secondary ignition (after the plug fires )
      an example of this would be if the octane is too high and ignites due to compression ( this type of misfire usually results in a broken piston)

      Its not that common at least in my experience but there is also a Pre-ignition induced Detonation
      where the A/F mixture ignites before the plug and then collides with the left over mixture igniting from plug fire.

      Quote Originally Posted by drive.euro View Post
      That's why you beef up a engine before you try and run straight 110 octane. You will blow your engine apart.the heat softened up metal, and the power warps it leading to failure. If your engine some how lives long enuff that's when you thin and boil off fluids. I know how gasoline works..
      higher octane does not mean it will burn hotter its just more resistance to pre ignition due to pressure temps and hot spots. That being said octane is not related to the energy content in fuels.

      E85 = 9.7:1
      pump gas (87+) = 14.7:1 or 12-12.5:1 for performance.

      we all know E85 has a higher octane rating and we also know that the resulting energy is much less than our typical 10% blend

      once the plug ignites the mixture premium burns at basically the same rate as regular.
      Last edited by stockstatus; 08-09-2012 at 10:28 PM. Reason: adding

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