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octane baby! (longish but possibly good reading)
no I am talking about racing fuel
ATS - Patrick Bureau - txrocco@sbcglobal.net
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=>-----Original Message-----
=>From: Erik [mailto:pats16v@columbus.rr.com]
=>Sent: Monday, September 15, 2003 7:59 AM
=>To: ATS - Patrick Bureau; Scirocco List; Dan Smith
=>Subject: Re: octane baby! (longish but possibly good reading)
=>
=>
=>Do you mean the fuel booster stuff at parts stores? 9 out of 10
=>times that
=>stuff has never helped. If anyone says it does I'd like to see it on a
=>dyno. It goes along with the louder muffler syndrome. If it makes more
=>noise run it harder, "Oh hey! my car is faster now!" There are no
=>miracles in a bottle. Well except for nitrous........
=>
=>----- Original Message -----
=>From: "ATS - Patrick Bureau" <txrocco@sbcglobal.net>
=>To: "Erik" <pats16v@columbus.rr.com>; "Scirocco List"
=><scirocco-l@scirocco.org>; "Dan Smith" <sad_rocc@yahoo.com>
=>Sent: Monday, September 15, 2003 8:48 AM
=>Subject: RE: octane baby! (longish but possibly good reading)
=>
=>
=>> one thing I dont understand then if your theory would be correct
=>> why do you need octane 105 to run a faster 1/4 mile. :)
=>>
=>> I think you got it backwards...
=>>
=>> ATS - Patrick Bureau - txrocco@sbcglobal.net
=>> ----------------------------------------------
=>> MSN:ATSGTX@hotmail.com |YAHOO:ATSGTX@yahoo.com
=>> ICQ:32918816 |AIM:Texasscirocco
=>> ----------------------------------------------
=>>
=>>
=>> =>-----Original Message-----
=>> =>From: scirocco-l-bounces@scirocco.org
=>> =>[mailto:scirocco-l-bounces@scirocco.org]On Behalf Of Erik
=>> =>Sent: Monday, September 15, 2003 7:41 AM
=>> =>To: Scirocco List; Dan Smith
=>> =>Subject: Re: octane baby! (longish but possibly good reading)
=>> =>
=>> =>
=>> =>There is theory that I have been working with for a while
=>(working third
=>> =>shift I have ALOT of time), and it goes a little like this:
=>> =>
=>> =>If the given Octane level is to resist Detonation (i.e. Hot spots in a
=>> =>cyliner) essentially what you are doing is slowing down your
=>> =>Flame front to
=>> =>a controlable level (Cooling Effect). That being said you are
=>> =>really getting
=>> =>a slower and possibly a less efficient combustion process with the
=>higher
=>> =>Octane Rating fuel.
=>> =>
=>> => So with a lower octane rating in reality the Flame Front is
=>> =>moving faster
=>> =>and burning more quickly, so at that point in essence the motor is
=>burning
=>> =>more of the given fuel ingested into the motor during it particular
=>> =>combustion process due to the faster flame front traveling across the
=>> =>combstion area.
=>> =>
=>> =>Example: 87 Octane fuel has less resistance to detonation than say 94
=>> =>Octane, hence there will be a hotter flame traveling arond the
=>> =>cylinder and
=>> =>conceivably (?) burning more of the air/fuel in the cylinder.
=>> =>
=>> =>One thing to remember with this is that it's not the Octane in
=>> =>the fuel that
=>> =>is making the power it is the cylinder pressure and camshaft
=>> =>profile. While
=>> =>a large cam will bleed off some presure in the cylinder it is
=>> =>also allowing
=>> =>a greater amout of Air/Fuel into the cylinder than a stock of
=>> =>very mild cam
=>> =>profile.
=>> =>
=>> =>This is why when a too low of Octane fuel is run a motor tends to
=>> =>run hot in
=>> =>most cases and will detonate under load. Add the high Octane fuel and
=>> =>Viola! cooler cylinders, no detonation. Detonation being hot spots in
=>the
=>> =>cylinder that pre-ignite the Air/Fuel mixture before the
=>ignition does.
=>> =>
=>> =>I get asked this question at least 10 times a day, "What Octane
=>> =>fuel should
=>> =>I run?" I answer "I can't give you an honest answer. There are far
=>too
=>> =>many variables to this, compression, cam profile, altitude, timing
=>curve,
=>> =>car weight, gearing, etc." What I try to convey is "Run the lowest
=>Octane
=>> =>possible." See definition above. "If the higer octane slows
=>down flame
=>> =>front you'll get a less efficient burn which equals less
=>power." I have
=>> =>been witness several dyno tests run where a motor has 87 run
=>> =>through it and
=>> =>then 92 and the motors make less power BFC goes up and V/E goes
=>> =>down. Why?
=>> =>Because the motor didn't need or want the higher Octane fuel.
=>> =>
=>> =>Before somebody say "HEY ASS what about Alch. and Nitro?" Well those
=>are
=>> =>not conventional fuels. Nitro is just totally nuts. If you pour some
=>on
=>> =>the ground and throw a match on it, it won't burn. Hit that same
=>> =>spot with
=>> =>a hammer and BAM! no more fingers, toes or hammer. Alch.
=>has a lower
=>> =>Specif. Gravity that Gasoline so you have to run a greater volume in
=>order
=>> =>to make power. Also note Alch. gets used in VERY high Compression
=>> =>applications, say 13-1 and higher. And if you notice it has a supreme
=>> =>cooling effect. This is part of the reason Top Fuel and Funny Cars
=>don't
=>> =>need cooling systems, and can run for as long and as hard as they
=>> =>do. Now
=>> =>adays these two classes are running usually 75-80% Nitro and
=>the diff in
=>> =>Alch. This way they can keep the Nitro under control and
=>still keep the
=>> =>motor cool.
=>> =>
=>> =>
=>> =>What was the original question again? Oh yeah. Higher Octane
=>> =>fuel does not
=>> =>equal better mileage. Tell you Housemates to do less burn outs,
=>> =>change the
=>> =>oil, and replace the air filter, and run the lowest octane
=>> =>possible that the
=>> =>motor will live on. An efficient package is the key. If you've ever
=>> =>noticed according to Bently most VW's total ignition timing is
=>> =>21-23 degrees
=>> =>before TDC. Even the best Small Block Chevy is typically more than 30
=>> =>degrees. VW has very efficient cylinder heads. They don't
=>need alot of
=>> =>ignition lead to make power. A 93-97 275 H.P. LT1 makes .785 Hp per
=>C.I.
=>> =>and basic 1.8L 100 H.P. VW makes .925 H.P. per C.I. sounds pretty
=>> =>convincing to me
=>> =>
=>> =>This was just my .02, but what do I know? Nothing about Weber
=>> =>carbs that's
=>> =>for sure! :)
=>> =>
=>> =>Cheers,
=>> =>
=>> =>Erik
=>> =>
=>> =>----- Original Message -----
=>> =>From: "Dan Smith" <sad_rocc@yahoo.com>
=>> =>To: <scirocco-l@scirocco.org>
=>> =>Sent: Sunday, September 14, 2003 6:27 PM
=>> =>Subject: octane baby!
=>> =>
=>> =>
=>> =>> Yeah, a corny play on a song title, but I couldn't resist.
=>> =>Anyways, CO has
=>> =>octane ratings at the pump ranging from 85 to 94. With gas prices
=>ranging
=>> =>from $1.77 to 1.99 respectively, I want to see if I can
=>settle this hot
=>> =>debate among my housemates. Does higher octane gas equal better
=>> =>gas mileage?
=>> =>And enough of a better mileage to make it cost effective? This
=>> =>would be for
=>> =>my relatively stock 84 8v, which doesn't deserve high octane gas if it
=>> =>doesn't make a difference mileage-wise. When responding, please
=>> =>try to keep
=>> =>the formula equations to a minimum as high school chem was a long time
=>ago
=>> =>and I just squeeked by.
=>> =>>
=>> =>> TIA,
=>> =>> Dan
=>> =>>
=>> =>>
=>> =>> ---------------------------------
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=>> =>
=>> =>
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