Ligger hjemme på sofan (doctor`s order) med en rygg som krangler, tia blir lang så jeg har pløyd internett og diverse forum om informasjon om Etanol, Toulene, Xylene, MBTE, (Methyl-tertiary-butyl-ether) møllkuler(!) -u name it. Skal prøve å gjøre en forståelig tråd om temaet, men det kommer til å bli en del klipping og liming av tekst fra eksterne engelsk-språklige kilder. Tradisjonelle oktan boostere som f.eks NOS octane booster koster fra 179-249kr rundt om. ------------------------------------------------------------------------------------------------------------------------------ Formula #1 - Toulene R+M/2.........114 Cost...........$2.50/gal Mixtures with 92 Octane Premium 10%...........94.2 Octane 20%...........96.4 Octane 30%...........98.6 Octane Notes: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $3/gal at chemical supply houses or paint stores. Formula #2 - Xylene R+M/2.........117 Cost...........$2.75/gal Mixtures with 92 Octane Premium 10%...........94.5 Octane 20%...........97.0 Octane 30%...........99.5 Octane Notes: Similar to Toulene. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Usually mixed with Toulene and advertised as *race formula*. Formula #3 - Methyl-tertiary-butyl-ether (MTBE) R+M/2.........118 Cost...........$3.50/gal Mixtures with 92 Octane Premium 10%...........94.6 Octane 20%...........97.2 Octane 30%...........99.8 Octane Notes: Oxygenate. Very common in octane booster products. Has lower BTU content than toulene or xylene, but oxygenate effect makes the gasoline burn better and produce more energy. Formula #4 - Methanol or Ethanol R+M/2.........101 Cost...........$0.60 - $1.75/gal Mixtures with 92 Octane Premium 10%...........94.3 Octane (Methanol) 10%...........94.7 Octane (Ethanol) 20%...........Not Recommended Notes: Methanol is wood alcohol. Ethanol is grain alcohol and found in Gasohol in 10% ratios. Both alcohols are mildly corrosive and will eat gas tank linings, rubber and aluminum if used in excessive ratios. Main ingredient in "Gas Dryers", combine with water. Formula #5 - Isopropyl Alcohol and Tertiary Butyl Alcohol R+M/2.........101 Cost...........$0.60-$1.50/gal Mixtures with 92 Octane Premium 10%...........94.5 Octane 20%...........Not Recommended 30%...........Not Recommended Notes: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing alcohol. Sample Mixture To make your own octane booster, it is easiest to make up a large batch, and then bottle it up in "dosage-size" uses. Below is the basic formula of one of the popular octane booster products. To make eight 16 ounce bottles (128 oz = 1 gal): 100 oz of toulene for octane boost 25 oz of mineral spirits (cleaning agent) 3 oz of transmission fluid (lubricating agent) This product is advertised as "octane booster with cleaning agent *and* lubricating agent!". Diesel fuel or kerosene can be substituted for mineral spirits and light turbine oil can be substituted for transmission fluid. Color can be added with petroleum dyes ------------------------------------------------------------------------------------------------------------------------------ Merk att oktan verdiene som oppgis her er us PON standard 92oktan tilsvarer det vi ville kallt 96 oktan. Nå er det ikke så fristende å eksperimentere med malingsfjerner på tanken, så Toulene og Xylene utgår selv om det helt sikkert fungerer. MTBE er det oljeselskapene ofte bruker for å øke oktan inholdet i bensin men tviler på att du får det over disk her... Så det som da gjenstår er alkohol, eller rettere sagt etanol, noe vi har i store mengder av her på Toten. Ikke fordi det brennes rundt om på gårdene men fordi Statoil på Kopperud Gjøvik selger E-85. Oktan verdien på E-85 er 100/105 PON/RON men har en "blandingsverdi" med bensin på 118 oktan PON, noe som gjør det til en effektiv billig booster. 10% etanol i bensinen vil øke oktanverdien med 2.7-3 poeng.(sprikende kilder) ------------------------------------------------------------------------------------------------------------------------------ Why is E85 a better fuel ? Ethanol and is a very turbo friendly fuel for many reasons. 1. It has a much higher evaporative cooling power than gasoline so the intake air charge in the cylinder is significantly cooler that it is with a comparable mixture of gasoline --- that means higher VE. 2. Its octane as blended in E85 is about 100, its blending octane when added to gasoline is rated at 118, so it is a very cost effective octane booster. 3. Ethanol burns faster than gasoline but has a slightly longer ignition delay during the slow burn phase of combustion so the engine does not do as much negative work fighting rising cylinder pressures due to large ignition advances. The total ignition advance for E85 is almost identical to the ideal advance for gasoline so it does not cause the ECU problems when you mix them. 4. At proper mixture you actually are releasing more energy in the cylinder due to the higher quantity of fuel you can burn. ( Ethanol can burn effeciently at much richer mixtures than gasoline can) That means about a 5% increase in energy release all by itself. 5. Peak combustion pressures are actually lower for ethanol than for gasoline but the cylinder pressures stay higher longer, so you have more (longer) crank angle that is usable by the engine. This lower peak cylinder pressure also helps with detonaton control. 6. It will, at proper mixtures lower EGT's by around 200 deg F, but due to the higher quantity of exhaust gas products it produces you do not lose any spool up (in fact I would wager spool up is better). ------------------------------------------------------------------------------------------------------------------------------ Når E85 blandes inn i bensinen øker oktanverdien brått med di første 10-20% som blandes inn, men øker ikke proposjonalt med mengden som tilføres. Skal ta utgangspunkt i ett blandingsforhold på 1/5 E-85/bensin, skulle tilsi 17% rein etanol. 17 deler 118 oktan + 83 deler 94 oktan tilsvarer 98 oktan PON eller noe rundt 102+ oktanRON avhengig av om du blander det i 98 eller 99 oktan slik vi kjenner det fra bensinstasjoner i Norge. Har vært i kontakt med kjemikere hos shell og statoil og forsikret meg om att det ikke finnes metaliske tillsetnings stoffer i bensin solgt i Norge, det vil i såfall "kverke" oktan gevinsten fra etanolen. Så di som evt. måtte tenke racefuel+etanol=rocketfuel, nope.. Så hva med blandingsforhold AFR i en 1/5 blanding? ------------------------------------------------------------------------------------------------------------------------------ what is the ideal fuel air mixture for E85 If you are tuning with a wideband O2 sensor you will want to switch it to Lambda mode to get valid fuel air mixtures with blended fuels. If you can only get gasoline AFR's, simply divide the gasoline AFR's by 1.5 to get the true AFR for 100% E85. If running a partial mixture you can make proportional changes based on the percentage of E85 in the mix. Here are some comparisons of stoichiometric fuel mixtures for different fuel blends: ======== stoichiometric AFR ===== max power rich AFR Gasoline ---------- 14.7:1 -------------------12.5 100% E-85 ------- 9.73-9.8:1 ------------- ~ 9:1 - 8:1 100% fuel ethanol - 9:1 ------------------- ~ 7.2:1 One source specifies that the proper fuel tune (stoich) for a VW Golf running 22% ethanol was 12.7:1 (this reference was probably from the Brazil tests) Ethanol reaches max torque at richer mixtures than gasoline will. Using a 99% ethanol mixture MEP increases with mixtures up to 40% excess fuel where with gasoline MEP is reached near 20% excess fuel. Over all thermal efficiency for both gasoline and ethanol is reached near 15% excess fuel. E85 burns faster than gasoline at best mixtures so it is an inherently more effecient fuel. It also produces more exhaust gas for a give weight of fuel air mix giving higher average cylinder pressures inspite of lower EGT's. With streight E85 in a properly tuned car its good for about +5% power / torque increase. I suspect on a turbocharged car the benefit is larger. ------------------------------------------------------------------------------------------------------------------------------ 14.7 delt på 1.1=13.4 AFR. 12.5 delt på 1.1=11.4 AFR. Dette stemmer og bra med testene fra Brasil. Ser du på energi i bensin kontra etanol vil en 1/5 blanding måtte økes med 6.5% for å inneholde like mye energi. Ved å senke AFR fra 14.7 til 13.4 økes ren energi i blandingen med 9%. For å gjøre det enklere, har du datasprut øker du åpningstider på dyser med 10% over det hele, evt øke bensintrykk fra 3 bar (43.5psi) til 3.6 bar (52psi). Merk att dette er rein mattematik utført med "injector scaling" i sprutet jeg har så ta det med ei lita klype salt. ----------------------------------------------------------------------------------------------------------------------------- Power available on E85 Many sources make a big deal about E85 having less thermal energy per gallon that a gallon of gas. They frequently draw the false conclusion that you cannot make more power on E85 than you can on gasoline. E85 actually has a higher specific energy at stoichiometric fuel air mixtures than gasoline, and at proper max power mixtures releases more thermal energy in the cylinder for a given amount of air to burn. Since an internal combustion engines power output is primarily air supply limited this means you can make 5% to nearly 30% more power on E85 than you can on gasoline. Ethanol specific energy at stoichiometric fuel air mixtures is actually higher than gasoline allowing a higher release of energy per lb of air burned than gasoline. Typical gasoline Thermal energy 19,000 BTU/lb max power fuel air mixture 12.5:1 Typical E85 Thermal energy 13,475 BTU/lb max power fuel air mixture 6.975:1 Typical ethanol Thermal energy 12,500 BTU/lb 6.429:1 If you are consuming 100 lbs of air, lets see how much fuel energy you release for each of these fuels using gasoline as the base 100% reference. 100/12.5 = 8 lbs of gasoline @ 19,000 BTU/lb = 152,000 BTU = 100% 100/6.975 = 14.337 lbs of E85 @ 13,475 BTU/lb = 193,189.9 BTU = 127% more heat energy 100/6.429 = 15.555 lbs of Ethanol @ 12,500 BTU/lb = 194431.5 BTU = 128.9% more heat energy Typical fuel energy contents: gallon of gasoline = 125,000 Btu 1 gallon of ethanol = 84,400 Btu 1 gallon methanol = 62,800 Btu 1 gallon of gasohol (10% ethanol, 90% gasoline) = 120,900 Btu 1 gallon of E-85 (85% ethanol, 15% gasoline) = 90,500 Btu 1 gallon of kerosene or light distillate oil = 135,000 Btu 1 gallon of middle distillate or diesel fuel oil = 138,690 Btu ------------------------------------------------------------------------------------------------------------------------------ Fant og litt om brennhastighet og tenning, dette gjelder riktignok rein E-85. ------------------------------------------------------------------------------------------------------------------------------ How does ignition timing change on E85 ? Timing on ethanol blends will not change very much. MBT timing for both gasoline and E85 are very nearly the same at light to moderate engine loads. At high engine load the E85 will want just slightly more advance. The big difference will be fuel/air mixture. The E85 will give improved torque with much richer mixtures than gasoline. Both gasoline and E85 will give best thermal effeciency at about 15% rich of stoich, so the equivalent of 12.78:1 on gasoline would be about 8.5:1 on E85, but E85 will continue to give better torque numbers up to about +40% rich of stoich or 7:1 mixtures, so on a utec you would want to richen up your WOT high load cells and add a tweak of timing to get the most out of E85 from what I've read. Quote: Are you sure you don't mean that E85 will allow more advance? Just passing on what I've found in the various sources. Logically you are correct, but one source says simply that MBT timing is the same for E85 and gasoline, and another report says at low loads the E85 and gasoline like the same MBT timing but at high loads MBT timing for the E85 is slightly more advance. I suspect this is due to them not running ideal max power mixtures but cannot confirm it. Burn speed for E85 changes quite a bit with mixture, so if they were just a little bit lean or rich of ideal the burn rate would be lower. Lots and lots of variables not well covered in some of the sources and in general they are focusing on emissions issues not max power torque so that would incline them to use less than best power timing advance. In a couple of the reports they also had limited control authority over timing and may not have explored the extremes very thoroughly. what data is available on combustion speed for E85? Just about a year ago (2003), I was finding conflicting information on alcohol fuel burn speeds and contacted The National Renewable Energy Lab here in Denver, they did a search and could only find a couple of references on it, one that showed ethanol fuels burn faster, so the literature is not very rich in data on the subject. Most reports are not entirely applicable to our needs like tests on lawnmower engines and alcohol fuels have some significant limitations Still digging for info but that is my best information at the present time. The report that mentioned the slight increased advance requirement on heavy load E85 fuels was : "Final Report Control of Exhaust Emissions from Small Engines Using E-10 and E-85 Fuels" http://www.michigan.gov/cis/0,1607,7...0064--,00.html http://www.michigan.gov/documents/CI...E-_87915_7.pdf On page 12 it says : "Tests were conducted to assess the impact of MBT ignition timing on fuel economy and exhaust emissions. The spark timing was varied until the least advanced timing was achieved for the maximum torque for a given setting of the engine throttle. The A/F ratio was adjusted to achieve near stoichiometric operation. ... " The MBT timing for E-85 fuel was a few crank angle degrees advances compared to E-0 fuel when the engine was delivering high loads, typically 100 - 75%. Not much difference was observed at lower engine loads." I'm assuming that this explains the timing change as they were using what would be closed loop fuel mixtures on the WRX. So in load cells that would continue to use closed loop fueling you would want to have slightly more ignition timing than you would with gasoline. In the case of WOT open loop fueling where your running a max power rich fuel mixture, I very strongly suspect the fuel burn speed would be noticably faster, and you would use less ignition advance than on gasoline and reap the benefit of less negative work on the late stages of the compression / early period of combustion prior to TDC. In a power point presentation presented by the EPA at the SAE Government and Industry Meeting in Washington D.C. on May 13, 2003 titled: "Ethanol-Gasoline Blends: Fuel Economy and Emissions Benefits" http://www.epa.gov/otaq/presentation...mjb-051303.pdf On page 9 of the presentation is a nice chart comparing laminar burn speeds of gasoline and Ethanol. It shows the following burn speeds: Mixture fuel/air---- 1:1 ------------ 1.1:1 Gasoline --------- 26 cm/sec ------- 30 cm/sec (max about 31 cm/sec) Ethanol ---------- 41 cm/sec ------- 45 cm/sec (max value) Clearly at +10% - +15% rich mixtures where ethanol shows max thermal efficiency it burns significantly faster than gasoline. Which could be quite important to a very over square bore engine like ours!! ----------------------------------------------------------------------------------------------------------------------------- Kilder: http://forums.nasioc.com/forums/showthread.php?t=803341 http://www.btinternet.com/~madmole/Reference/RONMONPON.html http://www.merkurencyclopedia.com/Fuel/fuelchem.html http://www.rx7club.com/showthread.php?t=339648 http://www.faqs.org/faqs/autos/gasoline-faq/part1/ Nå om noen skulle få lyst til å eksperimentere med Ræserbensin så er det på eget ansvar, all informasjon jeg har lagt ut her er annenhånds informasjon. The Jan 2008 HotRod Magazine has an article on E85 that is quite positive on its use as a performance fuel. (although nothing new in the article that has not known for several years by E85 experimenters) They have the results of a back to back dyno test of 100 octane race gasoline vs E85 on a 402 CID LS2 , 10.2:1 compression ratio, crate engine, done by Wheel to Wheel Powertrain in Madison Heights Michigan. Gasoline (100 octane race gas) 540 hp @ 6000 rpm, 509 ft-lb torque @ 5200 E85 ------------------------ 546 hp @ 6000 rpm, 524 ft-lb torque @ 5200 With a turbocharger kit installed fueled on E85 : 13 psi boost -- 850 hp @ 5900 rpm, 833 ft-lb torque @ 5000 rpm no comparison to gasoline you can't run that kind of boost on it with this engine.
