Cycle News - Archive Issues - 1960's

_- _ "' (l) ~, ~ POWER e, .... BY THE GALLON By Bob Ebeling "Swamp Gas" and "Chemical Warfare" are a pair of common definitions ~ for the mixtures of high oxygen content ~ fuels used by drag racers to make that :c: run of 1320 feet In the shor test possible ~ elap sed time. Some die- hard gas burner s look upon ~ the racer who uses these mixes as a CJ chea t, or someone Incapable of obtaining maximum performance tr om an engine without resorting to the " br ew." Nothing is further fr om the truth. F uel alone will not make a winner .An untuned or ineffici ent engine will not develop maxi mum power , regardless of what you do to It. In tact, If improperly pr epared you can expect a fuel bur ning engine's lite span to be about one revolution. There are many drag participants who would love to " ti p the can," but begin to back away Immediately due to a lack of knowledge in how and what to do. d The measur ing tool called a hydro meter is not as accurate, but Is handy expedi ent in measuring what you have. With no measuring cup available and an additive Is merely pour ed Into the nitro, there is no other way of determining a resulting percentage. But the hydrometer is calibrated at a certain temperature, usually either 68 or 78 degrees Fahrenheit. If the fuel temperature incr eases the percentage reading will be lower and, inver sely, If the temperature decrea ses the readlng Is higher . As a result you should have a mercury thermometer included in the same box as the hydrom eter and al ways measure the fuels' tempe r ature before reading the percentage. In illustration #2 you will find a correction chart that will enable you to make corrections of the percentage r eading in regards to the fuel temper ature . Facts and Figures NITRO (N02) METHANE (CH4): The basic Ingredient for fuel burners. Heavier than gasoline, high oxygen content, very hard to burn, produces excellent power increases due to rapid evaporation cooling and the oxygen that is released Into the cylinder uponvaporizing. Method of power content calibrated on a percentage scale (density). METHANOL (Cs H5 OH): Alcohol, used to "cut" or decrease nitro density. Produces an increas e In power by coolIng the combustion chamber with rapid evaporation. PROPYLENE OXIDE: Igniter! Low flash point, bolls at approxi mately 50 degr ees Fahrenheit. Addition to nitro methane automatically reduces nitro dens ity. BENZOL (C6 H6): Crud e benzene. Us ed to decrease nitro density and promote ignition by Increasing combustion temperatures. Extremely high carbon or ash content. HYDROMETER: Ins trument for measurIng the density or percentage of nitro methane. All of these fuels should be handled with care, but the propylene nxide deserves the greatest respect due to Its low flash point. Always avoid contact of all fuels to the eyes or mouth. If such a thing occurs, immediately contact your physician. Industrial chemical distributors and som e auto speed shops are the common outlets at which the fuels can be purchased. When n it r 0 methane Is purchased, It is rarely pure 100 percent stuff. Some state laws require that 2 percent alcohol be added so that It can be transported safely. The average racer burns a mix ranging from 70 to 90 percent of pure nitro. Of course, If he purchases a gallon rated at 98 he mus t " cut" or reduce the amount of purity. This Is done by adding one of the three additives. "P.O." (p r o py l e n e oxide), " Alky" (methanol) or Benzol. In illustration #1 you will find a chart which pr ovides the most accurate means of mixing fuels and determining what the resultant nitro percentage Is . This is the most accurate method of measurement. If you have 10 oz. of nitro and 10 oz. of alcohol and mix together, there of course Is a 50% nitro brew (not counting the two percent dealers have added). This never changes, regardless of temperature. lIIu~ #1 ADDInVE 26 oz. to bone white without bli ster ing the plugs ' porcelain. The gr ea test and really only problem In fuel burning Is the carburetion system. Nitro Is heavier or more dense than gasoline , thus thefuats r~thi~er when suspended in the liqui d. The float level must then be changed and you just can not change this efficiently In some carburetors. Remote fuatsare theideaJ, for they can be raised and lowered at will. Any four - s troke engine from 250cc upward In displacement will r un fuel with a main jet s ize of .160 thousandths. The jet size need never be changed, for the rich or lean condition can be r egulated by al tering the nitro methane percentage. The lower the percentage the r icher the mix; a higher percentage, a leaner mix. If you have a .160 main jet and run an 80 percent mix that shows lean on a plug reading. alter the mix to 75 percent or 70, 60, 50 until the proper atr fuel ratio Is obtained. Inversely, If r ich, proceed In the opposite direc tion of percentage . Oh, but walt! Having only the main jet at .160 Is not enough. If the fuel tank's petcock is only .140 or the needle jet of a s imilar s malier size than main jet, then fuel supply to the engine will not be s ufficient. All fuel passages from tank CORRECTION CHART lI us. #2 50' 40' 106 104 91 86 15 A 100 98 90 80 10 60' 50' 104 102 94 83 13 10' 60' 102 100 92 82 11 18' 68' 100 98 90 80 10 80' 10' 99 91 89 80 10 90' 80' 91 95 81 11 68 1000 90 0 94 93 85 15 65 110 0 1200 100' 110 92 90 90 88 83 80 13 10 63 61 Correcti on Chart for hydromet ers cali brated to read 100% at 68 & 78 degrees Fahrenheit. "A' ~umn down reads true percentace of nitro. Top column across Is fuel temp erature In f F) for 70 hydrometer. Second column across Is f uel temp. In f F) for 61t' hydrometer. The hydrometer can usually be obtained fr om the same outle t that sells fuels . Benzol and P.O. can be used as cutting agen ts but a great deal of care must be used In the amounts. Benzol is the least dangerous to engine life but is not good in exces sive amounts due to the amount of carbon residue that r emai ns after combustion. It is ideal for adding when the weather becomes cool or damp. Nitro and alcohol are engine coolants. while benzol Incr ea ses temp er atures . Also, nitro Is very hard to burn and benzol helps to Ignite the mix. P .O. can be used In more gener ous quantities In direct pr opor tion to air temperatures. I have used straight P .O.• cutting down to 80 per cent on extremely cold days . P .O. has a fantas tic rate of expansion and the r esultant chamber pressures are hard on pis tons , r ods and lower ends; also. the combined cylinder heat has been known to bur n holes In the mos t well r einforced pis ton domes . Even In the warmest temperatures ther e Is no harm In running about one ounce per gallon, to Insur e proper Ignition of the nitro. In mild weather. a day of approximately 80 degrees, 1 have run 50/50 cutting mixe s (half alcohol, half P .O.) and have s uffered no III r esults, but rather a great edge In power over those reluctant to use P.O . A quick look at what happens In the combustion chamber when nitro and alcohol are introduced will pr oduce a better under s tanding of why there is a grea t power incr ease . Alcohol alone will pr oduce an Increase of abo ut 20 per cent in produced horse- LIQU ID MEASUREMENT TABLE FORMIXING FUEL PERCENTAGE NITRO power . When alc ohol Is take n through the Intake valves on the Induction stroke, it comes Into conta ct with hot combustion gases that have not been exhausted and also the piston and cylinder walls that have retained heat. The alcohol Immediately vaporizes and absorbs the cylinder heat, causing the once-heated and expanded gases to cool and shrink allowing more room for a gr ea ter incoming 'quantity of fuel . Of course, the jets must then be larger and power output Is In direct r elation to the quanti ty of fuel correctly used and bur ned. With today's gasolines and their Improv ed octanes . alcohol will provide no greater compr es sion ratio usage. Ten-and- onehalf or eleven-and-a-half to one seem to burn gasoline as well or nearly as efficiently as al cohol , but gasoline will not cool and create the demand for a greater volume efficiency. Nitro methane has the same cooling properties as alcohol but goes one step farther In creating power output. About one half of the liquid Is atr! When the nitro hits those hot combustion surfaces and vapor izes , the oxygen content Is r eleased. The cooling process is accompli s hed as with alcohol, but al so oxygen Is added to the cylinder. It's g re a tl y like supercharging, or forcing great quantities of air Into the chamber and thus creating PER CENT QUANlllY 6 oz. 80 1 Quart 21.5 oz. 4.5 oz. 85 1 Quart 29 oz. 3 oz. 90 1 Quar· 30.5 oz. 103.5 oz. 109 oz. 1.5 oz. 25.5 oz. 19 oz. 95 80 85 1 Quart 1 Gallon 1G allon 116 oz. 121.5 oz. 12 oz. 6.5 oz. 90 95 1 Gallon 1 Gallon ' -. One half of the additive methanol or benzol, balance P.O. is consldered a "super mix'. the demand for more fuel. Alcohol cools and creates the demand but nitro does not only that, but provides additional atr In the cylinder due to Its own chemical properties. Average main jet size for alcohol Is .055, while nitro takes a main jet bore of approxima tel y .160 (thousandths of an Inch). Engine Modifications Nothing in the engine needs to be changed other than the carburetlon system, plug heat range and a hot enough ignition spark. Magneto ignitions If In top shape always s eem adequate but some collignitions just do not provide enough spark. Use the hottest coil unit you can obtain ' and efficien t burning will be guarantee d. Igniti on tim ing seems to be Immater tal, for I have seen spark leads run from 38 degrees advance to 55 degrees and the power output Is almost unchanged. Spark plugs r equired for burning the fuel mixes are generally a mlmimum of two ranges colder and maxim um of four. The perfect heat r eading of a plug will range fr om a darkest shade of ash grey III. #3 Hlus, #4 - Custom j ets for Amal carburetor s. to jets must ,be opened to the same diameter. Unfor tunately many carburetors do not have enough mea t to allowjet bore diameters so large. Ideal carburetors for altering to burn fuel are the Amal G.P .' s or T.T .' s and thll Dellorto carbs with remote bowls. For Harley-Olvidsons, the L&L units. In Illustration #4 you will s ee a jet alteration that can be custom made for the Amal carburetors and enable easy jet changes. As I said, you can run with only one jet size, but It 15 not the ideal way of tuning . Changing of the main jet Is recommended. An additional change required In some carburetors Is the plugging off of the idle passages and any air bleed passage. If the Idle adjustment Is by atr, plug It. The nitro contains enough oxygen of Its own, If the Idle is left open it will be i mpos s ible to add enough fuel for proper combus tion. The ai r bleed In G.P . and T.T. type carburetors adds the same type problems . With it open. the fuel de- JET AREA CORRECTION CHART Jet Dia. (In.) .145 .146 .141 . .148 .149 ;150 .151 .152 .153 .154 .155 .156 .151 .158 .159 .160 .161 .162 .163 .164 .165 Area (Sq. In.) .016513 .016142 .016912 .011203 .011431 .011612 .011908 .018146 .018385 .018621 .018869 .019113 .019359 .019601 .019856 .020106 .020358 .020612 .021124 .021124 .021383 Jet Dia. . (In) .166 .161 .168 .169 .110 .111 .112 .113 .114 .115 .116 .111 .118 .119 .180 .181 .183 .18.4 .185 Area . , (Sq In) .021642 .021904 .022161 .022432 .022698 .022966 .023235 .023506 .023119 ,024053 .024329 .024606 .024885 .025165 .025441 • 25130 .026302 .026590 .026880

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