TO OBTAIN THE MAXIMUM ENERGY FROM THE GASOLINE, THE COMPRESSED FUEL/AIR MIXTURE INSIDE THE COMBUSTION CHAMBER NEEDS TO BURN EVENLY, PROPAGATING OUT FROM THE SPARK PLUG UNTIL ALL THE FUEL IS CONSUMED. THIS WOULD DELIVER AN OPTIMUM POWER STROKE. IN REAL LIFE, A SERIES OF PRE-FLAME REACTIONS WILL OCCUR IN THE UNBURNT "END GASES" IN THE COMBUSTION CHAMBER BEFORE THE FLAME FRONT ARRIVES. IF THESE REACTIONS FORM MOLECULES OR SPECIES THAT CAN AUTOIGNITE BEFORE THE FLAME FRONT ARRIVES, KNOCK WILL OCCUR

THESE CYCLIC VARIATIONS CAN EVEN LEAD TO FAILURE OF CRANKSHAFT , SURFACE PITTING OF THE PISTON & EVEN BREAKDOWN OF ENGINE

THE COMBINATION OF INTENSE PRESSURE WAVES & OVERHEATING CAN INDUCE PISTON FAILURE IN A FEW MINUTES SINCE KNOCK & IGNITION BOTH ARE FAVOURED AT HIGH TEMPERATURES SO ONE MAY LEAD TO THE OTHER UNDER HIGH SPEED KNOCK MAY EVEN LEAD TO PRE IGNITION WHICH THEN ACCELERATES ENGINE DESTRUCTION

DURING KNOCKING SHOCK WAVES AT PRESSURES MORE THAN 150-200 BAR ARE PRODUCED AT TEMPERATURES GREATER THAN 2000 C. WHICH PRODUCES IMMENSE VIBRATIONS WITHIN THE ENGINE.

WHAT IS KNOCKING

IN RACING CARS SUCH AS FORMULA 1 , AUDI , BMW , MERCEDES, THE ENGINE IS DESIGNED SUCH AS TO RUN ON A HIGHER C.R. THE REQUIREMENTS OF SUCH AN ENGINE INVOLVE FUELS WITH OCTANE NUMBER GREATER THAN 95 TO 105. SUCH A FUEL WITH HIGN OCTANE RATING IS NOT FOUND ON OUR LOCAL PETROL PUMPING STATIONS. HENCE SUCH ENGINES WHEN RUN AT LOW SPEEDS HAVE TO CONSUME LEAN FUEL MICTURE WHICH ARE RESPONSIBLE FOR AUTOIGNITION OF FUELS i.e. KNOCKING OCCURS i.e. DETONATION

FOR THE MASSIVE ENGINES RUNNING AT HIGHER LOADS AS IN THE CASE OF SPORTS CARS AT FULLY OPENED THROTTLE OR AT RPM GREATER THAN 2000 -3000 KNOCKING BECOMES A MAJOR PROBLEM AT HIGH SPEEDS.

HENCE DOPING OF FUELS BECOMES NECESSARY TO ACHIEVE REQUIRED RON i.e. “ OCTANE NUMBER RATING “ TO SOVE THIS PROBLEM

AS A RESULT OF WHICH THE RATIO OF FUEL (HYDROCARBON) TO THE AIR BECOMES SUFFICIENT FOR COMPLETE COMBUSTION.

USING TOLUENE AS AN ADDITIVEWHY TOLUENE ?

THE FOLLOWING FACTORS HAVE AN IMPACT ON KNOCKING1) LENGTH OF ‘C’ CHAIN KNOCKING2)PRESENCE OF ALDEHYDES & PEROXIDES KNOCKING3)NAPTHENES HAVE A GREATER KNOCKING TENDENCY

HOWEVER THE SAME CAN BE BY 1)CENTRALIZING ‘C’ ATOMS IN HYDROCARBON MOLECULE2) DOUBLE BONDS3) BRANCHING IN HYDROCARBON CHAIN4)ADDING –CH3 TO THE CENTRAL ‘C’ ATOM IN HYDROCARBON CHAIN

CONCLUSION A MORE COMPACT MOLECULAR STRUCTURE TENDENCY TO KNOCK

WHY TOLUENE ?

TOLUENE IS DENSER THAN ORDINARY GASOLINE (0.87 G/Ml VS. 0.72-0.74)

AND CONTAINS MORE ENERGY PER UNIT VOLUME. THUS COMBUSTION OF

TOLUENE LEADS TO MORE ENERGY BEING LIBERATED AND THUS MORE

POWER GENERATED. THUS IT TAKES SMALLER QUANTITIES OF TOLUENE TO

ACHIEVE THE SAME OCTANE BOOST COMPARED TO 100 OCTANE RACING

GAS.

THIS IS IN CONTRAST TO OXYGENATED OCTANE BOOSTERS LIKE ETHANOL

OR MTBE WHICH CONTAIN LESS ENERGY PER UNIT VOLUME COMPARED TO

GASOLINE. THE HIGHER HEATING VALUE OF TOLUENE ALSO MEANS THAT

THE EXHAUST GASES CONTAIN MORE KINETIC ENERGY, WHICH IN TURN

MEANS THAT THERE IS MORE ENERGY TO DRIVE TURBOCHARGER VANES.

IN PRACTICAL TERMS THIS IS EXPERIENCED AS A FASTER ONSET OF TURBO

BOOST.

EFFECT OF TOLUENE CONTENT

THE OCTANE NUMBER OF FUEL FOR FORMULA 1 RACING IS LIMITED TO A MAXIMUM NUMBER OF RON 102. ADOPTING A HIGHER COMPRESSION RATIO IS EXPECTED TO IMPROVE BOTH POWER & B.S.F.C . HOWEVER AT THE SAME TIME THE POSSIBILITY OF KNOCKING BECOMES HIGHER. THEREFORE THE KNOCKING PROPERTIES OF FUELS DETERMINE MAXIMUM COMPRESSION RATIO. IT SOMETIMES APPEARS THAT DIFFERENCES IN FUEL INGREDIENTS EFFECT KNOCKING PROPERTIES EVEN THOUGH THE RON OF THE FUELS IS SAME. THE DEVELOPMENT OF A FUEL WITH GOOD KNOCKING PROPERTIES UNDER HIGH SPEED & BOOST CONDITIONS IS ESSENTIAL FOR ADOPTING A HIGH COMPRESSION RATIO.

THE TANK CAPACITY REGULATION LIMITS FUEL AMOUNT TO 150 LITERS. & REFUELING DURING A RACE EVENT IS FORBIDDEN. IN ORDER TO OBTAIN A LARGELY CALORIFIC IN CAPACITY IS NEEDED I.E. A DENSE FUEL. COMPARATIVE EVALUATION OF VARIOUS FUELS REVEALED THAT A FUEL WITH TOLUENE CONTENT IS MOST FAVORABLE TO MEET THE REQUIREMENTS.

OCTANE VALUES OF VARIOUS FUELS

THANX FOR UR KIND

ATTENTION