Abstract: A number of systems and methods are disclosed which increase the replenishment interval for anti-knock fluid. This is especially important during activities which require a large amount of anti-knock fluid, such as towing. In some embodiments, the systems and methods are used to reduce anti-knock fluid consumption. For example, changes to engine operation, such as rich operation, spark retarding, upspeeding, and variable valve timing, all serve to reduce the amount of anti-knock fluid required to eliminate knocking. In other embodiments, the composition of the anti-knock fluid is modified, such as by using a higher octane fluid, or through the addition of water to the anti-knock fluid. In other embodiments, the replenishment interval is increased through a larger anti-knock fluid storage capacity. In one embodiment, a three tank system is used where the third tank can be used to store gasoline or anti-knock fluid, depending on the driving conditions.

Abstract: The fuel injection apparatus includes: a fuel injector having a leading end portion that has an internal space in which fuel is accumulated and an injection port for injecting fuel; and an adsorbent disposed in the internal space, the adsorbent being capable of selectively adsorbing an alcohol component in a blended fuel of gasoline and alcohol. The fuel injection apparatus controls an injection amount from the fuel injector such that an air-fuel ratio of an internal combustion engine is a control target air-fuel ratio based on an alcohol concentration of the blended fuel to be supplied to the fuel injector. In this fuel injection apparatus, a fuel pressure is brought to a predetermined low fuel pressure when a request is issued for desorbing alcohol adsorbed on the adsorbent.

Abstract: To improve an ignitability to a fuel having a low compressed ignitability in a combustion chamber in a compressed self-ignition diffusive combustion mode operation.

Abstract: A fluid injector for an exhaust treatment device is disclosed. The fluid injector may have a housing at least partially forming a fluid chamber. The housing may have a central axis, and a fluid passageway configured to supply fluid to the fluid chamber. The supply of fluid may be in a tangential direction relative to the central axis.

Abstract: An engine system for a vehicle, comprising of a combustion chamber, a first in-cylinder direct injector configured to deliver a first substance including at least gasoline directly to the combustion chamber at a first pressure; and a second in-cylinder direct injector configured to deliver a second substance including at least an alcohol directly to the combustion chamber at a second pressure less than the first pressure.

Abstract: A dual fuel common rail fuel injector includes a first and second control valve assembly and a first and second check needle. The dual fuel injector is capable of selectively injecting two different fuels such as diesel and liquid natural gas. The first and second control valve assemblies operate using a single fuel, such as diesel, as the control medium. The dual fuel common rail injector further includes a hydraulic lock assembly.

Abstract: The present application provides a system and method for determining a secondary fuel amount for an engine. The method comprises measuring an injector signal from an engine's Engine Control Unit (ECU) for a primary injector. A delay time of the primary injector can be determined using a lookup table. An open time can be calculated based on the delay time and the primary timing value. An amount of fuel to be injected into the engine can be calculated based on the primary injector open time. An amount of secondary fuel equivalent to the amount of primary fuel can be determined. A timing value for a secondary injector signal for the secondary injector can be calculated to deliver the amount of secondary fuel to the engine.

Abstract: At least one donor cylinder is coupled to an intake manifold. The intake manifold is configured to feed a mixture of air and a first fuel, or a mixture of air, the first fuel, and a second fuel to the at least one donor cylinder. At least one non-donor cylinder is coupled to the intake manifold and an exhaust manifold. The intake manifold is further configured to feed air, or a mixture of air and the second fuel to the at least one non-donor cylinder. An exhaust channel extend from the at least one donor cylinder to the intake manifold for recirculating an exhaust emission from the at least one donor cylinder to the at least one donor, and non-donor cylinders via the intake manifold.

Abstract: Systems and methods of operating an engine with a varying fuel composition. In one example, a split injection is performed during engine cranking with at least some fuel injected in the intake stroke and some fuel injected in the compression stroke. Further, a split ratio of the injection is adjusted based on the alcohol content of the injected fuel.

Abstract: A fuel supply system for supplying a bi-fuel engine with a first fuel type, e.g., gasoline, includes a cooling circuit. The cooling circuit circulates the first fuel type through a direct injection pump assembly to prevent the first fuel type from overheating within the direct injection pump assembly.

Abstract: This engine utilizes the power of cylinder(s) that use diesel fuel which provides great power at slow crankshaft rounds per minute speed. It also utilizes cylinder(s) that operate on dedicated alternant hydrocarbon fuel(s). The fuels do not mix. The diesel cylinder(s) burn only diesel fuel. The alternant hydrocarbon cylinder(s) burn only their assigned fuel. An example would be an engine that had one diesel cylinder and one cylinder that burned natural gas while using a single crankshaft.

Abstract: A control system of an internal combustion engine in which a first fuel of ammonia and a second fuel which is easier to burn than ammonia are used as fuels. An ammonia ratio is usually set to a reference ammonia ratio which is determined in advance in accordance with an operating state of an engine. At the time when feed of the fuel is restarted after suspension of feed of the fuel at the time of deceleration, the ammonia ratio is temporarily made lower than the reference ammonia ratio in accordance with the operating state of the engine.

Abstract: Fuel injectors are disclosed that are capable of simultaneously delivering liquid and gaseous fuels to the combustion chamber of a compression ignition engine. For example, fuel injectors are disclosed that can deliver liquid diesel fuel, as a pilot liquid, along with a gaseous fuel, such as natural gas or other available fuels that are gases at atmospheric pressure and ambient temperature. The fuels are delivered to the needle control valve cavity sequentially via separate passageways. The delivery of the pressurized liquid fuel is actuated by the single actuator that is provided for each fuel injector. The actuator may be of a solenoid type or of a piezoelectric type or other suitable actuator as will be apparent to those skilled in the art. A liquid fuel check valve, in combination with the actuator, controls the delivery of the pilot liquid fuel to the needle control valve cavity.

Abstract: A multi-mode engine system comprising a first mode in which the engine is fuelled substantially entirely by a first fuel, and a second mode in which the engine is fuelled substantially entirely by a second fuel, or by a mixture of the first and second fuels, the engine comprising: a first engine control unit (ECU) for controlling the flow of the first fuel into the engine when the engine is operating in the first mode; and a second ECU operatively connected to the first ECU; wherein the first ECU comprises: a signal receiver for receiving the first input signals, and an output for emitting a first output signal; and the second ECU being adapted to modify the first output signal when the engine is running in the second mode to produce a first modified signal and a second calculated signal.

Abstract: The present invention relates to a dual fuel injection valve apparatus provided with a hybrid nozzle for a diesel engine and a gas engine and an objective thereof is to provide a dual fuel injection valve apparatus provided with a hybrid nozzle for a diesel engine and a gas engine, being capable of respectively injecting two kinds of different fuels from one fuel injection valve by pressure of fuel and tension of a spring. In a fuel injection valve apparatus for injecting fuel to a cylinder of a diesel engine or a gas engine, the present invention sequentially injects, without mixing, two kinds of fuel through respective nozzle holes by pressure of the two kinds of fuel introduced to a fuel valve and tension of a needle spring.

Abstract: A fuel system and a method of operation of the fuel system are described in the context of a multi-fuel internal combustion engine. In one example, the method includes varying a proportion of fuel supplied by a fuel pump to an engine and a fuel separator. The method may be particularly useful for a dual fuel engine.

Abstract: Internal combustion reciprocating piston engine and method for operating an internal combustion reciprocating piston engine which works according to the Diesel process and has at least one cylinder (10) in which is arranged a reciprocating piston (12) connected to a crankshaft (11), an air supply device (21) for providing combustion air in the cylinder, and a fuel injection arrangement (30) for injecting an LPG fuel from an LPG fuel reservoir (40) and a diesel fuel from a diesel fuel reservoir (50), wherein the method comprises: providing combustion air and compressing this combustion air in the cylinder, and injecting diesel fuel and LPG fuel by means of the fuel injection arrangement into the compressed combustion air in the cylinder, wherein prior to the injection of diesel fuel and LPG fuel the diesel fuel is mixed with the LPG fuel by means of the fuel mixing device (60) so that a homogeneous fuel emulsion of LPG fuel and diesel fuel is produced, and the fuel emulsion is subsequently injected into the at

Abstract: An ECU controls an internal combustion engine that creates a tumble flow in each engine cylinder and intensifies the tumble flow using fuel injected at a timing near the intake stroke bottom dead center during homogeneous combustion. The ECU includes a fuel property identifying mechanism identifying the property of fuel and combustion state changing mechanism changing the combustion state. When the fuel has a property that requires a stoichiometric air-fuel ratio lower than the stoichiometric air-fuel ratio for gasoline, the combustion state changing mechanism changes the combustion state by, for example, retarding the ignition timing, so that the combustion progresses moderately. This prevents an excessive increase in the combustion speed.

Abstract: A bio-diesel fuel engine system and bio-diesel fuel engine operating method capable of producing a biomass fuel from a liquid state biomass source material of a fat-containing vegetable or animal oil allowing fuel to be combusted in a conventional diesel engine while providing the benefits of low fuel consumption, stable engine operation, and extended engine service life, with compared to use a biomass fuel reformed by methyl-ester method.

Abstract: A control system of an internal combustion engine in which as fuel, a first fuel of ammonia and a second fuel easier to burn than ammonia are used. These two types of fuel are burned in the combustion chamber. A basic ammonia ratio is set in accordance with an engine load and engine speed. The set basic ammonia ratio is corrected based on at least one of a combustion state, knocking strength, temperature of an exhaust gas or temperature of a catalyst arranged in an engine exhaust passage, NOx concentration in the exhaust gas, actual compression ratio, air-fuel ratio, and fuel properties.

Abstract: The present invention relates to a method of improving vaporization of a fuel injecting an engine that can work at least a conventional mode during a high load and an at least partly homogeneous mode with an intake, compression, combustion and exhaust phase during the high load, said engine comprising at least one cylinder, a combustion chamber, at least one intake valve associated with an intake pipe, at least one exhaust valve with an exhaust pipe, control means for controlling opening-closing of the at least one valve and fuel injection means.

Abstract: An open or closed loop EFI system integrating an alcohol sensor is provided on a genset engine. The EFI system provides acceptable engine performance and efficiency when using fuels or fuel blends over a wide band and when starting from a cold state, i.e., starting the engine after the engine has not run for a relatively long period of time. The alcohol sensor enables acceptable operation while the genset engine is cold. The alcohol sensor sends data to the electronic control unit (ECU) and this data, as well as data provided by other sensors that may be available such as an air flow sensor, is used to determine the optimal air-to-fuel ratio (AFR). The ECU actuates the fuel injector which sends the correct amount of atomized fuel to mix with the air flow to be combusted. The fuel mixture, at the requested AFR, enables the engine to start and operate efficiently from a cold state even if the fuel blend has been changed from a previous operation of the engine.

Abstract: A control system and method for operating an engine includes an HCCI mode control module operating an engine in a homogeneous charge compression (HCCI) mode. The control system also includes a difference module determining an actual difference between a desired torque amount and a spark ignition (SI) threshold. An SI mode control module operates the engine in a SI state when the actual difference is above a threshold band. A HCCI mode control module operates the engine in the HCCI mode for a predetermined time when the actual difference is within the torque threshold band. The HCCI mode control module operates the engine in the HCCI mode when the actual difference is below the torque threshold band.

Abstract: Disclosed is a method and corresponding fuel injector for injecting gaseous and liquid fuel into an engine. The method comprises delivering a liquid fuel to a fuel injector, delivering a pressurized gaseous fuel to the fuel injector, entraining the liquid fuel within the gaseous fuel within a chamber of the fuel injector and injecting the gaseous fuel and atomized liquid fuel into the combustion chamber. The liquid fuel can be passed through and dispensed from a needle into a chamber in the injector nozzle where it is entrained in the gaseous fuel during an injection event. The liquid/gas mass ratio is controlled by the needle movement, hydraulic resistances or electronic valves so that the majority of the liquid is injected during the first part of the gas injection. The injector can be used for late cycle direct injection of natural gas, or any number of gaseous fuel blends combined with many liquid fuels such as diesel, biodiesel and DME.

Abstract: An engine system for a vehicle, comprising of a combustion chamber, a first in-cylinder direct injector configured to deliver a first substance including at least gasoline directly to the combustion chamber at a first pressure; and a second in-cylinder direct injector configured to deliver a second substance including at least an alcohol directly to the combustion chamber at a second pressure less than the first pressure.

Abstract: A dual fuel injector may be used to injector both gas and liquid fuel into a cylinder of a compression ignition engine. An injector body defines a first set of nozzle outlets, a second set of nozzle outlets, a first fuel inlet and a second fuel inlet. A dual solenoid actuator includes a first armature, a first coil, a second armature and a second coil that share a common centerline. The dual solenoid actuator has a non-injection configuration at which the first armature is at an un-energized position and the second armature is at an un-energized position. The dual solenoid actuator has a first fuel injection configuration at which the first fuel inlet is fluidly connected to the first set of nozzle outlets, the first armature is at an energized position and the second armature is at the un-energized position.

Abstract: A duel fuel quill assembly and method for assembling such an assembly for an engine are disclosed. The dual fuel quill assembly may comprise a cylinder head including a main bore and a receiving cavity, an outer quill tube, an inner quill tube nested within the outer quill tube, an adapter slidingly received inside the main bore of the cylinder head, and a manifold secured to the adapter. The adapter may be moveable between a first position and a second position and may define an axial bore configured to receive the outer quill tube and the nested inner quill tube. The manifold may define a recess configured to compress the outer and inner quill tubes against the cylinder head cavity when the adapter is in the second position.

Abstract: A fuel injection apparatus for an internal combustion engine including a fuel injector having a leading end portion that has an internal space in which fuel is stored and an injection nozzle for injecting fuel; and an adsorbent disposed in the internal space, the adsorbent being capable of selectively adsorbing an alcohol component in a blended fuel of gasoline and alcohol. The adsorbent has a characteristic such that an amount of alcohol adsorption is small when a fuel pressure is low and large when the fuel pressure is high. Adsorption of alcohol onto, and desorption of alcohol from, the adsorbent can be controlled by changing the fuel pressure in the internal space.

Abstract: In an internal combustion engine control device having an air-fuel ratio control device that controls the fuel injection amount so that the air-fuel ratio of exhaust gas of an internal combustion engine approaches a target stoichiometric air-fuel ratio, the control device further includes a device that calculates the lower calorific value of fuel, and a device that sets the target stoichiometric air-fuel ratio from the calculated lower calorific value based on a known relationship between the lower calorific value and the stoichiometric air-fuel ratio. It becomes possible to perform the air-fuel ratio control according to the fuel property by utilizing the relationship between the calorific value and the stoichiometric air-fuel ratio.

Abstract: A method for determining a fuel mass of a single injection that has been injected into at least one combustion chamber of a combustion engine with at least one injection under high pressure. The method includes determining a correction variable for the single injection with the aid of a comparison of a measure for the actual amount of the injected fuel of at least one test injection, which takes place due to a measure for a default nominal amount of a desired single injection, and a measure for the nominal amount of the test injection. The method additionally includes executing a plurality of timely directly successive test injections.

Abstract: A compression ignition (diesel) engine uses two or more fuel charges during a combustion cycle, with the fuel charges having two or more reactivities (e.g., different cetane numbers), in order to control the timing and duration of combustion. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot). At low load and no load (idling) conditions, the aforementioned results are attained by restricting airflow to the combustion chamber during the intake stroke (as by throttling the incoming air at or prior to the combustion chamber's intake port) so that the cylinder air pressure is below ambient pressure at the start of the compression stroke.

Abstract: A control system of an internal combustion engine enabling effect production of hydrogen and reliable promotion of burning of ammonia by a simple structure. The internal combustion engine uses ammonia as a fuel and is provided with a fuel injector injecting fuel into an intake passage and a variable operating mechanism able to change a valve opening operation of the intake valve. In the exhaust stroke, this temporarily opens the intake valve. Ammonia for hydrogen production is injected from a fuel injector into the gas flowing back at this time from the combustion chamber to the inside of the intake passage. As a result, hydrogen is produced from the ammonia. In the following intake stroke, this hydrogen is fed into the combustion chamber together with the ammonia and is burned together with the engine drive use ammonia.

Abstract: A diesel fuel additive package, diesel fuel containing the additive and methods for operating an engine on the diesel fuel and additive. The fuel additive includes a reaction product of (a) a hydrocarbyl substituted dicarboxylic acid or anhydride, and (b) an amine compound or salt thereof of the formula wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product contains at least one amino triazole group. Component (2) of the additive is a hydrocarbyl succinimide dispersant. The additive also includes (3) a C2 to C10 alkyl alcohol; and (4) optionally, a lubricity additive. In the additive, a weight ratio of component (1) to component (2) in the fuel ranges from about 1:3 to about 1:5.

Abstract: Boosted engine operation and spark timing of an engine may be adjusted with alcohol content of the fuel in a direct injection engine. Further, various adjustments may be performed in numerous related systems to account for increased maximum engine torque, such as traction control, transmission shifting, etc.

Abstract: An engine system for a vehicle, comprising of a combustion chamber, a first in-cylinder direct injector configured to deliver a first substance including at least gasoline directly to the combustion chamber at a first pressure; and a second in-cylinder direct injector configured to deliver a second substance including at least an alcohol directly to the combustion chamber at a second pressure less than the first pressure.

Abstract: The present invention is directed to a dual fuel system and a dual fuel system assembly where liquid LPG and diesel are mixed and then distributed via the common rail to the combustion chambers. The liquid fuel mixture remains in a liquid state and under pressure for introduction to the combustion chambers. With the preferred embodiment of the dual fuel system, only minor changes are required to the diesel engine without altering the manufactures specifications and voiding the manufacturer's warranties. The resultant combustion of the liquid fuel mixture provides a cleaner emission and relatively cheaper vehicle operational costs.

Abstract: A hybrid vehicle propulsion system and method of operation have been provided. As one example, the system comprises an internal combustion engine including at least a combustion chamber configured to propel the vehicle via at least a drive wheel, a motor configured to propel the vehicle via at least a drive wheel, an energy storage device configured to store energy that is usable by the motor to propel the vehicle, a fuel system configured to deliver gasoline and alcohol to the combustion chamber in varying relative amounts, a control system configured to operate the motor to propel the vehicle and to vary the relative amounts of the gasoline and alcohol provided to the combustion chamber in response to an output of the motor.

Abstract: In one embodiment, a fluid mixture composition is used at least in part as a fuel for engine-powered transportation vehicles, the mixture comprising an initial concentration of an ammonia-like reductant component and an initial concentration of an ammonia-like carrier component. The mixture may also include an optional third hydrocarbon component, e.g., gasoline or diesel fuel, with modified properties when compared to conventional gasolines or diesel fuels. The mixture is separated into a first and a second stream, with the majority of the first stream being used as a fuel for the engine and at least a first portion of the second stream being injected into the engine exhaust gases to reduce NOx emissions. A second portion of the second stream is aspirated into the engine and a lean air/fuel ratio may be used to improve fuel efficiency.

Abstract: A system, comprising, a combustion chamber, and a free-radical ignition system configured to inject free radicals into the combustion chamber at an ignition timing to trigger combustion of a fuel-air mixture.

Abstract: A system for supply of LPG/ammonia for direct-injection petrol or diesel engine includes an electronic control unit where the control unit governs a petrol/diesel pump, a supplementary petrol/diesel pump, a petrol/diesel-delivery solenoid vale, LPG/ammonia-return solenoid valve, LPG/ammonia pump, a supplementary LPG/ammonia pump, a LPG/ammonia-delivery solenoid vale and a LPG/ammonia injector, such that only one of LPG/ammonia and petrol/diesel is fed to the engine at any point in time, and a combination of i) LPG and petrol, ii) LPG and diesel, iii) ammonia and petrol, and iv) ammonia and diesel is never fed to the engine.

Abstract: A method of operation of an internal combustion engine including an intake valve coupled to a combustion chamber, and a port fuel injector positioned upstream of the intake valve in an intake manifold including a throttle, the port fuel injector fluidly coupled to a fuel rail included in a fuel delivery system housing a fuel at least partially composed of alcohol. The method including, during a start-up operation when the temperature of the engine is below a threshold value and fuel is actively being injected into the intake manifold, adjusting a cone angle of a fuel spray from the port fuel injector, via adjustment of the throttle and/or fuel delivery system, based on the position of the intake valve.

Abstract: For the direct re-entry in the CAI operating mode following a pull fuel cut off phase the CAI specific valve lift is maintained during its pull fuel cut off phase. Upon a request signal for the CAI re-entry after the closing time of the particular cylinder, an advance fuel injection quantity is injected in the combustion chamber and externally ignited and combusted in the following CAI interim compression phase of the exhaust stroke, as a result of which hot exhaust gas is formed in the combustion chamber, fresh air is drawn into the combustion chamber during the following intake stroke, a main fuel injection quantity is injected in a main compression phase during the following compression stroke, and the exhaust gas content brought about from the earlier auxiliary fuel injection, is mixed with the air-fuel mixture newly introduced for the main ignition to form a self-ignitable, homogenous fresh air-exhaust gas-fuel mixture.

Abstract: A separate igniter fuel injection system is described for use with diesel engines operating on tar based slurry fuel with a common rail slurry fuel injection system. The igniter fuel is injected prior to injection of the slurry fuel, during each engine compression stroke, so that the ignition and burning of the igniter fuel will supply hot gases for the evaporation and thermal cracking needed to ignite the tar fuel portions of the slurry. This separate igniter fuel injection system can also be used for cold startup of a diesel engine operated on tar based slurry fuels.

Abstract: A fuel supply control apparatus for an engine includes an alcohol concentration detector and an engine temperature detector. The apparatus increases an amount of fuel supplied to the engine as the detected alcohol concentration becomes higher. The apparatus increases the amount of fuel as the engine temperature becomes lower and as the alcohol concentration becomes higher. The apparatus feed-back corrects the amount of fuel by using a correction value such that an actual air-fuel ratio becomes a theoretical air fuel ratio. The apparatus determines that water is mixed with fuel when the correction value during a cold operational state indicates leaner than the lean value of the correction value used during a warm operational state. The apparatus reduces the increased amount of fuel when water is mixed with fuel.

Abstract: A catalyst composition and method of improving fuel efficiency and reduced emissions in combustion engines is disclosed. A liquid aerosol catalyst is introduced in to the air intake stream of a combustion engine and allowed to react during the oxidation of the fuel in the combustion chamber. The catalyst mixture contains platinum, rhenium, cerium, alcohol, and water.

Abstract: A control device for a premixed charge compression ignition (PCCI) internal combustion engine is provided, capable of stable operation over a wide operating range. The control device of an engine 1 comprises: a fuel supply means 20 of supplying the main fuel to the engine 1; an hydrogen supply means 30 of supplying reformed gas containing hydrogen; a fuel supply control unit 41 of controlling an injection timing and an injection period of the main fuel supplied from the injector 22 of the fuel supply means 20 based on the PCCI combustion condition of the engine 1; and a hydrogen supply control unit 42 of controlling an injection timing and an injection period of reformed gas from the gas injector 32 of the hydrogen supply means 30 based on the PCCI combustion condition.

Abstract: Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.

Abstract: A method adjusts fuel injection to account for fuel puddling in the engine intake. The fuel is adjusted based on the ethanol content of the fuel in the puddle, and the make-up of the various fuel components in the puddle. In this way, it is possible to better account for the effects of these parameters on puddle evaporation.

Abstract: The present invention relates to a fuel injection system for a combustion engine. The system comprises a source of fuel, an injector and a means for delivering pressurized fuel strokes to said injector, said injector being arranged for generating at least two fuel jets with different jet parameters at closely adjacent locations and having directions such that the jets interact with each other along a surface interface therebetween so as to generate a fine spray. The jet breakup time is shortened and the droplet size is substantially reduced.

Abstract: Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.