Gasoline Engine Ebook

Bourke Engine Documentary

This ebook comes to you from David S. Wolfe, engineer and owner of the, and this book shows you all about the best gasoline engine that was ever build, the specs on it, and how to build one of your own. You will also get the blueprints to this unique kind of engine, so that you can build a perfect version of it yourself. This engine has a 50:1 air-to-fuel ratio, and runs with more horsepower and torque than any other engine in history. The oil never has to be changed, and the engine runs extremely quietly. This engine also uses what is known as the Bourke Cycle, which allows the engine to use air and fuel at a far more efficient rate than any other engine in history. You will learn to build this engine yourself, with a complete guide and blueprints.

Bourke Engine Documentary Overview


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Comparison of twostroke and fourstroke cycles

The main difference between the two cycles is the power developed. The two-stroke cycle engine, with one working or power stroke every revolution, will, theoretically, develop twice the power of a four-stroke engine of the same swept volume. Inefficient scavenging however and other losses, reduce the power advantage to about 1.8. For a particular engine power the two-stroke engine will be considerably lighter an important consideration for ships. Nor does the two-stroke engine require the complicated valve operating mechanism of the four-stroke. The four-stroke engine however can operate efficiently at high speeds which offsets its power disadvantage it also consumes less lubricating oil.

132 Further comments on air standard cycles

Hence one would expect to achieve a limiting IMEP of rather less than half the theoretical value, i.e. 30 bar in a highly developed four-stroke diesel engine operating at a boost ratio of 3 1, and even less in a two-stroke engine due to its generally shorter effective stroke and the need for even more generous air-fuel ratios to ensure satisfactory scavenging and freedom from thermal overloading.

Loop Scavenging Diesel

Figure I.4 Twin Sulzer 4S47 type cross-flow scavenged crosshead engines served the Monte Penedo, the first large oceangoing vessel powered by two-stroke engines (1912). Four long tie-rods secured each cylinder head directly to the bedplate, holding the whole cast iron engine structure in compression scavenging, introduced in 1910, eliminated the gas exchange valves in the cylinder cover to create a simple valveless concept that characterized the Sulzer two-stroke engine for 70 years the change to uniflow scavenging only came with the RTA-series engines of 1982 because their very long stroke required for the lower speeds dictated for high propeller efficiency was unsuitable for valveless port scavenging.) There were, inevitably, some failures among the pioneers. For example, a pair ofJunkers opposed-piston two-stroke engines installed in a 6000 dwt Hamburg-Amerika Line cargo ship was replaced by triple-expansion steam engines even before the vessel was delivered. The Junkers engines...

211 Two Stroke versus Four Stroke

All engines go through four cycles intake, compression, power, and exhaust. Engines can be either two stroke or four stroke. In two-stroke designs, the four cycles are completed during each complete revolution of the crankshaft. Therefore, there is a power stroke during each revolution. In four-stroke designs, the four cycles are completed every two revolutions of the crankshaft there is a power stroke only every other revolution of the crankshaft. For this reason, two-stroke engines have higher power density than four-stroke engines. However, because the intake and exhaust functions do not achieve completion, the two-stroke engine is not as efficient as a four-stroke engine and has higher emissions.

917 Comparison of advantages

From the foregoing descriptions it will be realised that the high performance two-stroke engine cannot claim greater, mechanical simplicity than its four-stroke competitor, and it is still doubtful whether it will ever achieve equally favourable specific fuel consumption.

Turbocharger Designers Abb Turbo Systems

BBC's launch of the VTR 0 series in 1944 marked the end of an era in which each turbocharger was custom built for the application and made available a range of volume-produced standard turbochargers for serving engines with power outputs from 370 kW to 14 700 kW. Until then, turbochargers had been applied commercially to four-stroke engines but it now became possible to turbocharge two-stroke engines equipped with engine-driven scavenging air pumps. In order to eliminate the scavenging pumps and reduce fuel consumption, however, the turbocharging system had to be a pulse system. This feature was successfully introduced in 1952 on a B& W engine powering the Danish tanker Dorthe Maersk, the first ship to be equipped with a turbocharged two-stroke engine. The two VTR 630 turbochargers boosted engine output by some 35 per cent to 5520 kW.

633 Rotary Engine With Pm Motor The Mechanical Outlines

The drive line is a marriage of two techniques a permanent-magnet brushless DC motor and a Wankel two-stroke engine. The electric motor provides instant acceleration with 45 kW of power available from 1500 to 6000 rpm, on this design. A permanent-magnet design is used because it is lightweight, highly efficient, and results in an economical inverter. The concept is to exploit the machine characteristics using vector control. At low speeds, the permanent magnets provide the motor field. At high speeds, the field is weakened by introducing a reactive Id component at right angles to the torque-producing component Iq. The control objective is to maintain the terminal voltage of the motor constant in the high speed region, Fig. 6.6.

Dieselmechanical Drives

The direct drive of a fixed pitch propeller by a low speed two-stroke engine remains the most popular propulsion mode for deepsea cargo ships. At one time a slight loss of propulsive efficiency was accepted for the sake of simplicity but the introduction of long stroke and, more recently, super- and ultra-long stroke crosshead engines has reduced such losses. For a large ship a direct-coupled speed of, say, 110 rev min is not necessarily the most suitable since a larger diameter propeller turning at speeds as low as 60 rev min is more efficient than one of a smaller diameter absorbing the same horsepower at 110 rev min. The longer stroke engines now available develop their

1625 Screwtype compressors

However, some adjustment may then have to be made because the volumetric efficiencies of the engine and supercharger vary differently with speed and pressure. The two-stroke engine calls for a slightly different approach, since pressures and flows have to be related to the additional air requirements of scavenging.

Internal Combustion Engines

The two-stroke engine requires two piston strokes (or one crackshaft revolution) for each cycle. In one upward (compression) stroke of the piston, the combustible mixture is brought into the cylinder through the intake valve and ignited near the top of the stroke as the piston is forced downward (to provide power) the exhaust valve is opened and the spent gases are allowed to escape. Near the bottom of their stroke the intake valve is opened again and the combustible mixture again is brought into

209Hydrogen from methanol or DME

A system for producing hydrogen from methanol and water on a vehicle, Fig. 20.6, was introduced by Toyota in 1987. The vehicle has a range of 250310 miles (400-500 km) on a single tank of methanol, which would be refuelled from a forecourt pump, in the conventional manner. Some CO2 is produced during the reforming process but, because methanol contains less carbon than gasoline fuel, the quantity produced on the vehicle is half that from one with a gasoline engine of comparable output. The volumes of CO, HC and NO produced are one-tenth of those of the gasoline engine, and therefore meet the requirements of the American ULEV regulations.

Diesel injection equipment and systems

By virtue of its inherent durability, and high thermal efficiency and therefore low specific fuel consumption, the compression-ignition (ci) engine is by far the most favoured power unit for commercial vehicles and is encroaching significantly into the private car field too. The thermal efficiency of an indirect (idi) diesel engine, Section 6.11, is about 25 higher than that of the gasoline engine, while that of a direct injection (di) unit, Section 6.10, is of the order of 15 higher still. A considerable disadvantage of both idi and di types is their low power output relative to both weight and cylinder capacity, compared with the spark ignition engine. However, to a large extent, this can be offset by turbocharging the ci unit and even more so if charge cooling is employed too.

One Degree of Freedom

A single degree of freedom is not limited to simple mechanical systems such as the cylinder. For example, a 12-cylinder gasoline engine with a rigid crankshaft and a rigidly mounted cylinder block has only one degree of freedom. The position of all of its moving parts (i.e., pistons, rods, valves, cam shafts, etc.) can be expressed by a single value. In this instance, the value would be the angle of the crankshaft.

Pneumatics and Pneumatic Power

Compressed Air and Vacuum Systems- Fig. 1 compares the basic operation of compressed air and vacuum systems. In both systems a prime mover such as an electric motor or gasoline engine operates an air compressor or vacuum pump, converting electrical or chemical energy into pneumatic energy.

554 Calculation of thermal stress

Following analysis the results are post-processed into a form suitable for engineering assessment. The software can additionally be employed to assess the results against criteria of acceptability developed by experience. It is, for example, possible to obtain a direct plot of fatigue safety factors taking account of the minimum and maximum stress levels and the local material properties at each nodal point on the model. The results may be presented in a number of different ways, e.g. colour contour plots, deformed geometry, vectors, animations or graphs. Examples of predicted against measured temperatures for the cylinder head of a locomotive diesel engine are shown in Figure 5.15. Figure 5.16 shows an example of calculated high cycle fatigue factors for a piston of a gasoline engine.

205 Low pressure hydrogen storage on the vehicle

Some idea of the success of this system, Fig. 20.5, can be gleaned by comparing the weights of the 120 kg fuel cell plus the 100 kg hydrogen storage unit with the 450 kg of the sealed nickel-metal hydride battery used in the equivalent Toyota hybrid vehicle powered by a gasoline engine and electric generator and motor. This 100 kg nickel-metal hydride unit stores 2 kg of hydrogen, which is the equivalent of 20 000 litres of hydrogen gas at a pressure of 20 MPa.

Agricultural Requirements

Fertilizers present a transferring challenge due to the large volumes that are used, and the corrosive nature of most solutions. Two types of power modes are commonly used in the market for the transferring of fertilizers gasoline-powered centrifugal pumps and ground-driven positive displacement pumps. Gasoline-powered centrifugal pumps used are usually lightweight aluminum or plastic units with 2 in (50 mm) ports. The pumps are coupled to a 3 to 5 hp (2 to 4 kW) gasoline engine and are capable of transferring rates up to 150 gpm (568 l min). These high flowrate gasoline powered pumps are used to transfer fertilizer and water from large 1000 to 2000 gallon (3785 to 7570 liter) transport tanks into the application equipment's on-board storage tanks, 300 to 500 gallons (1135 to 1890 liters) in size. Ground driven pumps are mounted on the implement equipment such as planters and cultivators. The pumps are used to transfer and meter the fertilizer through a network of tubing that runs to...

244 Principles of pulse converter and other turbocharging systems

Pulse Converter Diesel Engine

A pulse converter system, in its simplest form, is shown in Figure 2.34, applied to a four-cylinder engine. A conventional pulse manifold is used, but a carefully designed junction connects the two branches of the manifold to a single entry turbine. Figure 2.35 shows pressure diagrams recorded from an automotive two-stroke engine with the pulse converter of Figure 2.34 and a conventional pulse system. By connecting all four cylinders to a single turbine inlet, windage periods between exhaust pulses are totally avoided. Turbine entry conditions are not steady, as per the constant pressure system, but the very low efficiency operating points of the pulse system are avoided. The junction is designed to minimize pressure pulse transmission from one branch of the exhaust manifold to the other, thereby avoiding a blow-down pulse from one cylinder destroying the scavenge process of another. This is achieved by accelerating the gas as it enters the junction, reducing its pressure at the...

Sulzer low speed engines

Flex Sulzer

Active in both four-stroke and two-stroke design sectors, Sulzer's links with the diesel engine date back to 1879 when Rudolf Diesel, as a young engineer, followed up his studies by working as an unpaid workshop trainee at Sulzer Brothers in Winterthur, Switzerland. The first Sulzer-built diesel engine was started in June 1898. In 1905 the company built the first directly reversible two-stroke marine diesel engine and, five years later, introduced a valveless two-stroke engine with an after-charging system and spray-cooled pistons. Airless fuel injection was applied to production engines in 1932. and turbocharging from 1954. Sulzer came under the umbrella of the Wartsila Corporation in 1997, the Finland-based four-stroke specialist committing to continued development of low speed two-stroke engines. The current RTA programme, summarized in Figure 12.4, embraces nine bore sizes

262 Air flow characteristics of engine and turbocharger Two-stroke engines The air flow characteristics of a two-stroke engine will depend on whether the engine is fitted with a turbocharger alone or has an auxiliary scavenge pump or blower. Consider first the situation when a turbocharger is used on its own. During the period when the inlet ports are open, the exhaust ports or valves will also be open and the air flow rate will depend on the pressure drop between intake and exhaust manifolds. The physical arrangement is analogous to flow through two orifices placed in series. The mass flow versus pressure ratio characteristic for steady flow through two orifices in series is a unique curve and it follows that the two-stroke engine will exhibit a similar characteristic. Thus the engine operating line, when superimposed on the compressor characteristic will be a unique curve, almost regardless of engine load or speed (Figure 2.47). Fortunately the compressor characteristics are well suited to this type of demand, and it is...

91 Threeport twostroke engine

Elimination of the 'bottom loop' showing the exhaust and suction strokes. This bottom loop is replaced, of course, by the indicator diagram, shown at (b), obtained from the crank case or scavenge pump cylinder. There is no possibility of eliminating this pump work from either the four-stroke or the two-stroke cycle - in one case it is done in alternate revolutions in the main working cylinder, and in the other in every revolution in the scavenge pump cylinder. Indeed, the 'phased pump' type of two-stroke engine, of which a later example is the Trojan design as shown in Fig. 9.5, may be regarded as a V-twin four-stroke engine in which the positive work is concentrated in one cylinder and the negative pumping work is done in the other, instead of each cylinder doing half of both.

Common Rail Injection Systems

Common rail systems existed in the early 1900s in mechanically-activated form but the recent re-emergence of the concept in four-stroke and two-stroke engine applications reflected advances in reliable and cost-effective electronic controls, as well as developments in materials and manufacturing technology underwriting systems capable of handling pressures of 1500 bar and higher. The following advantages

242 Principles of constant pressure turbocharging

If the exhaust manifold volume is not sufficiently large, the 'blow-down' or first part of the exhaust pulse from a cylinder will raise the general pressure in the manifold. Since all cylinders are connected to the same manifold, it is inevitable (if the engine has more than three cylinders) that at the moment when the blow-down pulse from one cylinder arrives in the manifold, another cylinder is nearing the end of its exhaust process. The pressure in the latter cylinder will be low, hence any increase in exhaust manifold pressure will impede its exhaust process. This will be particularly important where the cylinder has both inlet and exhaust valves or ports partially open and is relying on a through-flow of air for scavenging the burnt combustion products. A rise in exhaust manifold pressure at this time is virtually inevitable in an engine with more than three cylinders, unless the volume is large. This will be particularly important on a two-stroke engine, since if the exhaust...

10212 Air Standard Otto Cycle

SI engines can be four-stroke or two-stroke engines. Two-stroke engines run on the two-stroke Otto cycle, where the intake, compression, expansion, and exhaust operations are accomplished in one revolution of the crankshaft. The two-stroke cycles are used in smaller engines, such as those used in motorbikes. Most SI engines, or gasoline engines as more commonly known, run on a modified Otto cycle. The air-fuel ratio used in these engines is between 10 1 to 13 1. The compression ratios are in the range of 9 to 12 for most production vehicles. The compression ratio of the engine is limited by the octane rating of the fuel. If the octane number of the fuel is too low, a high compression ratio may lead to auto-ignition of the air-fuel mixture during compression, which is completely undesirable in a SI engine. SI engines were originally developed by limiting the amount of air allowed into the engine using a carburetor. The carburetor is the throttling valve placed on the air intake....

243 Principles of pulse turbocharging

A typical example illustrating the gain in available exhaust gas energy when employing narrow pipes is shown in Figure 2.21. This test data was obtained on a single cylinder, loop-scavenge, high speed two-stroke engine with three types of exhaust manifolds, a compact volume (pipe diameter pipe length) and two narrow pipes (pipe area cross-section port area ratio of 1.78 and 1.03). All the tests refer to the same engine speed, b.m.e.p., boost pressure, air flow rate and turbine area. The main diagram shows how turbine available energy varies with exhaust pipe volume (non-dimensionalized over datums of available energy if manifold volume equals half of cylinder volume), for all three manifolds. Note that increasing exhaust manifold volume by a factor of 5 halves turbine available energy. It is also interesting to note that there is little difference between the three types of manifold (volume or long narrow pipe) provided that their volumes are equal. The top set of diagrams shows the...

Low speed engines introduction

Low speed two-stroke engine designers have invested heavily to maintain their dominance of the mainstream deepsea propulsion sector formed by tankers, bulk carriers and containerships. The long-established supremacy reflects the perceived overall operational economy, simplicity and reliability of single, direct-coupled crosshead engine plants. Other factors are the continual evolution of engine programmes by the designer licensors in response to or anticipation of changing market requirements, and the extensive network of enginebuilding licensees in key shipbuilding regions. Many of the standard ship designs of the leading yards, particularly in Asia, are based on low speed engines. Evolution decreed that the surviving trio of low speed crosshead engine designers should pursue a common basic configuration two-stroke engines with constant pressure turbocharging and uniflow scavenging via a single hydraulically-operated exhaust valve in the cylinder head. Current programmes embrace...

Diagram Time-area Scavenging

The treatment in this section of port areas and timings can only be approximate since most two-stroke engines are now supplied with pressurized air by turbochargers. As mentioned earlier for turbocharged four-stroke engines, the exhaust and scavenge systems are likely to have marked wave effects in them, initiated in part by the sudden port openings. Depending on the arrangement of the exhaust pipes used to connect with the exhaust turbine of the turbocharger, their diameter and length and the nozzle ring area in the turbine, significant dynamic wave-like pressure variations can occur. In the case of the two-stroke engine, particularly, these waves can influence the scavenging process. Figure 9.21 shows a diagram of port opening, plotted vertically, against crank angle for a relatively small high speed two-stroke engine. Timings are with respect to piston BDC. During the period marked A the exhaust ports alone are open and the cylinder contents discharge to exhaust. Depending on the...

Doxford low speed engines

The last British-designed low speed two-stroke engine the distinctive Doxford opposed-piston design was withdrawn from production in 1980 but a few of the J-type remain in service and merit description. In its final years the company also designed and produced the unusual three-cylinder 58JS3C model, which developed 4050 kW at 220 rev min and was specified to power several small containerships. The 58JS3C design (Figure 14.16) was based on the J-type but with refinements addressing the higher rotational speed and relatively short piston stroke.

6 Engine and plant selection

In the past the shipowner or designer had the straight choice of a direct-coupled low speed two-stroke engine driving a fixed pitch propeller or a geared medium speed four-stroke engine driving either a fixed or controllable pitch (CP) propeller. Today, ships are entering service with direct-coupled (and sometimes geared) two-stroke engines driving fixed or CP propellers, geared four-stroke engines or high medium speed diesel-electric propulsion plants. Diverse diesel-mechanical and diesel-electric configurations can be considered (Figures 6.1 and 6.2).

152Generation of electrical power

There are two basic cycles, the two-stroke and four-stroke, each of which is illustrated in Figures 15.1 and 15.2 with their appropriate indicator diagrams. The two-stroke engine is mechanically simplified by the elimination of the mechanically operated valves. For the same rotational speed, the two-stroke engine has twice the number of working strokes. This does not, however, give twice the power. In the down-stroke of the two-stroke cycle both the inlet and exhaust ports are cleared, which allows some mixing of fuel air charge and exhaust gases, resulting in less thrust. For similar reasons, this also gives the two-stroke engine slightly higher fuel consumption.

10213 Air Standard Diesel Cycle

The nominal range of compression ratios in CI engines is 13 1 to 17 1, and the air-fuel ratios used lie between 20 1 and 25 1. The higher compression ratio aided by the work produced during combustion results in higher efficiency in diesel engines compared to gasoline engines. Efficiencies in diesel engines can be as high as 40 . The diesel engine has a lower specific power than the gasoline engine. Diesel engines also have a broad torque range, as shown in Figure 10.9.

910Compressionignition twostroke engine

This factor, combined with the unidirectional scavenge with cool air over piston head and valves, appears to have justified the development work that has been devoted over the years to the port scavenge, poppet valve exhaust two-stroke engine, which attained a considerable degree of success.

Fuel injection

The function of the fuel injection system is to provide the right amount of fuel at the right moment and in a suitable condition for the combustion process. There must therefore be some form of measured fuel supply, a means of timing the delivery and the atomisation of the fuel. The injection of the fuel is achieved by the location of cams on a camshaft. This camshaft rotates at engine speed for a two-stroke engine and at half engine speed for a four-stroke. There are two basic systems in use, each of which employs a combination of mechanical and hydraulic operations. The most common system is the jerk pump the other is the common rail.

Section Aa Pulse turbocharging of two-stroke engines The effectiveness of scavenging is the key to successful and efficient operation of the two-stroke engine. It has also been shown that, with the constant pressure system, the turbocharger is not self-supporting at low engine load. During the scavenge period the piston of the two-stroke engine moves only slightly and hence no work is done by the piston that could be utilized to supply energy lacking in the exhaust system. Turbocharging with the pulse system provides a large proportion of pressure energy during the blow-down period to the turbine and very effective scavenging at part load operation. This is achieved by keeping the exhaust manifold volume as small as possible and avoiding long pipes which could cause pulse reflections that interfere with scavenging. Thus two-stroke engines operating with the pulse system have turbochargers fitted very close to the cylinders, one turbocharger serving only two or three cylinders. major...

Twostroke Engines

Compared with four-stroke engines, the application of pressure charging to two-stroke engines is more complicated because, until a certain level of speed and power is reached, the turboblower is not self-supporting. Two-stroke engine turbocharging is achieved by two distinct methods, respectively termed the 'constant pressure' and 'pulse' systems. It is the constant pressure system that is now used by all low speed two-stroke engines. Figure 7.2 shows the variation in rotational speed of a turboblower during each working cycle of the engine, i.e. one revolution. This diagram clearly illustrates the reality of the impulses given to the turbine wheel. The fluctuation in speed is about 5 per cent. Each blower is coupled to two cylinders, with crank spacing 135 , 225 . It is now standard practice to fit charge air coolers to turbocharged two-stroke engines, the coolers being located between the turbochargers and the cylinders (Figure 7.3).

Engine Type

After the application has been defined and the welding process has been selected, the next step is to choose the engine. Diesel, gasoline or liquid propane gas (LPG) are the choices. A diesel engine offers better fuel economy than a gasoline engine, and diesel fuel does not ignite as easily as gasoline. Refineries almost always require diesel-fueled machines rather than gasoline-fueled machines. Another consideration for large jobs is whether the fuel is being supplied at the job site. If so, it is usually diesel, but whatever the fuel, the cost savings will usually determine the engine choice. Gasoline engines are sometimes preferred in cold weather climates because they start more easily without extra starting aids, such as ether start kits and winterized fuel for colder weather.

Fuel Systems

Gasoline Gasoline is used primarily with standby pumping units. Inasmuch as the spark ignition system first introduced the internal combustion engine to power applications, gasoline was used as the primary fuel. Commercial gasoline has an average heating value of 19,000 Btu lb (44.2 MJ kg). It is easy to transport and handle and, unlike gaseous fuels, does not require pressure storage and regulating equipment. The starting capabilities of a gasoline engine are satisfactory, provided the engine is in good operating condition. With the high-power engine of today, refinery control can produce a fuel matched to the operating conditions. Gas A gaseous fuel system using natural gas, LPG, or sewage gas may be a simple manually controlled system, such as a gasoline engine, or a carefully engineered automatic system. The basic gas carburetion system consists of a carburetor and pressure regulator mounted on the engine. A gas distribution system, like a water supply system, must be at some...

Problems Solutions

Problem Slabs of marble weighing 250 lb. are to be loaded and unloaded from a flat bed truck at the rate of one per minute. Vacuum will be used to protect the surface of the slabs. Since it will be mounted on the truck, the vacuum lifter is to be powered by a gasoline engine. A manufacturer of vacuum lifting devices is contacted. 7. The pump chosen must be large enough to compensate for a potential leak of this amount and still draw a vacuum of 20 in. Hg on the remaining cup. Table 15 indicates that a separate drive Gast Model 2065 (5.0 cfm at 20 in. Hg) will do the job and can be driven by belt from the gasoline engine.

To Atmosphere

Load Unload Cycling - An electrical pressure switch can also be used to provide overpressure protection when it is not possible or advisable to start and stop the drive unit (Fig. 26). Examples are compressors driven by gasoline engines or power takeoffs. Air compressors are furnished with or without an integrally mounted motor (Fig. 27). This allows the compressor to utilize whatever power may be available. For example, a separate gasoline-engine drive may be required in a remote outdoor location where there is no electric power. Separate-Drive Compressors -These units are used in applications requiring drive by variable step-down belt drive systems, or by power secured from power takeoffs, gasoline engines, or special electric motors. The drive unit and compressor are generally connected either by a flexible coupling or by a drive pulley containing a built-in cooling fan.

Working Cycles

A diesel engine may be designed to work on the two-stroke or on the four-stroke cycle both of these are explained below. They should not be confused with the terms 'single-acting' or 'double-acting', which relate to whether the working fluid (the combustion gases) acts on one or both sides of the piston. (Note, incidentally, that the opposed piston two-stroke engine in service today is single-acting.) Figure 1.6 shows the sequence of events in a typical two-stroke cycle, which, as the name implies, is accomplished in one complete revolution of the crank. Two-stroke engines invariably have ports to admit air when uncovered by the descending piston (or air piston where the engine has two pistons per cylinder). The exhaust may be via ports adjacent to the air ports and controlled by the same piston (loop scavenge) or via piston-controlled exhaust ports or poppet exhaust valves at the other end of the cylinder (uniflow scavenge). The principles of the cycle apply in all cases.

Rl Type Engines

The RLA56, a small bore two-stroke engine introduced in 1977, incorporated the basic design concept of the successful RND and RNDM series but extended the power range at the lower end. This engine, of comparatively long stroke design, was the first model in the RLA series. It retained many of the design features of the then most recent economical loop-scavenged RLB type (Figures 12. 36 and 12.37), both engines using many features of the earlier RND-M series.

Air lock

Air-fuel mixture mech eng In a carbureted gasoline engine, the charge of air and fuel that is mixed in the appropriate ratio in the carburetor and subsequently fed into the combustion chamber. 'er 'fytil .miks-chsr air gage eng 1. A device that measures air pressure. 2. A device that compares the shape of a machined surface to that of a reference surface by measuring the rate of passage of air between the surfaces. 'er .gaj air gap electr 1. A gap or an equivalent filler of nonmagnetic material across the core of a choke, transformer, or other magnetic device.

Fourstroke cycle

Four Stroke Diagram

Consider the piston at the top of its stroke where fuel injection and combustion have just taken place (Figure 2.3(a)). The piston is forced down on its working stroke until it uncovers the exhaust port (Figure 2.3(b)). The burnt gases then begin to exhaust and the piston continues down until it opens the inlet or scavenge port (Figure 2.3(c)). Pressurised air then enters and drives out the remaining exhaust gas. The piston, on its return stroke, closes the inlet and exhaust ports. The air is then compressed as the piston moves to the top of its stroke to complete the cycle (Figure 2.3(d)). A timing diagram for a two-stroke engine is shown in Figure 2.4.

Cooling Systems

FIGURE 5A Gasoline engine performance curves (A) maximum, (B) intermittent, (C) continuous ratings of engines with accessories (Waukesha Motor) FIGURE 5A Gasoline engine performance curves (A) maximum, (B) intermittent, (C) continuous ratings of engines with accessories (Waukesha Motor) Specific data and recommendations on cooling requirements vary from one manufacturer to another. In general, the heat rejection to an engine cooling system will range between 30 to 60 Btu hp min (25 to 51 MJ kWh) for diesel engines and up to 70 Btu hp min (59 MJ kWh) for natural gas and gasoline engines. This heat must be transferred to some form of heat-exchange medium.

Ships Service Pumps

Some vessels also carry portable fire pumps that can be moved throughout the vessel by the crew. A typical portable unit consists of a single-stage end-suction centrifugal pump that is close-coupled to a gasoline engine. An integral vacuum priming pump is often included with a portable unit to enable the fire pump to be used in areas of the vessel that are above the waterline.

Blower Surge

If one cylinder of a two-stroke engine should stop firing, or is cut out for mechanical reasons, when the engine is running above say 4050 per cent of engine load, it is possible that the turboblower affected may begin to surge. This is easily recognized from the repeated changing in the pitch of the blower noise. In these circumstances the engine revolutions should be reduced until the surging stops or until firing can be resumed in all cylinders.

Special Applications

Systems for Units Driven by Gasoline or Diesel Engines An automatic priming system using motor-driven vacuum pumps can be used for centrifugal pumps driven by diesel engines if a reliable source of electric power is available in the station. An auxiliary vacuum pump driven by a gasoline engine might be desirable for emergency use in case of electric power failure. Alternatively, a direct-connected wet vacuum pump with controls similar to those used in motor-driven automatically primed units is very satisfactory. The choice of the priming device for a gasoline-engine centrifugal pump depends on the size of the pump, the required frequency of priming, and the portability of the unit. Most portable units are used for relatively low heads and small capacities, for use in pumping out excavations and ditches, for example. Self-priming pumps of various types are most satisfactory for this service and are preferable to regular centrifugal pumps. It is possible to utilize the vacuum in the...

Fixed Sleeve Method

Parallel with the development of the Instantaneous IMEP method, a derivative of moveable bore methods termed the Fixed Sleeve method has been developed. To date this has been implemented on a 4.1 liter gasoline engine (7). Figure 13 shows a cross section of the Fixed Sleeve design. The original 4.1 litre engine liner which had an 88 mm bore is fitted with a smaller 80 mm sleeve which is attached to the outer liner by a pair of jam nuts located at the bottom of the assembly. Piano wire in tension is used near the top of the assembly to pilot the inner sleeve so that it does not touch the outer liner. O-rings are used to seed combustion gas, water and oil. Cooling water is permitted to circulate between the two sleeves. Strain gauges are mounted on both inner and outer surfaces of the necked-down section near the bottom of the outer liner.