Group 10 2011 Gate 3: Product Analysis

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Preliminary Project Review

Cause for Corrective Action

At this point we have resolved all of our initial issues by adhering very closely to our planning schedule and work flow. By delegating all tasks promptly and specifically, those who were not able to make group meetings were still able to complete the necessary work on time and with acceptable accuracy and validity. We plan on continuing the progression to be even more organized by making even more detailed schedules and project assignment lists.

Product Evaluation

Component Summary

Name Number of Times Used Material Manufacturing Process Function Available Part Number Picture
Air Cleaner Housing Cover 1 Plastic Injection Molding Channels air into the air cleaner element.
Air Cleaner Element 1 Plastic Fibers Rolling/Folding Filters impurities and debris out of the channeled intake air.
Air Cleaner Base 1 Plastic Injection Molding Encloses the air cleaner element and directs the filtered air into the air chamber.
Air Cleaner Screws 7 Steel Forging Fastens the air cleaner housing cover to the air cleaner base.
Air Chamber 1 Plastic Injection Molding Connects the air cleaner base to the carburetors and houses the air intakes.
Air Intake 4 Aluminum Forging/Machining Channel air from the air cleaner assembly into each individual carburetor.
Air Chamber Screw 16 Steel Forged Fastens the air chamber to the carburetors
Throttle Cable 1 Steel/Rubber Injection Molding/Pulling Sends throttle position input to throttle linkage.
Carburetor Insulator 4 Rubber Injection Molding Seals the connection between the output of the carburetor and the cylinder head.
Carburetor Fuel Tube 2 Plastic Injection Molding Supplies fuel to each carburetor.
Starting Enrichment Valve Cable Holder 1 Aluminum Machining Transfers motion of the throttle cable to the carburetors.
Starting Enrichment Valve 4 Brass Machining Control the air/fuel mixture in the carburetor.
Starting Enrichment Valve Spring 4 Steel Rolled Regulates the movement of the enrichment valve.
Starting Enrichment Valve Nut 4 Steel Forging/Machining Fasten the enrichment valve to the carburetor.
Thrust Spring 3 Steel Rolling Connects each carburetor so that the opening of every butterfly valve is synchronized with the starting enrichment valve cable holder position.
Air Vent Pipe 3 Rubber Injection Molding Distributes incoming air evenly between each carburetor.
Fuel Joint Pipe 2 Plastic Injection Molded Distributes incoming fuel evenly between each carburetor.
Vacuum Chamber Cover 4 Plastic Injection Molded Seals the carburetor from the environment.
Vacuum Chamber Cover Screws 12 Steel Forged Fastens the cover to the carburetor.
Diaphragm Spring 4 Steel Rolled Provides tension to regulate the movement of the diaphragm/vacuum piston.
Diaphragm/Vacuum Piston 4 Rubber/Plastic Injection Molded Regulates the amount of fuel allowed to enter the vacuum chamber.
Jet Needle Spring 4 Steel Rolling Provides tension to regulate the movement of the jet needle
Jet Needle Holder 4 Plastic Injection Molding Holds the jet needle assembly in place inside of the diaphragm/vacuum piston.
Jet Needle 4 Steel Extrusion/Machining Regulates the amount of fuel that is allowed to enter carburetor based on the position of the diaphragm/vacuum piston.
Float Chamber 4 Aluminum Die Casting Seals the bottom of the carburetor containing the float assembly.
Float Chamber Screw 12 Steel Forging Fastens the float chamber to the carburetor.
Float 4 Plastic Injection Molding Regulates the fuel pressure inside the carburetor.
Float Pin 4 Steel Machining Connects the float to the float chamber.
Main Jet 4 Brass Machining Injects fuel into the carburetor during open throttle.
Slow Jet 4 Brass Machining Injects fuel into the carburetor during idling.
Valve Cover 1 Aluminum Die Casting Protects all of the components inside of the cylinder from external debris while sealing lubricants inside. W428
Valve Cover Breather Tube 1 Rubber Injection Molding Provides a way for excess gases to escape the cylinder head.
Valve Cover Bolt 6 Steel Forging Fastens the valve cover to the cylinder head
Valve Cover Gasket 1 Rubber Injection Molding Provides an impenetrable seal between the valve cover and the cylinder head.
Camshaft Holder 2 Aluminum Die Casting Seat the camshafts in their proper locations within the cylinder head.
Camshaft Holder Bolt 20 Steel Forging Fasten the camshaft holder to the cylinder head.
Cam Sprocket 2 Steel Machined Connects the camshaft to the timing chain and advances or retards cam timing.
Cam Sprocket Bolt 4 Steel Forging Fasten the cam sprocket to the camshaft.
Camshaft 2 Steel Machining Opens and closes the intake and exhaust valves.
Cam Chain Tensioner 1 Aluminum Die Casting/Machining Provides the tension needed for the cam chain to operate correctly.
Cam Chain Tensioner Slider 1 Plastic Injection Molded Guides the cam chain from its connection to the crankshaft through the block to the cam sprocket.
Cam Chain 1 Steel Machining/Pressing Transfers rotational energy from the crankshaft to the cam sprockets in order to spin the cam shafts.
Spark Plug 4 Ceramics/Steel Die Casting/Extrusion/Machining Initiate combustion of the air/fuel mixture inside the cylinder via an electric spark.
Valve Lifter 16 Steel Machining Changes the position of the valves based on the rotation of the cam shaft lobes.
Intake and Exhaust Valves 16 Steel Alloy Turning/Machining Regulate the amount of air and fuel that enter and exit the combustion chamber.
Cylinder Head Bolt 10 Steel Forged Fastens the cylinder head to the block.
Cylinder head 1 Aluminum Die Casting/Machining Houses the valve-train and closes the top of the cylinder, forming the combustion chamber.
Head Gasket 1 Steel Composites Die Casting/Cutting Seals the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders.
Piston 4 Aluminum Alloy Die Casting transfers force from expanding gas in the cylinder to the crankshaft via the connecting rod.
Piston Pin 4 Steel Machining Provides a smooth and free moving connection between the piston and the connecting rod.
Connecting Rod 4 Steel Forging Connects the piston to the crankshaft in order to convert linear motion into rotational motion.
Connecting Rod Bearing 8 Aluminum Machining Provides a nearly friction-less contact between the connecting rod and the crankshaft.
Connecting Rod Bearing Cap 4 Steel Forging Fastens the Connecting rod to the crankshaft.
Connecting Rod Bearing Cap Nut 8 Steel Forging/Machining Fastens the connecting rod bearing cap to the connecting rod.
Crankshaft 1 Steel Forging Translates reciprocating linear piston motion into rotation.
Flywheel 1 Steel Forging/Machining
Timing Sprocket 1 Steel Machining Provides a connection for the cam chain on the crankshaft.
Cylinder Block and Upper Crankcase 1 Aluminum Dies Casting/Machining Houses the connecting rod/piston assembly as well as the coolant passages, intake and exhaust passages, and ports.
Lower Crankcase 1 Aluminum Forging/Machining Houses the transmission and crankshaft.
Right Crankcase Cover and bolts 1/8 Aluminum/Steel Die Casting/Forging Encloses the clutch in the crankcase.
Oil Filler Cap/Dipstick 1 Plastic/Steel Injection Molding/Forming Indicates the engine oil level.
Clutch Lifter Piece 1 Steel Machining Holds the clutch lifter arm in position.
Clutch Lifter Arm 1 Steel Machining Controls the position of the clutch.
Clutch Lifter Plate 1 Steel Machining Fasten the clutch springs to the clutch center, keeping the springs under tension.
Clutch Lifter Bolt 4 Steel Forging Fasten the lifter plate to the clutch center.
Clutch Spring 4 Steel Rolling Damp gear rattle while idling.
Clutch Center 1 Aluminum Die Casting Secure the clutch discs and plates inside the clutch outer.
Clutch Plates and Discs 8 Each Steel Machining Distribute varying loads of friction and rotational energy depending on the position of the clutch.
Clutch Pressure Plate 1 Steel Machining Pushes the clutch disc against the clutch outer, translating rotational energy from the crankshaft to the clutch assembly.
Clutch Outer 1 Aluminum/Steel Die Casting/Machining Houses the clutch plates and discs as well as connecting the clutch assembly to the crankshaft.
Needle Bearing 1 Steel Machining Reduces the friction between the rotating surfaces of the crankshaft and clutch outer.
Stopper Arm 1 Steel Machining Secures the shifter cam in place.
Stopper Arm Bolt 1 Steel Forging Fastens the stopper arm to the crankcase.
Stopper Arm Spring 1 Steel Rolling Regulates the movement of the stopper arm.
Gear Shift Spindle 1 Aluminum Turning/Machining Controls gear position based on gear selected by user.
Shifter Cam 1 Steel Machining Holds the shift drum in place and controls its motion.
Shift Drum Bearing 1 Steel Machining Provides a nearly friction-less contact between the shift drum and the shifter cam.
Shift Drum Bearing Set Plate 2 Steel Machining Secures the shift drum bearing against the shift drum.
Shift Drum 1 Steel Die Casting/Machining Rotates to move the the internal shift forks.
Shift Fork Shaft 1 Steel Turning/Machining Hold the shift forks in place within the crankcase relative to the shift drum.
Shift Fork 3 Steel Die Cast Moves back and forth, alternately disengaging from one gear and engaging another.
Main Shaft 1 Steel Turning/Machining Transfers rotational energy from the flywheel and holds one set of gears.
Counter Shaft 1 Steel Turning/Machining Transfers rotational energy from the main shaft and holds the second set of gears.
Transmission Gear 10 Steel Machining Manipulates rotational forces, based on ratios, of the output shaft.

Product Analysis

Product Complexity

Complexity will be evaluated for the manufacturing, implementation, and general form of the component. Manufacturing complexity is dependent on the time needed to complete a process, the cost needed to complete the process and the sophistication of the process itself. Manufacturing complexity will be measured on a scale from 1-5, in the order of increasing complexity. Here is an example of what can be expected at each extremity: very basic subtraction processes like sawing satisfy a 1, whereas photosensitive compounding processes like Jetting or Fused Deposition modeling are closer to a 5 due to their high costs and complicated processes.

Implementation complexity will be based on the function the component serves in the system. Complex functions will be defined as one that will be drastically compromised with even a small change or malfunction. Therefore, the exhaust manifold will be determined to be less complex than the camshaft as the exhaust manifold has little to no effect on its surroundings in the event of a malfunction, whereras a perfectly functioning camshaft is essential to engine performance. This scale will also be rated from 1-5 with increasing complexity.

For an engine, a low complexity rating can be misleading if it is located in place that can only be accessed by carefully handling engine vitals. Therefore, component form complexity will be determined based on factors outside of its function and production. For example, I would not consider a gear complex on its own, but when it rests on a spindle in a gearbox next to tens of other similar looking gears that are carefully ordered, and will not function in any other order, complexity may need to be reconsidered. By this understanding, the 1-5 scale, in order of increasing complexity will yield example extremities of an air filter at 1 and a transmission gear at 5.


The alternator is a component that is connected to the crankshaft in order to turn a small amount of the rotational mechanical energy of the crankshaft into electrical energy to power the electrical components of the vehicle and charge the battery. This electrical energy is used for tasks such as powering the electrical starter motor to start the engine, and the spark plugs which trigger ignition. As the alternator is attached to the crankcase, it is subject to the heat produced by friction and the vibrations of the moving components of the engine.

The component weighs 1 kg without the housing, which is due to the fact that it appears to be made mostly of copper. Copper is a very good, cheap conductor, which is most likely why this component utilizes this material. The conduction is required to generate electricity from rotation. The rotor appears to have a relatively fine finish, with some visible discoloration, and the wire on the exterior part of the rotor appears to be covered in a plastic to insulate it. An economic factor effecting the material selection of this product is the low cost of copper, while a societal factor effecting the design of this component is that the intended clients would have wanted a very compact engine design and this component is just large enough to produce enough electricity to power the required devices, yet still small enough to not be seen as a very large exterior component of the engine. Other than the small size of the housing and the covering of the exiting wires with rubber, this component is not meant to be a visible feature of the engine and is designed with this in mind.

The rotor itself seems to have been made with forging and finished with milling, as it has a fine finish and holes in a pattern around it, with rotational symmetry but not complete axial symmetry. The wire coils seem to have been made by drawing of copper to create long wires, as wires are usually made in this fashion. As with the chosen materials, the manufacturing processes used were probably dictated by the fact that the processes utilized were the lowest cost methods available to reduce the cost of the component and the overall machine to the customer, which is clearly influenced by the economic factor that customers will be more likely to buy a product if it has a lower price.

Based on the number of dimensions with significant features, the number of required manufacturing processes for production, and the moderate complexity of its function, this component is very complex. multiple processes.


The camshaft is an iron shaft about 35cm long and 2.5cm in diameter that features oblong lobes strategically placed and shaped to vary the valve openings allowing air into the engine block. In other words, it regulates the air entering the block (only the intake valve was examined). The camshaft receives the energy to operate in the form of rotational work transferred from the crankshaft by a chain and gear system. It is important to understand that the greater benefit of keeping the crankshaft and camshaft linked is that it ensures perfect engine coordination; as the crankshaft increases its rotational velocity, the camshaft rotational velocity increases at the same rate, ensuring that the energy (air) demand of the engine is always met.

The camshaft is rod-shaped, although not symmetrical because of the oblong lobes mounted along its axis. It is primarily 3-dimensional as it rotates through the x- and y-axes, and is mounted along the z-axis. The shape of the camshaft lobes determines the duration and extent of “lift” the intake valves experience during engine function. The lobes have a varied radius which means that during rapid rotation with a strong mounting, the lobes can press down in a rhythmic manner that is entirely dependent on the engine speed. The camshaft weighs between 3 and 5 kg, and is made of cast iron. Iron is both cheap and easy to acquire, without sacrificing much in the way of performance.

The camshaft was cast in iron and then machined and grinded until it had its intended shape. The casting is obvious after seeing the draft lines on the unfinished area, and the grinding was assumed after seeing the finish on the lobes. The lobe finish is crucial as physical contact between the camshaft and the lifters is constant and high friction will reduce efficiency. Grinding yields a uniformly smooth finish with little to no markings, whereas machining yields lines consistent with the direction of rotation during the subtracting process. Casting and grinding are two preferred processes for this application as casting can yield a very high output volume while still ensuring consistency from component to component. Grinding is a relatively simple process that may be more time consuming, but the finish is unparalleled, and given high volume production, the cost of the machinery necessary is marginal.

Manufacturing (2): Requires casting and grinding of a simple metal. Function (3.5): the camshaft controls the coordination and rhythm of the engine, a manufacturing flaw can compromise engine function easily. Form (3) The part itself is neither delicate or hard to get to, but its careful position in refererence to crankshaft position is essential to engine balance and smoothness


The crankshaft serves to transfer the linear work done by the expanding gases and upward/downward moving pistons to rotational work to be transferred to the flywheel and ultimately the wheels. In addition to this contribution, the crankshaft also transfers the same linear work of the pistons to rotational work to turn the cam chain to coordinate the opening and closing of valves. The crankshaft is housed underneath the engine block, completely enclosed. It partially rests in engine oil when the motorcycle is standing, and upon rotation helps lubricate many of the internals enclosed in the same housing.

The crankshaft is a widely recognized shape among engineers. It features radially symmetric rod journals that serve as mounting points for the connecting rods. The four (one for each cylinder) rod journals are located a perpendicular distance from the main journals which are in line with the axis of rotation of the crankshaft. Rod journals and main journals all lie within the same plane and each consecutive rod journal is mounted opposite the next one. All journals are roughly 2cm wide, 4cm in diameter, and the rod journals act at roughly 3cm from the axis of rotation. The crankshaft is 3-dimensional since the axis of rotation sweeps across the x and y axes with vertical forces acting along different points of third (z) axis.

The crankshaft is made by casting, and machining iron. The rough finish of the counterweight is an indication of the casting process; and the very smooth finish on the circular journals is an indication of a machining process. In addition to the visual cues, it is also logically consistent that the crankshaft was machined since imperfections in manufacturing can lead to substantial mechanical vibrations when rotating at high RPM. A machining process will ensure very precise dimensions, more so than other manufacturing processes for metal. Iron is both cheap and easy to acquire while still maintaining a high material strength, making it ideal for a mass-produced motorcycle. It may be important to note that given a more powerful engine, or a forced induction engine, cast iron may be replaced with forged steel to cope with the increased mechanical stress.

-Manufacturing (3) Made by casting, a relatively simple process, but followed by careful machining -Function (4) An imbalance or defective crankshaft will cause serious damage to your engine if not compromise it totally. -Form (4) The crankshaft is deep in the engine and requires a lot of knowledge and experience to remove it. Because of the counterweight system, it is also crucial to understand the balancing necessary for safe function.


The piston serves as a wall to transfer energy of the expanding gases to boundary work that propels the crankshaft. The piston operates and moves inside the cylinder walls of the engine block. It is largely unexposed and contained. The piston is cylindrical with a purposely shaped top and a hollow bottom with a mounting slot for the connecting rod. The piston is three-dimensional as it features radial symmetry across two axes and moves in the direction of a third axis. It is roughly 2.5-3in in diameter and stands about 1.5-2in tall. Its shape is driven entirely function; the “crown” on the top of the piston is curved to promote a better fuel atomization and better air/fuel mixing. These crowns control the movement of air and fuel entering the cylinder. The piston is hollow underneath to save weight, reducing the moving mass and therefore the mechanical resistance in the machine. Beyond the carefully machined finish, piston rings sit on the outer diameter of the piston wall to ensure a snug fit in the cylinder, improving the seal made and increasing thermal efficiency. The piston is made of aluminum, a lightweight metal to further reducing the moving mass. This will in turn improve fuel efficiency, increase power, and reduce the emission of harmful gases. The component was not made with aesthetics in mind as it is housed in the engine block and will most likely only ever be seen by a professional mechanic. The outer finish of the piston wall is very smooth to improve the seal between the piston and the cylinder wall.

The piston was made of cast aluminum-- the rough finish underneath is a good indication of the employed casting process. Aluminum can easily be used in casting, reducing manufacturing costs due to the high-volume production, and it satisfies the performance demands listed above. The decision to use cast aluminum was mostly an economically-minded decision, as lowered production costs with minimal performance losses (in fact, performance gains compared to iron) is a perfect compromise to enable lower consumer prices and better marketability.

Intake/Exhaust Valve

The intake/exhaust valves permit and deny the flow of gases into and out of the cylinders. The valves are activated in accordance with camshaft(s) movement and therefore receive both signal and energy from them. The lobes on the camshafts correspond to a “lifting” of the valves, opening the seal between the cylinder and head.

The valves are rods with a wide and flat bottom. They are axially symmetric, and are primarily two dimensional as they are symmetric about two axes. They are roughly 3in long with a 1in wide bottom and a upper diameter of about 0.25in. The wide bottom matches the dimensions of the respective intake/exhaust port with a chamfered tip to create a good seal. The wide bottom is achieved through a gradual increase in shaft diameter, promoting a less interrupted flow of gases. The component weighs only a few ounces and is made of stainless steel. It features a very smooth finish to improve air flow and is resistant to high temperatures to withstand the constant flow of exhaust gases. The valves were made using by some turning process, due to the axial symmetry and need for precision. Although turning processes require more time and attention, power and efficiency demands ultimately determined this choice as careful machining will ensure a good cylinder to head seal improving thermal efficiency and increasing power yielding to societal and environmental factors.


The transmission of the motorcycle is a component that transfers rotational energy from the crankshaft to the driveshaft. This component also changes gearing throughout operation to maintain an optimal rotational speed for the engine to operate at. It does this by changing the gear ratios between the crankshaft and the driveshaft. Because this component is so closely situated between the driveshaft and crankshaft, it must be able to handle mild vibrations and heat, and be capable of running at high rotational speeds up to the 10,000rpm attainable by the engine.

The transmission is made up of two rods with interconnecting gears on them. The rods are steel and about 1.5cm in diameter and 25cm in length, with gears ranging from 4cm in diameter to about 8cm in diameter. The rod and the gears are rotationally symmetric but not axially symmetry, as they have notches where the gears mesh. This rotational symmetry and notches directly relate to the function of the transmission, as the meshing of the gears is the mechanism by which rotational energy is transferred at varying ratios. There are no visibly unique aesthetic properties of this component, as it was not intended to be seen by the consumer, and the steel used for this component was most likely chosen due to its high durability, and its low cost compared to lighter materials such as titanium, an economic factor.

The gears appear to have been created by machining, due to the high surface finish needed and the very precise notch spacing needed. The rods themselves seem to be created in part by turning, as they are partially axially symmetric, and then machining to create the required notches in the rods. These processes would have been the only way to mass produce this product in a cost-effective manner, as rapid prototyping would be the only other viable option for creating these geometries and that would be much too expensive and slow, which is economically prohibitive. Even though this component requires precise manufacturing, the function is very simple, transferring rotational energy from one speed to another, and as such is not very complex compared to components that serve multiple functions or work on multiple scientific principles.

Valve Cover Gasket

The valve cover gasket provides an impenetrable seal between the valve cover and the cylinder head. This component helps to keep fluids inside of the engine from leaking as well as it keeps dirt and other grime out of the engine. The flows associated with this component are that of mass flows, such as the combustible gasses and lubricating oil. Since this component is in a motorcycle, the environment of which it is meant for is one of warm weather, but since it is not a mechanical piece of equipment it would be able to withstand pretty much any environment.

The valve cover gasket’s shape is a simple design that is meant to fit snug between the cylinder head and the valve cover. The design of the gasket is simple and has some symmetrical properties. It is a three dimensional part, and is approximately 14 inches by 8 inches by 1/2 inch. Its shape is coupled to its function because it is meant to fit tightly between the cylinder head and the valve cover, so it can perform its function. It has a weight of less than 1 pound. The material of the component is rubber, because it needs to be flexible in being able to seal any gaps that may be formed. The material makes the manufacturing process easy because it can quickly, cheaply, and easily be made. The global factor influencing the decision to make it rubber was that rubber is an easily obtained material and is very easy to work with in factories all over the world. The societal factor is that it needs to be able to be looked at as a reliable product by the consumer, so it needs to be made of a long lasting, durable material that will perform its function very well. The economic factor of using rubber for the material is that it is a very cheap material to use. Environmental factors influencing the decision on using rubber would be product life; a rubber gasket should last for many years. The product doesn’t really need to be aesthetically pleasing because it is inside of an engine, so as long as it works well it doesn’t need to be appealing to the eye. The color of the gasket is black because that is the color of the rubber used in making it. For functional purposes, the surface finish is that of a soft rubbery feel simply because it is made of rubber and needs to be able to stretch into gaps that may form.

The manufacturing process used for this product is injection molding. The excess material on the sides of the gasket is evidence supporting this. The material choice and shape both impacted the need for this manufacturing process because since it is able to use injection molding, it can produce these at high volumes and very cheaply. Global factors influenced this because it is a simple process to use injection molding and it is readily available worldwide. Economic factors influencing this are simply the mass production of the product, which makes cost of making the product very cheap. Environmental factors influencing this decision would be the idea of minimal waste from excess material.

Solid Modeled Assembly

The following 3D models were developed to further illustrate the complexity and precise designs required in the development of many of the Honda engines components. We chose to model the clutch assembly due to the importance of its function to the transmission and overall purpose of the engine. The 3D CAD program SolidWorks was chosen due to our prior experience and knowledge of the program, as well as the fact that it is a leading industry standard in 3D modeling.

                                                                  Clutch Lifter Plate
Clutch Lifter Plate
                                                                     Clutch Spring
Clutch Spring
                                                                     Clutch Center
Clutch Center
                                                                      Clutch Disc
Clutch Disc
                                                                      Clutch Plate
Clutch Plate
                                                                      Clutch Outer
Clutch Outer
                                                                    Clutch Assembly
Clutch Assembly

Engineering Analysis

One of the more important functions of the engine is developing the correct air/fuel ratio in the mixture that is sent into the combustion chamber. This is where engineering analysis becomes crucial in understanding what design features and testing methods were considered in the creation of the function.

The engineering analysis process would be used in the initial design and testing stages of the design process of the internal combustion engine. One factor of utmost interest in the design process of the engine would be that of the air-fuel intake ratio being used, while trying to create the maximum efficiency in the engine.

Problem Satement: The problem to be solved is that of creating the most efficient engine by using an ideal air-fuel mixture.
Figure 1: Combustion Cycle

System Diagram: See figure 1

Assumptions: It is known that maximum power is produced at 12000 rpm and the engine runs on gasoline and has a displacement of 599 cm2, with a bore of 4.52 cm, a stroke of 6.5 cm, and a compression ratio of 11.5. For our case of the air-fuel mix in the engine, we will assume that air is 21% oxygen by volume, the engine is at wide open throttle at maximum power, the air entering the engine through the carburetor at wide open throttle is at about the same pressure as the atmosphere, the pressure of air in the atmosphere is 100 kPa, the temperature of the atmosphere is 293K, gasoline is mostly octane (C8H18) and is an incompressible liquid with density of .703 g/mL, and the combustion chamber is completely filled during intake. Also assume that oxygen and air are ideal gases. Voxygen=.21Vair, Pair=100 kPa, Vchamber=Vair+Vgasoline, ρgasoline=ρoctane=.703 g/mL, 2C8H18+25O2 → 16CO2+18H20.

Governing Equations:

                           noctane=Moctane ρoctaneVoctane
                           R=8.3145 J/mol-K

The engineer would now use the equations to perform all of the necessary calculations that they need to, in order to find out what the best air-fuel ratio is. The engineer may have to use trial and error to determine the best air-fuel ratio.

After all of the calculations are made, it is time for the solution check. All of the units should be double checked, and the answer should also be checked to see if it is a reasonable value. The answer needs to be consistent with the units involved. If it is possible the efficiency that is calculated should be compared to an existing engine’s efficiency of a similar product, at best and worst case scenarios.

The final step in the engineering analysis process is the discussion of results. After the best ratio is determined, the designer of the engine needs to discuss the significance of the numerical answer, and asses the quality of the solution based on the assumptions that were made. Also, the sensitivity of the solution needs to be discussed, and the solution should be verified. The Engineer who designed the engine can now talk about the answer that was deduced after the solution check. After the engineer decides that they have found the best possible air-fuel ratio that yields the highest engine efficiency, they now can go back and try out different types of air intakes, different sizes or quantities of valves, or even different types of fuel. With the new ideas in mind, the Engineering Analysis Process then again starts over and needs to be shifted in order to fit the new constraints.

Design Revisions

Design Revision 1: Fuel Injection

The Honda CBR600F2 sport bike engine was designed to use carburetors to mix air and fuel to be used in the combustion process. The carburetor works on Bernoulli's principle: the faster air moves, the lower its static pressure, and the higher its dynamic pressure. The throttle linkage does not directly control the flow of liquid fuel. Instead, it actuates carburetor mechanisms which meter the flow of air being pulled into the engine. The speed of this flow, and therefore its pressure, determines the amount of fuel drawn into the airstream.

This is where fuel injection would make significant changes to the engine. The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure, while a carburetor relies on suction created by intake air rushing through a venturi to draw the fuel into the airstream. The benefits of using fuel injection as opposed to carburetors address all four factors of design consideration: global, societal, economic, and environmental concerns. In terms of societal benefits, fuel injection provides a smoother and more dependable engine response during quick throttle transitions, easier and more dependable engine starting, better operation at extremely high or low ambient temperatures, increased maintenance intervals, and increased fuel efficiency. This means that the comfort of use for the rider is improved and less money will be spent on maintenance and fuel. In terms of economic benefits, if mechanical fuel injection was to be implemented it would bring all of the improvements of modern technology while still being economically viable. The advantages would greatly outweigh the slightly increased manufacturing and raw material costs. In terms of environmental benefits, since fuel injection completely atomizes the fuel being injected into the combustion chamber, less fuel needs to be used. Exhaust emissions are also cleaner because the more precise and accurate fuel metering reduces the concentration of toxic combustion byproducts leaving the engine. The global benefits go hand in hand with the environmental benefits, as the engine would meet more strict international emissions standards.

Catalytic Converter

Emission concerns are seldom considered by motorcycle manufacturers—the EPA does not even rate motorcycles for fuel economy ratings. This means that motorcycles designers often don’t consider these factors and in fact, some motorcycles are even more harmful to the environment than some cars. Many harmful gases that a car removes before reaching the muffler are released into the environment by motorcycles, scot-free. The addition of a catalytic converter would be a wise addition to the motorcycle to help convert very harmful exhaust gases into much less harsh ones.