Group 18 - GM 2.2 Liter 4-Cylinder Inline Engine - Gate 3

Project Management: Coordination Review

Cause for Corrective Action

The members of Group 18 have been working together for six week and everything is going well except the materials that Group 18 submits into wiki page sometimes do not meet the requirement of the course. Group 18 always submits the work material into Wiki page at the last minute as it usually only gets done one night before the submission due date. As a result, we do not have enough time to double check the gate submission materials and end up missing a huge part of work that is required by the course. Group 18 took note of this when we got our results of the Gate 2 submission, where we scored only 14 out of 50 in the product dissection analysis.

The reason behind this is that 4 out of 5 of our group members are taking Junior level courses, and they each have assignments and group projects from other courses to juggle concurrently. Therefore, they did not have enough time to make sure that everything that was submitted to the Wiki page of Group 18 meets the demand by the course. To solve this problem, Group 18 decided to start on the next gate right after the previous gate. For example, we will start working on Gate 4 right after the submission of Gate 3. Besides that, we have assigned one of the group members to double check the work to make sure that we did not miss any part of the required work.

Product Archaelogy: Product Evaluation

Component Summary

Component Image	Component Name	Component Code	Material	Manufacturing Process	Function	Number of Parts
	Purge Solenoid	#DELPHI1997278	Plastic/Steel	Injection molding for the plastics; die casting for the steel parts; machining	This is a computer-controlled valve that prevents unused fuel vapors from escaping into the atmosphere while the engine is off. The vapors are stored in the charcoal canister system in the solenoid and are recycled into the combustion chamber when the engine is started.	1
	Oxygen Sensor	Not Available	Aluminum/Rubber	Drawing for the wire part; extrusion for the casing of sensor; drilling for the holes on the sensor	Detects the air-fuel mixture of by measuring the amount of oxygen in the exhaust gas. The date will be send to Engine Control Unit (ECU) for it to regulate the fuel amount needed for the engine.	1
	Crankshaft Position Sensor	Not Available	Steel/Plastic	Injection molding for the plastic; forging for the screw thread and the round metal part; stamped aluminum	Detects engine knock which occurs within a specific frequency and sends a voltage to the CDI. The CDI will then use the knock sensor to control the ignition timing.	1
	Engine Knock Sensor	# 10456209	Steel/Plastic	Injection molding for the plastic; forging for the screw thread and the round metal part, machine milling	Detects engine knock which occurs within a specific frequency and sends a voltage to the CDI. The CDI will then use the knock sensor to control the ignition timing.	1
	Engine Cover	#245772527	Aluminum	Die casting for the general parts; grinding for a smoother surface and accurate geometry	An aluminum cover that covers the engine head.	1
	Engine Head	#24576144	Aluminum	Die casting for the general body; drilling and milling for the final geometry and surface	Placed above the cylinders forming the combustion chamber and houses the valves, spark plugs and fuel injector.	1
	Engine Block	#2033-A3D	Steel	Die casting; drilling; grinding; milling	Houses the pistons and crankcase. It also has coolant, intake, and exhaust passages and ports.	1
	Belt Tensioner	#24574843	Steel/Plastic	Injection molding for the plastic wheel; die casting for the metal part	Increases belt tension to prevent belt loosening its grip on the sprocket.	1
	Engine Mounting Racket	#24575332	Steel	Die casting for the whole body; drilling for the holes on the part	Secures all pulleys in place.	1
	Engine Head Mounting Plate	#24576136	Aluminum	Die casting for the whole body; drilling for the holes in the body	Covers the coolant passage to prevent leakage.	1
	Piston Rings	Not Available	Steel	Rolling; milling	There are three piston rings and two compression rings which function as a compression sealing for the piston. Another ring is the oil control ring, which controls the supply of oil to lubricate the piston skirt.	16
	Piston	Not Available	Iron	Forging; milling	Compresses the air-fuel mixture before combustion occur, transfers explosion energy of air-fuel mixture to linear motion energy, and pushes out the exhaust gas to exhaust manifold.	4
	Crankshaft	#GMD-4618	Steel	Die casting for the general body; milling and grinding for the smooth surface finish and accurate geometry	Translates the reciprocating motion from the pistons into rotational motion.	1
	Crankshaft Holder	Not Available	Steel	Die casting; drilling for the holes on it	Holds the crankshaft in place in the crankcase.	5
	Belt Pulley	#10112371	Steel	Manufacturing process used; forging for the general body; drilling for the holes in the part	Connects to one end of the crankshaft. It is a belt and pulley system that provides power the electric generator and cooling system.	1
	Camshaft	#101012HB1	Iron	Forging; grinding	This component act as a "timer" for the valves (when to open and close) by pushing the lifter up.	1
	Camshaft Sprocket	#10198810	Steel	Die casting for the general body; milling and drilling for the holes and smooth gear surface	Acts as a physical connection towards the crankshaft through a steel chain.	1
	Lifter	Not Available	Steel	Forging for the general body part; grinding for the smooth surface	Transfers the signal (energy) from the camshaft to the rocker arm	8
	Push Rods	Not Available	Steel	Extrusion; milling	Transfers the energy from the lifter to the rocker arm.	8
	Rocker Arms	Not Available	Steel	Die casting for the body; drilling for the holes	Manipulates the valve pushing the valve and spring down and being push back up bring spring (closing and opening).	8
	Valve Spring	Not Available	Steel	Extrusion; milling	Manipulates the valve (closing and opening).	8
	Valve	Not Available	Steel	Extrusion; milling	Act as a “gate” to allow air-fuel mixture to enter the combustion chamber and seal the combustion chamber. It also allows the exhaust gas to escape from the combustion chamber to exhaust manifold.	8
	Exhaust Manifold	Not Available	Steel	Die casting; drilling	Expels exhausted gas from the engine safely to the exhaust pipe and eventually to the atmosphere.	1
	Oil Dipstick	Not Available	Aluminum/Plastic	Drawing for the stick; extrusion for the casing	Monitors the engine lubricant level.	1
	Oil Filter	Not Available	Foam/Magnet/Aluminum	Rolling for the “cup”; assembled using welding.	Filters dirty lubricant and expels clean lubricant.	1
	Oil Pump	Not Available	Steel/Aluminum	Die Casting	Pumps lubricant to all corners of the engine to maintain constant temperature and to decreases friction in the engine.	1
	Oil Sump	Not Available	Aluminum/Rubber	Die casting; drilling; milling	Acts as a reservoir to store excessive lubricant and the oil pump pumps the lubricant through the entire engine interior.	1
	Intake Manifold	Not Available	Plastic/Rubber/Aluminum	Injection molding; drilling; stamping	Evenly distributes air to each of the cylinders.	1
	Throttle Body	#C0967	Rubber/Steel/Plastic	Forging; drilling	Controls the amount of air flowing into the engine.	1
	Spark Plug	#25320502	Porcelain/Aluminum/Steel	Forging; extrusion; grinding	Creates electric spark to ignite compressed fuel.	3
	CDI Ignition Coil	Not Available	Aluminum/Copper/Rubber	Injection molding; drawing	Provides electricity to spark plug.	1
	Fuel Injector	Not Available	Aluminum/Copper/Rubber	Injection molding; extrusion	Injects fuel into combustion chamber.	1
	Coolant Tube	Not Available	Steel	Extrusion	Allows coolant to flow through engine to prevent overheating.	1
	Water Pump	#24576031JA	Steel/Aluminum/Plastic	Die casting; extrusion; drilling	Circulates water whenever engine is running.	1

Product Analysis

Camshaft

• Component Function:

The camshaft is used to lift the lifters and push rod which will then operate the intake valve and exhaust valve. As the camshaft spins, the lobes located on the camshaft will lift the lifters and push rod which will then open and close the intake and exhaust valves in time with the motion of the piston.

• Component Form:

The camshaft is primarily two dimensional as it has one long axis and there are eight lobes attached to it. It is about 3 feet long, 3 inches wide and 3 inches high. Each lobe is placed at different angle so that the valves open and close at the appropriate time. This component roughly weighs about 4 pounds. A mixture of alloys is used to produce this component. Economical factor influences the production of this component because a mixture of alloys allows this component to withstand wear and making the lobes harder. This component does not have an aesthetic purpose. The surface finish of this component is smooth to avoid as much friction as possible.

• Manufacturing Method:

Chill iron casting is used to produce this component. Evidence that shows this is the attachment of the lobes which are permanent to the camshaft. The material choice should have impacted this decision because a chilled alloy is much more resistance to wear and harder. Economical factor influences this decision because the production time required is fast and chilled iron casting is a good choice for high volume production.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 4 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Camshaft Sprocket

• Component Function:

The camshaft sprocket is attached to one end of the camshaft along with the timing belt and crankshaft sprocket. It is responsible for maintaining the timing between the crankshaft and the camshaft.

• Component Form:

The camshaft sprocket has teeth along the outside which allows it to link into the timing belt. It is primarily two dimensional. It is approximately 8 inches long, 0.5 inch wide and 8 inches high. This component roughly weighs about 2 pounds. It is basically made of aluminum. This component does not have an aesthetic purpose.

• Manufacturing Method:

Die casting is used to produce this component. The material choice should have impacted this decision because aluminum is strong, study and function for a long time without wearing down. Economical factor influences this decision because the production time required is fast and die casting is also a good choice for high volume production.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 2 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Lifter

• Component Function:

The lifter follows the lobes on the camshaft and pushes the pushrod to open and close the intake or exhaust valve. The lifter has a roller that provides optimum contact stresses with the lobes.

• Component Form:

It is primarily two dimensional. It is approximately 0.5 inch long, 0.5 inch wide and 2 inches high. This component roughly weighs about 1 pound. It is basically made of bronze. This component does not have an aesthetic purpose.

• Manufacturing Method:

Die casting is used to produce this component. The material choice should have impacted this decision because it helps prevent roller fatique. Economical factor influences this decision because the production time required is fast and die casting is also a good choice for high volume production.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 2 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Push Rod

• Component Function:

The pushrod is used to actuate the rocker arms by the camshaft and lifter.

• Component Form:

It is primarily two dimensional. It is approximately 8 inches long, 0.4 inch wide and 0.3 inches high. This component roughly weighs about 0.8 pounds. It is basically made of composite steel. This component does not have an aesthetic purpose.

• Manufacturing Method:

A grinding process is used to produce this component. The material choice should have impacted this decision because composite steel have long been the best engineered material for pushrods. Economical factor influences this decision because the production time required is fast and the precision is very good.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 2 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Rocker Arm

• Component Function:

The rocker arm conveys the movement form pushrod, lifter and the lobe on the camshaft to press down on the valve to open it.

• Component Form:

It is primarily two dimensional. It is approximately 6 inches long, 1.5 inches wide and 8 inches high. This component roughly weighs about 2 pounds. It is basically made of steel. This component does not have an aesthetic purpose.

• Manufacturing Method:

Die casting is used to produce this component. The material choice should have impacted this decision because steel rocker arms have a longer cycle life with higher ratios. Economical factor influences this decision because the production time required is fast and die casting is also a good choice for high volume production.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 3 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Valve

• Component Function:

The valve opens and closes to allow air in or exhaust out when the rocker arm conveys the movement to it.

• Component Form:

It is primarily two dimensional. It is approximately 2 inches long, 2 inches wide and 8 inches high. This component roughly weighs about 1 pounds. It is basically made of steel. This component does not have an aesthetic purpose.

• Manufacturing Method:

Manufacturing a valve requires a few processes such as CNC machining, grinding and surface treatment. The material choice should have impacted this decision because steel has been known as the best material for it. Economical factor influences this decision because the production time required is long and to ensure precision.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 2 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Valve Spring

• Component Function:

The valve spring ensure valve closure when the rocker arm is not conveying the movement from the push rod, lifter and lobes on the cam shaft.

• Component Form:

It is primarily three dimensional. It is approximately 1.5 inches long, 1.5 inches wide and 2.5 inches high. This component roughly weighs about 1.5 pounds. It is basically made of steel alloys. This component does not have an aesthetic purpose.

• Manufacturing Method:

Producing a valve spring requires a few processes such as piece hardening, low and high temperature process. The material choice should have impacted this decision because steel alloys have an exceptionally low force tolerances and relaxation that is required for the valve spring. Economical factor influences this decision because this long process helps improve material properties and increased residual compressive stresses.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 2 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Engine Cylinder Block

• Component Function:

An engine cylinder block has multiple functions. The first function is to act as housing for other components like crankshaft, pistons, and piston rods. The other function of the cylinder block is to ensure that the combustion of the air-fuel mixture can be carry out in a safe and closed environment.

• Component Form:

The general shape of the component is a rectangular block. It is designed with 4 holes aligned to fit pistons and piston rods. At the bottom, the shape is designed to fit with crankshaft. The dimension of the engine is approximately 2ft x 1ft x 2 ft (L x W x H). The approximate weight of it is around 100 lbs. The block is out of die casting with steel. Economic factor influenced with the usage of material as steel is durable therefore doesn’t need frequent maintenance. The product doesn’t have any aesthetic properties.

• Manufacturing Method:

The engine block is made using die casting methods. Die casting has been the preferred method by car manufacture to create engine block with a few reasons. First, steel can achieve high fluidity with enough energy and able to form any shape. Besides that, this engine is designed for mass production. Die casting is cheaper and preferred method for high volume production because it is cheaper, compare to other method such as investment casting or machining.

• Component Complexity:

The block is relatively simple it terms of complexity. The main design concern is the cylinder casing which must be as smooth as possible to reduce friction. It is also needed to be precise in geometry to ensure that there is no air leak for the air-fuel mixture to escape from the cylinder block.

Piston Rod/Piston

• Component Function:

Piston rod is used to join piston with crankshaft. For the piston, its function is to transfer the energy of air-fuel mixture to the crankshaft through piston rod. The piston and piston rod is function inside the cylinder block.

• Component Form:

The piston is generally in cup-cylinder shape. The top of the piston is smooth and flat to achieve maximum compression of the air-fuel mixture. A piston is weighed around 500 grams. Pistons are made by die forging, they take an alloy ingot and put it in a machine and press it towards the die and later on, subtractive process also take place to remove the excess material. The preferred material for pistons is steel. The component does not have any aesthetics purposes.

• Manufacturing Method:

Pistons are made by die forging, they take an alloy ingot and put it in a machine and press it towards the die and later on, subtractive process also take place to remove the excess material. Economic factors influenced this decision as piston must be able to endure the high temperature from air-fuel burning and also the force. Therefore, forging method is preferred since the component can be strengthen under this method.

• Component Complexity:

Pistons and piston rods are relatively simple in terms of shape. However, the geometry of the piston must be precise to be fitted in cylinder block otherwise the leakage of air-fuel mixture would happen.

Fuel Injector

• Component Function:

The fuel injector is attached to the cylinder block and has a main purpose in injecting fuel into the combustion chamber. The necessary amount of fuel flowing into the engine is controlled by the fuel injector.

• Component Form:

It weighs about 1 lb and has rough dimension of 15 inches long, 2.5 inches wide and 7 inches high. It is made of aluminum, rubber and copper and has no aesthetic purpose at all.

• Manufacturing Method:

High precision and ultra-precision machine tools such as diamond turning machines, diamond-milling machines, ultra precision grinding and lapping machines and high precision Electro-discharge machines are used to manufacture this component.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 3 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Capacitor Discharge Ignition (CDI)

• Component Function:

The capacitor discharge ignition (CDI) is the electronic ignition system used in this engine. The CDI uses capacitor discharge current output to fire the spark plugs. It work by storing energy in an external capacitor, which is then discharged into the ignition coil primary winding when required.

• Component Form:

Weighing 4 lb, the CDI consist of a block of 6 inches in length, 6 inches in width and 4 inches tall and a system of wires with a total length of 2.3 ft. It is made of aluminum, copper and rubber. The rubber in the CDI is used for insulating while the use of conductor should increase the efficiency of electricity flows. Similar to the fuel injector, the CDI has no aesthetic purpose.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 3 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Spark Plug

• Component Function:

The spark plug is an electrical device that is fitted into the cylinder head. Its function is to create electric spark to ignite the compressed fuel. The spark plug has an insulated central electrode which is connected by a heavily insulated wire to an ignition coil or magneto circuit on the outside forming a spark gap inside the cylinder.

• Component Form:

It weighs 0.11 lb and has a M12 size. It is manufactured from porcelain, aluminum and steel. The porcelain is used for insulating and the aluminum is used for ignition. Being positioned inside the cylinder head, the spark plug has no aesthetic purpose.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 2 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Throttle Body

• Component Function:

Being part of the air intake system, the throttle body controls the amount of air flowing into the engine. Its movements are directly in accordance to the driver accelerator pedal input.

• Component Form:

The throttle body has a 50mm diameter throttle plate and is made of rubber, steel and plastic. It has no aesthetic purpose.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 3 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Intake Manifold

• Component Function:

The intake manifold’s primary function is to evenly distribute air to each intake port in the cylinder head. It is connected to the engine head.

• Component Form:

It weighs 5.3 lb and is 16 inches in length, 12 inches in width and 12 inches in height. Made of plastic, rubber and aluminum, the intake manifold has no aesthetic purpose. The use of rubber prevents rust to the intake manifold.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 3 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Exhaust Manifold

• Component Function:

The exhaust manifold collects the exhaust gases from the four cylinders into one pipe and expels them from the engine safely to the atmosphere. It is also connected to the engine head.

• Component Form:

It is made of cast iron, weighs 10 lb and has dimensions of 14 inches by 5 inches by 2 inches. It has no aesthetic purpose.

• Component Complexity:

On a scale from 1 to 5, this component has a scale of 3 on complexity. An example for a scale of 1 is a nut and for a scale of 5 is the engine block. A nut is simple enough to produce, however, an engine block requires multiple processes to complete as there are holes and specific shape on it.

Solid Modeled Assembly

The CAD program that Group 18 used is the Pro/Engineer Wildfire by PTC. The reason we chose this program is because it is available on the lab computers in Furnas 1019. Besides that, Shinn Li and Yong Chyi Lim of Group 18 are taking MAE 377 this semester. Working on this solid models increased their experience in handling the CAD program.

The components that we chose to work on are: Rocker Arm, Push Rod and Lifter. We chose to recreate these components using a CAD program because the mechanism behind these components were astounding. A simple lifter is able to "lift" the push rod which then "pushes" the rocker arm that manipulates the valve (pushing the valve and spring down and being pushed back up). Thus, we decided to recreate these parts with a CAD program to look at a better assembly of the parts.

Figures 14 through 16 show the individual components, Figure 17 shows the assembly of the individual components, and Figure 18 shows the exploded view of the assembled components.

Figure 14: CAD View of a Lifter

Figure 15: CAD View of a Push Rod

Figure 16: CAD View of a Rocker Arm

Figure 17: CAD Assembly of Figures 14 through 16

Figure 18: CAD Exploded View of Figures 14 through 16

• A copy of the CAD files can be retrieved in the following link: (CAD Views)

Engineering Analysis

The crankshaft is the most important component in the engine; without it there would be no conversion of chemical energy to mechanical energy. The crankshaft is always spinning and has a radial movement. This may cause the crankshaft to be subjected to various forces such as stress and bending forces. Therefore, the material used must be able to withstand all the forces that might affect this component to function. Other than that, the material should be light too so that the crankshaft can obtain revolution without much loss of energy.

Problem Statement:

• What should be done to strengthen the crankshaft while the weight of the crankshaft fittingly commensurate so that obtaining a revolution is easy?

Diagram:

Assumption:

• Gravity is constant at 9.81 m/s²
• No friction

Equations:

• Total Force = mass x gravitational acceleration
• Total Moment = force x distance
• Normal Stress = force / area

Discussion:

• The main source of forces applied to the crankshaft is the product of pressure build-up in the combustion chamber acting on the top of the piston. This will, then, produce substantial bending, torsional moments, tensile, compressive and shear stresses on the crankshaft. Another source of force imposed on the crankshaft is piston acceleration. The combined weight of the piston, ring package, wristpin, retainers and the connecting rod are being continuously accelerated from rest to very high velocity and back to rest twice with each crankshaft revolution. Many of the common engine arrangements allow for complete balancing of these forces and moments by having certain angle of crankpin spacing. Steel alloy is typically used because it has the strength and hardness required.

Design Revisions

Figure 18: SOHC Engine Head Block

Figure 19: OHV Engine Head Block

The proposed main design is to replace the Overhead Valve (OHV) design with a Single Over Head Cam (SOHC) design. With this, there are three design changes that will need to be done to make sure that the SOCH design is complete.

The first design alteration is to remove the lifter and pushrod in the engine. Because the camshaft will be powered by a sprocket which is connected to the engine crankshaft with a belt. Therefore, push rods and lifters are not necessary and can be removed.

The second design alteration is to redesign the engine head block and cylinder block. For the engine head block, the position of valve and valve spring will need to be changed to V-shaped form to accommodate a camshaft in between them. Figure 18 and 19 shows an OHV engine head and a SOHC engine head.

Because the position of camshaft has changed, the cylinder block no longer needs to be fitted with the camshaft. Therefore, the cylinder block can be designed without creating a space for the camshaft.

The third design alteration is to add a belt to connect the camshaft sprocket to the crankshaft. An additional pulley might need to be attached to the crankshaft in order to rotate the camshaft sprocket.

The reason Group 18 proposed a SOHC engine is influenced by economic and environmental factors. By using SOHC layout, the camshaft lobes will be directly in contact with the rocker arms, unlike in OHV engine where the camshaft lobes have to transfer its energy to rocker arms through lifters and push rods. Therefore, pushrods and lifters can be eliminated and with less moving parts, the energy loss of the engine can be reduced and thus create a more efficient engine. For environmental concern, a more efficient engine can reduce emission. Besides that, a more efficient engine can also reduce the running cost and thus make it more economical for the user.

Furthermore, the SOHC design has less reciprocating mass than a OHV design, thus the engine can achieve higher revolution per minute (RPM). With higher RPM, the engine can create more horsepower even if the displacement is both the same. With this, a wider range of car model can share the same engine and the car manufacturer can reduce cost in developing more engines. With the cost of develop reduced, the vehicle can be sell at lower price and thus it’s economically beneficial for the user.