Group 18 - GM V-6 Engine

Members

• Brett Bowman
• Matthew Bradley
• Meredith Canty
• Derek Feld
• Andrew Ring

Gate 1: Request for Proposal

View our Request for Proposal:
Group_18_-_GM_V-6_Engine_Gate1

Gate 2: Preliminary Design Review

View our Preliminary Design Review:
Group_18_-_GM_V-6_Engine_Gate2

Causes for Corrective Action

The dissection of the GM V-6 Engine went very smoothly with a few minor problems. Our project plan worked out exactly as planned. The dissection took three weeks, and everyone was able to be at the lab on Wednesdays after class to work for an hour to an hour and half. The biggest challenge faced was setting up a time with the group thirty-four, and communicating with them at first. To overcome this, Meredith Canty from our group and Parth Kalia from group thirty-four exchanged emails since both are project managers. Both groups met at five on Wednesdays to work together on the dissection of the engine.

While dissecting the engine the groups realized that there were tools that needed to be acquired that were not offered in the lab to finish the dissection. The two tools needed were the pulley puller and the valve compressor. To get the tools needed, group thirty-four did not really offer any communication or effort into getting them. So it was left up to our group to find the tools. Andrew went to see if the Society of Automotive Engineers had the tools, and if we could use them. However, their tools were specially designed and could not be used, so Meredith tried to see if her father’s business had the tools. Her father’s business did not have them so Brett went home and got the tools needed to finish off the dissection.

Once we had the tools, the valve compressor was used to remove the valves. Then we went to use the pulley puller and realized the bolts were not long enough. To fix the problem, Brett and Derek went to Lowes to buy longer bolts. The bolts worked and the dissection was completed on Monday October 26th. For the small problems that did occur, every member was willing to help out and resolve it as fast as possible to get the dissection done in time. The group works very well together and there are no problem areas in the group.

Product Dissection Plan

The table below documents the procedure that was taken to dissect a GM V6 engine. Each step includes the part that is to be removed, which tool(s) will be used, and how difficult the step is on a scale of 1 to 5. Any additional concerns about removing the part are made in the "Notes" column.

Difficulty Scale

1	Quickly and easily removed by hand
2	Quickly and easily removed using tools
3	Easily removed, but time-consuming or repetitive
4	Required moderate force, skill, or special tools
5	Required excessive force and time

The Dissection Process

Step	Part Removed	Difficulty	Tools Used	Quantity / Size of Bolts Removed	Notes
1	Throttle Body	2	Socket Wrench	3 / 10mm
2	Electric Ignition	2	Socket Wrench	2 / 10mm
3	Upper Intake Housing	2	Socket Wrench	6 / 12mm	Fuel lines removed by hand
4	Intake Manifold	2	Socket Wrench	10 / 14mm
5	Valve Covers (2)	2	Socket Wrench	6 / 13mm
6	Exhaust Manifolds (2)	2	Socket Wrench	10 / 14mm
7	Heads (2)	2	Socket Wrench	26 / 13mm
8	Push Rods (12)	1	None	N/A
9	Plastic Lifter Covers (2)	2	Socket Wrench	4 / 10mm
10	Lifters (12)	1	None	N/A
11	Water Pump	2	Socket Wrench	4 / 14mm
12	Crank Pulley	2	Socket Wrench	2 / 14mm	There were supposed to be 3 bolts, but 1 was missing. The engine stand was rotated upside down after this step.
13	Oil Cooler	2	Socket Wrench	2 / 12mm
14	Oil Pan	2	Socket Wrench	12 / 12mm
15	Clamps connecting pistons to crankshaft (6)	3	Socket Wrench, Hammer	12 / 14mm
16	Harmonic Balancer	5	Pulley puller, Adjustable crescent wrench	N/A	This part was stuck and required a particular type of pulley puller, as well as excessive time and force to remove.
17	Camshaft Cover	2	Socket Wrench	5 / 6-point flange bolts
18	Camshaft Sprocket	2	Socket Wrench	3 / 13mm
19	Camshaft Mount	2	Socket Wrench	2 / T-20 torque bolts
20	Camshaft	1	None	N/A
21	Sprocket and Oiler Drive Gear	2	Socket Wrench	3 / 13mm
22	Oiler Mount	2	Socket Wrench	2 / T-20 torque bolts
23	Oiler	1	None	N/A
24	Flywheel	4	Socket Wrench	6 / 14mm	The flywheel had to be maneuvered around the engine stand.
25	Clamps holding crankshaft (4)	2	Socket Wrench	8 / 16mm
26	Crankshaft	1	None	N/A

Images through the Dissection Process

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Gate 3: Coordination Review

Component Summary

• Engine Block: The engine block is made out of Cast iron. This is because the block must be able to withstand extreme heat, extremely well. It is also cast iron because iron is cheap but durable and casting it is the easiest and most efficient way to produce it. Iron is also a good vibration dampener. The forces acting on the block when mounted are those of weight and vibration; however the vibration forces are negligible and cancel each other out. The block itself is not very complex, because after all it is just a piece of metal, but when looking a complete engine, all the various and meticulous holes and slots drilled turn it into a relatively complex piece of machinery. Although the block itself is casted, various parts on the block were machined to allow for seals and threaded holes, as well as smooth bold holes that are crucial to operation. The block itself houses the pistons, connecting rods, crankshaft, the intake/exhaust valves, and is the chamber in which the Otto cycle takes places; there is only one block for the engine. The model number stamped on the block reads: G096.

• Piston: The Piston on our engine is made out of casted then Machined aluminum. This is because the piston must be completely smooth on all surfaces to reduce friction and the casting process does not allow for this to take place. Also aluminum is a lightweight metal that can also withstand great heat and is durable. There are six pistons in total on our V-6 engine, each with a force of 184 pounds acting on it. The piston converts the energy of the combustion to the crankshaft, which in turn creates rotational force. The piston is a simple device; it does not contain any other moving parts other than the pin and rings. |
  

  

  Piston with rings, Connecting Rod

• Piston Rings: Piston rings are made of forged spring steel. Spring steel is made up of medium carbon steel, which has a high yield of strength and retains its shape after forces have been applied. The purpose of a piston ring is to seal the combustion chamber, and prevent the engine from burning unwanted oil. There are 2 piston rings per piston. (Totaling 12 rings per engine). Piston rings are extremely simple parts, and although aren’t complicated are important pieces of the piston.

• Connecting Rod: The Connecting Rods are die-casted and are made out of high carbon steel. These are Die-casted because it is easy to make and the majority of the part itself does not need to be completely smooth. However they are machined where the rod must be connected the piston head, as well as where the bottom clamp is bolted to the upper rod. The function of a connecting rod is to connect the piston to the rotating crankshaft. There are 6 connecting rods. (one for each piston)

Crankshaft
• Crank Shaft: The crankshaft is made out of die-casted steel. This is because it is simple and cheap to make, but still withstands great force. It is also machined where it is mounted to the block for friction-reduced rotation and where the connecting rods attach to it. The force exerted on the shaft at each connection to a piston is equal to 184 pounds and the torque is equal to 230 foot pounds (which we researched online). The shape of the crank shaft is specifically designed to use offset pivot points to convert the forces form the pistons and connecting rods to a rotational force. The complexity of the crank shaft is minimal, although its simplicity is the reason it has been so successful over the years.

• Camshaft: The camshaft of our engine is made from machined steel. The shaft must be machined because of the ever changing shape it posses and the need for friction-free usage. The shape of the shaft itself works in a similar fashion as the crank shaft, except the process is reversed. This is because it converts rotational force into 12 different linear forces which control the intake and exhaust valves. The torque acting upon is two times greater than that of the crank shaft due to the gear ratio from the crankshaft itself.

• Flywheel: The flywheel is made from machined steel and is used to maintain the momentum of the engine in between each piston firing (very quick). The shape of the flywheel is a wheel of large diameter with slots on the outside similar gears. It also has holes cut out from the center of it in order to reduce unused material to conserve weight and potentially increase inertia.

• Pushrods: The pushrods are made from machined steel. They extend the linear force of the lifters to control the opening and closing of intake and exhaust valves. |
  

  

  Oiler (pushrods visible)

• Timing chain: Made out of multiple links of machined steel, the chain transfers rotational energy from the crankshaft to the camshaft through a gear ratio. The steel chain is designed to be durable and easy to manufacture.

• Oiler/Oiler Gear: The oiler is made from die-cast steel. It is also machined at the ends where it rotates on the block. On one end there is a small gear which is connected to a gear running through the timing chain. The shape of the oiler is a rod with semi circles on opposite sides; this shape becomes a “paddle” which moves oil throughout the valve and camshaft assembly system to keep everything well lubricated.

• Lifters: The lifters are made from machined stainless steel. This is so the reduce friction and stay rust free. They are shaped like a small tube with a free rotating wheel which rides on the camshaft, converting rotational force to linear force to control the valves on the head.

• Water Pump: The water pump has a die-casted steel outer shell, which houses a machined steel gear pump. The water pumps purpose is to push coolant around the engine block, to keep the engine cooled down and running at a safe temperature which ensures efficiency. The pump is driven from a belt off of the crank pulley harmonic balancer.

• Intake Manifold: The manifold is made out of die casted steel, and is machined where the manifold is sealed to the engine block. It is made from steel because, steel is cheap and the manifold is not load bearing this not required to have high impact resistiveness. The purpose of this piece is to evenly distribute a fuel/air mixture to each of the 6 cylinders. This part must be specifically designed to deliver the correct air/fuel mixture. |
  

  

  Intake Manifold

• Exhaust Manifold: The exhaust manifold is a piece of die-casted steel. This is a system of tubes which delivers the exhaust components to the tailpipe and out of the vehicle. The Exhaust converts the 6 streams of exhaust from each cylinder to one main stream out of the car.

Oil Pan
• Oil Pan: The oil pan is made from a large piece of cast aluminum. This is aluminum because it is so large that aluminum is the only metal that would not become too heavy with heavy girth. Aluminum is also resistant to rust to ensure the pan to be long lasting since its under belly will be exposed to the road. The purpose of this piece is to house the majority of the oil to lubricate the engine.

• Harmonic Crankshaft Balancer: This is made out of two machined- steel pieces (circular) separated by a rubber ring. When the crankshaft spins, the inner ring of the balancer spins with it, and the outer ring resists acceleration due to the rubber ring. This then in tern reduces vibration of the crankshaft. The object itself is not complex however its purpose is one that could be described with extremely complex physical laws. The torque on this piece is equivalent to the torque on the engine as a whole (230 lb-ft.).

• Distributer: The distributor is a device that takes the high voltage electricity from the ignition coil, and routes it to the spark plug in the proper firing sequence. The cap of the distributor is made of molded plastic; and inside lies a steel rotating shaft. When the rotor spins, current jumps between small gaps in the shaft to the contacts that run from the distributor to the spark plugs. The rotational motion for the distributor is supplied by the camshaft so the piston location is synchronized with firing time.

Design Revisions

• The GM V6 4300 Vortec engine is one that is typically used in SUVs or pickup trucks, so the target audience for this engine would be looking into power and performance of their vehicle. One way to get a boost in power out of this engine is to perform a procedure called “port and polish” to the air intake manifold component. This procedure involves using a dremel tool to sand down the side walls of the throttle body and using a polishing wheel with a chrome or metal finish to give the surface a smooth, glass-like finish. Making this surface smoother reduces air friction during the intake stroke of each piston. Reduced air friction means more efficient air intake is occurring and therefore a greater rate of combustion takes place in each piston. Increased combustion leads to an increased power output from the engine.

• Another design change could be to change the material of the engine block. The engine block is currently made out of cast iron which is very heavy and adds most of the weight to the car. To make the car weigh less and perform better a different type of material would work better. Using aluminum for the engine would affect the horsepower which is what the target audience is concerned about. Also, by making the car lighter the fuel efficiency would be improved. Everyone is concerned about fuel efficiency is this economy. Finally, aluminum improves heat dispersion, so the engine is less likely to over-heat.

• One last design change could be to increase the compression ratio, which would increase the power and efficiency of the engine. A way to increase the compression ratio is to increase the cylinder swept volume. This would not change the combustion chamber volume only the cylinder volume. The compression ratio of the GM V6 engine is 9.1:1. By increasing the cylinder swept volume slightly it increases the compression ratio slightly. However, the compression ratio should not exceed 10, or else engine knock could start to cause problems with the engine as a whole.

Solid Modeled Assembly

The following models are of the camshaft, a lifter, and a push rod. These components were chosen because they are key components of an engine but are not as familiar to most people as the crankshaft and pistons. By showing these parts, it can be seen how the intake and exhaust valves for each cylinder are opened and closed at the right time, in order for the cycle of compression and combustion to take place.

Solidworks was used to model these parts because it is an intuitive program and it was the most readily available.

Camshaft

Lifter

Push Rod

This YouTube video shows these components being assembled in sequence. The video was made using Blender, a powerful open-source 3-D visualization program.

Engineering Analysis

The following engineering analysis procedure could be used by an engineer to test the friction that occurs in the cylinders of the GM V6 engine due to a lack of lubrication and the power loss that would result from that friction. One should also note that this procedure is based on both the pistons and cylinders being completely dry. Results would vary with increased lubrication and therefore a different coefficient of kinetic friction.

Problem: Calculate the torque lost in the crankshaft after each piston fire of the engine due to dry friction between the pistons and cylinders.

Diagram:

Assumptions:

• The oil runs completely dry instantly and now the steel pistons rub directly on the steel cylinders

• There are six pistons and six cylinders

• Distance between center of crankshaft and end of connecting rods = 2.5 inches = .2083 ft

• Torque applied to the crankshaft by lubricated cylinders = 230 ft•lb

• Length of the connecting rods = 7 inches

• Neglect the weight of the pistons and their connecting rods

• Coefficient of dry kinetic friction (steel on steel) = .6

• The angle θ represents the maximum angle between the connecting rod and the normal axis to the piston head

• Piston head radius = 2 inches = .167 ft

Governing Equations:

• Torque = (Force)(Distance)

• Kinetic Frictional Force = (Coefficient of Kinetic Friction)(Normal Force)

Calculations:

τ= F*d

230 ft•lb = F*(.2083 ft)

F = 1104 lb

θ = sin^-1(radius/connecting rod length)

θ = sin^-1(2.5 in/7 in)

θ = 21°

FN = F*sin(θ)

FN = (1104 lb)*(2.5 in/7 in)

FN = 394.3 lb

Ff = μk*FN

Ff = (.6)*(394.3 lb)

Ff = 236.6 lb

τlost = Ff*(Piston radius)

τlost = (236.6 lb)*(.167 ft)

τlost = 39.4 ft•lb → Each time a piston is fired

Solution Check:

All units check out and cancel properly in each step. All units are kept in the English system, as the engine is an American product. Units of length are converted to feet by multiplying the length in inches by 1/12 (ft/in). Forces are measured in pounds because on Earth, one pound mass is equal to one pound force, so there is no need to make a conversion from one to the other. The answer makes sense because the torque lost in one piston fire is approximately equal to one sixth of the fully lubricated torque, so the engine would within roughly six piston fires.

Discussion/Interpretation:

The calculations start with the given torque applied to the crankshaft converted into a linear force based on the distance from the center of the shaft to the start of each connecting rod. The reason that the assumption is made that the engine is operating with normal oil conditions initially is so that the crankshaft is receiving the most torque that it can. By assuming that the oil completely drops out instantly, it can be shown that 39.4 ft•lb of torque will be lost from the original 230 ft•lb each time that one of the six pistons is fired in its cylinder. The normal force on the piston was calculated by using the horizontal component of the force applied through the connecting rod. After frictional force is found, it is converted into torque as the τlost by multiplying by the distance to center of the piston, which is just the horizontal distance between the cylinder wall and the center of the crankshaft. The final result shows that by the time all six cylinders are fired, the engine should stop because the combined total of the torque lost at each piston (torque lost times six cylinders) will be greater than the original 230 ft•lb.

Gate 4: Critical Design Review

Product Reassembly

o With the engine inverted the crankshaft was set back into its place in the engine block.

o The four crankshaft bearings (2 bolts each) were bolted to the block in order to hold the crankshaft in place. (16 mm socket wrench: 8 bolts total)

o With the engine in upright position each of the six pistons were pushed into their respective position. Note: Instead of using a piston ring compressor, screwdrivers were used to push the rings in one side at a time to allow the head to fully enter the cylinder.

o While the engine was again inverted the connecting rods were attached to the crankshaft via clamp bearings. (14 mm socket wrench: 2 nuts each)

o Now with the engine in the upright position the oiler was fed back into the bearings that held it in place in top of the engine. The flange bolt was then screwed in to hold it in place.

o The camshaft was fed back into the bearings that held it in place in top of the engine.

o The camshaft mounting bracket was bolted on with T-20 torx head screws. (2 screws total)

o The oiler drive gear was placed over top of the camshaft. This was followed by the camshaft’s timing gear and chain from the crankshaft with three bolts that held it in place. (13 mm socket wrench: 3 bolts total)

o The flywheel was reattached to the opposite side of the engine with six bolts. (14 mm socket wrench)

o The oil pan was then attached with 12 bolts (12 mm socket wrench) and then the oil cooler adapter with 2 additional bolts. (12 mm socket)

o Next, the 12 rockers (AKA lifters) were put back into place riding on the camshaft, followed by one rocker cover per side. (10 mm socket wrench: 2 bolts each)

o Each head was bolted into place with 12 bolts per head. (13 mm socket wrench)

o The 12 pushrods were replaced and the valves were realigned to rest on top of the pushrod and valve spring. The valve nuts were tightened with a 13 mm socket wrench.

o The camshaft cover was replaced on top of the camshaft sprocket and timing chain area. (6 point flange bolts: 6 total, 1 was missing)

o Using a hammer, the harmonic balancer was pushed back into place.

o The crank pulley was bolted to the harmonic balancer using 2 bolts (14 mm socket wrench: 3 bolts total, 1 was missing). Then, the water pump was bolted to the block. (14 mm socket wrench: 4 bolts total)

o The intake manifold was then reattached to the block. (14 mm socket wrench: 10 bolts total)

o The 2 valve covers were attached to each head with 6 bolts each. (13 mm socket wrench)

o The 2 exhaust manifolds were then bolted to the block with 10 bolts each. (14 mm socket wrench)

o Next, the fuel injector lines were pushed back into place by hand.

o Then, the upper intake housing was bolted on (12 mm socket wrench: 6 bolts total), followed by the distributor (10 mm socket wrench: 2 bolts total).

o Finally, the throttle body was replaced with 3 bolts. (10 mm socket wrench)

Reassembly Details

- From the beginning the product was never in a state to fully test its functionality since it is missing several crucial components such as emf source, fuel tank, radiator, and alternator. During the disassembly many flaws were discovered to infer that the engine is not in a running condition such as a crack in the intake manifold and faulty piston rings.

- The reassembly process was very similar to the disassembly. The major difference was for the disassembly we needed a pulley puller that was not required for reassembly. To reattach the harmonic balancer there was force required, this was done so by means of a hammer to push it back in place. Also for reassembly screwdrivers were used in place of a piston ring compressor to feed each piston head back into a cylinder. Other than these differences in tools, all other tools were the same and the product was successfully put back together.

- An additional recommendation at the design level of the engine would be to take greater effort in making bolt size uniform throughout the whole engine. Also, it may make more sense to manufacture bolts in solely customary or metric sizings, as opposed to a combination of both.