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AutoTechnology Ch4-5
Ch 4-5 Test Information from Auto Fundamentals 12th Edition
| Question | Answer |
|---|---|
| What is an engine? | An engine is a group of related parts assembled in a specific order, designed to convert energy released by fuel into a useful form (a device in which fuel is burned) |
| What does internal combustion mean? | It means "burning within" |
| What is fuel? | Fuel is the substance being burned. |
| What is gasoline? | Gasoline is fuel. |
| What is petroleum? | Petroleum is a naturally occurring substance that is pumped from wells drilled into the earth. |
| How is gasoline obtained (produced)? | Gasoline is obtained by refining crude oil or petroleum. |
| What is one of the many items produced by crude oil? | Gasoline. |
| How many grades (octane rating) of gasoline are there? | There are (3) grades of gasoline. |
| What are the 3 grades of gasoline? | 87, 89, 92-94 |
| What does a gasoline's octane rating indicate? | It indicates how well the gasoline (fuel) will resist detonation in the cylinders (burning too rapidly) |
| What makes gasoline a complex mixture? | It's produced by mixing basic fuels and special additives (carbons and hydrogen atoms) make it a hydro-carbon. |
| Why was tetraethyl lead used in leaded gas? | It was used to raise octane. |
| Is unleaded gas sold today? | No, all gas that is sold today is unleaded. |
| Why isn't leaded gas used in late model engines? | Leaded gas would quickly destroy certain parts like the catalytic converter that help to reduce exhaust emissions. |
| Factors that affect the quality of any gasoline? | Must pass exhaustive test in both lab/actual use. Must burn cleanly, ignite readily, resist freezing or boiling, contain a minimum of harmful ingredients and resist detonation. |
| Does gasoline burn readily? | Yes gasoline burns readily, but only where it's exposed to oxygen. |
| What has to happen for gasoline to burn more rapidly? | Expose more area to air by breaking gasoline into smaller particles, |
| Once gasoline is broke into very tiny particles | Burning is fierce. |
| What does rapid burning produce? | Tremendous heat which causes a rapid and powerful expansion. |
| Heat is ? | Energy |
| Burning gasoline gives off what? | Energy in the form of heat. |
| Proper combustion is a what? | Very quick burning process. |
| How long does it take proper combustion to happen? | It takes less than 0.006 seconds (six thousandths of a second). |
| What is knocking? | Knocking is an inefficient use of fuel that causes engine damage. |
| What is it called if fuel explodes? | Knocking |
| What is trapped inside engines? | Expansions from burning gasoline. |
| Crankshaft change reciprocating motion into? | Rotary motion |
| These parts of a gasoline engine serve the same general purpose (B4CFP) | Block connecting rod connecting rod bearing crankshaft cylinder flywheel piston |
| Parts are fastened inside an engine block so the main bearings and cylinders do not move | True |
| Why are engine blocks made heavy? | To give it strength to withstand pressure exerted on it by the expansion of the burning fuel. |
| The lower engine block end forms? | a case around the crankshaft. |
| The lower block end is called ? | Crankcase |
| The crankcase allows you to have 2? | main bearings to support the crankshaft and give you a strong unit. |
| Making pistons longer prevents | Pistons from tipping sideways in cylinders |
| Pistons are made _________ to avoid having a piston that is too heavy. | Hollow. |
| The piston has to travel up and down and the connecting rod has to swing back and forth to follow the crankshaft | The connecting rod must be able to move at the point it is fastened to the piston to swing. |
| Why is a hole into piston and upper connecting rod. | They connect and to allow the connecting rod to swing |
| Connecting rods are secured to piston with? | Piston pins |
| Piston pin are also called? | Wrist pins |
| What is the combustion chamber on an engine? | It's the upper cylinder area on an assembled engine. |
| What is referred to as a removable top on an engine? | Cylinder head |
| How are cylinder heads fastened to engine block? | Bolts, studs or nuts |
| Cylinder heads are made of ? | Much thicker metal |
| Two passages in cylinder head that brings fresh air/ fuel into combustion chamber and exhausts burned gases? | Valve ports |
| Valves are what for combustion chamber? | Port control devices |
| When a valve sits on it's valve seat? | It seals the open port of combustion chamber |
| Valves guides are | holes bored through cylinder heads that hold valves in position. |
| Valve stems are guided up and down in a straight line by | Valve guides |
| Why is a valve spring necessary ? | Valve springs keep the valves tightly closed against it's seat. When the valve is opened the spring will close it again. |
| Valve spring, spring washer and keeper are used to? | Secure valves in cylinder heads. |
| The weight of the air that's pressing on all things? | 14.7 lbs per square inch (103 kPa) at sea level. |
| Vacuum is formed when | All existing air is drawn from cylinder |
| Any area where the air pressure is lower than the atmospheric pressure is _______________ | Vacuum |
| When a piston fits snuggly in cylinder, there is no air between the two, the piston is pulled downward | A large area where there is no air (you get vacuum) |
| Which parts of an engine form a vacuum pump? | Cylinder and piston (both valves closed). |
| The first stroke of a 4-cycle engine, when intake valve are opens, the piston is pulled down in cylinder and the air/ fuel mix is drawn into combustion chamber is called? | Intake stroke. |
| Intake Stroke begin with? | piston at top of cylinder, only intake valve open, and ends when piston completes it's downward travel. |
| How long does the intake stroke take? | 1/2 turn of crankshaft |
| The 2nd stroke of a 4-cycle engine, when both valves are closed, piston is forced up and air/fuel mix gets compressed or squeezed is called the__________? | Compression stroke |
| How long does the compression stroke take? | 1/2 turn of crankshaft |
| Compression stroke begins with ? | Piston at BDC, both valves closed and ends with piston at TDC |
| Compression stroke breaks | fuel into smaller particles due to sudden swirling and churning as it is compressed. |
| The amount that an engine will compress air-fuel mix depends on? | How small a space mixture is squeezed into. |
| The ratio of reduction in cylinder volume | Compression Ratio |
| What is the air-fuel ratio before spark that triggers power stroke? | 12 parts air to 1 part fuel |
| Leaner air-fuel ratios before spark will? | Slightly slow the combustion speed |
| The spark produced at the tip of spark plug during power stroke is generated by | Ignition System |
| On the power stroke, the piston is forced down in cylinder by? | Rapidly expanding gas |
| The 3rd stroke of 4 cycle engines, begins with piston at TDC, both valves closed, a spark, where piston moving down suddenly gives crankshaft a quick and forceful push, ending with piston at BDC is called? | Power Stroke |
| How long does power stroke require? | 1/2 turn of crankshaft |
| The 4th stroke of a 4-cycle engine begins with piston at BDC, exhaust valve open, intake valve closed, ends with piston at TDC | Exhaust Stroke |
| How long does exhaust stroke take? | 1/2 turn of crankshaft. |
| When piston reaches bottom of power stroke, the exhaust valve opens, the spinning crankshaft forces piston up in cylinder, pushing out exhaust gases | Exhaust Stroke |
| One complete cycle of a crankshaft in a 4-cycle engine requires | 2 revolutions of crankshaft ( 4 half turns) |
| Each cycle of crankshaft requires? | 1/2 revolution of crankshaft. |
| Round shafts located above each valve stem? | Camshafts |
| Camshafts are supported in bearings in cylinder heads at what positions? | Front and Rear |
| Egg-shaped bump, machined as an integral part of the camshaft | Cam lobe |
| Distance valves will raise, how long valves stay open and how fast valves open and closes can all be controlled by | Height and shape of cam lobe. |
| Cylindrical unit called cam follower | Valve lifter |
| Where are valve lifters installed? | Between cam lobe and valve stem. |
| Slides up and down in a hole bored in cylinder head metal that seperates valve stem from camshaft | Lifter |
| Camshaft, camlobe, valve, keeper, spring washer, valve spring and lifter make up ? | Valve train |
| What is the function of the camshaft? | It opens and closes the valves. |
| During which cycles on a 4-cycle engine are the valves closed? | Compression and Power Stroke |
| How fast does cam lobe need to turn to open valves at the proper time? | Fast enough to open the valve every 4th stroke. |
| Speedwise, than camshaft turns at what speed of the crankshaft. | Half the speed of crankshaft. |
| Gears and a belt are means of driving the ? | Camshaft |
| How to get the valves to open at the right time is called? | Valve timing |
| In relation to cam lobe positioning, when are valves open? | Valves are open when the cam lobe touches the lifter or valve stem |
| At which points are valves closed, in relation to to camshaft positions? | Valves are closed from the time lifter or valve stem touches either camshaft initial flank to camshaft's base to camshaft's opposite flank. |
| The only time crankshaft receives power is during the? | Power stroke. |
| Causes the crankshaft to continue spending through to next power stroke due to it's built up inertia? | Flywheel |
| Attached to opposite end of crankshaft from the timing gear, caused to spin by the power stroke. | Flywheel |
| Keeps the crankshaft running constant which causes engine to run smoothly. | Flywheel |
| Serves as a rigid metal foundation for all parts of an engine. | Engine Block |
| Contains the cylinders and supports the crankshaft and ofter camshaft? | Engine Block |
| Accessory units and clutch or torque converters are bolted to it? | Engine Block |
| The crankcase is formed with the? | Engine Block |
| Blocks are made of either? | Cast iron or aluminum |
| Two ways blocks are commonly formed? | Pour molten iron or aluminum into mold made of sand. Or force molten aluminum into a metal mold under pressure. |
| Advantages of pressure casting? | produces air bubble free block, gives sharp corners and is extremely accurate. |
| Pressure casting engine blocks requires minimum machining operations. (T F) | True |
| Using this method of engine block casting, the same mold can be used repeatedly. | Pressure casting |
| All parts of an aluminum block that are subjected to wear will have : | iron or steel inserts pressed in place or cast into block. |
| Providing it has sufficient strength, the lighter the block,? | The better. |
| The modern thin-wall casting process controls ? | Core size and placement much more accurately than the older casting processes. |
| The modern thin-wall casting process permits thinner block walls and a reduces block weight. (T/F) | True. |
| Since modern block casting processes result in uniform block wall thickness, block distortion from heat expansion is less severe (T/F) | True |
| Round holes formed in engine block? | Cylinders |
| Cylinders are first cast into block then bored and honed to a smooth finish (T/F) | True |
| A good cylinder will not vary in diameter more than? | Fifty-thousandths of an inch (0.0005" or 0.013mm) |
| Forms a guide for piston and acts as a container for taking in, compressing, firing and exhausting the fuel-air charge. | Cylinder |
| Most popular type of cylinder? | Cast Iron |
| Cylinders have been made of steel and cast iron. | True |
| What is installed when steel cylinders are desired in an aluminum engine block. | Cylinder sleeves |
| Round, pipeline liners | Cylinder sleeves |
| Cylinder sleeves are either cast or pressed into block (T/F). | True |
| Some engines use removable cylinder sleeves (T/F). | True |
| Cylinder sleeves are widely used in heavy duty truck and industrial engines | True |
| Cylinder sleeves are either ? | Dry or Wet |
| Pressed into a hole in block surrounded over it's full length by block metal | Dry Sleeve |
| Dry sleeves can be made thin because | It utilizes block metal to give it support over it's full length |
| Is only supported on at the top and bottom and engine coolant is allowed to directly contact the sleeve. | Wet sleeve |
| Wet sleeves must be made heavier due to no central support from block. | True |
| Cast iron or steel sleeves placed in an aluminum block can be | Cast into place. |
| Removable sleeves can be held in place by | Friction |
| The best method of securing a sleeve is to incorporate a flange on the top edge of cylinder sleeve that | Drops into a corresponding groove in the block |
| So that heat can be conducted away from it by surrounding block metal, all cylinder sleeves must have a | Fairly snug fit |
| Sliding plunger that rides up and down in cylinder, that must perform several jobs in proper sequence. | Piston |
| Pistons are usually made of | Aluminum. |
| Aluminum pistons designed for operation in aluminum cylinders are | Iron plated. |
| To allow proper break-in when engine is started, aluminum pistons are often | Tin plated. |
| Though commonly cast, aluminum piston can be | Forged. |
| What is the weight of aluminum pistons? | Light |
| Pistons can be made of | Aluminum or cast iron |
| What is the advantages of an aluminum piston compared to cast iron? | It's not too heavy so it can easily change direction at the end of each stroke and it helps to increase engine efficiency. |
| Why must pistons be carefully fitted into cylinders? | To prevent them from tipping from side to side (slapping) |
| What happens when pistons get hot? | They expand |
| Enough clearance must be left between piston and cylinder to allow for ? | Piston expansion. |
| Modern engines sometime reach speeds in excess of | 6,000 rpm (revolutions per minute) |
| Expand more than cast iron pistons | Aluminum pistions |
| Piston must change direction at the end of each? | Stroke |
| Must hold burning air-fuel charge above it"s head, be tight enough against cylinder walls to form vacuum, compress air-fuel charge, exhaust burned gases and prevent excess oil loss | Piston |
| A piston is subjected to | intense heat |
| The overall job piston performs is | difficult |
| Subjected to friction against cylinder walls and receives the tremendous thrust of power on the power stroke | Piston |
| Solutions to problem of fitting aluminum pistons close enough to prevent tipping while leaving enough clearance for an oil film to separate piston from cylinder? | Steel strut pistons, cam ground pistons, partial skirt pistons (cam ground) |
| Type of piston where steel struts or steel rings are cast into aluminum pistons. | Steel strut piston |
| What expand less than aluminum? | Steel |
| Steel struts minimize piston | Expansion |
| The popular piston type? | Cam ground piston |
| Instead of being round this piston is ground so that it is elliptical or egg shaped (one diameter is larger than the other) | Cam ground piston |
| Related to cam ground pistons, two sides of piston that contact cylinder walls at right angles to crankshaft and piston pin. | Thrust surfaces |
| Thrust surfaces support | piston and prevent tipping |
| Cam grinding will give minimum clearance at | Thrust surfaces |
| Diameter A is established that piston has minimum clearance in cylinder. | Cam ground piston |
| On cam ground pistons, the minimum clearance is | 0.001 of an inch (0.025mm) |
| Partial skirt pistons are also called | Slipper skirt pistons |
| On this piston, a large area of the piston skirt is removed. | Partial skirt piston |
| Removing a large area of piston skirt on Partial skirt pistons | Reduces piston weight and allows piston to move closer to crankshaft. |
| These sides of partial skirt pistons is removed | Non thrust sides |
| Removing non thrust sides on Partial skirt pistons | prevent piston contact with crankshaft counterbalances. |
| Nonthrust sides of pistons do not carry much of a load | True |
| A partial skirt piston is also a | Cam ground piston |
| Part of a piston that's subjected to direct heat of burning air/fuel mixture | Piston head |
| The piston crown's (very top) temperature can raise to from heat of burning air-fuel mixture. | Over 600 degrees F (316C) |
| Temperatures will be lower as you go down a piston. | True |
| Piston temperature varies according to engine design and application | True |
| Part of piston that expands more than other parts | Piston head |
| Part of piston that is made 0.0030 to 0.0040 of an inch smaller than it's skirt | Piston head |
| This area of the piston must be made thicker and stronger because it supports the piston pin. | Pin Boss |
| Most commonly used piston head shape. | Flat top |
| Pistons need clearance in cylinder | True |
| The piston skirt requires 0.001 to 0.002 of an inch of clearance in cylinder. | True |
| This solves the leakage problem in cylinder? Used to seal gap between piston and cylinder wall. | Piston rings. |
| A properly constructed and fitted piston ring rubs against the cylinder wall with | Good contact all around the cylinder. |
| Piston rings ride in a groove | Cut into the piston head. |
| The uncut piston area between ring grooves | Ring lands |
| Ring lands keep the rings in position and | Help to seal the sides of ring. |
| There is slight clearance between the | side of the ring and the edges of the groove. |
| Side clearance is generally | Around 0.002" |
| General rule for ring gap clearance | Allow 0.003 to 0.004" per inch of cylinder diameter. |
| Types of piston rings | Compression and oil control rings |
| Acts as a mild scraper, assists in surplus oil removal | Compression ring |
| On compression and exhaust strokes, rings will tend to slip lightly over oil film which will prolong life of rings. | True |
| Compression ring that is subjected to intense heat | Top compression ring |
| Used to minimize heat transferred to top ring from head of piston | Heat dam |
| Some aluminum pistons have nickel-iron or comparable metal inserts cast into piston head. Top ring groove is cut in this metal. This insert will prolong useful life of piston and ring. | True |
| Used to scrape surplus oil from cylinder walls and prevents oil escape to combustion chamber. | Oil control rings |
| Must make perfect contact with cylinder walls all they way round | Rings |
| It's impossible to secure perfect fit when rings are newly installed | True |
| How many miles does it take newly installed rings to wear into perfect contact with cylinder walls. | Several hundred |
| Why is a ring's outer surface left rough? | To facilitate a fast break in. |
| What are piston rings made from | High quality cast iron |
Created by:
ronricok