ENGINES 101, Chapter 1 Options

[macavely]

Well I been really bored at work and will be so for a long while.. So i wrote this up for anyone that wanted to learn an little more about cars...

Engine :
Is the source of power for the vehicle. A device that converts energy into useful mechanical motion.

The engine in our celicas run on a Four-Stroke Cycle. The four-strok cycle requires four pistons strokes to complete one cycles. One every fourth stroke the engine produces one power stroke (useful energy)


THE FOUR STROKE CYCYLE

Intake Stroke :
The stroke that is devoted to drawing the air-fuel mixture into the combustion chamber. The intake valve is open and the exhaust valve is closed. The piston slides down and forms a low pressure area(vacuum), in the cylinder. That forces outside pressuer to push the air-fuel mixture into the engnie.

Compression stroke :
This stroke squeeze the air-fuel mixture to prepare it for combustion (burning). When this mixture is pressuized it is more combustible. During this stroke the pistion slides up with the intake and exhuast valves closed.

Power Stroke :
This stroke burns the air-fuel mixture and pushes the piston back down with extrame force. This is the only stroke that consumes no energy, it produces the energy. Since both exhuast and intake valves are close, pressure formes on the top of the pistion. The pistion is then pushed down spining the crankshaft. This is caused when the spark plug fires and ignites the air-fuel mixture.

Exhuast Stroke :
The piston is pushed back up, with the exhuast valve(S) open. The bruned gases are pushed out of the exhuast valve into the header out of the rest of the exhuast system.

ENGINE BOTTOM END
Also known as the short block generally refers to the block, crankshaft, connecting rods, pistons, and other realted parts.

Engine Block :
Forms the main body of the engine. Other parts are bolted on and or fit into the inside of the block.

Cylinders :
These are large, round holes machined through the block from top to bottom. The pistons fit into the cylinders.

Pistons :
Fit into the cylinders and travel in an up and down motion making up the 4 stroke cycle.

Deck :
Is the top of the block this part is machined perfectly flat. This is what the cylinder head is bolted to. Oil and coolant passes throught the deck surface

Water jackets :
Are coolant passages through the block.

Core plugs :
Also known as freeze plugs, they are metal plug on the outside of the block. They are seal holes left in the block after casting. The plugs prevent coolint leakage out of the water jackets. The 7afe and 5sfe engines might not have these plugs i'm not sure.

Main bearing bores :
Holes machined in the bottom of the block to hold the crankshaft. Removable bearing inserts fit into these bores.

Main caps :
They bolt to the bottom of the block and hold the crankshaft and main bearing inserts in place

Crankshaft :
Harnesses the tremendous forced of the up and down motion of the pistions. It changes the up and down motion into a rotating motion.

Crankshaft main journals :
Are surfaces that are precisely machined and polished. They fit into the blocks main bearings.

Crankshaft rod journals :
They are offset from the main journals and are also machined and polished surfaces. The connection rods bolt to the rod journals.

Counterweights :
Formed on the crankshaft to preven vibration. This weight conuteracts the weight of the connection rods. pistons, rings and rod journal offset.

crankshaft snout :
It gives a mounting place for the camshaft drive mechanism, front damper, and fan belt pulleys. It sticks through the front of the block.


crankshaft flange :
It hold the flywheel, or the torque converter or input shaft. The flywheel bolts onto the flange, and the center of the flange has a pilot or bushing for the torque converter or input shaft.

Engine main bearings :
are removable inserts that fit between the blocks main bore and the crankshaft main journals.

Main thrust bearings :
This limits that amount of play the crankshaft has inside the block.

Main bearing clearance :
The space btween the crankshaft main journal and the main bearing insert. The clearance allows oil to enter and lubracat and separate the journal and bearing.

Crankshaft oil seals :
This keeps the oil from leaking out the transmission side and pully side of the engine.

Rear main oil seal :
Fits around the rear of the crankshaft to stop/prevent oil leakage.

Flywheel :
A gear/wheel that mounts to the crankshaft. A flywheel has sevral functions;
1.The flywheel connects the engine crankshaft to the transmission, Both manual and automatic transmissions use a flywheel.
2.For manual transmisission the flywheel is very heavy and can help smooth engine operation .
3.The flywheel also has teeth on the edge for use with the starte motor to crank the engine on start up.

Connecting Rod :
Fastens the piston to the crankshaft, it turns the up and down motion of the piston into turnning motion at the crankshaft.

Connecting rod small end :
also known as the top end, fits around the piston pin. Also called the upper end. it contains a one piece bushing. The bushing is pressed into the rod small end.

Connecting rod I-beam :
The center part/section of the rod. Is shaped makes for a every good stregnth to weight ratio and also pevents the rod from breaking, twisting and bending.

Connecting rod cap :
Bolts to the bottome of the connecting rod body. removable for removing the rod from the crankshaft.

Connecting rod big end :
Also known as the lower end, is a hole machined in the rod body and cap. The connecting rod bearing fits into the big end.

Connecting rod bolts :
Or nuts, hold the rod cap and rod together,

Connecting rod bearings :
They ride on the crankshaft rod jorunals, between thr connecting rods and the crankshaft these are removable.

Rod bearing clearance :
The small space between the rod bearing and crankshaft journal.

Piston :
Transfers the pressure of combustion to the connecting rod and crankshaft. It also hold rings and a pin while in the 4stroke cycle.

Piston head :
The top of the piston, the part that is exposed to the heat and pressure of combustion. The piston head had to be strong enough to take the force of the power stroke. It also has to be shaped to match and work with the shape of the combustion chamber for a proper combustion.

Piston ring grooves :
The slots on the side of the piston were the piston rings fit into. The two top grooves hold the compression rings. the bottom groove holds the oil ring.

Piston ring holes :
The groove at the bottom of the oil ring that lets oil pass through the piston and onto the cylinder wall. Thenn the oil drains back donw to the crankcase.

Piston ring lands :
The areas between and above the ring grooves. They support and sepatate the piston rings as they slide on the cylinder.

Piston skirt :
The side of the piston below the lasdt ring. It keeps with the pistion from slamming on to the cylinder wall.

Piston boss :
The reinforced area around the piston pin hole.

Piston pin hole :
The mechined area in the middle of the piston where the piston pin is inserted.

Piston pin :
Or wrist pin, lets the piston swing on the connecting rod. The pin fits throught the pin hole and the connecting rod small end.

Piston clearance :
The amount of space between the side of the the piston and the cylinder wall. It allows oil to form a lubrcating film between the piston and the cylinder. It also space for the piston to expand when the piston heats up.

Piston ring :
A split ring installed in a groove in the piston. Seals the compression chamber from the crankcase.

Compression rings :
Prevent combustion pressure leaking into the engine crankcase (blowby).

Oil rings :
Prevent oil from entering the combustion chamber. They scrape the excess oil off of the cylinder wall.
(if you see blue smoke its cause your oil rings are letting to much oil into the combustion chamber)

Ring gap :
The are between the end of the piston rings. This gap allows the ring to be opened and installed on the piston.

TOMORROW HEAD

This post has been edited by macavely: Jun 29, 2004 - 11:58 AM

[macavely]

Well I did engine classifications before fuels for 2 resons.. one you will have a better understanding of fuels if you understand better how the engine works and compresses the fuel air mix and second i can't find the note book or the books that i have one fuels so i don't want to write everything from memory i like to look back and re-read stuf so i don't leave important details out.


Chapter 2

ENGINE DESIGN CLASSIFICATIONS
- Cylinder arrangement
- Number of cylinders
- Cooling system type
- Valve location
- Combustion chamber design
- Type of fuel burned
- Type of ignition
- Number of strokes per cycle
- Number of valve per cylinder

Cylinder Arrangement :
This refers to the position of the cylinders in relation to the crankshaft. The four basic cylinder arrangments are inline, V-type, slant, and opposed(boxer).
(A) Inline engine :
In this engine the cylinders are lined up in a single row. each cylinder is located in a straight line that is parallel to the crankshaft. the most comon inline engines are four, five and six cylinder engines..
(B) V-type engine :
The engine looks like a V, The two banks of cylinders sit at and angle from each other. This set up reduce the length and the height of the engine.
© Slant engine :
One bank of cylinder that leans to one side. like a V type engine.. this save space and allows the body and hood of the cehicle to be much lower. making a large engine fit into a small engine bay..
(D) Opposed engine :
Lies flat on either side of the crankshaft. With this type of engine there is less frictional horspower loss at the main bearings cause the pistons are not moving up and down but left to right so there will always be a power stroke from the left and right side.. and not just on the down stroke as in a Vtype or inline engine..

Number of cylinders :
Car and trucks usally have four, six and eight cylinders. but you can also find cars and trucks with 3, 5, 10, 12 and 16 cylindeers.. The more cylinders an engine has the smoother the engine opertates.. and the more cylinders the greater the power output of the engine.. "No replacment for displacement" .

Cylinder Numbering and Firing Order :
Engine makers number each engine cylinder so techs know were to make repairs. Service manuals will provide an inllustration showing the number of each cylinder.

Cylinder Numbering:
Normally stamped on the connecting rods. Sometimes they are cast into the intake manifold.

Firing order :
Is the sequence in which the cylinders fire. The position of the cranshaft rod journals in relation to each other determines engine firing order.

Cooling system type :
The two types of cooling systems are liquid and air cooling. the liquid cooling is the most common.

Liquid cooling system :
It surrounds the cylinder with coolent, a water and antifreeze solution. the coolant carries combustion heat out of the cylinder head and engine block to prevent engine damage caused by overheating.

Air cooling system :
It circulates air over cooling fins on the cylinders. This helps remove heat from the cylinders to prevent overheating.

Fuel types:
An engine is also classified by the type of fel it burns. A gasoline engine burns gasoline. A diesel engine burns diesel fuel. These are the two most common types of fuel for vehicles. I'll go more into fuels later.. check for the post tittled FUELS

Ignition types :
The two basic ways of ignition are spark ignition and compression ignition.

Spark ignition engines :
This type of engine uses an electic arc at the spark plug to ignite the fuel. The arc makes enough heat to start the fuel burning. Gasline engines use spark ignition

Compressed ignition engines :
They squeeze th air in the combustion chamber until it is hot enough to ignite the fuel. No spark plugs are used, A diesel engine is a compression ignition engine.

Valve location :
Another classification can be made by comparing the location of the valve.

L-head engine :
Both intake and exhaust balves are in the block, They type of engine is also known as a flat head engine. Its cylinder head simply forms a cover over the cylinders and valves. the camshaft is in the block and pushes upward to open the calves.

I-head engine :
Or Over Head Valve (OHV) engine, has both valves in the cylinder head.

Camshaft location :
There are two common locations for the camshaft one is in the block and the other is in the cylinder head..

Cam-in-block engine :
This engine uses push rods to transfer motion to the rocker arms and valves.

Overhead cam engine :
The camshaft is located in the top of the cylinder head. In this engine push rods are not needed This type of engine has less moving parts in the head and is more efficant. The cames can be placed at and angle to allow for better air flow in and out of the engine..

SOHC :
Single OverHead Cam engines have only one camshaft per cylinder head. the one cam operated both the intake and exhaust valves.

DOHC :
Dual OverHead Cam engines have two camshafts per head. One for the intake and one for the exhuast. Engines with DOHC mostly use a four valve combustion chamber.

Chambustion chamber shapr :
Look another way to classify any engine, The three basic combustion chamber shapes for gasoline engines are pancake, wedge, and hemispherical.

Pancke combustion chamber :
Also called bath tub chamber , it has valve heads that are almost pallel to the top of the piston. This forms a flat pocket over the piston head.

Wedge combustion chamber :
Or wedge head is shaped like a triangle a squished area is commonly formed inside a wedge head. When the piston reaches TDC(top dead center) it comes very close to the bottom of the cylinder head. the air-fuel mix is squeezed in that area and causes it to squirt(squish), out into the main part of the chamber. This can be used to improve air-fuel mixing at low RPMs.

Hemispherical combustion chamber :
Better know as the hemi-head or just Hemi. is shaped like a dome. The valves are centerd on each side of the combustion chamber. The spark plug is also located near the center of the chamber. A hemi-head is super efficient, because there are no hidden pockets making the chances of incomplet combustion every unlikly. heat loss from the chamber is reduced cause of the very small surface area. the location of the spark plug makes a very short flame path for combustion.

tomorrow Section 2 of engine classifications