Engine theory

Red = on unit test

Cylinder arrangement - Inline

Cylinder arrangement – V

Gasoline engine cylinder arrangement - Horizontally

opposed

Engine Parts• Many parts must work together for the engine to run properly.• The parts listed below are major engine parts you will need to know

on your unit test.

• 1.Cylinder Block 10. Valves• 2. Cylinder head 11. Valve spring• 3. Crankshaft 12. Piston • 4. Camshaft 13. Connecting rod • 5. Timing chain 14. Piston rings• 6. Bearing shell 15. cylinder sleeve • 7. Oil pump 16. Intake manifold• 8. Water pump 17. Exhaust manifold • 9. Flywheel 18. Rocker arm

Engine Block

• Typically made of cast iron or aluminum.

• Cast with hollow areas for coolant.

• Oil passages often cast & machined into block.

• Forms the foundation of the engine ( all parts attach to block in some way.

Pouring molten aluminum into a mold to cast an engine block

Aluminum V-8 cylinder Block.

Cylinder block

Aluminum V-6 Cylinder Block.

Crankshaft, Connecting rod & Piston Change reciprocating motion

to rotary motion.

Crankshaft

Piston & connecting rod

It takes two complete revolutions of the Crankshaft to complete the four stroke cycle

Cast or forged iron.

Bearings support Crankshaft & connecting rods

Cylinder head

• Seals off top of cylinder block

• Has spark plug & combustion chamber.

• Made of Aluminum or cast iron

• Contains valve train

• Has coolant & oil passages.

4 valve per cylinder - Cylinder Head

Renault F1 New Engine - Google Video

Four cycles

Typical ignition timing: About 4 degrees BTDC

(strokes)

Know piston direction in each stroke& which valves are open.

Crankshaft – Camshaft ratio is always 2 - 1

Camshaft

Cam & lifters in block

*Driven at 2 to 1 ratio off crank shaft

Camshaft opens the valves

Cam lobe

Timing chain

• Engines may use a timing chain, timing gears or a toothed belt to synchronize the crankshaft and camshaft (s).

Valves allow Air/fuel or exhaust in/out of the combustion chamber.

Valves & valve springs

Intake valve is always larger.

Valve spring closes valve.

Over head camshaft engine

valve

piston

cat

crankshaft

Intake manifold

oil pan

con - rod

Rocker arm

Rocker arm changes direction of motion

Transfers motion of cam to over head Valves.

PISTON & Ringsmust seal compression & keep oil out of combustion chamber.

Piston shape affects compression ratio – typical ratio about 9 to 1

Oil pumppressurizes oil for use through the engine

Water pumpCirculates coolant from engine to radiator & back to cool

engine

Intake ManifoldProvides a path or runner for air to enter engine.

Exhaust Provides a path for hot exhaust to leave engine.

Exhaust Header Fabricated tubing

Exhaust manifold ( cast iron )

FlywheelUsed to smooth engine operation & transfer power to the

clutch disk.

Flywheel - cast iron 20 – 40 lbs

Basic engine parts

Can you identify these parts?

HEMI

f1 engines - Google Video

Turbo charging Turbo charging uses an exhaust driven compressor to force air into the engine. The more exhaust the more “boost” and the more air that can be pushed into the engine.

Compressing air will cause it to become hot – not good for horse power – so an intercooler ( air to air radiator) is often used to cool the air after the turbo has compressed it.

Turbochargers increase the efficiency of any engine – because the power is essentially free.

Turbo charger – cut away

Supercharging A super charger is a type of compressor - typically belt driven by the engine that is used to push more air into the cylinder during the intake stroke.

Because superchargers depend on engine power to turn - they are not as efficient as a turbocharger .

Superchargers will make “boost” from very low engine speeds.

Superchargers can also be intercooled.

Positive displacement supercharger

Nitrous oxide Nitrous Oxide is a way to chemically add more oxygen to the incoming air / fuel mixture .

Nitrous is most commonly used to boost performance of gasoline engines & infact was developed during wwII.

More Fuel will also need to be added to keep the A/F ratio from leaning out & damaging the engine.

The basic parts of a “NOS” system are: Nos storage bottle, delivery lines, Solenoid valves & injection nozzle (s) .

The more nitrous that is used the more likely engine damage will occure.

A Nitrous Kit

DieselDiesel engines use a fuel much less refined than gasoline. Diesel is thicker & more oil like than gasoline. Importantly, It also has a much higher ignition point.

Diesel engines have no spark plugs. The timing of Ignition event is controlled by when the diesel is injected into the combustion chamber. ( all diesel engines use direct injection.)

As the molecules of air in the cylinder are squeezed they become hot - (Diesel’s use twice the compression as a gasoline engine) The instant the diesel fuel is squirted into the combustion chamber – combustion takes place.

Diesel engines are called :

“compression Ignition engines”

Diesel injector

Bio fuel Bio fuel is fuel made from materials growing in our environment.

Both Gasoline compatible & more commonly Diesel compatible fuels are made using everything from corn & cooking oil to algae & plant matter.

Bio fuels often burn cleaner & have the potential to help the united states dependency on foreign oil.

Many people are attempting to produce enough Bio diesel fuel to offset the high cost of Diesel around the world.

A small Bio – Diesel refinery

Hybrid vehicle

• Small gas / Diesel engine & Battery /electric motor powers vehicle.

• When working on a Hybrid – be aware of high voltage areas marked with orange (144 – 650 v ) , yellow – up to 42 volt.

• Use electrical gloves & special glasses when working around high voltage – one hand rule.

Hybrid vehicle

Battery pack

Hybrid power train

(Hydrogen) Fuel cell vehicle

Wankle (rotory) Engine

Good luck on your unit Test!!

Advanced dash diving