Diesel Engines

Question 1

Diesel Engine Features

Answer 1

No spark plug - combustion occurs due to heat
High compression ration 14:1/28:1
Increased power output and thermal efficiency
Uses Jet A1

Question 2

Jet A1 Features

Answer 2

SG 0.8/0.9
Less volatile and higher flash point than AVGAS
Poor lubricant

Question 3

Advantages and disadvantages to a diesel engine

Answer 3

More fuel efficient than gasoline engines
Requires less scheduled maintenance
More suited for turbocharging
Simple and reliable (less systems like ignition needed)
Kerosene is safer/cheaper than AVGAS

• Higher operating pressure requires stronger heavier design

Question 4

Induction stroke in diesel engine….

Answer 4

Air enter via intake valve
Fuel introduced later
No need for a throttle butterfly valve

Question 5

Compression Stroke in Diesel Engine

Answer 5

Compressed at at around 15:1 or 20:1
(Compression ignition engine)
Temperatures around 500/600 degrees

Question 6

Auto ignition temp of Jet A1

Answer 6

210 degrees

Question 7

Power Stroke in Diesel Engine

Answer 7

Correctly timed fuel injected into cylinder which immediately ignites
Very compressed in small volume generating huge amounts of pressure

Question 8

Diesel Engine and detonation?

Answer 8

No risk of detonation as no end gas

Question 9

Exhaust stroke in diesel engine

Answer 9

Same as petrol although diesel much more dirtier than AVGAS engines

Diesel particulate filter fitted to burn off unburnt fuel in exhaust

Question 10

Types of Diesel Injection Systems - Common Rail

Answer 10

Common rail - high pressure pump supplying fuel to common rail.
Electrically opened injectors controlled by ECU or FADEC

Question 11

Glow plugs

Answer 11

Electrically heated coil used on cold starting to ensure high temp in cylinders
Powered by battery and does not operate when engine is warm

Question 12

Comparison to petrol vs diesel engine

Answer 12

Diesel has lower power to weight ratio
Diesel uses a liquid cooling system

Question 13

What’s the lowest mixture a diesel engine can withstand

Answer 13

There is now low limit for mixture

Question 14

Ideal compression ratio for a diesel engine

Answer 14

14:1 to 28:!

Question 15

Summary of diesel engine

Answer 15

Higher compression ratio
Intake system is never heated because diesel engine is an injection engine
Produce less maximum power output

No mixture control
Power determine by fuel flow only
Thermal efficiency is higher than petrol engine

Question 16

Intake of a diesel engine is never

Answer 16

Heated because diesel engines in an injection engine

Question 17

What determines the power delivery in diesel engine

Answer 17

Fuel Flow

Question 18

Is there mixture control in diesel engine

Answer 18

No