3. Much more efficient than Gasoline, with
50% of its energy going to motion!
(Gasoline is only 25% efficient on a
good day)
4. Cetane rating – A measurement of ignition
quality of fuel and refers to the fuel’s
ignitability under compression (opposite of
octane)
Specific gravity – The density of diesel
fuel should be tested whenever there is a
driveability concern, or if gasoline
contamination concerns exists.
5. Tool Tip! Specific Gravity is .82-.92 @60 degrees
API Gravity is 30-42 @ 60 degrees
NOTE! Gasoline is around 58-60 API Gravity
And the Specific Gravity is .7 (Inverse)
6. Cloud point - Temperature when the waxes
(added for lubricity) tend to form crystals that
can clog the filters.
Pour point – Temperature when the diesel
fuel thickens and will no longer pour, also
known as “Gelling”. In this state the fuel can’t
pass through filters.
Without additives diesel fuel cloud point would
be 40F and its pour point at 15F.
7. Flash point – Temperature to which the
fuel must be heated to produce a vapor
that will ignite when exposed to an open
flame.
On most diesels the flash point is between
100F and 125F (gasoline is -45F)
8. Due to its higher flash point, Diesel fuel will
not evaporate as easily, causing liquid fuel to
take days to evaporate!
Auto-Ignition – Temperature at which the
fuel will ignite when heated. Usually
around 446F (Gasoline is 572F)
9. Petroleum based Diesel is produced by
heating crude oil and collecting oil vapors
through a process known as distillation. Oil
molecules are separated into fractions or
“cuts” based on the boiling point
temperature of each fraction.
10. Biodiesel is produced by reacting biomass
(vegetable oils and animal fats) with a
catalyst such as Ethanol and Methanol to
separate methyl esters (biodiesel) and
glycerin (glycerin makes biomass 8 times
as viscous and is sold to the cosmetic
industry)
11. Biodiesel in its pure form is designated
B100 where the “100” refers to 100%
biodiesel.
Biodiesels blended with petrodiesel follows
a similar nomenclature. For instance, a
blended fuel comprised of 20% biodiesel
and 80% petrodiesel is called B20.
12. Biodiesel produces less emissions.
Higher Cetane number.
Low sulfur content, is biodegradable and
non toxic.
Biodiesel is chemically different from
petrodiesel and renewable diesel.
13. CAN I SWITCH TO BIODIESEL?
Vehicles that have been in service for any
length of time using petrodiesel will have a
buildup of lacquers and other petroleum
deposits on the walls of the fuel tank and
fuel lines, so please consider the following:
14. Because Biodiesel contains alcohol it
tends to “clean” these deposits and carry
them to the fuel filters and can clog the
filter resulting in engine damage.
Biodiesel also has to have special care for
storage since its hygroscopic (meaning it
readily absorbs water).
15. Because Biodiesel contains oxygen atoms
it is prone to oxidation, cause seals to
swell and harden, and may not be
compatible with certain metals such as;
-Zinc
-Copper alloys
-Tin
-Lead
16.
17. Renewable Diesel is produced by reacting
biomass (vegetable oils and animal fats)
with a catalyst such as hydrogen in
elevated temperatures and pressures.
(Hydrogenation)
This converts triglycerides into
hydrocarbons and removes atoms such as
sulfur, oxygen and nitrogen.
18. This hydrogenating process creates a fuel
that is very chemically similar to
Petrodiesel and also produces propane as
a by product.
Renewable diesel may not be 100%
renewable if the hydrogen used in the
hydrogenating process is derived from fossil
fuels.
19. Since this process is already used by
petroleum refineries, Renewable Diesel can
be produced with existing refineries.
There are other ways to create Renewable
Diesel such as;
-Thermal Depolymerization
-Biomass to liquid
20. Renewable Diesel (unlike Biodiesel) meets
the strict specifications of both ASTM
D396, and ASTM D975 fuel standards.
CLP Motorsports created this car to
operate on Renewable Diesel (VW
TDI engine), to drive it coast to coast
on 48 gallons of fuel. Similar to what
Clessie Cummins did in 1931 to
increase diesel interest, costing him
$11.22 during the depression.
21.
22. Clean diesel is the new generation of
diesel made up of a three-part system that
combines cleaner diesel fuel, advanced
engines and effective emissions control
technology.
Lets explore what this means!
24. Cleaner diesel fuel enables advanced
engines and emission control devices that
can't operate effectively with higher sulfur
content. This three-part clean diesel
system enables emission reductions of
over 95 percent.
26. The development of Ultra-low sulfur diesel
has reduced sulfur content from 500ppm to
15ppm beginning in 2006 and 10ppm
beginning in 2011.
Strict diesel exhaust emission standards
require the removal of sulfur so exhaust
after treatment devices can be used.
(Part 3).
28. Advanced new technologies such as
electronic controls, common rail fuel
injection, variable injection timing,
improved combustion chamber
configuration and turbocharging have
made diesel engines cleaner, quieter and
more powerful than past vehicles.
29. The basic concept of common rail is simple,
supply fuel at injection pressure (30,000psi)
to a common accumulator rail and a fuel
nozzle which electronically controls the
injection event (notice I said event)
In conventional diesel, each injector has its own
supply of diesel fuel directly from the injection
pump or increases the pressures internally.
33. There are three types of Common Rail
Diesel injectors (fourth coming soon) that
allow us to control injection events with high
accuracy and maintain high injection
pressures through the event. They are as
follows;
35. Piezo Crystal Electric Actuators
In these injectors the electromagnetic coils are
replaced with hundreds of thin piezo crystal wafers
to form the actuator for improved control of
injection events. (reverse polarity with no lag)
36. Hydraulically amplified common rail
Hydraulically amplified CR injectors are the most
recent innovation. Called CRI4, they are capable
of injection pressures as high as 35,280psi by
multiplying pressure inside the injector using an
amplifier piston. (similar to Hydraulic Electronic
Unit Injection or HEUI)
38. Early CR injectors could manage two or
three injection events during one
combustion cycle. Currently the fastest CR
injectors can produce seven separate
injection events during that same
combustion cycle!
39. NOTE:
Swapping injectors or replacing new injectors
require the use of a scanner to change the
calibration file in the ECM. Due to “Zero Mass
Calibration” the computer has to be able to
recalibrate for wear and any changes in operating
characteristics.
40. Warning:
Depending on the type of system, injector wiring
can reach voltages of up to 250V with the key on.
Anything over 60V is considered lethal. Special
gloves and equipment are required.
Wiring will be labeled with a special color,
depending on voltage levels reached.
41. WARNING:
Never crack open an injector fuel line when engine
is running. Fuel pressure can achieve as high as
35,000psi (ouch) easily cutting and penetrating the
skin and causing SERIOUS bodily harm. Follow
ALL bleeding procedures before opening fuel
system.
42. WARNING:
Due to the extreme fuel pressure of diesel systems
(and direct injection gasoline systems) fuel lines
are usually not reusable. They are one time use,
with deformable ends to accommodate fuel
pressure sealing. Make sure all lines are new,
clean, and properly torqued.
43.
44.
45. Greener and cleaner diesel engines now
use a variety of emission reduction
technologies centered in the exhaust
system to meet strict emission standards.
These systems include the following;
46. Diesel Oxidation Catalyst
Catalytic converters consist of a honeycomb
substrate coated with a platinum catalyst.
The honeycomb structure with many small
parallel channels presents a high catalytic
contact area for the exhaust gasses. As the
hot gases contact the catalyst, several
exhaust pollutants are converted into
harmless substances: carbon dioxide and
water.
47. Exhaust Gas Recirculation (EGR)
By reintroducing exhaust gases back into the
cylinders, a major reduction in the NOx emissions
produced by the diesel combustion is achieved.
(slowing the rate of combustion, and reducing
combustion pressures.)
48. EGR Cons:
-Increasing EGR flow combined with
retarding fuel injection and ignition timing, to
meet modern emission requirements
reduces fuel economy and power
49. Diesel Particulate Filters (DPF)
Exhaust component designed to remove soot and
other solid particles from diesel exhaust, not
lessened by fuel injection event timing. Eliminates
microscopic particles down to 50 nanometers.
50. DPF Continued
The concept for removing particulate matter
(PM) is simple. Soot and other exhaust
particles must pass through a filter that traps
it before reaching the outlet.
51. DPF Continued
Trapped soot and other particles collected in
the walls of the filter will eventually plug the
filter. To clean the DPF a regeneration
process monitors exhaust pressure and
purges soot by supplementing heat which
literally burns the soot out.
52. DPF cons:
-During active regeneration the DPF is
heated by adding fuel to the exhaust stream,
either by directly injecting it behind the turbo
or through a post combustion fuel injection
event.
(Equals poor mileage and hot exhaust)
53. WARNNIG:
During active regeneration the exhaust pipe will
reach temperatures that can burn you if you come
in contact with the pipe or you are standing close
to the exhaust gases out the back. DO NOT modify
special designed exhaust pipe, or serious injury
can occur.
54.
55.
56. Selective Catalyst Reduction (SCR)
Is a process where a Diesel Exhaust Fluid is sprayed
into the exhaust stream to destroy NOx molecules.
Diesel Exhaust Fluid or DEF is the generic name of
the liquid. It is a clear, nontoxic, and nonflammable mix
of synthetic urea.
Urea decomposes in the exhaust gases to form
ammonia which chemically reacts with NOx in the
catalyst to form harmless nitrogen and water.
57. Advantages of SCR:
-SCR enables lowest fuel consumption, while
improving power output and durability. (due to less
EGR flow)
-Future use of SCR technology may eliminate DPF
and regeneration.
(again due to less EGR,
and being able to
advance injection timing.)
58. Disadvantages of SCR:
-Need to add about four gallons of DEF every oil
change.
-If you run out or “tamper” with mixture, the vehicle
will give up to five stages of warnings before it
limits engine speed to an idle.
Need to fill up with DEF and clear code with scan
tool to resume normal operation
59.
60. Note:
Some vehicles use a SCR without injecting
liquid. This system is known as Lean NOx
trap or LNT. It uses a NOx adsorbing
catalyst to chemically trap NOx during lean
conditions and then uses the engine
management system to increase exhaust
HC to react with the NOx, turning it into
harmless nitrogen (like the liquid SCR)
62. Lower sulfur fuels enable the use of
exhaust emission reducing technologies
Common Rail systems provide high
injection pressures available at an
accumulator directly to the injector for
better control, emission reduction, and
atomization (efficiency).
63. Exhaust after treatment systems reduce
NOx, HC, CO, and Particulate matter,
while allowing us to maintain greater fuel
efficiency, and power.
64.
65.
66. Continued Reading
ISBN# 9780131574533
Pick up this book if you have extra
questions about diesel operation.
It’s a great resource filled with
general theory and operation of
various diesels.
