Octane rating is the measure of a fuel's ability to resist "knocking" or "pinging" during combustion, caused by the air/fuel mixture detonating prematurely in the engine. In the U.S., unleaded gasoline typically has octane ratings of 87 (regular), 88–90 (midgrade), and 91–94 (premium)

1. Rating of fuel

2. Contents
Introduction
How the knocking occurs
Octane Number
Octane Rating Methods:
Why Do We Care About
Octane ?
Latest updates on octane Number
Cetane number
Measuring cetane number
A high-cetane diesel fuel provides

3. Why
Defination
History

4. How the knocking occurs ?

5. Introduction :
Normally the fules are rated for
their antiknock qualities.
1.octane number.
2.cetane number
Cetane number (diesel fuel) and
octane number (gasoline) both
measure the tendency of the
fuel to ignite spontaneously

6. The fist scientist Marker Russell.
Octne number:
The octane Number (or octane rating) of a
gasoline (or any other Ic engine fuel) is the
percentage of iso-octane in a mixture of
iso-octane and n-heptane, which matches
the fuel under test in knocking
characteristics.

7. N-hepatane:
It is straight chain hydrocarbon
ex: heptane C7H16
octane number zero(0)
2,2,4-Trimethylpentane:
octane number is 100
it has branched hydrocabons

8. octane number: 106 83 92

9. WHY DO WE CARE ABOUT
OCTANE ?
the higher octane rating means that
your car will burn slower.
In addition that every single engine has a
specific octane number and when it use a
lower number the engine can be
damaged for a short term.
performance of an engine.
The higher the octane number higher compression ratio

10. Ron method
Mon method
Aki method

11.  RON describes the behaviour of a fuel in an engine at
low temperature and speeds
 MON describes the behaviour of a fuel in an engine at
high temperature and speeds

12. Research Octane Number (RON)
The most common type of octane rating worldwide is the Research Octane
Number (RON). RON is determined by running the fuel in a test engine with a
variable compression ratio under controlled conditions, and comparing the results with
those for mixtures of iso-octane and n-heptane.
Motor Octane Number (MON
Another type of octane rating, called Motor Octane Number (MON), is determined at
900 rpm engine speed instead of the 600 rpm for RON.[1] MON testing uses a similar
test engine to that used in RON testing, but with a preheated fuel mixture, higher
engine speed, and variable ignition timing to further stress the fuel's knock resistance.
Depending on the composition of the fuel, the MON of a modern pump gasoline will be
about 8 to 12 octane lower than the RON, but there is no direct link between RON and
MON. Pump gasoline specifications typically require both a minimum RON and a
minimum MON.
Anti-Knock Index (AKI) or (R+M)/2
In most countries in Europe (also in Australia and New Zealand) the "headline" octane
rating shown on the pump is the RON, but in Canada, the United States, Brazil, and
some other countries, the headline number is the average of the RON and the MON,
called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2. It may also
sometimes be called the Posted Octane Number (PON).

13. Decreasing Factors OCTANE NUMBER
1. Octane number decreases when increasing
carbon chain length.
2.lead and sulfur

14. IMPROVING OCTANE NUMBER
How to improve it.
o There is an improving and reforming unit in
every refinery processing company and its
mission is to improve the quality of the product
(specially fuel products).
1. By putting some additives into the fuel which
discourage auto ignition such as : Aromatics,
organometals and oxygenates.
2. By some treating and reforming processes that
changes the properties of the fuel like: catalytic
reforming, cracking, isomiration and alkylation.

15. LATEST UPDATES
RON & MON TESTING
ENGINE
1. Using ASTM method for testing
octane rating a machine that is called
“knocking engine”was made by CFR
company to give a specific values of
RON and MON for any fuel .
2.The CFR engine measures octane
by combusting the fuel and
physically measuring the knock that
occurs.

16. LATEST UPDATES
Octane boosters
1 Octane booster can be added to the
fuel in the car and it has the ability to
improve the fuel and increase its
Octane number.
2 These octane boosters use anti-knock
additives which, when added to the
fuel,
prevent the onset of knock (detonation
or
pre-ignition).
3 By preventing the knock, the effective
octane of the fuel is raised.
Different types of
Octane boosters

17. LATEST UPDATES
SHELL V-POWER
Shell's Friction Modification Technology, or
lube, helps the engine turn more freely. Less
friction means less wasted energy and more
power from the fuel can be transmitted to
the wheels. Also, whereas ordinary unleaded
fuels have a research octane number of 95
RON, V-Power Nitro+ is rated at 99 RON.
Shell says it'll work in anything, old or new.
It can help maintain the performance levels
of a new car and help restore lost
performance to older motors.

18. OctaneNumber–Above100 :
1.Bydefinition,themaximumoctanenumberis100,i.e.,10
0%ofiso-octanecharacteristics.
2.But,somefuelsaremoreknockresistantthaniso-
octane,andhencetheoctanenumberisextendedtoallowf
ornumbersgreaterthan100.
3.Theoctaneperformanceofcertainsubstanceshavehigh
ershockresistanceandhasbeenassignedwithnumbersgre
aterthan100.
4.OctaneBoosterssuchastetraethyllead(TEL),toluene,etc
,alsoincreasestheoctanenumberofgasoline.

19. Aviationgasoline
has hydrocarbons in lowboiling range(40-
170oC),whichshowshighoctanenumber.
During‘take-
off’,anaircraftenginedevelopsincreasedpowerwhichisprov
idedbyanincreaseoffuelsupplytogivearichmixtureofairand
fuel.
Usinghigheroctanenumberfuelinaircraftengines,increase
sthepowertotake-off.
Achangeinfuelfrom90octaneno.to100octaneno.leadsto1
0-30%increaseinpoweravailablefor‘take-
off’,duetoincreaseinCR.
OctaneNumber–AviationGasoline 16

20. Efficiencyofenginecyclemaybedefinedbyanexpres
sion:
E=1-(1/CR)0.258
Considertheoctanenumberofanaviationfuelisincr
easedfrom90to100andthecompressionratiochang
edfrom7.8to9.5,letuscalculatetheincreaseinefficie
ncyoftheengine.
Initialefficiency,E1=1–(1/7.8)0.258=0.411
Subsequentefficiency,E2=1–(1/9.5)0.258=0.441
Increaseinefficiency=0.441–0.411=0.030
%increaseinefficiency=(0.030/0.411)=7.29%
OctaneNumber–AviationGasoline 17

21. Ignition quality order a monghydrocarbon
constituents of a dieselfuel is as follow:
n-alkanes >naphthalenes >alkenes>
branchedalkanes> aromatics
Thus, hydrocarbons which are poor gasoline fuels
are good diesel fuels.
DieselEngineFuels 18

22. The suitability of a diesel fuel is determined by cetane
number or cetane value.
Definition of Cetane number:
Cetane number is the percentage of hexadecane in a
mixture of hexadecane and 2methylnaphthalene, which
has the same ignition characteristicsas the diesel fuel
under test.
CH3-(CH2)14-CH3
Hexadecane or cetane
Cetane no.:100

23. The cetane number of a diesel fuel can be raised
by the addition of small quantity of certain
compounds like ethylnitrate, acetoneperoxide, iso-
amylnitrite, etc. Such compounds are called“pre-
ignitiondopes”.

24. A high-cetane diesel fuel provides:
More complete combustion
Improved cold starts
Less engine noise and knocking
Reduced white smoke and warm-up time
Fewer misfires
Lower exhaust emissions: nitrogen oxide, hydro
carbon, carbon monoxide, and sometimes
particulate matter.