PRODUCT INFORMATION
INDEX
DATE
Dep.2
IO-G-M-40-001e D
July 2015
GAS ENGINES AND ETHANOL ENGINES CARBURATION
1/2
1. INTRODUCTION
Tuning of an engine in order to ensure its correct operation means that different elements or parameters of the
same, namely ignition timing and the air/fuel ratio, are adjusted.
Depending on the application of the engine and on the specifications or regulations to be complied with, tuning
will be the most appropriate to meet these requirements, e.g. maximum thermal efficiency, lowest emissions, etc.
As for compliance with the regulations on permissible emission levels, it is essential to determine the proper
air/fuel ratio and to this effect, the
Kohler
engines include adequate tuning capabilities.
2. SPECIFICATIONS
The thermal balance-sheets of
Kohler
for gas engines and ethanol engines (lean burn in both cases) specify
the NOx emission level that can be achieved for each engine, based on the preset ignition timing and the different
cooling water temperature settings. The engine carburation is adjusted so that the specified NOx level is complied
with in each case. Normally, the NOx value is related to 5% Oxygen (provided the applicable legislation does not
specify another reference oxygen level for correction).
ATTENTION
Never carburet an engine, taking the percentage value of oxygen in the exhaust as a reference, but the NO
x
referred to above.
In rich burn engines, the target is to maximize the emissions’ reduction; therefore, a 3 Way catalyst is used. In
these cases the carburetion must be done in order to get the conjunction of the minimum possible NOx and CO
emissions.
NOTE
To calculate the emissions, refer to doc. IC-C-D-40-001e “Emission Units Conversion”.
3. REMARKS
1- Compliance with this specification is conditional upon correct tuning and adequate maintenance of the engine,
in particular with regard to ignition timing and spark plugs.
2- On gas engines with mechanical controller, engine carburation faults may occur mainly due to any of the
following circumstances:
-
Change in the gas supply conditions (pressure, temperature, humidity and composition of gas).
-
Change in room temperature or in the temperature of the intake manifold.
-
Plugging of air filters.
4.1.43
O&M_2.002211.810_A_10_2016
