1. ECO-FRIENDLY MODIFICATIONS OF A SMALL
GASOLINE ENGINE
Jesus Bravo, Jerry Hwuang, Faizan Ahmed, Ryan Wilson, Brandon Wagner, Edgard Jimenez,
Miguel Ferrer, Dong Kwak, Stephanie Bajorek, Prof. Michael Muller
Center for Advanced Energy Systems, Mechanical and Aerospace Engineering,
Rutgers, The State University of New Jersey
Objective Project Management
To create eco-friendly modifications to a
standard small gasoline four stroke engine.
Current engines run on gasoline and create a lot
of noise. The goal for this project is to modify an
engine to run on 100% ethanol, a green and
renewable energy source, and to reduce noise
pollution using a muffler addition.
To combat the lower energy content of the
ethanol fuel, more fuel needed to be injected into
the engine. The extra fuel needed is calculated using
air-to-fuel ratios. To increase efficiency, new
compression ratio calculations are done for the
engine. The muffler is designed to limit back
pressure while still reducing noise.
Project management was done using Gantt
charts and sub-teams. This was necessary in order
to keep the project organized and time efficient.
The sub-teams made were for muffler design,
ethanol modifications, and engine rebuild.
Administrative tasks were handled by the leader.
Background Design & Results
The ethanol engine modification was done mainly on the carburetor. The fuel jet diameter was increased by
80% so the engine run fuel rich and does not see a performance loss. The gaskets in the carburetor were
changed to silicone and the pump-fed fuel system was replaced with a gravity-fed fuel system. This was done in
order to avoid corrosion from the ethanol. The muffler design chosen is a glass pack muffler. It utilizes a flow-
through design to minimize back pressure while still reducing noise. The noise reduction is done using a
perforated inner tube that is surrounded by an outer tube with fiberglass insulation packed in the middle.
Conclusions
A standard, small engine was modified to be
quieter and more environmentally friendly. It
became quieter using a muffler modification and
more environmentally friendly by using ethanol
rather than gasoline. The muffler reduced the
noise emitted by the engine by an average of 3 dB
at a distance of 7 feet from the muffler. The
backpressure caused by the muffler had minimal
effects on the efficiency and fuel consumption of
the engine. The engine was more efficient in
converting the ethanol into usable energy than
gasoline, but it consumed much more of it. The
core goals of the project were accomplished. With
more time, the compression ratio of the engine
would be changed using piston modifications.
Also, with additional resources, the maximum
power of the ethanol engine would be measured
using a dynamometer.
Most small engines use gasoline as their fuel
supply. In the US, gasoline at the pump can
contain up to 10%-15% ethanol. Ethanol is an
alcohol created by the fermentation of starches,
such as corn, wheat, barley, and potatoes. Since it
is created from plants, it is considered a green and
renewable resource. By moving to a 100% ethanol
fuel supply, the dependence on fossil fuels can be
gradually dissipated and the high carbon release
in to the atmosphere by fossil fuels can be curbed.
A properly modified engine can run on ethanol
approximately as well as a standard engine runs
on gasoline. Currently, ethanol is slightly cheaper
than gasoline per unit volume, but contains 33%
less energy than pure gasoline. As fossil fuels run
out, ethanol will become more cost effective
while being more environmentally friendly.
Theoretical Approach
Compression Ratio Thermal Efficiency
Glass Pack Muffler Design