FHSAE Next Generation Engine Configuration

=Problem Statement=

To maintain a competitive advantage in the Formula Hybrid SAE competition, a new exotic and legendary engine design is needed for the University of Idaho race car. The solution is to reverse engineer a Honda CRF-150r one-cylinder engine with computerized micro measuring and laser scanning technology and turn it into a two-cylinder 250cc engine.

Background
The Formula Hybrid team at the University of Idaho is in need of a new engine configuration to remain competitive for future competitions. To incorporate the electric motor and maximize engine displacement, a new engine must be designed that has separate engine cylinders. This will require research of an engine with comparable features and design.

Deliverables
One of the main goals of this project was to reverse engineer the Honda CRF-150R engine, while this process took place we documented any findings we made as well as how we took apart the engine. This project required more than just reverse engineering the engine but also required that we learn to use the metrology equipment and Solid Model the engine using the CAD program Solidworks. The Metrology equipment we used included calipers, CMM, laser scanning technology and scaled photographs.

The second goal of the project was to combine CRF-150r engines together and reduce their displacement to a total displacement of 250 cc. The original CRF-150r is a 150cc, so that meant altering the crankshaft of each engine. We designed a configuration with the engines parallel to each other and with the engines co linear. The configuration of the parallel engines is based of a gear box design from another project relating to a Yamaha engine.

Metrology


Computerized Micro Measurement (CMM) at University of Idaho Metrology Lab | ''Laser scan of the crank case for the motorcycle motor"

CAD Modeling
In order to draw complex shapes in Solidworks, it proved easier to scan or photograph images of parts and then trace them in Solidworks. This helped reduce the amount of dimensions we had to measure, it also speed up the process.

In the beginning we thought that laser scanning everything would work, but it does not. The laser scanner is great for highly complex shapes; however, it creates very large files in Solidworks that need to cleaned up in order to be used correctly. We found the laser scanner to be a valuable tool, but it does not replace hard work and the other methods that we used.

Matlab Simulation
The 150cc CRF-150r needs to be modified to a 125cc and fuel injected. We investigated building air fuel ratio (AFR) maps and optimizing spark timing. These images show theoretical power curves and brake specific fuel consumption (BSFC) for a 125 cc version of our engine. By reducing the engine size, a power loss of about 4 hp should be expected.

Following is the dimensions required to make our 150cc into a 125cc, these dimensions were used in the Matlab model: L = (36.5/1000) Stroke of Engine [m], B = (66/1000)   Bore of Engine [m], l = (75.4/1000)         Length of Engine Connecting Rod [m], C_r = 11.8       Compression Ratio, IVC = 0          Time [degrees] when Intake Valve Closes, EVO = 314       Time [degrees] when Exhaust Valve Opens

Reconfiguration
After modeling was completed the next task was to reconfigure the motor for potential formula hybrid competitions. This configuration places the crankshafts parallel to each other. The power is then transmitted from each crankshaft and the electric motor to a ring gear on the flywheel. From there the power goes out to the wheels thru a differential. Some issues with this include creating enough room for an air intake and considering if a balance shaft is necessary.

We also considered a configuration where the crankshafts would be coaxial. In this case we would build a new crankshaft that served both pistons. In between the engines along the crankshaft there would be room for an electric motor.



Document Archive
Documents (Meeting Minutes, Agendas)