Cooperative Fuel Research (CFR) Engine
- Check Engine Oil Level
- Check Coolant Level
- Open Coolant Valve for Pressure Transducer
- Input Desired Fuel
- Check Compression Ratio
- Micrometer Reading
- Double Check The Head Is Securely Tightened
- Check The Valve Clearances
- Exhaust: 0.010”
- Intake: 0.008”
- Set Timing For Current Compression Ratio
- Compression Ratio
- Spark Advance BTDC
- Connect Ignition Wires to 12V Battery
- Turn On Circuit Breaker to Engine
- Turn On Lab Exhaust Fan
- Open Exhaust Gate Valve
- Engage Starting Motor
- Turn On Ignition Switch
- Turn Throttle to Wide Open Position
- Back Out Fuel Needle Valve, Adjust Until Backfiring Stops
- Let Engine Warm Up, Readjust Fuel Needle Valve as Needed
|Engine Speed||Constant at 900 rpm|
|Oil Pressure||25-30 psi|
|Intake Air Humidity||25-50 grains/lb|
|Carburetor Venturi||19/32 in.|
|Lubricating Oil||SAE 30|
Test Run Preparation
- Turn on the main switches, crankcase heater, and coolant heater.
- Turn on the circulating cooling water. When coolant temperature approaches 180°F, turn the heater to low.
- Fill one of the carburetor bowls with regular gasoline.
- Start the electric motor, then turn on the ignition switch.
- Turn selector dial to the bowl containing regular gasoline.
- After the engine has run for a while, check the manifold temperature. Turn on the heater if it is well below 300°F.
- Check the specific humidity while engine is warming up.
Bouncing Pin Adjustment
- Check and record barometric pressure.
- Adjust the compression ratio of the engine to the corresponding micrometer setting (Manual page 96)
- Switch from regular gasoline to a reference fuel with a known octane rating.
- Adjust the bouncing pin to read 55+3 on the knockmeter.
- Adjust the elevation of the reference fuel bowl until a maximum knock is reached. This varies the AFR.
- Now, just read the bouncing pin to the 55+3 reading.
Note: From this point forward, do not touch the bouncing pin
Testing the Unknown Fuel
- Drain the reference fuel.
- Set up the four bowls in such an order that they can be easily remembered.
- Turn selector to the bowl containing the unknown fuel.
- Adjust the compression ratio so that the knockmeter reads 55+3.
- From this point forward do not change the compression ratio.
- Using pipettes and graduates, mix a reference fuel of iso-octane and normal heptane. 200 mL should be enough to run the engine and obtain a good reading.
- Use of conversion tables makes it possible to obtain known blends using the reference fuel with either the iso-octane or normal heptane.
- Turn the selector to the newly mixed reference fuel blend.
- Adjust the bowl containing the newly mixed blend to give maximum knock.
- Repeat this procedure until two reference blends not differing more than two octane numbers bracket the fuel.
- Interpolate between the two octane numbers to obtain the octane rating of the unknown fuel.
Note: If you want to test more than one unknown fuel, repeat only the 'Testing the Unknown Fuel' section.