Camshaft Overlap
Location
CSU 203
Start Date
20-4-2015 10:00 AM
End Date
20-4-2015 11:00 AM
Student's Major
Automotive and Manufacturing Engineering Technology
Student's College
Science, Engineering and Technology
Mentor's Name
Bruce Jones
Mentor's Email Address
bruce.jones@mnsu.edu
Mentor's Department
Automotive and Manufacturing Engineering Technology
Mentor's College
Science, Engineering and Technology
Description
One of the major factors in determining a vehicles power is its camshaft. The camshaft is the device that opens and closes the valves to let air/fuel in and out of the engine. If you modify a stock engine the camshafts don’t always work and custom ones are expensive. Instead of making a whole new camshaft it is possible to modify the stock one so it meets this year’s Exhaust gas temperature (EGT) goal of under 1200F°. Since this year’s FSAE car is turbocharged, the turbocharger creates a restriction in the exhaust system and can cause back-pressure to be greater than the boost coming into the cylinder. When the intake and exhaust valve are open at the same time (Overlap) the back-pressure can push the boost back up the intake and the exhaust can be ignited again and cause the EGTs to reach over 1200F°. With high EGTs the exhaust port can melt and trying to burn gasses that have already been burnt doesn’t make power either. The stock camshafts have 27° of overlap and by modifying the stock camshafts it is possible to have 0° of overlap or less. Fitting a back-pressure gauge up to the exhaust will get the readings needed to determine the amount of overlap desired. The plan for modifying the stock camshafts consists of pressing the sprocket off and on but repositioning it so when it lines back up to the crankshaft it will have the desired overlap to make under 1200F°EGTs.
Camshaft Overlap
CSU 203
One of the major factors in determining a vehicles power is its camshaft. The camshaft is the device that opens and closes the valves to let air/fuel in and out of the engine. If you modify a stock engine the camshafts don’t always work and custom ones are expensive. Instead of making a whole new camshaft it is possible to modify the stock one so it meets this year’s Exhaust gas temperature (EGT) goal of under 1200F°. Since this year’s FSAE car is turbocharged, the turbocharger creates a restriction in the exhaust system and can cause back-pressure to be greater than the boost coming into the cylinder. When the intake and exhaust valve are open at the same time (Overlap) the back-pressure can push the boost back up the intake and the exhaust can be ignited again and cause the EGTs to reach over 1200F°. With high EGTs the exhaust port can melt and trying to burn gasses that have already been burnt doesn’t make power either. The stock camshafts have 27° of overlap and by modifying the stock camshafts it is possible to have 0° of overlap or less. Fitting a back-pressure gauge up to the exhaust will get the readings needed to determine the amount of overlap desired. The plan for modifying the stock camshafts consists of pressing the sprocket off and on but repositioning it so when it lines back up to the crankshaft it will have the desired overlap to make under 1200F°EGTs.
Recommended Citation
Hoppe, Nathan. "Camshaft Overlap." Undergraduate Research Symposium, Mankato, MN, April 20, 2015.
https://cornerstone.lib.mnsu.edu/urs/2015/oral_session_03/4
