Original H-O's
Otto Cycle
Overlap Flow Calculator

This calculator determines the net air flow during the intake & exhaust overlap phases of the Otto Cycle. Select a Cylinder head and Camshaft type profiles or enter your own values. Then click on the Calculate button.

Before and at TDC, if exhaust air flow exceeds intake air flow, the intake air flow is lost out the exhaust. After TDC, if there is any exhaust air flow, it reduces the intake air flow by that amount.

The values shown under the Overlap Net Flow is the difference between intake (positive) and exhaust flow (negative) at the crank degree listed. A negative number means the intake charge is reduced by that amount. The Adv Net value is simply the sum of the Overlap Net flow column.

The 050 Net value is the net total for ALL degrees between IVO and EVC (overlap at 0.050" lobe lift) corrected to 5 degree crank increments. These values are NOT shown on the display.

NOTE: The values shown are NOT the actual flow numbers in an engine because RPM, flow momentum, piston pressure etc. are not included in this calculator. The values are for information and comparison purposes only.




Adv Net 050 Net
Crank degree Intake Exhaust Overlap
Valve lift Air flow Valve lift Air flow Adv Net 050 Net
45BTDC
40
35
30
25
20
15
10
5
TDC
5 ATDC
10
15
20
25
30
35
40
45