30-09-2018, 01:08 PM
(This post was last modified: 30-09-2018, 08:30 PM by Colin Morgan.)

Looking at the spreadsheets - the original version is missing x Pi in the Clearance Volume calculation (B11), and as Mark says the ratio at the end needs to be total volume (not just the swept volume) divided by the compressed volume. With these corrections the two spreadsheets agree - compression ratio of 5.9:1.

Colin

PS - Notice from playing with the numbers in the spreadsheet that a change of only 0.1mm (4 thou) in the assumed head gasket thickness makes a 0.1 difference in the calculated compression ratio (e.g. a decrease in thickness of 0.1mm increases the calculated compression ratio from 5.9 to 6.0).

Colin

PS - Notice from playing with the numbers in the spreadsheet that a change of only 0.1mm (4 thou) in the assumed head gasket thickness makes a 0.1 difference in the calculated compression ratio (e.g. a decrease in thickness of 0.1mm increases the calculated compression ratio from 5.9 to 6.0).