The compression ratio calculator takes bore diameter (b), combustion chamber volume, head gasket thickness (t), deck clearance (c), gasket bore (g), intake valve closing point, number of cylinders, piston volume, rod length, piston stroke (s), sin and cos and returns dynamic compression ratio, displacement volume and compressed volume. It is built for quick answers, for checking somebody else’s arithmetic, and for the moments when a formula book is not within reach.
What Is the Compression Ratio Calculator?
The compression ratio calculator turns bore diameter (b), combustion chamber volume, head gasket thickness (t), deck clearance (c), gasket bore (g), intake valve closing point, number of cylinders, piston volume, rod length, piston stroke (s), sin and cos into dynamic compression ratio, displacement volume and compressed volume.
It is a quick way to get from the numbers you have to the number you need, without setting up a spreadsheet or reaching for a formula.
How the Compression Ratio Works
Each result follows from the ones before it, and the calculator shows every step, so a surprising answer can be traced back to the input that caused it.
Round your inputs to the precision you actually know, and keep more precision than that in the intermediate steps.
Getting a Result You Can Trust
Run the calculation twice with slightly different inputs. A sensible calculator moves its output in proportion; a wild change points to a unit or a decimal point problem in what you entered.
Write the inputs down next to the answer. It takes a moment and it is the difference between a number you can explain and one you cannot.
A Worked Example
Working through an example, with bore diameter (b) set to 10, combustion chamber volume set to 5, head gasket thickness (t) set to 2, the calculator returns displacement volume of 392.69908, and gasket volume of 157.07963, and clearance volume of 7,853.98163. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out dynamic compression ratio?
Enter bore diameter (b), combustion chamber volume, head gasket thickness (t), deck clearance (c), gasket bore (g), intake valve closing point, number of cylinders, piston volume, rod length, piston stroke (s), sin and cos. The calculator then works through the relationship and reports dynamic compression ratio, displacement volume and compressed volume.
What does the compression ratio actually calculate?
It takes bore diameter (b), combustion chamber volume, head gasket thickness (t), deck clearance (c), gasket bore (g), intake valve closing point, number of cylinders, piston volume, rod length, piston stroke (s), sin and cos and converts them into dynamic compression ratio, displacement volume and compressed volume using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter bore diameter (b)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.
Does anything you type get stored?
No. The whole calculation runs inside your browser, and nothing you enter is uploaded, logged or sent anywhere.