Sunday, October 18, 2015

Now we know! Compression ratio analysis...

We're beyond buying stuff and planning. It's time to get going.

Since we have new shorter conrods (143mm) and new pistons, which we combine with the standard Volvo forged crankshaft (stroke 90mm) the first step was to understand if we would need to lower the deck height (the distance from crankshaft center to top of cylinder block) of the engine block or not. Here's some Salt Slush Science.
Anders had an old syringe which seems suitable for elephants injections and compression ratio check.
With a piece of acrylic glass, some soap water and concentration, we managed to measure both the volume of the combustion chamber and the piston accurate.
We measured cylinder two as well just to underline or seriousness. It had the identical volume. Tolerance ok.
 Analysis completed. This time we even used understand all consequences.
Conclusion: We will lower the deck height with 1mm to 219mm, which will give us a compression ratio of 8:1, which is on the low side, but it allow us to use the standard timing drive. Now we just need to find a suitable milling tool for our Sajo 54 (our favorite machine).

To be continued...

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