I've been doing some calculations to see the effect of my engine rebuild on the swept volume and the compression ratio.

My engine has been re-bored and fitted with over sized pistons. The bores are now 91.5mm

I've calculated the clearance volume of a standard engine using data from the FSM and the information given on wikipedia:-

http://en.wikipedia.org/wiki/Compression_ratio

Here is a step by step re-working of the equation (each new line is a step to obtain the final formula)



Vc is the clearance volume, Cr is the compression ratio, and Vs is the swept volume

Using this formula I got a value of about 150 cubic centimeters of clearance volume.

Using the new dimensions of the re-bore (same stroke!) I've now got a 3038cc engine instead of a 2998cc engine.

Assuming that the clearance volume did not change during the engine rebuild I've come up with an estimation of the new compression ratio => I think it is now 21.26:1 instead of a 21:1

So my conclusion? (Considering it was an inconvenient unexpected engine rebuild)

...Well at least I now have a larger engine with a slightly higher compression ratio!

Attached Thumbnails

 

Attached Files

OM617 swept volumes.pdf (21.5 KB, 282 views)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!