How do you measure the efficiency of a Stirling engine?

[stuffandthings]

I know the formula is work done / heat input

But how would you get working efficiency in a percentage? How would you measure work done and heat
I'm talking about practical efficiency, not the theoretical maximum efficiency defined by Carnot's limit.

[mayya]

If you can solve these little problems, then your engine has a better performance in the future.

[Ian S C]

The efficiency is the ratio of the power/heat put in, against the power out at the crankshaft. Ian S C