So as this topic is always one of those areas that no one ever actually knows the answer i thought i would weigh the 2 engines before installing my LS1.

They are both in the same level of build (Engine, Gearbox, Headers, All Ancillaries)

So the F20C first. As the photo shows this weights 227KG on the scales but 18KG of that was the pallet so 209KG

The LS1 weighed 302.5KG and take of the 18KG is 284.5KG

This makes a difference of 75.5KG between the 2 engines which is obviously less than the weight of a normal passenger.

Pallet on the scales
F20C close up
LS1 close up