Does Compression Ratio effect fuel economy?

[sunfire_starter]

Does CR effect fuel economy?
and one more question. What is the differnet between headers, intake manifold and exhast manifold? I always thought these were the same thing.

[drdisque]

a header is a word for an exhaust manifold made of individual tubes for each cylinder that meet at a collector. an exhaust manifold is the general term for the piece that collects exhaust fumes from the exhaust ports and combines them into the exhaust pipe. The intake manifold divides air from the intake pipe or carburetor into the individual cylinders.

[SaabJohan]

Compression ratio affects the fuel consumption, in general the higher the ratio is the lower the fuel consumption will be. But the engine will also require a higher octane fuel.

[drdisque]

this is of course holding power and displacement constant though.