Increased head size for improvements

[pantheas18_hj47]

Just wondering if bolting on a bigger head size would show any improvements or changes.

What I am thinking of doing is putting the head of a bigger engine from the same family on top of mine.

Specifically I have an isuzu 4fb1 1.8ltr (bore 84mm)
the options are 4fc1 2ltr (bore 84mm)
4fd1 2.2ltr (bore 88mm)
4fg1 2.4ltr (bore 89.3)

I am not sure if the different bore size will mean anything but put it in just in case

Or just tell me I have no idea what i am talking about and to give up this one

Cheers

[Dougal]

I'm not familiar with those engines. But in general installing a head from a bigger engine will lower the compression ratio. This could be an advantage if you need to lower the compression ratio due to large numbers of turbo boost. But otherwise lowered compression will lose power and hurt fuel economy.

[denis]

you could get bigger valves on the "bigger" heads for increased max. hp but then if they don't fit the smaller bore that will be of little use