difference between 1.8 injection and 1.8 carb

rubjonny said

nah carby and gti are both 10:1, you may be thinking of the 1.6 carb which is lower compy, not sure off hand what it is but 9:1 could be right.  

there were lower spec 1.8 in the US and euro MK3s, but in terms of euro MK1 and MK2, 1.8 all 10:1

From “difference between 1.8 injection and 1.8 carb”

So what happens if you put a 1.6 carburetor head on top of a 1.8 fuel injection bottom end, will I change the compression ratio so that you would have to find 99octane fuel or would it just up the ratio a little and make it run a little warmer?