So one is a S1 engine in a s2, the other is a s2 in a s2.

What chips are fitted, how do you know they are chipped, have you had the ecu's checked?

How retarded? you haven't measured it, so how do you know how retarded it is?

Have you removed the cam, and check it is std? have you set the cam timing on adj verniers on each car? as ones been apart and most prob a skim, and the others got a comp plate,
In which case what cam timing figures have you used?
If been done with std marks, 1) cam timing wrong, so compressions wont be the same, 2) as cam timing wrong the ign will be out too, unless set up with a timing light, or det checked by a skilled person.


If neither of the above is done, they both aren't tuned/set up.