Swapping A20 heads and blocks

[anchovies]

Helping a friend out. He's got an 86 DX and wants to play around with the compression. Lower it for turbo/maybe up it for NA.

So the similarities and differences are and tell me if I'm wrong here:

Similarities:
1) Blocks on all models (carb vs. FI / 86-89)
2) Bore and stroke
3) Head gaskets (swaps shouldn't be any problem)

Differences:
1) Piston
2) Head

This is what I vaguely remembered for the CR:
86/87 carb : 9.1
86/87 FI : 8.8
88/89 carb : 9.1
88/89 FI : 9.3

thanks

[AccordEpicenter]

i think you are correct but 86/87 FI compression was 9.3 too i believe. Is it the heads that make for the compression change? Everybody I asked says the bottom ends are completely the same...

[carotman]

The heads are all the same except for the cam

The block is also the same except for the Pistons.

There is no real gain from swaping the piston. They will not support Turbo applications and do not have a real high compression Ratio

There are no easy gain...

[anchovies]

The CR for the 86/87 carb and FI I stated above looks wrong but is what the Honda manual and Chilton states.

So the only thing that makes the CR different on the different years and models is the piston.
Yeah not worth it...even from carb 8.8 to FI 9.3 CR, the gain is 2%. Wooohooo
From 98 HP to 100 HP.

Well, then I guess it's cam, headers and intake and take off the vacumm lines.