ok so reading on lots of other boards(nasioc and others) ive heard it mentioned to put ej18 heads on the ej22. its supose to raise compression to 11.5 to 1,

 

here is my question. who has done this and could you run it on reg gas if the comp is raised that fare?

i guess teh ej18 has roller cams and what not.

 

anyway. what you think.

Need to run premium for sure with that. If its an older 2.2, the heads are virtually the same in terms of design, its just the compression chamber thats different.

I'm pretty sure the intake and exhaust ports are smaller in size, so you might be negating the compression increase.

 

If you want to get the *most* out of something like that...

 

new cams (cobb spicy?)

EJ18 valvetrain, possibly if the valves are bigger, having the valve seats enlarged to accept EJ22 valves

some headwork (porting)

possibly a valve job (5 angle, whatever)

EJ22 manifold

EJ25 injectors (or if the manifold is EJ22 '95+ it should have the red injectors anyhow)

EJ22 ecu

 

by my calculations... if both motors have the same wristpin location (exactly) and the same rod length (exactly) and the only differences are bore, gasket, and heads, you should get 11:1 with EJ18 heads and EJ22 gasket (1.52mm, stock EJ22 phase I) or if you wanted, which I think is the right measurement, the phase II EJ22 at 0.68mm (0.027") would net you 12.7:1 CR!!

 

And you'd have one cool SOHC motor. But the 12.7:1 would require either an ECU change or really high octane gas.