i have a feeling im losing my vtec, at quater or half throttle the vtec hits fine but when full throttle it kinda sputters or doesnt work at all... any advice on how to fix it? and if not does the b20 head fit the b18 c1 block?

 

hows your oil.? clean or really dirty ? is your oil full?

 

As already stated check your oil level.. Your VTEC solenoid might be taking a **** on you.