i have a crx si with a d16a6 motor and i have a spare d16z6 motor wondering if its a straight swap.

 

not exactly a straight swap - the D16Z6 is an OBD1 VTEC engine and in order for it to work correctly you should convert the car to OBD1 - the engine itself will bolt in if you swap the driver's side mount that is attached to the block from your A6 onto the Z6 - you would need to use your D16A6 engine wiring harness and would need to make some changes to it - the changes needed would depend on whether you were going to run it as OBD0 or OBD1 - some changes to the wiring would be the same in either case, like the cooling fan switch and the MAP sensor

 

but if switch the d16a head on to the d16z block what will that do

 

if you stick with the a6 head it will run and you will be able to stay obd0. I just did a d16y8 swap but i left the a6 head on it cause im on a low budget as well. Most D series parts will bolt up the same.