do you mean d16 SOHC? no such thing as a d18.

I am assuming you were given the engine of the 2000 civic EX, the D16Y8. or possibly the 2000 Civic DX, the D16Y7. The Y8 makes more power, about 127 crank, the DX makes like 107 crank (?).

i think the HX's stock motor is about the same as the Y7. Pop your hood, and on the front side of the engine block, left side (right beneath the head) there should be an engine code. Let us know what it is, then we can elaborate more.

edit: damn youre fast WCS.