i have a strange problem with my car.i just got the sr20det(s14) motor from gs motorsports in irving texas.from a guy named german.he sold me a motor that had 19,000 miles on it. i get back to my town and drop the motor in.i turn it on and it DOES NOT miss fire,blow any type of smoke,burn oil,back fire,hessitate,or act strange.the motor runs perfect like a champ. BUT when we do a compression test it comes out 40,50,40,50. it has super low compression. we just dont get how this motor can run and drive so perfect with no issues but no compression.what could be the cause of this?i really need some help with this one.please help!!!!!