Hi everyone. This is my first post. Tomorrow I may purchase a 2004 XJ8 with the 4.2 L engine. I will want to see the diagnostics at the dealership first, and especially want to know what the compression test revealed. I'm assuming that factory spec will be indicated on the printout along with the actual tested figures for each cylinder. But just in case, does anyone know what the ideal compression is on the 2004 XJ8? Many thanks.

 

If the compression ratio is say 10:1 and atmos.pressure is 14.7psi then the cylinder

compression will be about abot 150 psi.