Hi I have a couple of questions about an engine in a 2003 XKR, that I am hoping someone can clarify for me. What is the difference between the AJ33 and the AJ33S? Is there a physical difference, (bigger crank journals, bigger block webbing, etc.) what I am getting at is would an AJ33 long block work in place of an AJ33S long block. Is the difference just that one is supercharged or does the supercharged engine have a stronger block? Thanks for any info you can share on this.

 

Compression ratio is lower the n the S/C version, that's a big difference. There are some other more subtle things like the oil sprayers to cool the bottom of the pistons, or the VVT that the N/A engine has that the S/C doesn't.

The long (or short) block are not interchangeable if you are thinking of an engine swap.

 

VVT was added later to SC. Maybe that made it AJ34?

 

Thank you for the information, makes sense.

 

Different cam profiles.

 

Different cam profiles and fuel injectors.

 

Could an 2003 XJR motor be used for a swap into a 2003 XKR?

 

The 2003 XJR should be a 4.0L so you would need a 2004+ XJR as a donor to get a 4.2L. And you would have to use the intake from the XKR but otherwise it should transfer from a 4.2L XJR.

 

Thanks guys you have been very helpful.

 

Keep in mind that the XJR and XKR with the AJ27$.0L engines had the oil filter in a different position.
I do not know if the same is true for the 4.2L engines but you may want to look into it.