00-03 na 4.0's I can find here locally.98-99 na and 98 sc I can find on ebay.the na are alot cheaper and have less miles.thats why I wanted to know if I can use a 00-03 4.0 na.

 

In my opinion you need a sc engine. If you get a na you will need to change the pistons. The compression ratio is different and I think you are asking for trouble if you put supercharger on a na block. If you change the pistons you will need new rod bearings and rod bolts. Plus you will need a gasket kit which might add up to $500 plus. Check out craigslist for cars that might have problems but a good motor.

 

Yea I was thinking about that.so best bet is 98-99 4.0sc and second would be 00-03 4.0sc,

 

In my opinion yes.
The 00 + engines will have more cost to them by adapting them to your car.

 

Ok.thanks for ur help again.are the 00+ 4.0sc rated for more power or are they the same.probably wont matter anyway as id have to swap parts from mine to it.

 

I believe they have the same horsepower

 

Hi,
as you're undertaking a major repair/overhaul, you should consider replacing your blower with a generation V Eaton m112 supercharger. The 4.0 SC engines (whether AJ26S or AJ27S) had the genIV m112, while the 4.2l SC cars (STR, aluminium body XJRs etc) used the genV blowers.
The genV superchargers came with better bearings for the rotors, which are supposed to last longer (and run slightly more quiet too). They're bolt in - except for the gasket to the intake elbow (cause of the slighly bigger needle bearings, which protrude a little bit at the back). You have to discard the gasket from the 4.0 and order the one from the 4.2 instead.
In case that your old supercharger has done many miles and you can get your hands onto a cheap used 4.2 blower, this'd be worth thinking about in terms of a sustainable upgrade for your car.
I didn't do this yet to my car, but the genV supercharger (with coupler and oil replaced) and gasket is already sitting on the shelf and waiting for the swap.

EDIT: The part no for the genV supercharger is AJ89855 and it's used in the STR, x350 XJR, 4.2L XKR and 4.2L V8 XF SC. The gasket is AJ83292.