Keep in mind that the amount of boost that you are putting into the engine will depict how much power and what other engine mods that you will need to do. Doing up to about 5-6 psi of boost, you can get away with simply putting the supercharger on to the engine with no major upgrades. Granted, if your car already requires the use of premium, you may find that you will be limited to 3-4 psi of boost due to pre-ignition of the fuel. If pre-ignition of the fuel occurs, the only way to fix this is to either add more octane to the fuel or rip apart the engine and put in lower compression pistons (normally people use something in the 8.0-8.5 range. Odds are, using this minimal boost, you will see about a 50 hp gain from the engine.

If you are looking for more power than that, then you are looking to do a lot more internal upgrades to the engine. Lower compression pistons are a must. Upgrading the connecting rods probably would not be a bad idea. As for the crank, may handle it, may not. Probably need to talk to a shop that specializes in what you are talking about.

Keep in mind that if you engine has over about 100K miles (160,000KM), then an engine rebuild will be a good idea regardless of how much boost you add. For a lot less money, you can probably get away with porting/polishing the heads and get say 30-40 hp gain and not require the use of any specialized fuels or major reworking of the engine. All this gain is from allowing the air/exhaust to flow more efficiently through the engine. Less drag means more air/fuel makes it into the cylinder to make more power and the energy necessary to push it out of the engine is that much less, therefore the energy spent to expell the exhaust gases can now be applied to the crankshaft.

If you need some more ideas, just hollar. While I am not intimately familiar with Jaguar engines and their weak points, I have done a lot with Ford engines in general.

Chris "Thermo" Coleman