Jaguar XJ Tuning

"The Classic XJ"

The XJ is the very definition of what Jaguar are to many, the XJ had a long production run and is as Quintessentially British as it is possible to be. For me the XJ has to be in British racing Green, any other colour just doesn't seem right to me.

In this article we shall give you an overview of the best tuning mods for your XJ and help you to turn your car into a racer! There are many different engine options over the years and with some carefully chosen mods you can really transform the performance and handling of your XJ. These are really big cars so weight reduction really does pay off, lose the excess interior refinements and beef up the torque and you'll have a fun car.

If you do your research then you can create an awesome XJ but don't be fooled there are lots of performance parts out there that will simply not suit it read our unbiased guides first.

Tuning tips and articles

Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Improving the handling should be your first priority in your XJ tuning project. We suggest that you fit uprated suspension and lower the car by 30-35mm. Larger drops require arch work - especially on models already equipped with sports suspension.

Top end power should be your overall aim on the XJ with a nice fat peak torque band.

Following our guidance for modding your XJ you will make a practical but hot car that will potentially embarrass bigger cars.

Smaller engines do not provide much of a return in terms of power so start with a bigger engine. Engine swaps are a good option if you have a small engine size.

Power mods.

The following modifications are usually performed by our members, decide how far you want to push your car before you get going.

Getting the right mods for your planned usage of the car is essential. Stage 3 motorsport mods just won't work well on the road as it makes the car hard to control in slow traffic.

Stage 1 mods: Panel air filter,Sports exhaust,Alloy wheels,Lighter flywheel,Remap,Suspension upgrade (drop 30-40mm).

Stage 2 mods: Power clutch,Ported and polished head,Fuel injector & fuel pump upgrades,Fast road cam,.

Stage 3 mods: Sports gearbox,Internal engine upgrades (pistons/head/valves),Competition cam,Adding or upgrading forced induction (turbo/supercharger),Engine balancing.

You need to keep as much low end power as possible and aim for a wide power band rather than a narrow top end power spike. The whole aim of this article is to give a brief overview of car tuning performance parts and point you in the right direction, our forum is where you can ask for more detailed advice and tips on your project and all aspects of modding cars.

Fast road cams offer one of the biggest performance gains for your money as far as a bolt on part goes on a NASP engine. The intake and exhaust flow play a large part in your cars power band, but be careful here, getting this wrong can upset the idle and make the car hard to drive in traffic. You'd need to follow a camshaft upgrade with other mods and finish with a remap for the best performance gains.When pushing up the power you will need to pay attention to the fuelling. More power needs more fuel.

If you find you have flat spots and surges after your modifications you should check the fuelling and try a higher octane fuel as well. Uprated injectors will enable you to supply sufficient fuel to the engine. If have increased your fuelling with bigger injectors you will also need to get a bigger fuel pump to supply it.

Intake and Exhaust Tuning.

Now we move on to the intake and exhaust and ensure proper flow through the engine. Please note that WE DO NOT RECOMMEND INDUCTION KITS, unless you have tuned your car extensively and are finding that the standard air itnake has become a restriction. For most XJ engines TorqueCars would suggest you just go with a washable panel air filter. On heavily tuned engines and turbo vehicles an induction kit will help release the power providing you address the problem of supplying cold air.

Sports exhausts balance the flow of air through the engine. But if your exhaust is too large, ie: over 2.5 inches bore, you will lose a great deal of the exhaust flow rate and end up losing power and torque.

Head work including a gas flow (ported and polished) and 3 or 5 angle valve job will really help to release the potential of the engine. In nearly all cases of XJ tuning your clutch will start to suffer and this needs an upgrade - read our overview on clutches for more information. Turbo engines are just asking to be flashed. You will see large power gains on most modern turbochaged cars including diesels making a remap one of the most cost effective and large modifications for your money.

We've also come across some owners experimenting with twin charging applications and making some very high power figures.

Despite the large cost involved adding forced induction to a NASP engine will give large power gains. Superchargers are generally easier to add than turbos. With a turbo the boost curve is related exponentially to the engine speed making it more challenging to map. The nice correlating boost and rpm characteristics of the supercharger make them more straighforward to map. To cope with forced induction you will usually need to decrease the engines compression ratio .

Alloy wheel upgrades.

The benefits of alloy wheels include reducing your unsprung weight and more efficient brake cooling. The drawback to large alloy wheels on your XJ is that you're changing your final drive ratio so this will have a negative effect on acceleration and performance. Although some people have fitted larger wheels we would restrict ourselves to a 19 inch rim size as the maximum.

For more information on Tuning your car please join us in our friendly forum where you can discuss XJ options in more detail with our XJ owners. It would also be worth reading our unbiased Jaguar tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below. We love to hear what our visitors have got up to and which mods work best for them on each model of car. Comments are used to improve the accuracy of these articles which are continually updated.

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