This is a quick guide to modifications to get more from any diesel engined car. While it is possible to go to much further, most of these diesel tuning suggestions are relatively cheap, quick and simple.
Engine Upgrades
As diesel engines use compression ignition, the two main areas we are looking at for diesel tuning is the injection system and air intake.
Adding a tuning chip or external tuning box allows you to get more from your engine. Diesel engines often come in several performance variants, and are tuned to run on a wide range of fuel qualities. Modern diesel tuning systems - either the external diesel tuning box or internal chip remapping will adjust the engine parameters dynamically to give better power at all rev ranges. As a bonus, since you have more power available, you will often find you use less fuel overall - unless you have a very heavy right foot.
Choosing between a external tuning box and diesel remapping is largely a matter of preference. Costs are similar - normally around 300-500 for a quality system. Diesel tuning boxes can often be installed at home, while engine remapping will require a visit to a workshop, or a mobile workshop visit. The external tuning boxes also have the advantage that they can be removed if the car is going to a main dealer for servicing, or you want to transfer it to a new vehicle.
Some older systems for tuning diesel engines just 'fooled' the ECU into think it was colder, causing smoking and idling problems, but modern tuning boxes and tuning chips are much more complex, varying the adjustments they make depending on the engine requirements. These modern diesel tuning systems are probably the single biggest upgrade available to most people, with up to 35% more power promised, depending on your make and model.
A replacement air filter will give increased air flow, so giving more potential power. Almost all modern diesel engines will automatically allow the for increased air flow, giving a small boost of a handful of percent. Even replacing your current filter with a new standard filter will help, as they do become clogged over time.
Tyre Upgrades
Surprisingly, tyres can give a significant boost to performance - although perhaps not straight line acceleration. Sports tyres give better grip (generally at the cost of reduced lifespan), which will improve cornering and braking. Switching to a lower profile type tyre improves handling by reducing the amount the tyres distort under heavy cornering. They do, however, generally give a harsher, noisier ride quality
Sport and low profile tyres are more expensive than regular tyres, but the only way to see if the gains are worth is is to try them, or try two identical vehicles with and without them fitted.
One other tyre upgrade worth mentioning is winter tyres. With a rubber compound that stays softer at lower temperatures, and tread designed to cope with water, snow, slush and ice, winter tyres will give significantly better grip that standard all year tyres. This will allow you to drive faster and more confidently when you would otherwise have to be very cautious. These are especially useful for higher performance or tuned diesel engined vehicles, as the large amount of torque available can easily lead to unwanted wheel spin in icy conditions.
Body Upgrades
Contrary to what some believe, there are very few body upgrades that will have any beneficial effect on a cars performance. Add on wings, body kits and similar only add to the cars weight, and have a negligible effect on handling - some may even make it worse!
However , one body upgrade, that is worth considering is shock absorbers. Especially if your originals are more than a few years old, upgraded sport versions can offer better grip and handling. As most diesel engine cars are heavier than their petrol equivalents, firmer shock absorbers can help reduce body roll in corners, and power lost to unnecessary movements.
Driver Upgrades!
One element we have not yet mentioned is driver habits. There are a few simple things you can do that will provide benefits on any vehicle.
Keep the weight down by not carrying unnecessary weight.
Keep the car aerodynamic by keeping windows and sunroofs closed, and not adding external add-ons
Keep the car maintained regularly, with oil, filters and general maintenance to get the most from it
Go on an advanced driver training course or a track experience day to get some tuition from a professional driver, who can teach you how to drive safely at speed, reading the road ahead, racing lines, handling skids and more.
