Audi 2.5 R5 TDi Tuning

"All you need to know about performance tuning the Audi 2.5 R5 TDi engine!"

The Audi 2.5 R5 TDi make a good tuning project and with the right parts like a remap, turbo improvements and camshafts you will really increase your driving fun.

Here we examine the options for your 2.5 R5 TDi tuning and show the premier upgrades.

History, Power & Specs of the Engine

2.5 R5 SDI 40-55kW

  • 55kw 74 bhp 160nm 118 lbft @2,250 rpm — Volkswagen LT  LT28 & LT35 AGX: 05/96-04/01

2.5 R5 TDI 65-121kW

  • 65kw 87 bhp 195nm 144 lbft @1,900 rpm — Volkswagen Transporter T4
  • 75kw 101 bhp 250nm 184 lbft @1,900 rpm — Volkswagen Transporter T4
  • 80kw 107 bhp 280nm 207 lbft @1,900 rpm — Volkswagen LT
  • 85kw 114 bhp 265nm 195 lbft @1,900 rpm — Audi C4 100
  • 88kw 118 bhp @3,250 rpm 275nm 203 lbft @2,500 rpm — Audi C3 100, ANG: 02/02-
  • 103kw 138 bhp 290nm 214 lbft @1,900 rpm — 1994 Audi C4 100, Audi C4 A6, as Volvo D5252T: Volvo 850Volvo S70, Volvo V70, early Volvo S80s
  • 111kw 149 bhp 295nm 218 lbft @1,900 rpm — Volkswagen Transporter T4   AHY, AXG: 1998-2003

2.5 R5 TDI CR 65-120kW

  • 65kw 87 bhp @3,500 rpm; 220nm 162 lbft @2,000 rpm — BJJ
  • 80kw 107 bhp @3,500 rpm; 280nm 207 lbft @2,000 rpm — BJK
  • 100kw 134 bhp @3,500 rpm; 320nm 236 lbft @2,000 rpm — BJL
  • 120kw 161 bhp @3,500 rpm; 350nm 258 lbft @2,000 rpm — BJM

2.5 R5 TDI PD 96-128kW

  • 96kw 129 bhp — Volkswagen Transporter T5 128kw 172 bhp @3,500 rpm; 400nm 295 lbft @2,000 rpm

Tuning the Audi 2.5 R5 TDi and best 2.5 R5 TDi performance parts.

Best 2.5 R5 TDi parts

The best 2.5 R5 TDi upgrades on an engine are in our opinion the ones that give the biggest return for your cash.

We won't be swayed by popular 2.5 R5 TDi upgrades, they need to be cost effective.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen camshaft profile, so large torque gains are on offer for camshaft upgrades.

Fast road camshafts tend to push up the power through the rev range, you might lose a little low end power but the higher rpm power will be higher.

Competition camshafts, push up the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a car used daily, really you should, ideally aim to match your engines power to your cars usage.

I would be surprised if you have ever thought or claimed that a 2.5 R5 TDi Race cam is a pleasure to live with when on the daily commute, because the lumpy idle will make the car prone to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

Some 2.5 R5 TDi engines respond better to more aggressive cam durations than others.

The map and injectors and fuel pump also will make differences on the power gains you'll make.

Altering valve durations can alter the power band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

Please watch our video which covers the 5 principles of tuning your car. Be sure to subscribe and support our new channel.

Best Engine Mods for your car

  1. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

Typical stage 1 mods often include: Intake manifolds, Remaps/piggy back ECU, Fast road camshaft, Panel air filters, Sports exhaust header/manifold, drilled & smoothed airbox.

Typical stage 2 mods often include: Ported and polished head, Sports catalyst & performance exhaust, Fast road cam, fuel pump upgrades, induction kit, high flow fuel injectors.

Typical stage 3 mods often include: Competition cam, Crank and Piston upgrades to alter compression, Twin charging conversions, Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves).

The 2.5 R5 TDi engines make great tuning projects and we see that there are plenty of upgrades and performance parts out there.

ECU mapping helps release the full potential of all the tuning mods you've fitted to your 2.5 R5 TDi.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but the end result will depend much on the tuning mods you've done and the condition of your engine.

It is vital to any tuning job to force fuel and air into your 2.5 R5 TDi

The intake manifolds flow rates are important because this channels the air from the filter and allow it to be sucked into the engine and mixed with fuel.

Shape and flow characteristics of the Intake manifold can make a substantial improvement to fuel atomisation and engine efficiency on the 2.5 R5 TDi.

On popular production engines intake are ripe for an upgrade, although a few car makers provide decently flowing intake.

Fitting big valve kits, doing some 3 or 5 angle valve jobs and porting and head flowing will also increase bhp and torque, and as an added benefit will raise potential for a greater bhp and torque increase on other upgrades.

Turbo upgrades

There are many mechanics spending a lot of money on turbocharger upgrades on the 2.5 R5 TDi only to suffer the indignity of watching the motor throw a rod just after it's first rolling road session.

Big turbochargers will usually experience low end lag, and little turbochargers spool up much more quickly but won't have the high rpm bhp gains.

In recent times the choice of turbo chargers is always developing and we now see variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end performance.

Twin scroll turbo chargers divert the exhaust gases into two channels and push these at differently profiled vanes in the turbo charger. They also improve the scavenging effect of the engine.

It is not unusual that there is a restriction in the air flow sensor MAF/MAP on these engines when loads more air is being drawn into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although harder to configure. We have this article covering twinchargers if you want to read more.


You will need to ensure that the engine is not starved of fuel so need to uprate the fuelling when you start exceeding 20% of a bhp increase.It makes sense to over specify your flow rate on the injectors.

As a rule of thumb add 20% to the flow rate when specifying an injector, this accounts for injector deterioration and affords you some spare capacity should the engine require more fuel.


You only need to improve your exhaust if the current exhaust is actually creating a restriction.

On most factory exhausts you should find that your flow rate is ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Note that with the largest exhaust you can source you'll reduce the exhaust flow rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Usual exhaust restrictions can be located the catalyst installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots Issues & problem areas on the 2.5 R5 TDi

The 2.5 R5 TDi engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the 2.5 R5 TDi, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your 2.5 R5 TDi engine please join us in our friendly forum where you can discuss tuning options in more detail with our 2.5 R5 TDi owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We love to hear what our visitors have got up to and which tuning mods work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these 2.5 R5 TDi tuning guides which get regular updates and revisions.

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