2.5 TFSi engine tuning

Guide to the VAG 2.5 TFSi engine

The 2.5 TFSi is the VAG Group 5 Cylinder turbo engine, as fitted to the TTRs RS3 TSQ3 and the Quattro concept.

Voted engine of the year 5 times in a row (2015) we start to see that this is a very special engine indeed. It is a chain driven DOHC, with variable valve timing.

The Block is aluminum Alloy with a DJV-450 vermicular graphite cast iron cylinder block. The firing order is 1-2-4-5-3 and it runs at a 10.0:1 compression ratio thanks to the knock resistant inlet design and direct fuel injection.

These blocks were designed to tolerate power figures in the region of 700bhp so make a great base for a tuning project.

This engine won awards every single year in the '2.0-litre 2.5-litre' category from 2010 to 2018 annual competition for International Engine of the Year!

FSi injection running at upto 1770psi on a common rail. The ECU is a Bosch Motronic MED unit and it uses two knock sensors, allowing it to manage each cylinder separately.

Currrent engine codes include CEPA, CEPB, CTSA, CZGA, CZGB, DAZA, DNWA

Engine Codes CEPA on the early engines, later engines from mid 2011 were CEPB.

CEPA in Aug 2010 had some revisions to the engine crankcase, new pistons, sealing flange and oil spray jets.

DAZA was launched in 2017 with further revisions pushing power to the 400bhp mark. Peak torque of 354lb-ft comes in at only 1700rpm!

CEPB came with the TTRS Plus offering 355bhp and 343lbft of torque in 2012.

Then in 2019 we had the DNWA engine block revision where peak torque came in at 1950rpm, interestingly this adds fuel economy and feels more powerful in everyday driving.

  • 335bhp 332lb-ft - TTRS
  • 355bhp 332lb-ft - RS3 TTRS
  • 355 bhp & 343 lb-ft TTRS plus
  • 306bhp 343lb-ft - RS Q3
  • 363bhp  343 lb-ft RS3 from 2015
  • 394bhp 354lb-ft TTRS & RS3 from 2017

Interestingly VAG managed to squeeze 402bhp and 354 lbf-ft from this engine in the Audi Quattro concept.

The engine timing and injectors and fuel pump used will also have an effect on the bhp gains you'll make.

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

Fast road camshafts normally bump the bhp and torque throughout the rev band, you could sacrifice a little low down torque but your high end rpm power will be higher.

Motorsport and race camshafts, bump the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

Extending exhaust or intake durations can alter the bhp 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.

Stage 1 mods: Intake headers, Sports exhaust manifold, Panel air filters, Fast road camshaft, Remaps/piggy back ECU, Drilled & smoothed airbox.

Stage 2 mods: Fuelling (fuel pump and port injectors), Ported and polished head, induction kit, fuel pump upgrades, Fast road cam, Sports catalyst & performance exhaust.

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

Many of our forum members report that gains of 70bhp are possible with just a remap alone, combine this with a turbo upgrade and you'll have a potent engine.

Upgrading the downpipe will allow the turbo to spool up more quickly and releases some extra HP. The GTX3576R works well on this engine, allowing you to see a 100bhp+ power gain on standard low octane fuel. There is an APR conversion around which wil realise 665bhp on 104RON fuel!

ttrs-engine

Headers carry the air from the air cleaner and allow it to be pulled into the engine and mixed with fuel.

The shape and flow rate of the Headers can make a noticeable effect on to fuel atomisation and engine efficiency on the 2.5 TFSi R5.

It's not uncommon that intake headers are in desperate need of aftermarket tuning parts, although some manufacturers provide reasonably well designed intake headers.

Big valve conversions on the 2.5 TFSi R5, carrying out 2.5 TFSi R5 port enlargement and head flowing will also improve bhp, the fantastic side effect is it will afford you a better bhp increase on other parts.

2.5 TFSi R5 Turbo upgrades

The more air to get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes massive power gains.

When your car is turbo charged mods are going to net you a larger power gain and you'll see that turbo engines are made using stronger components.

However you will find an engines will need better parts at higher power limits and thankfully the 2.5 TFSi is very well build and the block can handle around 400bhp.

It is important to find these restrictions and upgrade to better pistons and crank to cope with the power.

We see many mechanics spending a loads on turbo upgrades on the 2.5 TFSi R5 only to suffer the indignity of watching the engine block throw a rod soon after it's used in anger.

Bigger turbo chargers commonly suffer low end lag, and small turbo chargers spool up more quickly but do not have the top end power band gains.

We are pleased that the world of turbos is always evolving and we now see variable vane turbos, allowing the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbos divert the exhaust flow into 2 channels and flow these at differently designed vanes in the turbo. 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 the when loads more air is being drawn into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more difficult to setup. We have a twincharger bhp and torque adding guide if you want to read more.

When upgrading to the GTX3576R turbo you should add a higher pressure fuel pump, uprate the intercooler and we would also recommend some exhaust upgrades namely a high flow downpipe and sports catalyst. There may be additional pipe/mounting point work required to site this turbo depending on whether you purchase it in a kit for the 2.5TFSi.

Fuelling

When you boost the power you will need to uprate to the fuel system.

More power needs more fuel. This is the simple basic fact of tuning a car.

Most tuners we speak with say to be generous with your injectors flow rate. The TFSI high-pressure injection pump supplying up to 122 bars or 1,770 psi gives quite a bit of headroom but you might need to add more capacity for larger power increases.

Port injection kits are available which can help mitigate the carbon build up and provide more fuel when you need it.

The accepted safe increase is to add 20% when specifying an injector, helps cope with injector deterioration and gives a little spare capacity should the engine need more fuel.

These engines really do appreciate high octane fuel, timing, fuelling etc are adjusted to fully realize the potential of the higher octane and you will see more power and greater economy. For most drivers the extra miles per tank will cover the cost of the higher price of the fuel.

Problems and issues

The 2.5 TFSi R5 engines are generally reliable and solid as long as they are regularly serviced and maintained.

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

Carbon build up is still an issue on these engines, although significant improvements have been made. Avoid problems by using good quality fuel, adding a good quality cleaner to your fuel like BG44K and run the engine hot and use the full RPM range when warm. You should get over 70,000 miles on an engine before carbon build up can cause a problem on these although if you only do short runs this will happen much sooner.

When there is significant carbon build up you'll lose power and a full intake clean will restore this lost power immediately.

There was  brake squeal recall in 03/2013 where a modified brake caliper has removed this issue.

Please submit your tuning tips, comments and details of common faults below so we can update this article and keep it current.

To discuss tuning these and the full range of VAG engines in more detail please join our very friendly international car forums.

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