Guide to tuning the Prince engine from PSA

"PSA Prince Tuning tips and guide"

We review and look at Prince tuning and outline the best mods that work.

PSA Princes make a good tuning project and with carefully picked motorsport enhancements you can definitely maximize your driving enjoyment.

History, Power & Specs of the Prince Engine

A joint venture with Peugeot, Citroen, Renault and BMW with BMW labelling the engine N13 N14 and N18.

Using the Vanos tech from BMW the Prince replaced the TU engine family offering more power and better economy.

The Prince engine won 8 consecutive titles for engine of the year in the 1.4 to 1.8 liter capacity.

  • 1.4 litre EP3/EP3C 89 to 94 bhp 100 to 103 lbft
  • 1.6 litre EP6/EP6C naturally aspirated  118 bhp 118 lbft) at 4250 rpm
  • 1.6 litre turbocharged  148 to 270 bhp (see below)
    • EP6DT THP 150 (177 lbft) at 1400 rpm
    • EP6DTS THP 175  (182 lbft +19 overboost) at 1600 rpm
    • EP6CDTS (182 lbft +19 overboost) at 1600 rpm
    • EP6CDTX 200bhp (203 lbft) @ 1700 rpm.
    • EP6CDTM THP 163 (177 lbft) at 1400 rpm
    • EP6CDT MD
    • EP6FDT - 178 bhp (133 kW; 180 PS) Euro 6
    • EP6FDTX - 205 bhp (153 kW; 208 PS)/208 bhp (155 kW; 211 PS)/210 bhp Euro 6
    • EP6FDT - 222 bhp (166 kW; 225 PS) Euro 6
    • EP6FDTR - 250 bhp (186 kW; 253 PS)/270 bhp Euro 6
    • EP6CDTR - 270 bhp (201 kW; 274 PS) Euro 6

Best Prince parts

The best tuning mods on an engine are in our opinion the ones that give the best value for money.

We won't be swayed by popular Prince tuning mods, 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 bhp gains are on offer for camshaft upgrades.

Fast road camshafts usually bump the torque throughout the rpm range, you may lose a little low down bhp but the high end rpm power will be higher.

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.

For a typical daily driver should ideally to optimize your power band to your driving style.

I'd be amazed if you find a Motorsport camshaft is a pleasure to live with when driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

Each engine responds better to less aggressive cam durations so view each engine as unique.

The ECU mapping and fuelling also have an effect on the torque gains you'll hit.

Longer valve durations can alter the torque 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.

Typical stage 1 mods often include: Remaps, Fast road camshaft, Sports exhaust manifold, Intake headers, Panel air filters, .

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

Typical stage 3 mods often include: Twin charging conversions, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Internal engine upgrades (pistons/head/valves), Competition cam, .

The Prince power trains are great to work on and we're finding that there are increasing numbers of modifications and performance parts out there.

Mapping will help fully realize the full potential of all the tuning mods you've fitted to your Prince.

(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 15% on NASP engines, but you mileage will vary depending on the tuning mods you've done and the condition of your engine.

Pushing air into the Prince engine is the whole point to any engine upgrade job.

Intake manifold carry the air from the air cleaner and allow it to be drawn into the engine and mixed with fuel.

The size of bore and shape and flow characteristics of the Intake manifold can make a substantial difference to to fuel engine efficiency on the Prince.

Commonly we find the intake are in desperate need of motorsport parts, although a few OEM provide decently flowing intake.

Fitting big valve kits, doing some port matching and head flowing will also improve power, this will afford you raising the power increase on other mods.

Prince 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.

NASP engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your Prince

If your car is turbo charged tuning mods are more reliable and you'll see that turbocharged engines are made with harder and stronger components.

Can you add a turbo to the non turbo Prince engines? No the compression ratio and mapping are dramatically different. After you've altered the pistons, crank head and got the mapping sorted it would have been easier to just swap in the turbo engine and tuned that up.

However every engine will have power limits so research these limits and install better quality crank and pistons to cope with the power.

It's not unheard of drivers spending a a stack of money on turbo upgrades on the Prince only to suffer the humiliation of seeing the whole thing throw a rod just after it's been completed.

Big turbo units commonly suffer low end lag, and smaller turbo units spool up more quickly but won't have the peak rpm bhp gains.

In the last 10 years the market of turbochargers is always increasing and we commonly find variable vane turbochargers, permitting the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbochargers divert the exhaust gases into two channels and feed these at differently designed vanes in the turbo charger. They also help the scavenging effect of the engine.

You'll commonly see there is a limitation in the air flow sensor AFM/MAP on these engines when considerably 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 was restricting power at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although more challenging to install. We have a twincharger performance adding guide if you want to read more.


Don't omit to increase the fuelling when you are increasing the bhp - it makes the car more thirsty. It makes sense to over specify your injectors flow rate.

The accepted safe increase is to add 20% when buying an injector, this allows for injector deterioration and gives a little spare capacity should the engine need more fuel.

Prince Exhaust

You should look to improve your exhaust if the existing exhaust is creating a flow problem.

On most factory exhausts you'll find your flow rate quite well even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts generally help improve air flow through the engine but avoid an exhaust that is too big or you could very well end up with a reduced flow rate. So generally speaking, keep to 1.5 to 2.5 inches as a rule of thumb.

Usual exhaust restrictions are traced to the catalyst installed, so adding a better flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

Weakspots and problem areas on the Prince

The Prince engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oilthey 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 Prince, especially when tuned and will help extend the life and reliability of the engine.

There have been factory recalls for failing HPFP (high pressure fuel pumps) in the Prince engines.

Carbon build up has been noted, and we recommend a good regular thrash with some BG fuel cleaner to keep on top of things.

If you would like to know more, or just get some friendly advice on Tuning your PSA engine please join us in our friendly forum where you can discuss Prince tuning options in more detail with our Prince owners. It would also be worth reading our unbiased PSA 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 parts work best for them on each model of car. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these articles which are continually updated.

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