PSA XU (XU5 XU7 XU8 XU9 & XU10) Tuning

"All you need to know about tuning the PSA XU engine!"

Now we will examine the options for your XU tuning and point out the ultimate modifications for your car. PSA XU make a good tuning project and with carefully picked motorsport mods like remapping, turbo upgrades and camshafts you will really enhance your driving fun.

History, Power & Specs of the Engine

introduced in 1981 and came as a SOHC or DOHC with 2 or 4 valves per cylinder and ranges from a 1.6 to 2.0. Reboring the cast iron block is relatively simple without worrying about liners or weak areas.

  • XU5 J 105 PS (77 kW; 104 hp)
  • XU5 1C 80 PS (59 kW; 79 hp)
  • XU5 2C 92 PS (68 kW; 91 hp)
  • XU5 M3/Z 89 PS (65 kW; 88 hp)
  • XU5 S 94 PS (69 kW; 93 hp)
  • XU5 JA 115 PS (85 kW; 113 hp)
  • XU7  90–112 PS 89–110 hp
  • XU8 T 200 PS (147 kW; 197 hp)

 

  • XU9 2C 105 PS (77 kW; 104 hp)
  • XU9 2C 110 PS (81 kW; 108 hp)
  • XU9 4 126 PS (93 kW; 124 hp)
  • XU9 J1 98 PS (72 kW; 97 hp)
  • XU9 J1/Z 105 PS (77 kW; 104 hp)
  • XU9 J2 125 PS (92 kW; 123 hp)
  • XU9 JA/K 130 PS (96 kW; 128 hp)
  • XU9 JA/Z 122 PS (90 kW; 120 hp)
  • XU9 J4 / D6C/L 160 PS (118 kW; 158 hp)
  • XU9 J4/Z / DFW 148 PS (109 kW; 146 hp)
  • XU10 2C 114 PS (84 kW; 112 hp)
  • XU10 J2C/L / RFX 121 PS (89 kW; 119 hp)
  • XU10 J2 130 PS (96 kW; 128 hp)
  • XU10 J2U / RFW 109 PS (80 kW; 108 hp)
  • XU10 J2U / RFL 110 PS (81 kW; 108 hp)
  • XU10 J2TE / RGY 141 PS (104 kW; 139 hp)
  • XU10 J2TE / RGX 147 PS (108 kW; 145 hp)
  • XU10 J4D/Z / RFT 150 PS (110 kW; 148 hp)
  • XU10 J4R/L3 / RFV 134 PS (99 kW; 132 hp)
  • XU10 J4RS/L3 / RFS 166 PS (122 kW; 164 hp)
  • XU10 J4TE 196 PS (144 kW; 193 hp)
  • XU10 J4/L/Z / RFY 152 PS (112 kW; 150 hp)

Tuning the PSA XU and best XU performance parts.

Best XU mods

The best XU parts on an engine are as we have found the ones that give the biggest return for your cash.

We won't be swayed by popular XU parts, they need to be cost effective.

Altering your XU cam will make a dramatic difference to the engine power band. Choosing a higher performance cam profile raises the power band accordingly.

Fast road cams usually increase the power across the rev range, you may sacrifice a little bottom end torque but higher rpm power will be better.

Race cams, increase the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Race camshaft will just annoy you whilst 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.

You should ideally optimize your engines power to your driving style so for a road car stick with a fast road XU camshaft

Different XU engines respond better to more or less aggressive camshaft durations than others.

The map and injectors and fuel pump also have a large bearing on the power gains you'll make.

A longer valve duration 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.

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

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

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

Plan your options and then buy your tuning mods and set yourself a power target to save yourself from expensive mistakes.

remap helps fully realize the full potential of all the mods you've done to your XU.

(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 NASP engines, but figures achieved usually depend much on the mods you've applied and the condition of your engine.

Shoving more fuel and air into the XU engine is the aim to any engine modification task.

Intake headers take the air from the filter and allow it to be sucked into the engine cylinders.

Design and flow characteristics of the Headers can make a noticeable effect on to fuel delivery on the XU.

Many mass produced engine intake headers are crying out for a performance upgrade, although a few manufacturers provide fairly well optimized intake headers.

Fitting big valve kits, carrying out port matching and head flowing will also lift performance, the fantastic side effect is it will afford you a greater performance increase on other modifications.

Turbo upgrades

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 XU

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

When your motor is fitted with a turbo parts are going to make more power and turbo charged engines use stronger components.

There are practical limits for every engine, with some being extremely strong and some only able to handle stock power

Research these restrictions and install better quality crank and pistons to handle the power.

It's not unheard of tuners spending a lot of money on turbocharger upgrades on the XU only to watch the car catastrophically fail when it's used on the roads.

Large turbos commonly suffer no power at low rpm, and smaller turbos spool up much more quickly but won't have the high rpm bhp gains.

Thankfully the selection of turbochargers is always improving and we commonly find variable vane turbochargers, permitting the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust gases into 2 channels and flow these at differently profiled vanes in the turbocharger. They also help the scavenging effect of the engine.

You'll commonly see there's a restriction in the air flow sensor AFM/MAP on the XU when considerably more air is being pulled into the engine.

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

Adding a supercharger or additional turbo will make large torque gains, although harder to install. We have this in depth look at twinchargers if you want to read more.

Fuelling

Don't overlook the need to uprate the fuel system when you are increasing the torque - it makes the car more thirsty. We would recommend you to be generous with your injectors flow rate.

As a rule of thumb add 20% when fitting an injector, helps cope with injector deterioration and provides some spare capacity should the engine require more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

Exhaust

You only need to to boost your exhaust if the existing exhaust is creating a restriction in flow.

On most factory exhausts you should find that the exhaust flow rate is still ok 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 will certainly help air flow through the engine but avoid an exhaust that is too large or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to around 2.5 inches to maximise flow rates, and this should take into account the amount of air your engine is moving.

Usual exhaust restrictions are in the catalyst and filters installed, so adding a freer 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 XU

The XU engines are generally reliable and solid 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 XU, 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 XU engine please join us in our friendly forum where you can discuss tuning options in more detail with our XU owners. It would also be worth reading our unbiased 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 XU articles which are continually updated.g

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