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Li, H. PSA XUD. Encyclopedia. Available online: (accessed on 02 December 2023).
Li H. PSA XUD. Encyclopedia. Available at: Accessed December 02, 2023.
Li, Handwiki. "PSA XUD" Encyclopedia, (accessed December 02, 2023).
Li, H.(2022, October 28). PSA XUD. In Encyclopedia.
Li, Handwiki. "PSA XUD." Encyclopedia. Web. 28 October, 2022.

The PSA XUD is a Diesel engine designed and built by PSA - Peugeot and Citroën. It is an Indirect injection (IDI) engine, that uses a version of the Ricardo Consulting Engineers Ricardo Comet V prechamber cylinder head design. The engine comes in 1.8 L (1,769 cc) N/A, 1.8 Turbo, 1.9 L (1,905 cc) N/A, Turbo, 2.1 12 valve N/A and Turbo and was the predecessor to the HDI range of engines. Early HDi Engines were a PSA design, later 16 valve engines were jointly developed with Ford.

diesel psa citroën

1. Design

The XUD was available with either SOHC 8-valve or 12-valve heads. It was mainly applied transversally in front wheel drive vehicles, tilted by 30°. However, some applications in non-PSA vehicles had the engine installed longitudinally, with rear-wheel drive. The XUD is built in Citroën's plant in Trémery, near Metz.[1]

Displacement ranges between 1.8 and 2.1 L (1,769 and 2,138 cc), and all XU diesel engines have a stroke of either 88 or 92 mm (3.46 or 3.62 in). The former was shared with the XU9. Bore sizes range from 80 to 86 mm (3.15 to 3.39 in), some of which are shared with other XU engines.

Upon its release the engine was noted as one of the best diesel engines (for cars and light vans) in the world with its high power output and refinement it made all other diesel engines seem agricultural.[1] It was also particularly light, with a ready-to-run XUD9 weighing 157 kg (346 lb), 15% less than a comparable diesel of the previous generation.[1]

1.1. Vegetable Oil Fuel

The engine, because it is indirect injection, with a slower combustion burn time than direct injection, is suitable to run on SVO (pure vegetable oil). A feature of the Ricardo Comet pre-chamber design is that it makes the engine tolerant of low Cetane value fuels such as SVO.[2] The viscosity of vegetable oil when cold is too great for rotary injection pumps, (in particular the weaker Lucas CAV pump, the Bosch VE fuel pump is superior), preventing it from acting as a lubricant and increasing the workload on the distributor/rotary injection pump and damaging it. The Lucas EPIC pump fitted to the 2.1 L 12 valve turbo-diesel engine after 1995 is the weakest pump of all.[3] Different fresh vegetable oils have different viscosities: thinnest are; sunflower, rapeseed (often only labelled vegetable oil, but with pictures of distinctive yellow flowers), then soya and corn oil, but palm oil (may be only marked vegetable oil) is thickest and may be solid at room temperature. Vegetable oils thicken when used for cooking, so used oils can be much thicker than any fresh oil, they may even solidify at room temperature. It is necessary for used oil to be very well filtered (ideally cold filtered to 1 micron), to avoid filter plugging and/or injection pump damage. Heavily used oil may be highly acidic and corrode the inside of the injection pump. Such oil can only be used as fuel without the risk of damage, if it has been chemically processed into bio-diesel. The open market price for used oil is often quite close to special offer supermarket prices for new oil, which can be used straight away. In order to reduce the viscosity of the SVO, it should be heated to engine coolant operating temperature, typically with a two tank system, in order to start and shutdown on diesel or bio-diesel. Versions of this engine from the early '90s onward, are typically fitted with a Peugeot-type coolant heated fuel filter that helps heat fuel and reduce viscosity. Fuel / engine coolant heat exchangers, usually required for straight vegetable oil conversions, are still needed for long term life expectancy, or there will be accelerated wear of the fuel injection pump. Heated vegetable oil is a good injection pump lubricant. This is especially important in cold weather ambient temperatures. Mixing with major oil company brand diesel, (which in winter is thinner and contains anti-waxing winterising agents) to thin the vegetable oil fuel, choosing a thin vegetable oil, winterising additive, or electric heating, or a combination of these are helpful especially when starting and warming up, as coolant heating will not yet be at operating temperature.[4] The difference between the use of good quality fuel and supermarket diesel, in a diesel / vegetable oil fuel mix, will be very noticeable, especially at lower temperatures. The fuel systems used on this engine return heated fuel to the fuel tank. Running with half a tank of fuel instead of fully filling up, will allow the tank to be heated more effectively by this warmed fuel in low ambient temperatures. Due to different calorific values some oils will give less mpg and some more.

2. XUD7

The XUD7 has a displacement of 1.8 L (1,769 cc), with a bore and a stroke of 80 mm × 88 mm (3.15 in × 3.46 in). Output is 60 PS (44 kW; 59 hp) for the naturally aspirated version or 78 PS (57 kW; 77 hp) for the turbocharged model. An intercooled turbocharged version was introduced later, with 90 PS (66 kW; 89 hp) on tap. All are Diesel engines.

Model Output Notes Model of car
XUD7 T/K 78 PS (57 kW; 77 hp) Turbo  
XUD7 TE 90 PS (66 kW; 89 hp) Turbo with intercooler Citroen BX TRD/TZD TURBO, Peugeot 405 Turbo, ROVER 200 MK2 TD
XUD7/K 60 PS (44 kW; 59 hp)   Citroën C15D/BX RD, Peugeot 205
XUD7/Z catalyst  

3. XUD9

XUD9A engine in FSO Polonez Caro.

The XUD9 has a displacement of 1.9 L (1,905 cc), with a bore and a stroke of 83 mm × 88 mm (3.27 in × 3.46 in). Both turbocharged and naturally aspirated versions were produced. Most turbocharged versions feature an intercooler, although a limited number of installations in the Citroën Xantia featured a Turbocharger without intercooler. Both engines also featured either a Bosch or a Lucas mechanical fuel pump and injectors. The engine version with the Bosch pump is known to have been run with vegetable oil. The original XUD9 engine is known as the "square port" engine, as its cylinder head has square exhaust ports. Later (and noticeably improved) XUD9A engines have oval ports.

Model Output Notes Model of car
XUD9 65 PS (48 kW; 64 hp) Diesel Citroën BX, Peugeot 205 Export, Peugeot 309, Talbot Horizon
XUD9 A 71 PS (52 kW; 70 hp) ROVER 200 MK2 D
Citroën Berlingo
FSO Polonez
Citroën BX
Lada Niva
XUD9 TE/L 92 PS (68 kW; 91 hp) Diesel turbo with intercooler Citroën ZX
Citroën Xsara
Citroën Jumpy
Peugeot 306
Peugeot 405
Peugeot Expert
XUD9 SD 63 PS (46 kW; 62 hp) Diesel turbo catalyst Suzuki Samurai
XUD9 SD 75 PS (55 kW; 74 hp) Citroën Xantia
Suzuki Baleno
Lada Niva
XUD9 TE/Y 90 PS (66 kW; 89 hp) Diesel turbo with intercooler catalyst Peugeot 406
Citroën Xantia
XUD9/Z 68 PS (50 kW; 67 hp) Diesel catalyst Hyundai Lantra

4. XUD11

The XUD11 was available in two displacements:

  • 2.1 L (2,138 cc) — XUD11 A naturally aspirated
  • 2.1 L (2,088 cc) — XUD11 ATE/BTE turbocharged

Both were 12-valve SOHC engines with a 92 mm (3.62 in) stroke. The naturally aspirated XUD11 A was bored to 86 mm (3.39 in) for a total displacement of 2.1 L (2,138 cc), while the turbocharged ATE/BTE versions were reduced in bore to 85 mm (3.35 in) for a total of 2.1 L (2,088 cc).

Model Output Notes Model of car
XUD11 A 83 PS (61 kW; 82 hp) Diesel 12-valve SOHC Citroën XM, Peugeot 605
XUD11 ATE 110 PS (81 kW; 108 hp) Diesel 12-valve SOHC turbo Citroën XM
XUD11 BTE Diesel 12-valve SOHC turbo catalyst Peugeot 406, Peugeot 605, Citroën Xantia

5. Vehicles

The engine has been installed into the following vehicles:-


  1. Pirotte, Marcel (1984-04-19). "Citroën BX 19 TRD" (in French). Le Moniteur de l'Automobile (Brussels, Belgium: Editions Auto-Magazine) 35 (793): 21–23. 
  2. Diesel Cetane Ratings. Describing how diesel burns. Nick Sauer
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