XU5 M3/Z¹ (BDY)

The XU5 M3/Z 89 PS (65 kW; 88 hp) was used in:

• Peugeot 205 Si
• Peugeot 405 GRi
• Peugeot 205 XS, GT, Roland Garros (1993)
• Citroën ZX

What are the differences between the different xu5 (xu5j, xu5ja and the xu5m)?

Cranks are the same. Rods are the same.
The biggest differences are the camshaft and inlet manifold.
Not clear why the compression ratios are different (XU5M 8.95:1; XU5J, XU5JA: 9.8:1). One theory is that the heads are the same, except for the early GTi which had smaller valves, and that pistons vary to determine CR. Others have taken the pistons out of an XU5 JA but couldn't find any difference at all from the Si (XU5M) pistons, suggesting that it might be the head.²

Cooling system

The fan relays in the plastic box at the front give problems, two of mine (originals) crapped themselves (burn marks on case). The connections also some times corrode up. Get some new relays if you doubt them (Repco).³ Also check the fuses in the little box beside the larger relay box. The other thing that fails (gives trouble) is the radiator sender switch (screws into the radiator almost immediately below the smaller fuse box.⁴

There are three relays to control the two fans. When on low speed the fans are connected in series. When on high speed the fans are connected in parallel. There is a sensor in the LH side of the radiator which turns on the relays. Remove the connector. If you connect two of the wire (not sure which two) the fans should go to low speed. If you bridge out all three wires the fans should go to high speed.⁵ The fans in an Si/late GTi/Mi16 are earthed the relay to switch them on. Early 205's are the opposite.⁶ Above is the 405 wiring diagram. The Si/S3 205 is basically identical, except that the relays 733, 733A and 733B are grounded by the radiator switch rather than the Bitron H114. If you have a multimeter you'll be able to identify which of the three wires is earth.⁷

XU9 1.9l engine conversion

Only thing wrong with the Si is lack of torque so yes, putting in a 1.9l XU9 DKZ motor is a good conversion. Unless you want to rewire the whole front part of the car you will need to leave the Si ECU in place, just cut and tape up the leads you don't need. Add the DKZ (Motronic) ECU and ignition, most leads just go between this and the engine so not hard to join it into the Si wiring system. Alternatively you could simply use the Si manifold and management complete as it is, the question is how well will the Si management cope with the extra 300cc?⁸

The DKZ is the later 1.9l (122hp) fitted to S3 205s and late series 1 405s, also Citroen BX TZi and TRi122. The Si head and block are the same as DKZ, but the crankshaft, pistons, rods and cam are different.⁹ The rods need to be shorter on the 1.9s as the piston pin to crown height is the same for 1.6 and 1.9.¹⁰ The DFZ is the (lazy¹¹) 1.9l (105hp) fitted to earlier Australian GTis. Australia never got the 130hp 1.9l fitted to 205 GTis in other countries.¹²

The important thing with 8V's is to spend money wisely. You can spend a lot of money for very little return. Don't get hung up on the differences between DFZ, DKZ, D6B etc. If what you have is in good order, just freshen it up by doing the following:

• compression test to determine condition of bottom end
• skim head 1mm
• 3 angle seat cut and blend ports
• Cometic head gasket #C4225-027, (0.68mm thick)
• regrind cam to something slightly warmer (around 225º @ 0.050"), but most importantly, have them advance the grind 2º (4º crank) to make up for thinner head gasket and skim.

This will result in around 9.8:1 CR and give you a nice, crisp, responsive engine that pulls like a train. It will still work with the standard ECU & ignition and get excellent fuel economy.¹³

Other XU Engines¹⁴

Engine	XU5J - 180A	XU5JA - B6D	XU5JA/K - B6E	XU9J1 - DFZ	XU9JA - D6B	XU9JA/Z - DKZ
Capacity	1580cc	1580cc	1580cc	1905cc	1905cc	1905cc
Years	1984-1986	1986-1992	1986-1992	1989-1993	1986-1992	1989-1994
Bore (mm)	83	83	83	83	83	83
Stroke (mm)	73	73	73	88	88	88
Compression Ratio	9.8:1	9.8:1	9.25:1	8.4:1	9.6:1	9.2:1
Power (DIN)	105bhp @ 6250rpm	115bhp @ 6250rpm	115bhp @ 6250rpm	105bhp @ 6000rpm	130bhp @ 6000rpm	122bhp @ 6000rpm
Torque	99lb.ft @ 4000rpm	98lb.ft @ 4000rpm	98lb.ft @ 4000rpm	101 lb.ft @ 4000rpm	119lb.ft @ 4750rpm	111lb.ft @ 4000rpm
Fuel Injection	Bosch Multipoint LE2 Jetronic	Bosch Multipoint LE2 Jetronic	Bosch Multipoint LU2 Jetronic	Bosch Multipoint LU2 Jetronic	Bosch Multipoint LE2 Jetronic	Bosch Multipoint Motronic M1.3
Idle (rpm)	850 - 900	850 - 900	850 - 900	850 - 900	850 - 900	850 - 950
Fuel Type	95 RON Regular	95 RON Regular	95 RON Regular	95 RON Regular	98 RON Super	98 RON Super