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BX 16 Valve Club

Home of the Citroen BX 16valve Enthusiast

You are here: Home / Technical Info / BX 16 Valve Engine
  • Citroen BX 61 Valve Engine Drawing
    BX 16valve (D6C) Engine
  • 1988 Brochure
  • P1 Press Pack
  • 1991 Brochure
  • GC Croft 2004 BX 16 Valve
    Gary Cole Croft 2004
  • 1989 Brochure
  • Brands Hatch 2005 BX 16 Valve
    Gary Cole Brands Hatch 2005
  • P1 Brochure
  • Exclusiv Tuning for Citroen Poster
    Exclusive Tuning for Citroen Postert
  • 1987 Brochure
  • Cadwell Park 2005 BX 16 Valve
    Gary Cole Cadwell Park 2005
  • 1990 Brochure

BX 16 Valve Engine

XU9J4 (D6C) Engine

The majority of the BX 16v engines were the non cat version fitted with Motronic 4.1 engine management (2 row ecu) which is explained in detail in the Technical sub-pages. The later engines were fitted with the Motronic 1.3 management (3 row ecu) utilising a knock sensor mounted on the front of the engine block, this allows the ecu to adjust ignition timing if pinking occurs.

The cam pulleys are numbered and there seem to be several factory combinations – The most common variations seem to be the early engines using a #2 exhaust cam pulley and a #4 inlet cam pulley this later changed to a #2 cam pulley on both the inlet and exhaust cam. The combination of #2 and #4 seems to give the more harsh power delivery often noticed with the mi16 engine.

The engine is of all alloy construction utilising removeable cast iron cylinder liners.

XU9J4/Z (DFW) With Catalytic Converter

This is the cat equipped engine using the Motronic 1.3 engine management (3 row ecu) along with a lambda (oxygen) sensor and is essentially the same as the D6C apart from the details below.These differences are achieved using lower height pistons and the common cam pulley arrangement is a #3 inlet cam pulley with a #2 exhaust cam pulley. It appears that the #3 pulley was used to improve power delivery and help make up for the loss of power due to the cat and lower compression ratio.

Compression Ratio 9.7:1
Max Power 148BHP
Cam Pulleys #2 – 114 deg
#3 – 111 deg
Citroen BX 61 Valve Engine Drawing

A drawing of a Citroen BX 61 Valve Engine

Engine

Model application D6C (XU9J4)
Compression ratio 10.4:1
Maximum power DIN (BHP) 160 at 6500 rpm
Maximum torque DIN (lbf ft) 133 at 5000 rpm

Valves

Cam Pulleys #2 – 114 deg
#3 – 111 deg
#4 – 108 deg
Head diameter:
Inlet 34.7 mm
Exhaust 29.7 mm
Cam followers Hydraulic (no adjustment)

Valve Timing

Valve lift 9.2 mm
Inlet opens* 1º 35’ BTDC
Inlet closes* 45º 50’ ABDC
Exhaust opens* 47º 0’ BBDC
Exhaust closes* 0º 30’ ATDC

*With valve clearance of 1.0 mm

Crankshaft

Endfloat thrustwasher thicknesses 2.33 to 2.53 mm
(in increments of 0.05 mm)
Crank journal diameter 59.7 to 60.0 mm
Crankpin diameter 49.7 to 50.0 mm

Lubrication system

Oil pressure:
At 850 rpm 2.0 bar
At 3000 rpm 4.8 bar
At 6500 rpm 5.5 bar
Oil pressure warning lamp threshold 0.8 bar
Oil filter bypass threshold 1.2 bar
Maximum running oil temperatures 140 – 150 degrees C
Oil filter Champion F104
Oil type (recommended) SAE 10W40 or 15W40
(to API SG/CD standard)
Oil capacity (with filter change) 5.3 litres (9.3 pints)
Dipstick minimum to maximum 1.5 litres (2.6 pints)

Torque wrench settings Nm lbf ft

Camshaft bearing cap Allen screws 10 7
Main bearing cap bolts and nuts 50 37
Centre main bearing cap side bolts 25 18
Sump pan bolts 20 15
Big-end bearing cap nuts:
Stage 1 40 30
Stage 2: slacken, then tighten to 20 15
Stage 3: then immediately Tighten a further 70º
Oil pump bolts 20 15
Flywheel bolts 50 37
Clutch cover bolts 25 18
Crankshaft sprocket bolt 110 82
Coolant pump bolts 15 11
Camshaft sprocket bolts 45 33
Timing belt tensioner locking screw 20 15
Engine mounting bracket at timing cover end:
Larger bolts 72 53
Smaller bolts 45 33
Crankshaft damper bolts 25 18
Camshaft rear pulley bolt 45 33
Inlet manifold bolts 20 15
Exhaust manifold bolts 25 18
Cylinder head bolts:
Stage 1 60 43
Stage 2: slacken, and then tighten each bolt in turn to 20 15
Stage 3: then immediately Tighten a further 300º

General information

The D6C engine is fitted to the majority of UK BX 16 valve models and is a development of the 8v engine.

Introduced in July 1987, the essential difference is the 16 valve double overhead camshaft cylinder head, this head is based upon the legendary T16 cylinder head and spent 6 years in development alone.

The camshafts are driven by a toothed belt tensioned by two idler rollers.

The need for valve clearance adjustment is eliminated by the incorporation of hydraulic tappets (cam followers).

The pistons have been re-designed, with valve head recesses machined in the piston crown and the gudgeon pins are now of the “floating” type, secured by circlips in the piston.

The undersides of the pistons are cooled by oil jets located in lubrication pipes within the crankcase.
The crankshaft has lighter balancing counterweights with a damper fitted to the sprocket end.

Pressurised oil is supplied by an oil pump located within the sump pan, the pump being driven by chain from the crankshaft.

An oil to water heat exchanger is also fitted to which the disposable canister type oil filter is fitted.

Cylinder Head

Further details of the cylinder head are available in the Downloads section which features pages from the Technical Manuals.

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