BDY (and DKZ/D6B) head1

diameter length
Inlet Ø41.5mm 108mm
Exhaust Ø34.5mm 108mm
stock XU5 M3/Z XU7 piston and crank XU7j4 piston and crank2
chamber (8mm deep) 3 34.0cc 34.0cc 34.0cc
piston dish 9.0cc4 12.0cc [?] 2.0cc
head gasket (1.2mm) 6.5cc 6.5cc 6.5cc
deck clearance 0.1cc 0.0cc 0.0cc
compressed volume 49.6cc 52.5cc 42.5cc
bore 83mm 83mm 83mm
stroke 73mm 81.4mm 81.4mm
displacement volume 395cc 440.5cc 440.5cc
compression ratio 8.95:15 9.4:1 11.4:1
rod length 150.5mm 150.5mm 150.5mm
piston compression height 37.5mm 33.3mm 33.3mm

XU5/XU7 Hybrid

A Si XU5M motor fitted with XU7JP4 crank, rods, pistons, liners, oil pump and sump ... makes a free reving 1.8 8v motor with a very nice rod ratio. Compression ratio will be up there at around 11:1. as pistons are almost flat (maybe-1 or -2 cc) and they sit flush with deck.6

aussiefrogs performance 8v cylinder head buiild
aussiefrogs Cheap 205 kW (archive)