Fuel and Air Management
Combined with a good set of cylinder heads, it's the turbos and intercoolers that are responsible for the big power numbers, permitting a mild cam for kitty-cat idle quality. Duttweiler has put together a judicious combination of twin Precision turbos and big intercoolers. That latter are top-mounted for the intended application's specific packaging requirements. Funco, the intended owners, are no-compromise dudes; they sprung for only the best: a MoTeC controller and exotic Type 321 stainless headers.
Engine Builder's Specs
All dimensions in linear inches, except as noted.
SHORT BLOCK
Displacement: 265.2 ci
Bore x stroke: 3.940 x 3.625
Rod length: 6.300
Rod/stroke ratio: 1.74:1
Block deck height: 9.530
Piston compression height: 1.400
Piston deck height: 0.0175
Piston volume: -35 cc (dish)
Head gasket compressed volume: 8.6 cc
Compression ratio: 8.46:1
Bore finish: Sunnen 623
Piston-to-wall clearance: 0.0045 cold
Main-bearing clearance: 0.0022
Rod-bearing clearance: 0.0020
Rod side-clearance: 0.012
Crankshaft thrust clearance: 0.005-0.007
Piston compression-ring endgap: 0.030/0.030
Piston oil-ring rail endgap: 0.012 minimum
Floating piston pin-to-rod: 0.0012
Piston-to-head clearance: 0.0565
Engine oil: Lucas 10W30 synthetic, 7 quarts with filter
CYLINDER HEADS
Valve size: 1.940/1.600
Combustion-chamber volume: 50 cc
Intake-port volume: 156 cc before porting
Max flow as ported: 250/190 cfm @ 28 in H20
Exhaust/intake flow: 76%
Valvespring od/id: 1.509/0.697
Valvespring seat pressure: 122 lb @ 1.790
Valvespring open pressure: 311 lb @ 1.256
Valvespring coil-bind height: 1.150
CRITICAL FASTENERS
Values are with ARP lube, except as noted.
All studs: Bottom hand-tight (dry or light oil)
ARP main stud nuts (1⁄2): 100 lb-ft
ARP main stud nuts (7⁄16): 60-65 lb-ft
ARP main stud nuts (3⁄8): 45 lb-ft
ARP main cross-bolts (7⁄16): 55-lb-ft nominal*
ARP main cross-bolts (3⁄8): 35 lb-ft nominal*
ARP head stud nuts (7⁄16): 80 lb-ft
Crower rod bolt (7⁄16): 0.005-0.007 stretch @ minimum of 75 lb-ft
ARP balancer bolt (3⁄4): 200-250 lb-ft (oil)
TA rocker-shaft-stand stud nuts (7⁄16): 55 lb-ft (oil)
Cam bolt: 45 lb-ft (red thread-locker)
*Tighten after vertical main stud nuts; adjust torque as needed to maintain a round main bore as measured with a dial-bore gauge.
CAMSHAFT
Type: Hydraulic roller-tappet
Grind: Comp Cams Magnum 3108S
Duration, 0.006 tappet lift: 271/271 degrees
Duration, 0.050 tappet lift: 215/215 degrees
Lobe displacement angle: 114 degrees
Installed intake centerline: 114 degrees
Lobe lift: 0.334/0.334
Rocker-arm ratio: 1.60:1
Valve lift at zero lash: 0.534/0.534
Valve lash: Zero plus 1⁄2 turn
Pushrods: 5⁄16 od x 8.600 long
Piston-to-valve clearance: Ample
Camshaft thrust: 0.005-0.015
FUEL, SPARK AND AIR
Engine management: MoTeC M-600
Fuel injectors: MSD 72 lb/hr
Fuel pressure: 50-psi base, increasing 1 psi per 1 psi of boost
Throttle-body: Wilson 90 mm
Ignition: GM Gen III coil-packs
Spark plugs: Champion C63YC, 0.030 gap
Fuel (on dyno): VP-112, 112 octane
Max boost: 18.36 psi @ 5,700-5,800 rpm
Timing: 38 degrees base; 22 degrees at max boost
PERFORMANCE
Max torque @ rpm: 668.4 lb-ft @ 4,100
Max power @ rpm: 707.8 hp @ 5,700
Peak BMEP: 380 psi
Power/ci: 2.67 hp/ci
Cost (parts and labor): $35,000
Dollars/hp: $49.45 HRM