ATK HP05 GM 383 TBI Stroker 320 HP Stage 1 Long Block Crate Engine

Description

Cast iron block construction reinforces the ATK HP05 GM Crate Engine 383 TBI Stroker configuration. Engineered as a drop-in upgrade for GM trucks, Suburbans, and vintage Chevrolet chassis, this 6.3-liter small-block V8 produces 320 brake horsepower at 4,400 RPM. Increased stroker displacement and a hydraulic roller camshaft produce massive low-RPM pulling torque, transforming sluggish throttle-body injected vehicles into muscular tow platforms.

Machinists start with a hand-selected GM cast iron four-bolt main block, align-honing the main journals and squaring the block decks. A nodular cast iron stroker crankshaft spins inside a one-piece rear main seal structure. Heavy-duty 5.7-inch forged 5140 steel connecting rods connect to 4.030-inch hypereutectic aluminum pistons across a 3.750-inch stroke. A 9.5:1 compression ratio pairs with cast iron cylinder heads. Sump volume holds 5.0 quarts. Dry long block weight totals 435 lbs.

Key Features of ATK HP05

Fleet operators and restomod builders buy ATK HP05 crate engine packages to modernize tired GM small-block trucks with dependable stroker torque. The long block bolts flush into Chevrolet and GMC engine compartments using original motor mounts.

• 3.750-inch stroke crankshaft expands displacement to 383 cubic inches for massive tow torque.
• Four-bolt iron main caps secure the rotating group against bottom-end journal flex.
• Hypereutectic aluminum pistons maintain thermal stability under continuous heavy pulling loads.
• Hydraulic roller camshaft profiles reduce friction while enhancing valve motion efficiency.
• Cast iron cylinder heads feature hardened exhaust valve seats for unleaded fuel durability.
• One-piece rear main seal design prevents oil weeping past the flywheel flange.
• Stamped steel oil pan holds 5.0 quarts to ensure continuous oil pickup feed.
• Balanced rotating group parts isolate harmonic vibrations under sustained highway load.

Dynamic Torque Dyno Output Curves

Operating across an effective 1,500 to 5,000 RPM power band, this stroker long block generates 320 brake horsepower and 410 lb-ft torque on 87-octane or 91-octane pump gasoline. The hydraulic roller camshaft specifies 206 degrees intake duration at 0.050-inch lift with 0.450-inch valve lift. Manifold vacuum measures 18 in-Hg at a 650 RPM curb idle. Hot engine oil pressure holds between 40 to 60 PSI, providing continuous lubrication to valve gear and rod journals during extended trailer towing pulls.

Chassis Crossmember Bellhousing Fitment Clearances

This small block Chevrolet engine utilizes the standard GM 90-degree V8 transmission bellhousing pattern, bolting straight to 700R4, 4L60E, and TH400 transmissions. Internal neutral balance protects flexplates from torsional vibration. Motor mount pads align with factory truck chassis crossmembers. The rear sump passenger-car and truck oil pan clears front suspension steering linkages.

Break-In Protocol Maintenance Duty Limits

Prime oil passages with a mechanical priming tool using 10W-30 high-zinc mineral break-in oil before starting ignition. Bleed cooling jackets through the thermostat housing to remove air pockets. This engine package is not engineered for forced induction exceeding 6 PSI, continuous RPM past 5,200, or raw marine water cooling.

• Drain break-in motor oil after the initial 50 road miles.
• Renew standard mineral or synthetic motor oil every 3,000 miles.
• Inspect ignition timing and valve adjustment every 12 months.

Warranty Coverage Pallet Crate Manifest

A 12-Month limited warranty protects against material and manufacturing defects. The banded wooden pallet crate houses the complete long block, stamped steel oil pan, cast iron cylinder heads, valve covers, timing cover, dyno test certification sheet, and installation guide. Components arrive sealed against environmental moisture.