ATK HP103 Chrysler 5.7L Hemi 400 HP Gen III Long Block Crate Engine

Description

During demanding high-speed highway passing situations the ATK HP103 Chrysler Crate Engine 5.7L Hemi Gen III package outputs relentless modern Mopar horsepower. Producing 400 brake horsepower at 5,600 RPM, this 5.7-liter V8 repowers Dodge Chargers, Challengers, and classic Mopar restomods. Featuring factory-engineered aluminum cylinder heads and hydraulic roller valve motion, it combines aggressive acceleration with dependable street manners.

Technicians select seasoned Chrysler Gen III cast iron blocks, precision align-honing cross-bolted main journals and squaring block decks. A nodular iron crankshaft rotates with internal neutral balance weighting inside a one-piece rear main seal. Forged powder metal connecting rods attach to 3.917-inch hypereutectic pistons across a 3.578-inch stroke. A 9.6:1 compression ratio pairs with twin-plug aluminum Hemi cylinder heads. Wet sump configurations require 7.0 quarts. Bare long block weight totals 430 lbs.

Key Features of ATK HP103

Mopar enthusiasts buy ATK HP103 crate engine base long blocks to repower late-model Dodge vehicles or power vintage muscle car restomods. The long block bolts flush into modern engine compartments or restomod chassis using swap mounts.

• Genuine Gen III Hemi combustion chamber geometry maximizes thermal efficiency and flame propagation.
• High-velocity aluminum cylinder heads feature dual spark plug ports per cylinder for complete combustion.
• OE hydraulic roller camshaft profiles reduce friction while optimizing mid-range torque output.
• Cross-bolted main bearing caps lock the crankshaft in position under high-RPM acceleration.
• 345 cubic inch displacement balances compact external dimensions with strong 400-horsepower output.
• Powder metal connecting rods withstand severe reciprocating loads without structural fatigue.
• Internal neutral balancing protects driveline components from destructive vibrational frequencies.
• Blueprinted ATK HP103 tolerances ensure dependable oil clearances under continuous operation.

Dynamic Gen III Hemi Dyno

Operating across an energetic 2,500 to 6,000 RPM power band, this 5.7-liter Gen III Hemi generates 400 brake horsepower and 410 lb-ft torque on 89-octane or 91-octane pump gasoline. The OE hydraulic roller camshaft specifies 204 degrees intake duration at 0.050-inch lift with 0.500-inch valve lift. Manifold vacuum measures 17 in-Hg at a 650 RPM computer-controlled idle. Hot oil pressure holds between 45 to 65 PSI, keeping cam lobes and rod bearings coated with pressurized lubricant during hard acceleration.

Engine Bay Subframe Fitment Clearances

This Chrysler Gen III Hemi engine utilizes standard modern Mopar transmission patterns, bolting straight to NAG1, 8HP70, and Tremec manual transmissions. Internal neutral balancing requires matching zero-balance flexplates or flywheels. Motor mount bosses accept factory modern car brackets or aftermarket swap mounts for classic A, B, and E-body chassis.

Break-In Protocol Maintenance Duty Limits

Pre-lube engine oil galleries with 5W-20 or 5W-30 synthetic blend oil using an external pressure tank before initial start-up. Bleed cooling jackets through the radiator and block drain plugs to expel air pockets. This engine package is not engineered for centrifugal supercharging exceeding 6 PSI on stock ring gaps or raw marine sea water cooling.

• Drain initial break-in motor oil after the first 50 road miles.
• Renew synthetic motor oil every 3,000 miles or six months.
• Inspect dual spark plugs and ignition coil boots 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 base long block, aluminum cylinder heads, dyno test certification sheet, and step-by-step installation guide. Components arrive sealed in vapor-barrier plastic wrap to prevent oxidation during storage and transit.