ATK HP89C-EFI GM 350 390 HP Stage 3 Multi-Port EFI Crate Engine

Description

Meet stringent multi-port fuel injection standards with the ATK HP89C-EFI Crate Engine in Stage 3 EFI trim. This 350 cubic inch 5.7L Chevrolet V8 generates 390 horsepower at 5,300 RPM and 405 lb-ft torque at 3,800 RPM. Equipped with multi-port EFI, throttle body, computer, and long water pump, it provides reliable turn-key operation across fluctuating weather conditions.

A precision-machined cast iron GM block provides stable foundation support, featuring a 1-piece rear main seal to stop lubricant weeping. The reciprocating group pairs a nodular cast iron crankshaft with forged connecting rods and 10.0:1 hypereutectic pistons inside 4.000-inch bores. Stroke measures 3.480 inches, supported by balanced rotating components and a 5-quart steel oil pan.

Key Features of ATK HP89C-EFI

Street rodders buy ATK HP89C-EFI crate engine packages to enjoy modern electronic fuel injection paired with classic small-block Chevrolet muscle. This complete EFI power unit transforms vintage muscle cars, off-road trucks, and classic street cruisers.

• Multi-port electronic fuel injection system self-calibrates fuel delivery curves without requiring complex manual jetting.
• Throttle body electronic intake mounts the system securely while promoting even fuel distribution across all ports.
• High-flow aluminum cylinder heads dissipate excess combustion heat to resist detonation on service-station fuel supplies.
• Hydraulic roller camshaft profiles reduce valvetrain friction while sustaining broad power from 1,800 to 5,500 RPM.
• ATK HP89C-EFI electronic systems include a standalone computer and wiring harness for straightforward electrical hookup.
• Included electronic distributor integrates with engine management to maintain accurate ignition advance timing.
• Long-style cast iron water pump provides correct hub height for standard GM accessory belt drive pulleys.
• Pre-installed harmonic balancer and matching flexplate streamline mating to automatic transmissions in the chassis.

Dyno Profile ECU Tuning

Dynamometer calibration tests confirm 390 brake horsepower at 5,300 RPM and 405 lb-ft torque at 3,800 RPM across an effective 1,800 to 5,500 RPM range. The 10.0:1 compression ratio operates safely on 91-octane service station gasoline. The throttle body preserves an 800 RPM idle producing 14 in-Hg manifold vacuum. Operating oil pressure registers between 40 and 60 PSI warm.

Bay Packaging Transmission Drop

Casting bounds follow classic Chevrolet small-block geometry, dropping between front frame rails without chassis cutting. The crank tail requires the included flexplate to mate with TH350, 700R4, or 4L60E automatic transmissions. Motor mount pads align with factory GM frame perches, clearing manual steering boxes and tubular exhaust headers.

Pre-Run Setup Misuse Prohibitions

Prior to turning the ignition switch, pressure-feed the lubrication passages using a mechanical priming tool to wet internal bearings. Fill the crankcase with 10W-30 mineral break-in oil fortified with zinc additives. This power unit is not built for boat marine drives, continuous forced-induction boost beyond 6 PSI, or unmetered nitrous systems.

• Drain the break-in lubricant and mount a fresh spin-on oil filter after completing the first 500 street miles.
• Inspect high-pressure fuel line fittings, harness connections, and grounds every 3,000 miles of street operation.
• Examine throttle linkage operation and check coolant hose integrity every 12 months or 12,000 highway miles.

Warranty Information Package Manifest

ATK warrants this small block for 12 months against defects in materials and craftsmanship. The secure wooden crate holds the complete engine, EFI throttle body, computer, wiring harness, distributor, long water pump, harmonic balancer, flexplate, spark plugs, wires, and certified dyno test report sheet.