ATK HP89M 350 Crate Engine – 390 HP / 420 TQ Small Block Chevy

The Premium 350 Stage 2 Crate Engine for Serious Street Performance

The ATK HP89M 350 crate engine delivers dyno-proven performance in a Stage 2 Mid Dress package that’s ready to transform your classic Chevelle, Camaro, Nova, truck, or street rod. As part of our extensive Small Block Chevy collection, this 5.7L/350 cubic inch V8 produces an impressive 390 horsepower and 420 lb-ft of torque—making it an ideal choice for enthusiasts seeking serious street performance without sacrificing drivability.

Built on a handpicked 1996-2000 OE 4-bolt main roller block with ATK High Performance aluminum cylinder heads, this 350 Pro Series engine is dyno-proven and backed by a 2-year/unlimited mileage warranty. Whether you’re building a weekend cruiser, a street machine, or a show-stopping classic, this ATK 350 crate engine provides the foundation for an unforgettable driving experience.

What Makes the ATK 350 Stage 2 the Ultimate Small Block Crate Engine?

The HP89M is engineered for enthusiasts who want maximum performance with turn-key convenience. ATK has been building engines for over 75 years and has assembled this dyno-proven crate engine package to power up your ride. This “Mid Dress” variant includes the intake manifold, distributor, water pump, harmonic balancer, flexplate, and all necessary components—making it a near turn-key solution.

Every ATK engine is hand-assembled and balanced to help them put out 390 hp and 420 ft.-lbs. of torque that will tear up the street or strip.

350 Stage 2 Horsepower and Torque Figures

This 350 crate engine produces impressive output:

• 390 horsepower – dyno tested and verified

• 420 lb-ft torque – strong mid-range power for street driving

• 10.0:1 compression ratio – pump gas friendly

• Hydraulic roller cam – low maintenance, excellent durability

Complete 350 Stage 2 Engine Specifications

Seasoned OE Roller Block

The foundation of this ATK 350 crate engine is a handpicked 1996-2000 OE 4-bolt main roller block featuring:

• 4-bolt main caps for exceptional bottom-end strength

• 1-piece rear main seal for leak-free operation

• 4.040-inch bore x 3.480-inch stroke (350 CID / 5.7L)

• OE reground crankshaft – external balance rear / internal balance front

• OE powder metal 5.700-inch connecting rods

• Hypereutectic pistons – 10.0:1 compression

• Moly piston rings

ATK High Performance Aluminum Cylinder Heads

The ATK High Performance aluminum cylinder heads provide exceptional flow:

Hydraulic Roller Camshaft Specifications

What’s Included with Your HP89M Mid Dress Crate Engine

The HP89M is a Stage 2 Mid Dress long block with the following components included:

Important Note: The following components are NOT included and must be sourced separately:

• Carburetor (Quick Fuel 680 CFM recommended)

• Fuel pump (Holley mechanical 110 GPH recommended)

• Spark plugs (Autolite #3923 recommended)

• Spark plug wires (8mm recommended)

• Air cleaner

• Flexplate bolts

Installation Notes and Critical Considerations

Important Notes Before Installation

Before installing your ATK HP89M crate engine, review these critical notes:

• Oil pan compatibility: Rear sump 5qt oil pan is NOT compatible with Chevelles with steering behind crossmember, some Corvettes, and 1962-1967 Chevy IIs

• Octane requirement: 91+ premium fuel required

• Ignition timing: 34-36° total advance

• Max RPM: 5,800

• Spark plug gap: .035″

• Firing order: 1-8-4-3-6-5-7-2

• Stall converter: 2200-2800 RPM recommended for automatic transmission

• Exhaust: 1-5/8″ headers recommended

• Oil: 10W30 conventional (non-synthetic) during break-in

Core Return Information

A core charge of $510.00 applies. Core return can be any Small Block Chevy 350ci engine, except 1992-1997 LT1-style engines.

Emissions Compliance

Non-Emissions: This product does not require an Executive Order in California. By nature of its design, it is legal for sale and use in all 50 states. However, it is not for use in pollution-controlled vehicles – computer-controlled vehicles may need updated chips or other modifications.

Break-In Procedure

ATK recommends the following break-in procedure:

• Use break-in oil or conventional (non-synthetic) 10W30 oil with zinc additive for the first 500 miles

• Do not drive for long periods at any single speed – vary your speed

• Do not tow a trailer or put heavy loads on the vehicle

• Check engine oil and coolant levels daily

• At 500 miles, change oil and filter using conventional (non-synthetic) oil

• After the first 5,000 miles, synthetic engine oil may be used

Warranty

ATK High Performance backs the HP89M with a 2-year / unlimited mileage warranty.

ATK HP89M Engine FAQs

What is the horsepower and torque of the HP89M?

The ATK HP89M produces 390 horsepower and 420 lb-ft of torque.

What vehicles is the HP89M compatible with?

The HP89M is a direct replacement for any vehicle originally equipped with a small-block Chevy, including street rods, muscle cars, and trucks. Note the oil pan compatibility restrictions: not for Chevelles with steering behind crossmember, some Corvettes, and 1962-1967 Chevy IIs.

What’s included with the HP89M?

The HP89M is a Stage 2 Mid Dress long block including the block, aluminum heads, intake manifold, distributor, valve covers, timing cover, oil pan, oil pump, water pump, harmonic balancer, and flexplate. Carburetor, fuel pump, spark plugs, and wires are not included.

What fuel does the HP89M require?

91+ octane premium fuel is required for optimal performance.

What certifications does ATK hold?

All of ATK’s manufacturing facilities have achieved both QS-9000 and ISO 9001 certification levels—one of the few engine remanufacturers in the world to have done so.

What is the core charge and process?

A core charge of $510.00 applies. Core return can be any Small Block Chevy 350ci engine, except 1992-1997 LT1-style engines.