ATK HP89C-EFI 350 Crate Engine – 390 HP / 420 TQ with Self-Learning EFI

The Ultimate 350 Stage 3 Crate Engine with FiTech EFI

The ATK HP89C-EFI 350 crate engine delivers dyno-proven performance with the convenience of self-learning EFI in a complete Stage 3 package that’s ready to drop into your classic Chevelle, Camaro, Nova, 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—while the FiTech Self-Learning EFI system provides trouble-free cold starts and optimal drivability regardless of elevation, driving habits, or modifications .

Whether you’re building a weekend cruiser, a street machine, or a show-stopping classic, this ATK 350 EFI crate engine delivers the power, reliability, and modern drivability that Chevy enthusiasts demand.

What Makes the ATK 350 Stage 3 with EFI the Ultimate Small Block Crate Engine?

The HP89C-EFI is engineered for enthusiasts who want maximum performance with modern EFI 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 “Stage 3 Complete” variant includes the FiTech Self-Learning EFI system, performance intake manifold, distributor, water pump, harmonic balancer, flexplate, and all necessary components—making it a true turn-key solution .

Every ATK engine is hand-assembled and balanced by professional craftsmen, and each engine is reverse-engineered to eliminate any well-known factory defects .

350 Stage 3 EFI 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 

• 10.1:1 compression ratio – pump gas friendly 

• Hydraulic roller cam – low maintenance, excellent durability 

• Self-learning EFI – no tuning required regardless of elevation, driving habits, or part swap 

Complete 350 Stage 3 EFI 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 – 10.1:1 compression 

• Moly piston rings 

ATK High Performance Aluminum Cylinder Heads

The ATK High Performance aluminum cylinder heads provide exceptional flow :

Hydraulic Roller Camshaft Specifications

FiTech Self-Learning EFI System

The FiTech Self-Learning EFI system includes :

• Throttle body with integrated fuel injection

• Wire harness for plug-and-play installation

• Handheld unit for monitoring and adjustments

• Self-learning technology – no tuning required

What’s Included with Your HP89C-EFI Crate Engine

The HP89C-EFI is a complete Stage 3 dressed engine with the following components included :

Important Note: The fuel pump is not provided – you must run an electric pump, in-tank pump, or the FiTech Fuel Command Center . This engine is a race-only product for competition use only and is not legal for street use .

Installation Notes and Critical Considerations

Important Notes Before Installation

Before installing your ATK HP89C-EFI 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 

• Spark plug gap: .035″ 

• Firing order: 1-8-4-3-6-5-7-2 

• Stall converter: Stock recommended 

• Exhaust: 1-5/8″ headers recommended 

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

Fuel System Requirements

The FiTech EFI system requires a fuel supply. ATK recommends using either :

• An electric fuel pump (in-line or in-tank)

• The FiTech Fuel Command Center (a self-contained fuel reservoir system)

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

This is a Race Only product that is to be used solely for competition. It cannot be used on vehicles operated on public streets, roads, or highways. Its use is limited to closed-course and open-course racing formally sanctioned by a recognized racing organization . Shipping restrictions apply to CA, NY, and ME .

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 HP89C-EFI with a 2-year / unlimited mileage warranty .

ATK HP89C-EFI Engine FAQs

What is the horsepower and torque of the HP89C-EFI?

The ATK HP89C-EFI produces 390 horsepower and 420 lb-ft of torque .

What vehicles is the HP89C-EFI compatible with?

The HP89C-EFI 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 HP89C-EFI?

The HP89C-EFI is a complete Stage 3 dressed engine including the block, aluminum heads, FiTech EFI system, intake manifold, distributor, valve covers, timing cover, oil pan, oil pump, water pump, harmonic balancer, flexplate, spark plugs, and wires . Fuel pump is not included .

What fuel does the HP89C-EFI require?

91+ octane premium fuel is required for optimal performance .

What is the warranty on the HP89C-EFI?

ATK High Performance backs the HP89C-EFI with a 2-year / unlimited mileage warranty .

Is the HP89C-EFI emissions legal?

No. This is a race-only product for competition use only and cannot be used on vehicles operated on public streets, roads, or highways . Shipping restrictions apply to CA, NY, and ME .