Chevy 454 HO - High Output Big Block

Now, GM Performance Parts has a 454 cubic inch Chevy crate engine that is way up on power and low on price. 454 HO Horsepower is a healthy 425 with 500 lb.-ft. of big-block torque for a lot of big block fun.

GMPP started with a brand new Gen VI four-bolt main engine block. The 454 HO is stuffed with a forged steel crank, forged connecting rods and forged pistons. A roller camshaft with .510/.540" lift generates a bold and nasty idle. Cast iron cylinder heads deliver 8.75:1 compression ratio which keeps the overall price of the engine down and allows you to run pump gas.

The 454 HO includes: water pump, balancer, intake manifold, and 14" automatic transmission flexplate. Add your carburetor, ignition, and starter to complete the engine.


  • Add a big-block legend to your ride
  • The perfect replacement for a big-block
  • Change your small block to a BBC

*Applications have not been validated. They are merely suggestions of how you might enjoy your GM Performance Parts crate engine. Some applications may affect engine warranty. See specific warranty information. Some applications may not be emission legal; check state and local ordinances.

Part Number: 12568774
Engine type: Chevy big-block V-8
Displacement (cu in): 454
Bore x stroke (in): 4.25 x 4.00
Block (P/N 12561353): Cast iron with 4-bolt main caps
Crankshaft (P/N 14096983): Forged steel
Connecting rods (P/N 10198922): Forged steel
Pistons (P/N 10215228): Forged aluminum
Camshaft type (P/N 24502611): Hydraulic roller
Camshaft lift (in): .510 intake / .540 exhaust
Camshaft duration (@.050 in): 211'c1 intake / 230'c1 exhaust
Cylinder heads (P/N 12562920): Iron rectangular port; 118 cc chambers
Valve size (in): 2.19 intake / 1.88 exhaust
Compression ratio: 8.75:1
Rocker arms (P/N 12523976): Stamped steel
Rocker arm ratio: 1.7:1
Water pump (P/N 12484890): Cast iron, long-style
Flexplate (P/N 10185034): 14"
Recommended fuel: 92 octane
Ignition timing: 4'c1 BTDC
Maximum rpm: 5500

454 HO engine image

Part #:12568774

454 HO dyno image

Installation Notes

  • NOTE: Distributor with melonized steel gear MUST be used with long blocks and partial engines with steel camshafts, or engine damage will occur. GMPP HEI distributor P/N 93440806 is recommended.
  • Requires addition of carburetor, starter, fuel pump, distributor and ignition system (not included).
  • Clutch linkage boss is cast into block, but must be drilled and tapped. When using cast iron exhaust manifolds, lower head bolts may need to be replaced with bolts with shorter heads for clearance.
  • Comes with a 14" automatic transmission flexplate; use flywheel P/N 14096987 and 11" clutch assembly for manual transmission.
  • Intended for pre-1977 street vehicles or all off-road vehicles.
  • Not intended for marine applications.