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MTM111-421 - Mast Motorsports Turnkey Naturally Aspirated LSX 440 HO (640hp), Includes M-90 DBW ECM and Harness

This product may require vehicle validation(s) for proper fitment. Please contact us to confirm correct vehicle fitment and usage.

Availability: Item has been discontinued and is no longer available
Shipping: FREE 48 State Shipping


The X-Block 440’s heart and soul is the new GM Performance LSX iron block. This X-block engine family utilizes a Mast Motorsports engineered camshaft that is custom ground on a Mast Motorsports 3 bolt cam core. The 440 foundation is a fully machined iron block with a forged Callies rotating assembly with Mahle pistons that is topped off with CNC LS3/L92 heads and a L76/L92 intake manifold. ARP fasteners are used throughout and Manley pushrods ride on LS3 hydraulic roller lifters. The X-Block 440 HO is a powerful yet reasonably priced offering by Mast Motorsports that has slightly more lope than the X-Block 440 with as cast LS3/L92 cylinder heads.

Type: X-Block 7.2L
Displacement: 440 Cubic Inches
Compression Ratio: 11.4:1
Bore x Stroke: 4.185 x 4.000
Rev Limit: 7000 RPM
Crank: Callies Forged
Rods: Callies H-Beam
Pistons: Mahle Motorsports
Cam: Mast Custom 3-Bolt Core Cam
Heads: Mast CNC LS3/L92 Heads
Intake: GM LS3 Intake
Valve Springs: Mast Nitrided Beehive

LSX Iron Block
Plateau Honed to 4.185”
True Surfaced Deck
Engine Block Deburred
Blueprinted Shortblock
Clevite Rod and Crank Bearings
Callies Forged 4.000” Stroked Crankshaft
Callies Forged H-Beam Connecting Rods
Custom Mahle Motorsports Pistons
Mast Black Label LS3 280cc Heads
ARP Head Bolts
ARP Main Studs
Cometic Head Gaskets
Mast Custom Hydraulic Roller Cam
GM LS7 Hydraulic Roller Lifters
Mast Black Label Pushrods
Mast Double Valve Springs
Mast Solid Stainless Intake Valves
Mast Solid Stainless Exhaust Valves
Mast Black Label Titanium Retainers
Mast Black Label Locks
M-90 DBW Calibrated ECM
Main Wiring Harness
MAP/IAT Harness
Bosch EGO Sensor
GM LS3 Intake Manifold
GM 90mm DBW Throttle Body
Bosch Dead Headed Fuel Rail
Bosch LS7 Fuel Injectors
Mast 8 Layer Air Filter with IAT Bung
Intake Air Temperature Sensor
Crankshaft Position Sensor
Camshaft Position Sensor
Oil Pressure Sensor
Oil Temperature Sensor
Engine Coolant Temperature
Engine Knock Sensors
Manifold Air Pressure Sensor
Ignition Coils
Spark Plugs
Plug Wires
GM Foot Pedal
GM Starter
GM Oil Filter
Mobile 1 Synthetic Oil
Engine Break in Oil Additive
F-Body, Y-Body, or Truck Water Pump
Balancer, and Oil Pan
Runs on Premium 91-93 Octane

Application List



  • 111-421
  • 111-421
  • Mast Motorsports
  • Item has been discontinued and is no longer available
  • New


Shipping Information

  • Item Requires Shipping
  • 500.0 lbs.
  • FREE 48 State Shipping


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