For when your stock sleeve LT engine just isn't enough. This Darton Sleeved 427 LT longblock is the "bee's knees" of our LT engine lineup. Setup for all the boost you want to throw at it, this longblock won't disappoint.


BoostPrep 427 Sleeved LT Longblock


Bore: 4.125"

Stroke: 4.000"

Connecting Rod Length: 6.125"

Displacement: 7.0L / 427c.i.

Piston Volume: -16.0cc or -24.5cc dish with valve reliefs

Compression Ratio:

9.6:1 with -16cc dish pistons

10.4:1 with -24.5cc dish pistons


Horsepower Rating: Up to 1400whp


Engine Block: OEM LT1 6.2L Aluminum Block with 4.125" bore Darton Sleeves

Crankshaft: Callies 8 Counter Weight Magnum Crankshaft

Pistons: Diamond Racing Forged Pistons

Connecting Rods: Callies Ultra Billet H-Beam Connecting rods w/ ARP rod bolts

Main Fasteners: ARP Main Studs

Main Bearings: King XP-Series Race Bearings

Rod Bearings: King XP-Series Race Bearings

Cam Bearings: Durabond one piece bearings


Cylinder Heads: CID Aftermarket Casting LT Heads

Valves: 2.126" intake / 1.590" exhaust

Valve Springs: .660" Lift Dual Valve Springs w/ Titanium retainers

Camshaft: Application Specific Spec'd Camshaft

Timing Chain: Katech C5-R Timing Chain

Lifters: OE Replacement LS7 Lifters

Push Rods: 3/8 Diameter Chromoly Pushrods

Rocker Arms: TSP LT1 Roller Rocker Arms w/ Bronze trunnion bushings

Head Fasteners: ARP Head Studs

Head Gaskets: Cometic MLS Head Gaskets

Oil Pump: OEM GM Oil Pump


427 Sleeved LT BoostPrep Longblock