You Ask, They Deliver: LSX Crate Engines and Heads by GM

The wait is over. GM Performance Parts announced today that their crate motor production for LSX engines would be starting with two combinations. The 376 will be their budget engine and the LSX 454 being the all out LSX bad boy.

GMPP durability tests each engine component before they put into production. They don’t slap it into a car and drive it down the track a few times; they beat the ever-living hell out of it. The test is simple: can it live for 50 hours on an engine dyno without breaking at full load? Insane it may seem. The equivalent is:

• Running the 24 hours of Daytona twice.
• The Daytona 500 for the last 15 years
• 9,000 20-second circle track laps
• 16,000 11 second drag strip passes

The LSX Block

The whole foundation of this engine program is the relatively new LSX block, designed by GM and Warren Johnson. The blocks are cast iron and built to withstand over 2000 horsepower. I know what your thinking, a block that can handle that type of power for under $2000? Yeah right. I can be one to attest that’s true. We produced a video for GM showing the capabilities of the LSX block at Thomson Automotive. Brian Thomson built a twin turbo LSX engine that came in at a mere 400 cubic inches and made over 2000 horsepower. This isn’t a single pull to achieve that power. The combination had been pulled on the dyno over 80 times. Also with the tall deck LSX block version, you can run over 500 cubic inches out of this small block. GM is considering the production of an aluminum version, though there is nothing set in stone.

The Six Bolt Heads

As we all know, the stock production LS heads are a four-bolt design. Enthusiasts on high horsepower applications have seen some deflection problems from the center of the heads. The new six bolt (which is what the LSX block was designed for) heads will add to the much-needed clamping force. This has increased the 6 and 12 o’clock clamping by 100% and an overall increase of 21%. Now you don’t have to worry about pushing gaskets at 20 PSI. Based on the LS7 heads, the LSX heads will flow up to 420 CFM. GM plans to release many new LSX head castings, ranging from L92 to LS7 port configurations and engineered for drag racing to circle track applications. Pricing on the heads will be competitive but are unreleased at this time.

Rotating Assemblies

To add to the barrage of new parts includes the ever-so-obvious rotating assembly. GM Performance Parts will have an array of internal components, ranging from 4340 cranks, H Beam Rods, pistons, and cams for various applications. There will also be carbbed intake manifolds with the option to add injector bungs. Of course, if you buy one of their crate motors, these wonderful parts already come pre-installed.

Crate Engine One – The 376

The tamer of the two, the 376 is GM’s economical LSX crate engine. The MSRP will come in at the $7000-$9000 price range. This engine would be best suited for road cars and light competition. The 6.2-liter features new LSX forged pistons, LS3 Heads and a tame street hydraulic roller cam. The overall compression weighs in at 10.7:1. This package comes without induction, but GMPP claims 450 horsepower with production style induction. In the end, you’re left with a step up from a production motor that will accept a nice dose of nitrous and good gas mileage while cruising.

The Big Boy – LSX454

If a 505 horsepower LS7 Z06 engine isn’t enough, then the 454 is here to answer your needs. The 454 packs 620 horspower and 600 foot pounds of pure carbureted insanity. Reggie Jackson’s SEMA show-stopping Camaro was the test bed for the 454 in ’06. Out-of-the-box performance put the 454 into the high 10-second quarter mile range. The compression is upped to 11:1, which is supported by an all forged rotating assembly. There will be a slight compromise on drivability with the installed 236/240 cam that pushes .635 inches of lift. GM plans to add a fuel injected 454 sometime in 2009.

Forced induction on LS-based engines is a growing trend. Turbo combinations dominated the LSX Shootout this last weekend in Memphis. GMPP does not have immediate plans for a low compression crate engine, though they will have a much-needed short block version.

Part number: 19171049
Engine type: LSX Series Gen IV small-block V-8
Displacement (cu in / L): 376 / 6.2L
Bore x stroke (in / mm): 4.06 x 3.62 / 103.25 x 92
Block (P/N 19166454): LSX cast iron with six-bolt, cross-bolted main caps
Crankshaft: nodular iron
Connecting rods: powdered metal
Pistons: forged aluminum
Camshaft type: hydraulic roller
Valve lift (in): 0.551 intake / 0.522 exhaust
Duration (deg @ 0.050 in): 204 intake / 211 exhaust
Cylinder heads (P/N 12598594): LS3 rectangular port; as cast with 68cc chambers
Valve size (in): 2.16 intake / 1.59 exhaust
Compression ratio: 10.7:1
Rocker arms: investment cast, roller trunnion
Rocker arm ratio: 1.7:1
Recommended ruel: 92 octane

Part number: 19166972
Engine type: LSX Series Gen IV small-block V-8
Displacement (cu in / L): 454 / 7.4
Bore x stroke (in / mm): 4.185 x 4.125 / 164 x 162
Block (P/N 19166454): LSX cast iron with 6-bolt, cross-bolted main caps
Crankshaft: 4340 forged steel
Connecting rods: 4340 forged steel
Pistons: Forged aluminum
Camshaft type: Hydraulic roller
Valve lift (in): 0.635 intake / 0.635 exhaust
Duration (deg @ 0.050 in): 236 intake / 240 exhaust
Cylinder feads (P/N 12598594): LSX454 rectangular port; with 70cc chambers Valve size (in): 2.20 intake / 1.61 exhaust
Compression ratio: 11:1
Rocker arms: investment cast, roller trunnion
Rocker Arm Ratio: 1.8:1
Recommended Fuel: 92 octane
Reluctor wheel: 58X
Balanced: internal
Reluctor wheel: 58X
Balanced: internal

About the author

Mark Gearhart

In 1995 Mark started photographing drag races at his once local track, Bradenton Motorsports Park. He became hooked and shot virtually every series at the track until 2007 until he moved to California and began working as a writer for Power Automedia. He was the founding editor for its first online magazines, and transitioned into the role of editorial director role in 2014. Retiring from the company in 2016, Mark continues to expand his career as a car builder, automotive enthusiast, and freelance journalist to provide featured content and technical expertise.
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