427 LSX Twin Turbo Engine - Engine Builder Magazine
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Engine of the Week

427 LSX Twin Turbo Engine

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We’ve now covered a couple of engine builds done by Ramiro Ramirez of Fat Boys Racing Engines, and each one gets better than the last. We were first introduced to Ramiro during fall 2020, when he messaged us on Instagram to tell us about his shop and his engine work. Located in Monterrey, Nuevo Leon, Mexico, Ramiro’s shop, Fat Boys Racing Engines, has been building high-performance V8 engines for nearly 17 years.

Standard deck 427 LSX block

Fat Boys Racing Engines has a focus on naturally aspirated and nitrous engine builds, and has recently started to offer forced induction builds as well. The shop’s engines are most commonly used for street/strip, drag racing and sand drag applications.

As Ramiro continues to push the envelope with his builds, he takes pride in showing off his work, and we’re glad he chooses to share his engine builds with us. Previously, Ramiro shared a 502 cid LS build and a forced induction 427 LSX.

4.000˝ stroke crank

This most recent engine build is another 427 LSX that’s slated to be boosted via a twin-turbo setup and will be going in an SS Silverado pickup. Ramirez started the build utilizing a 427 LSX Bowtie block with 11:1 compression in order to deliver strong horsepower and torque figures in a naturally aspirated setup at first. The twin turbos will be added to the build later so they can be configured in the best possible position.

CP flattop pistons and 6.125˝ rods

The LSX block is a 9.260˝ standard deck block that will be outfitted with ARP head studs, Mahle H-style main and rod bearings, and a rotating assembly that includes a 4.000˝ stroke, 8-counterweight crankshaft, billet 6.125˝ I-beam connecting rods, and CP forged flattop 4.127˝ bore pistons with .230˝ wall chromoly wrist pins. In fact, all the parts in this build are quality components ready to take the abuse of twin turbos.

Cam Motion camshaft

The valvetrain setup features a hydraulic camshaft, which Ramiro got custom designed from Cam Motion that has 670 lift and a 115 lobe center. For cylinder heads, Fat Boys Racing Engines chose a set of Frankenstein M311 heads with titanium valves. The heads were completed with Johnson hydraulic short-travel lifters, Texas Speed rocker arms and trunnion kit, Manton custom-length pushrods with a .145˝ wall, and .040˝-thick head gaskets.

The LSX has Frankenstein M311 cylinder heads

Some of the other components include a Melling high-volume oil pump, an ATI super damper, a CSR aluminum flexplate, Holley Terminator X EFI, Injector Dynamics injectors, and a Holley 105mm throttle body with a Holley Hi-Ram LS3-style intake.

The LSX engine will run naturally aspirated at first before the twin turbos are added to the setup. Once fully completed, this SS Silverado will be used on the street and on the track in Houston and in Mexico.

Engine of the Week is sponsored by PennGrade Motor OilElring – Das Original and Scat Crankshafts. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected]

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