Granatelli Motor Sports twin-turbo engine combination with 120mm intake
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Torque Journal Features the 2,712-HP Twin-Turbo LS Built at Granatelli Motor Sports

By Joey Granatelli2 min read

Torque Journal profiled the twin-turbo 421ci LS that J.R. Granatelli built for his son JoJo's Pontiac-bodied door slammer. It made about 2,712 horsepower on the dyno.

Torque Journal profiled the twin-turbo, 421-cubic-inch LS engine that J.R. Granatelli built at Granatelli Motor Sports for his son JoJo's Pontiac-bodied door slammer. According to the article, the engine made about 2,712 horsepower on the dyno and is expected to exceed 3,000 once it is tuned for the track.

The feature, "Speed & Beauty From Granatelli Motor Sports," was written by Mike Magda and published on June 24, 2025.

The Engine at a Glance

These are the figures as reported by Torque Journal.

Displacement 421 cubic inches
Block Dart, bored to 4.145 inches
Crankshaft Callies, 3.900-inch stroke
Cylinder heads Dart Pro1, 285cc intake ports, 66cc chambers
Turbochargers Twin HPT 84mm
Intake Custom Granatelli intake with twin 120mm throttle bodies
Headers Custom Granatelli
Dyno output About 2,712 horsepower
Expected in the car More than 3,000 horsepower at about 32 psi of boost
Expected rpm Upwards of 9,200

From a 4,500-Pound Street Car to a Door Slammer

Torque Journal traces the project back to JoJo's street car, a 4,500-pound machine he drove to college and to work and raced part-time at LS Fest and other events. The article says the weight of that car made it hard to keep parts alive on the track.

So the program started over. J.R. built a new engine for a Pontiac-bodied door slammer, a Comp Eliminator car that Granatelli bought and modified to handle 3,000 horsepower.

The Granatelli Parts on the Engine

The article highlights two pieces made in-house:

  • A custom Granatelli intake built for boost, with a burst panel, twin 120mm throttle bodies and provisions for methanol injection
  • Custom Granatelli headers

The rest of the combination reads like a who's-who of race hardware, including a Dailey Engineering dry-sump system, a Holley Dominator ECU and a TH400 transmission built in-house.

The race engine is a one-off, but Granatelli also makes production billet LS and LT intake manifolds and large-bore drive-by-wire throttle bodies for street and race builds.

"Pride of Workmanship"

Torque Journal describes J.R. as coming from an IndyCar background, where he learned to value what the article calls "pride of workmanship." That is why the engine is as tidy and color-matched as it is powerful, and it is where the "Speed & Beauty" headline comes from.

What the Article Previewed

The feature also previewed Granatelli products that were in development at the time, including Gen 5 LT billet engine blocks, companion cylinder heads, oil pumps and direct-injection fuel pumps.

Read the Original Coverage

Read "Speed & Beauty From Granatelli Motor Sports" at Torque Journal

Related reading: JoJo Granatelli Sets the Red List Series Quarter-Mile Record: 7.06 Seconds at 157 MPH

More about JoJo Granatelli

Building a Boosted LS? Shop Granatelli Parts

Not sure which intake fits your build? Start with the LS and LT Intake Manifold FAQ.

About Granatelli Motor Sports

Granatelli Motor Sports, based in Oxnard, California, has built performance parts for street, street/strip and race vehicles since 1989, including ignition coils, spark plug wires, throttle bodies, turbo components and electronic exhaust cutouts.

Shop Granatelli Motor Sports

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