Aesthetically pleasing engines have become somewhat of a dying artistry in the hot rod and racing worlds. Most of the OEMS have certainly forgotten how to design an attractive engine under the hood. Even high-end show cars costing hundreds of thousands of dollars are hiding their engines under silly air-cleaner covers.
When JR Granatelli of Granatelli Motor Sports set out to build an engine for son JoJo’s 2018 Pontiac-bodied door slammer, it had to be eye candy as well as powerful.
“I come from an IndyCar background,” he says. “Whether it’s the richest or the poorest team there, the engineers must all have pride of workmanship—having all the wires where they’re supposed to be and everything being compact and orderly. I want to take that background and push it forward on everything we do. The car, the engine, everything will be tidy and color matching.”
The engine was first built by Kenny Duttweiler for the 4,500-pound street car that JoJo drove to college and work every day and then raced parttime at LS Fests and other events.
“We could never get that car to go down the track the right way. The weight made it nearly impossible to keep parts working, so I decided to start from scratch and build a proper car,” remembers Granatelli. “I bought a Comp Eliminator car and modified the chassis to handle 3,000 horsepower.”
The short block is comprised of a Dart cylinder block bored to 4.145-inch and a Callies crankshaft with a 3.900-inch stroke, resulting in a total displacement of 421ci. Calles Ultra I-beam 6.125-inch connecting rods swing with 3D-milled Diamond 2618 alloy pistons that feature lateral gas ports to help 1.5 x 1.5 x 3.0mm Total Seal rings seal effectively. The skirts are moly coated to reduce friction under extreme boosted conditions, and the pistons are held in place with H13 tool-steel wrist pins.
Lubrication starts with a custom Dailey Engineering billet dry-sump oil pan that is integrated with a belt-driven pump—eliminating the need for short external scavenge lines. The system also includes a separate scavenge section for the turbochargers and an anti-foaming feature. Granatelli uses Valvoline synthetic VR1 motor oil.
Dart set up a custom CNC program for Granatelli to machine its Pro1 cylinder heads that feature 285cc intake ports and 66cc combustion chambers. The heads are fitted with Ferrea 2.200-inch stainless steel intake valves and 1.625-inch Inconel exhaust valves along with PAC intake and Manley exhaust valve springs. Other valvetrain components include steel Jesel 1.7:1 rocker arms, Manton 7/16 to 3/8 tapered heavy-wall pushrods and Jessel roller lifters. Granatelli Motor Sports designed the camshaft in concert with Comp Cams for 270/280 degrees duration at .050-inch and 115-degree lobe-separation angle. Maximum valve lift is .717-inch.
The engine was assembled with SCE gaskets, ARP custom aged fasteners and a complete RCD billet-gear timing set. “Then we put a set of HPT 84mm turbos on it and made 2,712 horsepower on the dyno. It’s a testament how much power these LS motors will make today,” says Granatelli. “We are confident this combination will exceed 3,000 horsepower once dialed in in the car. The engine dyno is intended to prove out the combination, not to get the ultimate number. It’s not a bench racer, it’s a drag racer.”
The turbos are fed via custom headers fabricated by Granatelli Motor Sports, and routing that forced air is a new Granatelli Motor Sports intake manifold designed for boost applications. Each turbo tube on the cold side is captured by Granatelli HD double O-ring clamps capable of holding 300 psi.
Previous LS intake manifolds from the company were a traditional “bread box” design that made power from 3,000 to 7,000 rpm and were designed to fit under the hood. The new intake has a burst panel and twin Granatelli 120mm throttle bodies with provisions for methanol injection, and will help allow this engine to turn upwards of 9,200 rpm. The fuel system starts with a cam-driven Aeromotive fuel pump and includes HPT AFIS 800-pound injectors controlled by a Holley Dominator ECU.
The engine will be backed by a TH400 transmission building in house with help from Justin Robbins at Big Juicy Transmissions and features a trick Neil Chance lock-up style torque converter. The engine is expected to run with about 32 pounds of boost. The ultimate insurance policy is courtesy of Aaron Schwartz of All Out Tuning and Performance. He is the mastermind by the keyboard telling the engine what’s important. Adds Granatelli, “the best LS engines need the best tuning, All Out has that covered.”
Granatelli expects the 2025 season to be a rolling marketing campaign that highlights the company’s renewed commitment to high-performance parts. “Over the next six months you will see several new and unique components coming out of Granatelli Motor Sports, such as Gen 5 LT billet engine blocks, companion cylinder heads, oil pumps and direct-injection fuel pumps. Jojo’s race car will be our rolling test bed, and streetable 2,000 horsepower combinations will be the norm.”
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