Our friend Jeff Huneycutt of The Horsepower Monster gets to be a part of some unique engine builds. This one is no exception. Huneycutt headed over to Wilkins Racing Engines and followed along as Sandy Wilkins tore apart his standard-bore-space big-block Chevrolet NHRA Top Sportsman engine, and made some significant updates to the combination in order to stay on top and continue his winning ways.

This particular engine has been around for 14 seasons of racing, racking up round wins, race wins, and even an NHRA season championship in 2019. While components have been replaced over the years, this isn’t a case of George Washington’s axe — this is the same block as day one. It’s a Brodix aluminum 4.84-inch bore-space block with a tall 10.7-inch deck height. Part of its durability comes from undergoing the hot isostatic pressing which eliminates porosity in cast blocks.

A Proven Foundation

Also being reused is the crankshaft. It’s a Callies Magnum unit with a whopping five inches of stroke. Forged from 4340 steel, the material has been treated with Callies’ Ultra Case deep nitriding process. The crank is held in place by five four-bolt billet-steel main caps, the center three of which have splayed outer studs.

The custom pistons measure 4.610 inches in diameter and are forged from 2618 aluminum. They are drilled with vertical gas ports, and are sent to Wilkins without any valve reliefs cut into the crown — he cuts those himself in his shop. He then sends the pistons to Calico Coatings for a heat-reflective crown coating and a wear-resistant friction-reducing “anti-scuff” coating on the skirts.

Connecting the pistons to the crank are pieces of automotive jewelry — MGP billet aluminum rods. The aluminum rods aren’t used in this application for their minor weight savings, but rather for the material properties. The aluminum acts as a shock absorber which can be especially critical in a violent nitrous application like this Top Sportsman engine. The rod bearings are coated and doweled, and the wrist pins are retained with buttons to help support the rings. Those rings are Total Seal pieces measuring .043 inches wide for the top and second ring, with a 3.0mm oil-control ring.

Sealing up the bottom of the short-block is a Moroso two-piece dry-sump oil pan. The two-piece design allows for easy servicing of the bottom end while the engine is in the car, potentially for any between-round maintenance. A five-stage dry sump system keeps as much oil out of the pan as possible. To keep everything in time, Wilkins uses a Jesel belt drive modified with a magnet in the camshaft sprocket for the Holley EFI cam position sensor. An ATI Super Damper with an aluminum hub and shell helps keep any unwanted harmonics in check.

The Upper Deck

Topping off the short-block are a pair of Brodix 12-degree aluminum cylinder heads, which are loosely based on the Big Chief cylinder head design. Out of the box, the intake ports on the heads flow 571 cfm at .900 inch of lift. The combustion chamber design is something the Wilkins has spent a significant amount of time and effort on, and each chamber houses massive 2.520-inch intake and 1.860-inch exhaust valves, both of which are made from titanium. The heads are sealed to the block through stoute head studs and Wilkins Racing Engines-specific MLS gaskets made by Cometic.

The brain of the Top Sportsman engine is a COMP Cams billet 60mm camshaft ground to Wilkins’ specs, which he’s playing close to the vest. However, Huneycutt was able to pry out of him that he utilizes the LS firing order and has gross lift numbers of over an inch on both the intake and exhaust. In the spirit of increasing longevity, Wilkins has added some extra exhaust duration to get the gasses out and help cool the chamber as well.

A set of .937-inch diameter Jesel Sportsman tie-bar solid roller lifters translate the cam lobes’ shape into vertical motion. They have been coated in Diamond Like Carbon to increase both lubricity and wear resistance in the lifter bore. The lifters also feature .180-inch offset pushrod cups in order to help straighten out the pushrod geometry.

The pushrods are not only two different lengths, as is typical in a big-block, but also different diameters. The intake pushrods are 10.875-inch-long 1/2-inch-diameter units, while the exhaust pushrods are 11.100-inch long, and a massive 9/16-inch in diameter. They actuate a set of steel shaft rockers with a 1.9:1 ratio on the intake and 1.85:1 on the exhaust side. The valves are kept under control by PSI triple valve springs with a significant, undisclosed amount of pressure, and are secured by Del West titanium retainers. This valvetrain setup is designed to be stable at the 8,200 rpm Wilkins turns through the traps.

The New Hotness

When switching from twin dominators to EFI, there are a number of changes that go along with that. And while Wilkins could have adapted his existing intake manifold to EFI, he opted for an all-new design. The new setup features eight individual 2.375-inch (60mm) throttle bodies feeding the common plenum, but each is centered over an intake runner.

Each runner has a single nitrous nozzle right at the port, plumbed with three separate nitrous feeds for a three-stage direct-port setup controlled through the FuelTech ECU, in a dry setup — that is, only nitrous will flow through the nozzles, and supplemental fueling will be handled through the fuel injectors and controlled by the FuelTech as well. The triple-feed nozzles easily flow the 700-plus horsepower-worth of nitrous oxide Wilkins typically sprays on a 6.30-second quarter-mile pass. To keep up with the engine’s fuel demands, a Waterman Racing mechanical fuel pump is driven off the camshaft

“One of the reasons we’re converting this over to EFI is so that we’ll have better control over what’s happening in each cylinder,” Wilkins explains. “With the carbureted setup, we can have cylinders robbing each other of fuel. With EFI we can have direct port injection that controls exactly how much fuel goes into each cylinder.” This Top Sportsman engine should make 2,000 horsepower on the low side (1,300 naturally aspirated, with another 700 of the giggle gas), and run that 6.30-second number for a full season, at least.