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820CI, 2,500HP, Big-Block Chevrolet - Horsepower!

Shafiroff Race Engines, Bohemia, NY

By , Photography by Courtesy Of Shafiroff Race Engines

For this month's Horsepower!, we were going to run a photo of a 625-inch Top Sportsman BBC we've had lying around for a while (the picture, not the engine). Yes, that's a big engine, but it made us wonder if there was bigger stuff available. The answer to that question came a short Google search later when this engine popped up on our screen. This Shafiroff 802 really made that 625 look inadequate, as ridiculous as that sounds.

The guys at Shafiroff were cool enough to send us a high-res picture and spend awhile on the phone talking through the components with us. Yes, the massive displacement and astronomical horsepower figures are impressive, but the amount of technology that goes into making engines at this performance level is just staggering. Our guy at Shafiroff, Tom Tilford, couldn't be too specific with the details-just as with all highly competitive race programs. We're only scratching the surface, but here are a few highlights of this behemoth.

A. Camshaft
The cam is one of Shafiroff's own, and the specs are a closely guarded secret. You might find us rolled up in a carpet in a South Jersey landfill if we ratted them out, so we won't. Tilford would acknowledge that the cam lobes are egg shaped-but the bottom of the egg is the top of the lobe. It's a 4-7 swap (cylinders 4 and 7 trade places in the normal firing order), and it is ground on a 60mm core. The cam bearings are bigger than an early small-block's main bearing diameter. The cam is driven by a 1-inch, raised, Jesel beltdrive. Jesel also makes the 1.062-inch keyed roller lifters, which operate "baseball bat"-sized pushrods that are 1/2 inch wide and 11 inches long.

B. Dry-Sump
Among its many advantages, a dry-sump oiling system allows the engine to be mounted in the chassis as low as possible. This engine has four pressure feeds and one suction line. The Moroso can holds 8 quarts of oil to ensure that the pump is never starved even at the incredible g-forces experienced during a 5-second quarter-mile pass.

C. Carbs and Nitrous
Those are Book Racing Enterprise Custom HP Split Dominator carburetor, and like the cam specs, their airflow numbers are kept under lock and key. To keep up with all this displacement at 7,000-plus rpm, think Goodyear Blimp volumes of air, though. The 4-Stage nitrous Fogger system is electronically controlled. Each stage can be triggered to come in at a combination of rpm, throttle position, or amount of time, and the crew is constantly changing the tuning based on track conditions and driver feedback.

D. Heads and Intake
CFE Racing Products provided the symmetrical-port, CNC-ported cylinder heads. They house ultralightweight titanium valves and Jesel stainless steel, shaft-mounted rocker arms. Aluminum rockers just won't stand up to the valvespring pressures-which are also a secret, by the way. The intake manifold is handmade with sheet aluminum and CNC-machined billet runners.

E. Block
The Dart billet block would be worthy of display at the Smithsonian, in our opinion. It's almost a shame to hide it underneath all this stuff. It literally began life as a 600-pound solid brick of 6061 aluminum that was CNC-machined around a 5.20-inch bore spacing to allow a final bore size of 4.875 inches. A call to Dart revealed that it takes the company about 14 weeks to produce a block like this. Each one is specifically made to the customer's specs, so each one requires a specific setup and programming. You can't just click a button and churn out these things. So far, the biggest bore spacing Dart makes is 5.30 inches, so it is possible to build an engine even bigger than the one here. How much bigger could you go? "At this point, the car becomes too small," Tilford told us. "More bore spacing means the engine is that much longer from the firewall out. There comes a point where you'll have to build a bigger chassis to make it fit."

F. Reciprocating Assembly
A custom block requires custom components, so the crank, rods, and cam are all machined from either steel or aluminum billet. The crank is from Sonny Bryant and hefts a 5.375-inch stroke. The MGP connecting rods are interesting not just in their size but because they are machined to provide pressurized oil to the wristpin. The rod caps are also doweled and machined with circular serrations that can only fit together one way. The wristpins are made from tool steel, and they retain custom-forged, Ross gas-ported pistons sized to deliver a lofty 14.0:1 compression ratio. The 1.10mm Akerly & Childs rings are also made from tool steel because, according to Tilford, "nitrous burns off the moly coating found on most performance rings." The bearings are all from Clevite and treated to Calico Coatings' dry-film lubricating coating.

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