Video: 673 Cubic Inch Ford Hemi Makes 1,300+ HP On Engine Dyno

Our friends Down Under have a fascination with horsepower in all its forms; their exploits are legendary when it comes to car shows, race machines, and some of the wildest builds around. So when we found this video featuring Aussie builder John Saad’s sick 673ci Ford Hemi making more than 1,300 horsepower on the dyno at BK Race Engines, we had to reach out to him for more details.

It turns out that the engine is one of Sonny Leonard’s massive Ford big-blocks wearing a set of Hemi-style cylinder heads and Sonny’s fabricated sheetmetal intake manifold. It’s parked between the fenders of Saad’s 1971 XY Falcon — dubbed FAT XY — and is outfitted with brand-new E85-friendly APD Billet Enforcer 1175 carburetors to make the most of the corn.

The engine features a Sonny’s/Brodix 5.000-inch bore space block that uses a 1.000-inch raised camshaft location and several other machining tricks to maximize performance.

“We recently put in a smaller camshaft and changed the carbs to switch it over to E85,” he said. With these changes, the engine put down 1,319.4 horsepower and 1,054.4 lb-ft of torque on the BKRE dyno. In a previous configuration, it put out a bit more power but didn’t have the friendliest street manners.

To handle all of that power, Saad’s Falcon has been completely reworked. Fitting the engine proved challenging as there wasn’t nearly enough room in the engine bay. To clear up the issue, he installed a McDonald Bros. Racing Products independent front suspension system, then backed the engine up with a Turbo 400 transmission, 9-inch differential, and four-link rear suspension built by JT Performance and CS Engineering. Saad, an accomplished builder in the Aussie car world, has several awards to his credit including Grand Champion of the Street Machine Summernats in 2016 with his 1972 Mazda rotary-powered RX3.

“This is a different concept of a car, a street car that I can enjoy and drive, as much as it looks ridiculous with this engine. The whole goal of this build was to look like a [Falcon] GT on steroids,” he said.

Based on the engine’s performance on the dyno, we’d have to agree that he’s achieved his goal.

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About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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