This is a Jon Kaase Racing Boss Nine V8 crate engine with a displacement of 547 cubic inches (9.0 liters) that is capable of 848 bhp and 766 lb ft of torque.
This engine was built in early 2024 and it had remained unused since. Looking over the spec sheet it’s clear that this was a blank cheque engine build and the final recipt reflects this – the total cost to build it was $42,466 USD. The engine is now being offered for sale out of Florida.
The engine was built this year at a cost of $42,466 USD, it remains unused and it’s now being offered for sale.
This engine is based on the design of the high-performance Boss 429 V8 developed by Ford in the late 1960s to go racing in the NASCAR Grand National Division (now known as the NASCAR Cup Series).
In order to race with the engine they first needed to homologate it by fitting it to a minimum of 500 production cars that would be available to buy to the general public. Discussions were had at Ford about which car to fit the new Boss 429 engine into, and it was eventually decided to use the Mustang.
A key reason for choosing the Mustang was that the engine bay in the model had been increased in size for the 1967 model year to allow the fitment of Ford’s road-going big block V8 – the 428 cubic inch engine that would be used in the Shelby GT500 and the Mustang, as well as the Mercury Cougar, Ford Fairlane, Ford Torino, and others.
The Ford 429 V8 was based on Ford’s newer engine architecture, and they were hoping to take it racing in NASCAR to challenge the long-in-the-tooth (but very successful) Chrysler 426 Hemi V8.
The original Ford version of the 429 V8 featured four-bolt main caps, a forged steel crank, forged steel connecting rods, aluminum cylinder heads, and an unusual semi-hemispherical combustion chamber which Ford called the “Crescent” to differentiate it from the Chrysler Hemi.
The road-going version of the Ford 429 V8 was rated at 375 bhp at 5,200 rpm with 450 lb ft of torque at 3,400 rpm. The racing versions could produce far more, though the exact numbers were a closely guarded secret.
The spec sheet for this engine (see it below) reads like a blank cheque wishlist, and it should probably be no surprise that it’s capable of 848 bhp and 766 lb ft of torque.
A total of 1,359 Ford Mustang Boss 429s were made in total, they’re now among the most collectible of the “special” Mustangs from the era, and far more rare than the Boss 302 which had been built to homologate its engine for Trans Am racing.
The Boss Nine V8 Crate Engine Shown Here
This is a Jon Kaase Racing Boss Nine V8 crate engine, and as noted above, it was built earlier this year and there is a dynamometer report showing that it can produce 848 bhp at 6,500 rpm with 766 lb ft of torque at 5,100 rpm.
The engine has a displacement of 547 cubic inches (9.0 liters) and it was built up on a lightweight aluminum block with aluminum Kaase Racing Boss Nine cylinder heads, Mahle pistons and rings, H-Beam connecting rods with ARP bolts, a Lunati forged crankshaft, a COMP Cams hydraulic roller camshaft, Beehive valve springs, and T&D shaft rocker arms.
It also has a Ford Racing double roller timing chain, a KaaseStack Injection intake manifold, Borla TWM throttle bodies, and a Holley/MSD programmable electronic fuel injection and distributor.
The engine is being sold with a set of cast exhaust manifolds, a steel engine shipping cradle, a wooden shipping crate, and build documentation.
The total cost of the build was $42,466 USD and sadly it has never actually been used. It’s now being offered for sale in as-new condition as a crate engine out of Boynton Beach, Florida with a set of cast exhaust manifolds, a steel engine shipping cradle, a wooden shipping crate, and build documentation.
If you’d like to read more about it or place a bid you can visit the listing here on Bring a Trailer.
Images courtesy of Bring a Trailer
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