Volume I, Issue 1, Page 44

Sonny Leonard’s Ultimate 762-inch RAT
Makes 1100+ hp / 1100+ lbs Torque
on 89 Octane Pump Gas

click images to enlarge

Sonny Leonard invited MaxChevy to the dyno test of his new 762-cubic-inch pump gas monster. Burning 89 octane real pump gas, the all-aluminum monster motor registered peak torque (1121) at 4900rpm and peak horsepower (1162) at just 6500rpm. The fuel was bought from the local Exxon station on the corner. Sonny is always at the throttle when one of his engines is dyno-tested

It seems relatively common these days to pick up a magazine and read all about the newest 1000-horsepower “pump gas” engine for your balls-out street machine. Just about every enthusiast publication has done that story. But the Sonny Leonard-built, 1000-horse, 89-octane burning, big (as in 762 cubic inches!) engine that MaxChevy is about to introduce you to is unique in many ways, not the least being the fact that it produces its prodigious power burning genuine 89-octane pump gas, not the $5.00 a gallon 100+ octane fuel you can only buy at the racetrack.


Sonny had the block custom cast for this specific application by the folks at Donovan. It has full water jackets for max-cooling and street applications. It does have a five-inch bore space and has the camshaft galley moved up a full inch to facilitate better valve train geometry. This is a sleeved block and has a finish bore size of 4.750

The rods can be either Carillo billet steel or forged aluminum depending on your application. The crankshaft is a billet piece from the legendary Sonny Bryant. The bore and stroke combination is 4.750x5.375.

Sonny’s ultimate street/strip, Chevrolet-style Rat motor delivers awesome numbers of more than 1000-horsepower and 1100-ft-lbs of torque at just 4800rpm! This is an engine designed with the Pro Street, Pro Touring, or Street Rod gearhead in mind. No sir, you don’t have to wind this big boy up to a parts-killing 8-grand in order to enjoy massive power and torque. I challenge you to find any another engine combination that develops the kind of power Sonny Leonard’s 762-inch Fat Rat does at under 5000 RPM, and on 89-octane gas station fuel, to boot.

Make no mistake about it, this is an exotic and expensive engine, not one for the faint of heart (or pocketbook). The engine that we were invited to witness being dyno-tested in Sonny Leonard’s Lynchburg, Virginia, shop was built using parts and technology made famous by Leonard, whose record-holding 815-cubic-inch Chevy engines can be found in many IHRA Pro Stockers, with smaller cubic-inch versions powering record holding Competition Eliminator cars.

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