Jay Leno’s Garage has featured six especially outsized or unconventional engine builds: a tank-powered Blastolene Special, a pair of Bentley projects, a Rolls-Royce Merlin-powered car, a Hispano-Suiza with an aero engine, and a Plymouth with a radial aircraft engine. Robin Nooy’s 2020 Monochrome Watches feature reports their specifications; the figures below are attributed to that article and have not been independently confirmed.
What makes these six cars stand out?
They are linked less by a single make or era than by engines adapted from military vehicles or aircraft, or by unusually large automotive powerplants. The builds range from a replica to modified historic chassis and custom cars, so “biggest” here refers to engine displacement and character—not a verified ranking of every vehicle in Leno’s collection.
Nooy estimated that Leno’s collection contained more than 350 cars and motorcycles in 2020. That is a dated estimate, not a current inventory count. The feature also says Leno had been building the Jay Leno’s Garage YouTube channel since 2006; its references to weekly Monday episodes and CNBC television episodes describe the period when the article was written, not today’s schedule or availability. (Monochrome Watches)
How the six engine builds compare
| Vehicle | Engine and reported output | Build character |
|---|---|---|
| Blastolene Special, or Leno Tank Car | 29-litre tank-derived V12; 1,100 hp reported after twin turbos were added | Randy Grubb-built car, modified after Leno bought it |
| 1924 Bentley Twin Turbo | Twin-turbo 8-litre Bentley engine; 400 hp reported | Bentley 3.0 Litre base rebuilt in Leno’s workshop |
| 1934 Rolls-Royce Merlin | 27-litre supercharged V12; about 1,000 hp reported | Handcrafted aluminium body; engine mounted backward |
| 1930 Bentley 27 Litre | 27-litre Rolls-Royce Meteor V12; output not stated by Nooy | Petersen Engineering replica build |
| 1915 Hispano-Suiza | 18.5-litre aero V8; about 300 hp reported | Hispano-Suiza chassis adapted for an aircraft engine |
| 1939 Plymouth Radial Air | 12.4-litre, seven-cylinder radial engine; output not stated by Nooy | Custom Plymouth with boat parts in the drivetrain |
All specifications and descriptions in this table are as reported in Nooy’s 2020 feature; the article does not establish independent verification for them. (Monochrome Watches)
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Tank-derived engines: the Blastolene Special and Bentley 27 Litre
Blastolene Special: the Leno Tank Car
Built by Randy Grubb, the Blastolene Special is described as having a semi-exposed 29-litre V12 taken from an M47 Patton tank. Nooy reports that Leno added two turbos after buying the car, bringing its reported output to 1,100 horsepower. The combination of an enormous tank engine and later turbocharging makes it the most powerful of the six by the figures in the feature.
1930 Bentley 27 Litre: a replica with a Meteor
The “1930 Bentley” is not presented as an original period Bentley: Nooy identifies it as a replica build by Petersen Engineering. Its 27-litre Rolls-Royce Meteor V12 is the key distinction from the Merlin in the 1934 car. The Meteor was used in tanks, while the Merlin was an aircraft engine. No output figure is given for this Bentley, so it cannot be ranked against the cars with reported horsepower.
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Aircraft engines adapted for the road
1934 Rolls-Royce Merlin
Nooy describes this car as a handcrafted aluminium-bodied build with a 27-litre supercharged V12 mounted backward. The article reports about 1,000 horsepower and says Leno and his team took 25 years to finish it. It attributes to Leno the description of its acceleration: “it’s like the hand of God, it just pushes you”. The reviewed article does not provide a primary transcript or recording context for that quotation, so it is best understood as an attribution made by Nooy.
1915 Hispano-Suiza
This build pairs a Hispano-Suiza chassis with an 18.5-litre V8 aero engine. According to Nooy, the engine was built under licence in the United States, and the car was restored and modified for automotive use. Its reported output is about 300 horsepower. It is a distinct kind of adaptation from the V12 installations: a licensed aircraft engine fitted to a historic car chassis.
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1939 Plymouth Radial Air
The Radial Air is described as a custom Plymouth powered by a 12.4-litre, seven-cylinder radial engine from a Cessna seaplane. Nooy also notes boat parts in its drivetrain, another sign that the project is a custom conversion rather than a stock Plymouth. The feature does not state a horsepower figure.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the numbers do—and do not—show
In Nooy’s reported figures, the Blastolene Special leads the cars with stated output at 1,100 horsepower, followed by the Merlin at about 1,000, the 1924 Bentley Twin Turbo at 400, and the Hispano-Suiza at about 300. Those are figures from one secondary enthusiast feature, not independently verified test results. Because the Meteor Bentley and Plymouth Radial Air have no output figures stated there, the list is not a complete horsepower ranking.
Displacement alone also does not explain how each car was engineered. The Blastolene Special’s V12 received twin turbos; the Merlin installation is described as supercharged and backward-mounted; the Plymouth uses a radial aircraft engine; and the Hispano-Suiza combines an aero V8 with a restored and modified chassis. The projects are united by their unusual origins, but they are not interchangeable engine swaps.
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