The Pontiac Trophy 4 engine (also called the ''Indianapolis 4'', or ''Indy 4'') is a inline four-cylinder engine produced by the Pontiac Motor Division of

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

for model years 1961 through 1963. Created from one bank of Pontiac's powerful '' Trophy V8'', its only application was in the first generation

Pontiac Tempest The Tempest is an automobile that was produced by Pontiac from 1960 to 1970, and again from 1987 to 1991. The Tempest was introduced as an entry-level compact in October 1960 at the Paris Auto Show for the 1961 model year. Built on GM's first ...

. It was dubbed by Pontiac the ''Trophy 4'', playing off the racing success that had earned the 389 V8 engine the nickname ''Trophy V-8'' after just two years of competition.

History

The Trophy 4 engine is a short-stroke, 45-degree inclined inline four created from the right bank of the 389 V8 for the debut of the Tempest in 1961. Its displacement is precisely half of the 389, with an identical bore and stroke of . It shared most of the 389's tooling and up to 120 of its parts. This degree of commonality enabled it to be produced on the same lines as the V8, allowing substantial cost savings. The Trophy 4 weighs about , as compared to the V8 it was based on. The brainchild of auto industry legend

John DeLorean John Zachary DeLorean ( ; January 6, 1925 – March 19, 2005) was an American engineer, inventor, and executive in the U.S. automobile industry. He is widely known as founder of the DeLorean Motor Company, as well as for his work at General Motor ...

, then the head of a design team responsible for the birth of the Tempest line, the Trophy 4 produces ( gross) at 3,800 rpm and at 2,000 rpm with a single-barrel

carburetor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Ventu ...

(as fitted with

manual transmission A manual transmission (MT), also known as manual gearbox, standard transmission (in Canadian English, Canada, British English, the United Kingdom and American English, the United States), or stick shift (in the United States), is a multi-speed ...

using regular gas, and with premium); with regular gas (and with premium), as fitted with

automatic transmission An automatic transmission (AT) or automatic gearbox is a multi-speed transmission (mechanics), transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. The 1904 ...

; and at 4,800 rpm and at 2,800 rpm with the optional four-barrel carburetor and automatic transmission. A "power pack" option for the 1962 four-barrel carburetor increased rated power to . The Tempest's

drivetrain A drivetrain (also frequently spelled as drive train or sometimes drive-train) or transmission system, is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering, the driv ...

features a rear-mounted

transaxle A transaxle is single mechanical device which combines the functions of an automobile's transmission (mechanics), transmission, axle, and differential (mechanics), differential into one integrated assembly. It can be produced in both manual tra ...

connected to the engine via a torque tube, giving the car a near-perfect 50-50 front-rear weight balance. As the

driveshaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power, torque, and rotation, usually used to connect ...

runs at engine speed, rather than the transmission output speed, it runs at a higher speed and lower torque than a conventional driveshaft for a

rear wheel drive Rear-wheel drive (RWD) is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars. Most rear-whee ...

car. This allows it to be an unusually small solid rotating shaft, inside the pressed steel square torque tube. Uniquely, the shaft is also bent downwards into a curve, which has the effect of making the

critical speed In solid mechanics, in the field of rotordynamics, the critical speed is the theoretical angular velocity that excites the natural frequency of a rotating object, such as a shaft, propeller, leadscrew, or gear. As the speed of rotation approaches ...

of such a flexible shaft higher than the engine's maximum rpm. The curve of this flexible, thin driveshaft earned it the nickname "rope drive". A downside of the Trophy 4 is engine vibration, as an inline four-cylinder engine suffers from inherent secondary imbalance resulting from its 180 degree crankshaft. The Trophy 4 is cushioned by flexible rubber engine mounts designed to isolate the engine from the rest of the car, and its forces are further damped by the Tempest's unusual drivetrain that distributes these forces through the torque tube to the rear-mounted transaxle. The timing chain in the Trophy 4 was originally the same as the 389, but was prone to stretch and break from engine vibration; a special high-strength version was developed as a replacement. The Trophy 4 was dropped from the Tempest line when it upgraded from a compact to an intermediate for the 1964 model year.

References

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Popular Science Popular science (also called pop-science or popsci) is an interpretation of science intended for a general audience. While science journalism focuses on recent scientific developments, popular science is more broad ranging. It may be written ...

, last=Fermoyle , first=Ken , url=https://books.google.com/books?id=3yUDAAAAMBAJ , publisher=Popular Science Publishing Co. , date=September 1960 , title=Pontiac Tempest: Radical New Compact , pages=53–58 , access-date= {{cite magazine , last=LaChance , first=Dave , date=August 2010 , title=1961–'63 Pontiac Trophy 4 , url=https://www.hemmings.com/stories/article/1961-63-pontiac-trophy-4 , magazine=Hemmings Motor News , location= , publisher= , access-date= {{cite web , url=https://www.autoweek.com/car-life/a1830896/cut-down-engine-week-pontiac-trophy-4/ , title=Cut-Down Engine of the Week: Pontiac Trophy 4 , last=Martin , first=Murilee , date=20 September 2017 , website= Autoweek , publisher= , access-date= {{cite magazine , author= , date=December 1960 , title=The New Sweet Running Trophy 4 Engine from Pontiac Performance Specialists! , url=https://books.google.com/books?id=0tsDAAAAMBAJ&dq=pontiac+%22trophy+4%22&pg=PA4 , magazine=Popular Science , page=4 , location= , publisher= , access-date= {{cite web , url=https://www.vintageautoappraisal.com/single-post/2015/11/28/whats-it-worth-1962-pontiac-tempest-trophy-4-convertible-johnny-d-decides-to-put-the-tran , title=What's It Worth? 1962 Pontiac Tempest "Trophy 4" Convertible ..A Johnny D Gem , last=Baumann , first=Johnny , date=3 June 2021 , website=Vintage Auto Appraisal , publisher= , access-date= {{cite web , url=https://classiccarcatalogue.com/PONTIAC_1962.html , title=Pontiac 1962 , author= , date= , website=Classic Car Catalogue , publisher= , access-date= Products introduced in 1961 Pontiac engines Slant-four engines Straight-four engines John DeLorean

History

See also

References