Editing Ford small block engine (section)

===289 HiPo (K-code)===
[[File:1968 Shelby GT350 engine.JPG|thumb|250px|Ford 289 K-code engine in a [[Shelby Mustang|Shelby GT 350]]: The horizontal orientation of the thermostat housing on the intake manifold is a telltale Windsor feature.]]

A high-performance version of the Challenger 289 engine<ref name="Gunnell 1987" /> was introduced late in the 1963 model year as a special order for Ford Fairlanes. The engine is informally known as the HiPo or the "K-code", after the engine letter used in the VIN code of cars so equipped. It was the only 289 engine available in the intermediate Fairlanes, with lesser-powered cars receiving the 260 V8. Starting in June 1964, it became an option for the Mustang.

The HiPo engine was engineered to increase performance and high-rpm reliability over the standard 289. It had solid valve lifters with more aggressive cam timing; 10.5:1 compression; a dual point centrifugal advance distributor; smaller combustion chamber heads with cast spring cups and screw-in studs; low-restriction exhaust manifolds; and a bigger, manual-choke 595 [[cubic foot per minute|CFM]] carburetor (105 CFM more than the standard 289-4V). The water pump had fewer vanes to minimize high rpm foaming and cavitation, the fuel pump received an extra spring to keep up with high rpm demand, alternator/generator pulleys were larger diameter to slow their relative speeds at high engine revs, and a special fan was fitted.

Bottom-end high-rpm improvements included a flaw-free selected standard block, thicker main bearing caps and crankshaft damper/balancer, larger-diameter rod bolts, a crankshaft made from 80% [[nodular iron]] as opposed to the regular item's 40% (with each one checked for correct 'nodularity' by polishing an area of the rear counterweight and comparing a magnification of that surface against a standard), and increased crankshaft counterweighting to compensate for the heavier connecting rod big ends. (The external counter weighting at the front was split between the crankshaft damper and a supplementary counterweight placed adjacent to the front main bearing journal, all designed to reduce the 'bending moment' in the crankshaft at high-rpm.)

The HiPo equipped with a single 4-barrel [[Autolite]] 4100 carburetor carried [[Horsepower#SAE gross power|SAE gross]] ratings of {{cvt|271|bhp|PS kW|0}} at 6,000&nbsp;rpm and {{cvt|312|lbft|Nm|0}} at 3,400&nbsp;rpm.<ref>{{cite web|url=http://www.thecarsource.com/fords/engines/289engine.shtml|website=thecarsource.com|title=289 engines|access-date=July 12, 2018}}</ref>

The K-code HiPo engine was an expensive option, and its popularity was greatly diminished after the [[Ford FE engine|390 and 428 big-block engines]] became available in the Mustang and Fairlane lines, which offered similar power, lower cost, and cheaper maintenance at the expense of greater weight and a more unbalanced front/rear weight distribution.

====GT-350====
The HiPo engine was used in modified form by [[Carroll Shelby]] for the 1965–1967 [[Shelby Mustang#1965–1966 Shelby GT350|Shelby GT350]], receiving special exhaust headers, an aluminum intake manifold, and a larger 4-barrel [[Holley Performance Products|Holley]] 715 CFM carburetor, which raised rated power to {{cvt|306|bhp|PS kW|0}} at 6,000&nbsp;rpm and {{cvt|329|lbft|Nm|0}} at 4,200&nbsp;rpm of [[Machine torque|torque]].<ref>{{cite web|url=https://www.ultimatecarpage.com/car/201/Ford-Shelby-Mustang-GT350.html|website=ultimatecarpage.com|title=1965 - 1966 Ford Shelby Mustang GT350|access-date=June 23, 2018}}</ref><ref>{{cite web|url=https://www.myclassicgarage.com/knowledge-base/1965-Ford-Mustang|website=myclassicgarage.com|title=1965 Ford Mustang|access-date=June 23, 2018}}</ref> Shelby also replaced the internal front press-in oil gallery plugs with threaded plugs to reduce chances of high rpm failure, and installed a larger oil pan with baffles to reduce oil starvation in hard cornering.

From 1966 to 1968, Shelby offered an optional [[Paxton Automotive|Paxton]] [[supercharger]] on Shelby GT350 289s, raising power to around {{cvt|390|hp|kW|0}}.{{cn|date=May 2024}}

====Production numbers====
About 25,000 K-code 289s were manufactured at Cleveland Engine Plant 1 (CEP1) between March 1963 and June 1967.