Trunk

Trunk (pronounced truhngk)

(1) The main stem of a tree, as distinct from the branches (limbs) and roots (also as bole; tree trunk).

(2) Of, relating to or noting a main channel or line, as of a railroad, waterway or something which assumes a similar shape (topographically).

(3) A large, sturdy box or chest for holding or transporting clothes, personal effects or other articles.  Such trunks usually have a hinged (sometimes domed) lid and handles at each end, provided because such is the size & weight, it takes at least two to carry one when loaded.

(4) A compartment, most often in the rear coachwork of an automobile, in which luggage, a spare tire, and other articles may be kept (a “boot” in the UK and certain other places in the English-speaking world and a “dicky” in India and elsewhere in South Asia).

(5) A storage compartment fitted behind the seat of a motorcycle and known also as a top-ox or top-case (as distinct from a “pannier” or “saddlebag” which is fitted at the side (usually in pairs), below the level of the seat).

(6) In anatomy, the body of a person or an animal excluding the head and limbs (the torso).

(7) In pathology, the main body of an artery, nerve, or the like, as distinct from its branches.

(8) In ichthyology, that part of a fish between the head and anus.

(9) In engineering and architecture, a name for a conduit, shaft, duct, channel or chute etc, used variously for airflow (thermal or blown), water, coal, grain etc.

(10) In steam engines, a large pipe forming the piston rod of a steam engine, of sufficient diameter to allow one end of the connecting rod to be attached to the crank, and the other end to pass within the pipe directly to the piston, thus making the engine more compact.

(11) In extractive mining, a flume or sluice in which ores are separated from the slimes in which they are contained.

(12) In architecture, the dado or die of a pedestal.

(13) In architecture, the part of a pilaster between the base and capital, corresponding to the shaft of a column.

(14) In hydrology, the main channel, artery or line in a river, railroad, highway, canal or other tributary system.

(15) In telephony, a telephone line or channel between two central offices or switching devices that is used in providing telephone connections between subscribers generally (also called a “tie-line”).

(16) In telegraphy, a telegraph line or channel between two main or central offices.

(17) In telecommunications, to provide simultaneous network access to multiple clients by sharing a set of circuits, carriers, channels or frequencies.

(18) In clothing, brief shorts (loose-fitting or tight) worn by men chiefly for boxing, swimming and athletics (some historically known as “trunk hose”.

(19) In zoology, the elongated prehensile, flexible, cylindrical nasal appendage of the elephant and certain other creatures (the proboscis).

(20) In nautical use, a large enclosed passage through the decks or bulkheads of a vessel, used as air ducting for purposes of heating, cooling, ventilation and such.

(21) In shipbuilding, any of various watertight casings in a vessel, as the vertical one above the slot for a centerboard in the bottom of a boat.

(22) A long tube through which pellets of clay, peas etc are driven by the force of the breath; a peashooter (archaic).

(23) In software engineering, the most current source tree, from which the latest unstable builds (so-called “trunk builds”) are compiled.

1400–1450: From the late Middle English tronke & trunke, from the Old French tronc (alms box, tree trunk, headless body), from the Latin truncus (stem, a stock, lopped tree trunk), a noun use of the adjective truncus (lopped; cut off, maimed, mutilated), (the later related to the English truncated).  Trunk & trunking are nouns & verbs, trunkful is a noun, trunked is a verb & adjective and trunkless is an adjective; the noun plural is trunks.

There are a myriad of “truck” terms in human pathology and other derived phrases include “elephant's trunk” (rhyming slang for “drunk”), “hand trunk” (a piece of luggage smaller than the traditional trunk and able to be carried by one), “junk in one's trunk” (corpulence of the buttocks, the alternative forms being “dump truck” or the vernacular “fat ass”), “the apple does not fall far from the trunk” (a variant of “the apple/pear etc does not fall far from the tree”) (children tend in appearance & characteristics to resemble their parents), “trunklid” (literally obviously “the lid of a trunk” and used of the opening panel which provides access to a car’s trunk), “bootlid” the UK equivalent and confusingly in the US used also as “decklid” on the basis of the trunk being a part of a car’s “rear deck”), “trunk novel” (a novel abandoned by the author while still a project), “trunk or treat” (an organized alternative to trick-or-treating where candy is handed out to children from cars in a parking lot; it was introduced as a child safety measure), “trunk show” (an event in which vendors present merchandise directly to store personnel or customers at a retail location or other venue, based on the idea of selling “out of a trunk”), “trunk sale” (and event at which goods are displayed for sale in the trunks of cars), “boot sale” the companion term)), “trunking” (travelling sitting in the trunk of a car”), and “trunk shot” (in film-making, a cinematic shot from within a car trunk (although there was a case of a serial killer who shot his victims while concealed in the trunk of a car.

Louis Vuitton Trunk #5 (left) and Louis Vuitton Trunk on Fire (right) by Tyler Shields (b 1982).

The original idea of a trunk being a “box; case etc” may lie in the first such “trunks” being hollowed-out tree trunks although some suggest the post-classical development of the meaning “box, case with a lid or top” was based on the notion of human body’s trunk being a “case” in which the organs were transported.  The modern idea of a “luggage compartment of a motor vehicle” dates from circa 1930, about the time trunks cease to be something separately carried and replaced by and space for luggage integrated into the bodywork.  The use of trunk had long been familiar in the medical literature (both of the torso and blood vessels etc) and the idea was by 1843 extended to railroad trunk lines and telephone networks by 1889.  “Trunk-hose” were first sold in the 1630s and seems to have been a kind of thermal underwear, the description a reference to them covering the whole torso (ie, the trunk) as opposed to most “hose” which was for the lower limbs.

The use of trunk to describe the “long snout of an elephant (or other beast with a similar appendage)” appeared first in the 1560s but etymologists are divided on whether it was an allusion to a tree’s trunk or has some connection with “trumpet”, based on the loud sound elephants are able to generate although the evidence does suggest the early use as a reference to the thing’s ability to hold water.  Predictably, by the early eighteenth century, it was a slang term for the human nose.  The use in clothing (always in the plural as “trunks”) emerged in the mid 1820s and initially described “short breeches of thin material”; it was a use of trunk in the sense of “torso”.  Use began in theatrical jargon but, as was not uncommon, soon it was applied to breeches generally, especially in US English and for the short, tight-fitting breeches worn by swimmers and other sporting types, adoption was close to universal by the 1890s.  “Swimming trunks” has survived as a regionalism; even within the one country, there are often several different names for what is one of humanity’s most simple garments.

Trump Trunks: MAGA (Make America Great Again) swimming trunks.  Trump trunks are made from a “silky, breathable, 4-way stretch mesh fabric” and features include (1) a small internal pocket, (2) a built-in anti-chafe liner.  The country of manufacture is not disclosed.  Clearly, the DNC (Democratic National Committee) in 2016 missed an opportunity by failing to release the "Crooked Hillary Clinton Bikini".

One linguistic curiosity was “subscriber trunk dialing” (later changed to “subscriber toll dialing” which later still switched to DDD (Direct Distance Dialing).  The “other” use of STD was as “sexually transmitted disease”, previously known as VD (venereal disease) and it wasn’t until the 1970s the initialism VD began to be replaced by STD (VD thought to have to have gained too many specific associations) but fortunately for AT&T, in 1951 they renamed their STD service (for long-distance phone calls) to DDD, apparently for no better reason than the alliterative appeal although it's possible they just wanted to avoid mentioning “toll” with all that implies.  Many countries in the English-speaking world continued to use STD for the phone calls, even after the public health specialists had re-purposed the initialization.  In clinical use, STI “Sexually Transmitted Infection” seems now the preferred term).

The evolution of the trunk: 1851 Concord stagecoach on display at the Smithsonian's National Postal Museum, Washington DC (left) with truck strapped to the back, additional trunks carried on the roof; 1928 Mercedes-Benz Nürburg 460 K Pullman Limousine (W08, centre left) with separate trunk still carried on a rear frame; 1936 Studebaker Dictator 4-door sedan (centre right) with the trunk now an integrated part of the bodywork; The US full-sized cars of the era had most capacious trunks but few could match Leyland Australia's infamous P76 (1973-1975, right) which effortlessly could carry a 44 (imperial) gallon (209 litre) drum.

The compartment which is most located in the rear coachwork of an automobile is used for luggage and historically also the spare tyre a toolkit (neither now not always supplied).  In North American use, this is called a “trunk”, an inheritance from the time when the passengers’ trunks (ie, in the sense of the box-like suitcases) were strapped on to an extension at the back of horse-drawn carriages.  In the early automobiles, the practice continued (often with lined wicker baskets because they were of lightweight construction) and when these were integrated into the bodywork, the space provided continued to be called “the trunk”.  The British called the same thing a “boot”.  In horse-drawn carriages in the UK, a “boot” was a compartment used to store travel essentials, among which (in an age of rutted, poorly maintained roads) included boots, the male passengers sometimes required to push the coach when it became stuck in mud, the frequent inclusion of a “boot box” or “boot locker”, made typically of leather and attached at the rear.  The other suggested origin is the French boute (compartment; box).  The term “boot” thus spread throughout the British Empire although, under the Raj, in India & Ceylon (later Sri Lanka) it became the “dickie”.  That was based on the dicky seat (also as “dickie seat” & “dickey seat” and later more commonly known as the “rumble seat”), an upholstered bench mounted at the rear of a coach, carriage or early motorcar and as the car industry evolved and coachwork became more elaborate, increasingly they folded into the body.  The size varied but generally they were designed to accommodate one or two adults although the photographic evidence suggests they could be used also to seat half-a-dozen or more children.  Why it was called a dicky seat is unknown (the word dates from 1801 and most speculation is in some way related to the English class system) but when fitted on horse-drawn carriages it was always understood to mean “a boot (box or receptacle covered with leather at either end of a coach, the use based on the footwear) with a seat above it for servants”.  Under the Raj, “dickie” was preferred while the colloquial “mother-in-law seat” was at least trans-Atlantic and probably global.

Lindsay Lohan illustrates how there are trunks and there are frunks:  The rear-engined Porsche 911 Carrera (997, 2004-2013) cabriolet (Los Angeles, 2012, right) has a frunk while the front-engined Mercedes-Benz SL 550 (R230, 2001-2011) (Los Angeles, 2009, left) has a trunk.  The R230 range was unusual because of the quirk of the SL 550 (2006-2011), a designation used exclusively in the North American market, the RoW (rest of the world) cars retaining the SL 500 badge even though both used the 5.5 litre (333 cubic inch) V8 (M273).

The Fiat X1/9 (produced by Fiat 1972–1982 and Bertone from 1982–1989, centre) featured both a frunk (left) and a trunk (right.

Most cars built have had the engine mounted in the front, thus most trunks appeared in the rear bodywork.  There have however been cars with engines behind the driver (such things were quite numerous until well into the 1970s) and these usually had a storage compartment at the front (where the engine otherwise would sit, under the hood (bonnet)).  Until the early years of the twentieth century, these seem just to have been called a “trunk” or “boot” but as electric vehicles began to appear in volume “frunk” (the construct being f(ront) + (t)runk) and the less popular “froot” (the construct being fr(ont) + (b)oot)) came into use.  There have been mid-engined cars which have both a trunk and a frunk and those in the diminutive Fiat X1/9 were surprisingly large while others (such as Ferrari's Dino 308 GT4 (1973-1980) & 208 GT4 (1975-1980), both badged as Ferraris after 1976) were of a less generous capacity, the frunk in the Dinos most suited to storing something the size of a topless bikini but it was a genuine four-seater (2+2), something not often attempted with the mid-engined configuration.

Slant

Slant (pronounced slant or slahnt)

(1) A surface, structure, line etc at a slope or in an oblique direction.

(2) In (US) football, an offensive play in which the ball-carrier runs toward the line of scrimmage at an angle (known also as the “slant-in”, a pass pattern in which a receiver cuts diagonally across the middle of the field).

(3) In prosody, as “slant rhyme”, a synonym for the “half rhyme”, “near rhyme” & “quasi-rhyme” (a form of imperfect rhyme in which the final (coda) consonants of stressed syllables (and, in modern English poetry, any following syllables to the end of the words) are identical in sound, but the vowels of the stressed syllables are not.

(4) In typography, a synonym of slash ( / ⟩, particularly in its use to set off pronunciations from other text (not used in IT where the distinctions are between the forward-slash (/) and the back-slash (\) which nerds call respectively the slash and the slosh.

(5) In biology, a sloping surface in a culture medium.

(6) In hydro-carbon extraction, as “slant drilling”, a technique in which the drilling is undertaken at an oblique angle rather than the traditional vertical orientation.

(7) In extractive mining, as type of run in which a heading is driven diagonally between the dip and strike of a coal seam.

(8) In informal use, a glance or look.

(9) To veer or angle away from a given level or line, especially from a horizontal; slope (in to incline, to lean).

(10) Figuratively, to have or be influenced by a subjective point of view, bias, personal feeling or inclination etc (often as “slant towards”, “slanted view” etc); a mental leaning, bias, or distortion (“feminist slant”, “MAGA slant”, “liberal slant”, “business slant” et al).

(11) To cause to slope.

(12) Figuratively, to distort information by rendering it unfaithfully or incompletely, especially in order to reflect a particular viewpoint (more generously sometimes described as “spin” or “massaged”).  The concept is known also as “angle journalism” (the particular mood or vein in which something is written, edited, or published).  In Scots English, the meaning “to lie or exaggerate” captures the flavor.  When used to describe the composing, editing, or publishing of something to attract the interest of a specific sub-group (a “slanted” story), “slanted towards” is necessarily pejorative if used only to suggest something optimized to appeal to a certain market segment or demographic (ie it’s more like “aimed at” or “intended for”).

(13) In slang, as “slant eye” (a racial slur now listed as disparaging & offensive), a reference to people from the Far East (applied historically mostly to the Chinese & Japanese), based on the shape of the eyes.  The variants included “slit eye”, “slitty-eyed” & “slopehead”, all equally offensive and now proscribed.

(14) In painting (art) a pan with a sloped bottom used for holding paintbrushes; a depression on a palette with a sloping bottom for holding and mixing watercolors; a palette or similar container with slants or sloping depressions.

(15) In US regional slang, a sarcastic remark; shade, an indirect mocking insult (archaic).

(16) In US slang, an opportunity, particularly to go somewhere (now rare).

(17) In historic Australian colonial slang, a crime committed for the purpose of being apprehended and transported to a major settlement.

Circa 1480s: From the Middle English –slonte or -slonte, both aphetic (in phonetics, linguistics & prosody, “of, relating to, or formed by aphesis” (the loss of the initial unstressed vowel of a word)) variants of aslant, thought to be of Scandinavian origin.  The other influence was probably the earlier dialectical slent, from the Old Norse or another North Germanic source and cognate with the Old Norse slent, the Swedish slinta (to slip) and the Norwegian slenta (to fall on the side), from the Proto-Germanic slintaną (which, in turn, was probably in some way linked with aslant.  Slant & slanting are nouns, verbs & adjectives, slanted is a verb & adjective, slantish is an adjective, slantwise is an adjective & adverb and slantingly & slantly are adverbs; the noun plural is slants.  The pleasing adjective slantendicular is listed by some as non-standard and presumably is proscribed in geometry and mathematics because it's an oxymoron; it’s a portmanteau word, the construct being slant + (perp)endicular.  It may be useful however in commerce or engineering where it might be used to describe something like a tool with a shaft which at some point assumes an oblique or skewed angle.   So it’s there to be used and slantindicular should be applied to stuff which is neither wholly nor fully slanted and in architecture, such structures are numerous.  In commerce, it could be used as a noun.

The noun slant by the 1650s was used to mean “an oblique direction or plane” and began in geography & civil engineering (of landforms, notably ski-slopes), developed from the verb or its adjective.  The now familiar (in the Fox News sense) meaning “way of regarding something, a mental bias” dates from 1905 while the derogatory slang sense of “a person of Asian appearance” came into use some time in the 1940s, a direct descendent from the earlier "slant-eyes", documented since 1929.  The verb slant is documented since the 1520s in the sense of “obliquely to strike (against something)”, an alteration the late thirteenth century slenten (slip sideways), the origin of which is murky but etymologists have concluded it came (via a Scandinavian source (noting the Swedish slinta (to slip)) and the Norwegian slenta (to fall on one side), from the Proto-Germanic slintanan.  The intransitive sense of “to slope, to lie obliquely” was in use by the 1690s, while the transitive sense of “to give a sloping direction to” had emerged by the early nineteenth century.  As early as the late fifteenth century forms were in use as an adverb, the adjectival use attested from the 1610s.  The technical use in literary theory as “poetic slant rhyme” was first used in the mid 1920s (assonance or consonance) although such lines had appeared for centuries, used sometimes deliberately as a device, sometimes not.  In the following stanza by English poet Peter Redgrove (The Archaeologist, published in Dr Faust's Sea-Spiral Spirit (1972)), the second and third lines contain a form of slant rhyme while the first and fourth have pure rhymes:

So I take one of those thin plates
And fit it to a knuckled other,
Carefully, for it trembles on the edge of powder,
Restore the jaw and find the fangs their mates.

You are watching Fox.

While it’s unlikely volumes of the poetry of Emily Dickinson (1830–1886) sit upon the bookshelves of those members of the Fox News audience who have bookshelves, they likely would concur with her words: “Tell the truth but tell it slant.”  “Slanted reporting” has become something which in recent years has attracted much attention (and much hand-wringing by the usual suspects) as an increasingly polarization of positions has been alleged to be a feature of political discourse in the West.  There is little doubt the effect (as reported) is obvious but there’s some debate about both the mechanics and the implications of the phenomenon.  As long ago as 2018, a study found that although the tenor and volume of things on X (formerly known as Twitter) was found to be increasingly toxic and surging, the number of active users engaged in these political polemics was found to be tiny and their effect was distorted by (1) the huge number of tweets they tended to post, (2) the propensity of their fellow-travelers to re-tweet and (3) the use of bots which were more prolific still.  If anything, recent voting patterns suggest it would seem the views of the general population appear to be trending away from the extremes towards the more centralist positions offered by independents or small-parties, something most obvious in Australia where compulsory voting exists.  Outfits like Fox News offer a slanted take on just about everything (and promote country & western music which truly is inexcusable) but this is something which has been identifiable in the news media as long as it’s existed and their blatant bias is hardly subversive or threatening, simply because it is so blatant.  What was most interesting in what emerged from the recent defamation suit filed by Dominion Voting Systems against Fox News suggested the network’s stance on things was motivated more by the financial imperative than ideological purity.  Intriguingly, what some analysts concluded was that if the universe shifted and the Fox News audience transformed into a bunch of seed-eating hippies, there would follow Fox’s editorial position, the slant being towards the advertising revenue rather than a particular world view.  Of course, there are some slants which are unalterable and dictated by ideological purity but with commercial media, it’s likely sometimes cause is confused with effect.

The Leaning Tower of Pisa (left) and Lindsay Lohan in The Parent Trap (1998) in front of London’s perpendicular Big Ben (1859) (right).  The architect’s original name for the latter was a typically succinct “Clock Tower”, chosen because it housed the “Great Bell of the Great Clock of Westminster” but it was in 2012 renamed “Elizabeth Tower”, marking the Diamond Jubilee of Elizabeth II (1926-2022; Queen of the UK and other places, 1952-2022), something little noted by Londoners or those beyond who continue to prefer the nickname “Big Ben” although strictly speaking that’s a reference only to the “Great Bell” a 13.5 ton (13.7 tonne) casting in bell metal (a bronze which is an alloy of about 77% copper & 23% tin).  The origin of the nickname is contested but there are no romantic tales, all the possible inspirations being worthy white men as was the Victorian way.

Although in Italy alone there are seven leaning towers (three of which stand (ie lean) in Venice), it’s the torre di Pisa (Tower of Pisa) which is by far the best-known and a frequent Instagram prop.  Built between 1173-1372, the structure in the Piazza del Duomo (Pisa’s Cathedral Square) is the campanile (the freestanding bell tower) of the adjacent Pisa Cathedral and the famous lean of some 4^o (actually somewhat less than its greatest extent after more than a century of compensating engineering works) was apparent even during construction, the cause the softness of the sub-surface.  That geological feature has however contributed to the tower’s survival, the “rubber-like” sponginess below acting to absorb movement and despite a number of severe earthquakes in the region over the centuries, the tower remains.  It is of course known as the leaning tower than a sloping, oblique or slanted tower, probably because of the conventions of use which evolved in English.

The words “sloping”, “oblique”, “slanted”, & “leaning” all describe something not vertical or horizontal there tend to be nuances which dictate the choice of which to use.  Sloping generally is used of something which inclines or declines at a gentle or continuous angle, the implication being of a gradual or smooth transition from elevation to another, such as the way a hillside rises gradually rises to its summit.  Oblique is mostly a matter of specific angles and is thus common is mathematics, geometry and engineering.  Again, it’s a reference to something neither parallel nor perpendicular to a baseline but it tends to be restricted to something which can be defined with an exact measurement; in geometric or technical use, an oblique line or angle is one neither 90^o nor perfectly horizontal.  Slanted describes something positioned at a diagonal, often used to imply a more noticeable or sharp angle but also is widely used figuratively, metaphorically and in idiomatic phrases.  Leaning refers to something tilted or positioned at an angle due to external pressure, the object in an unstable position and in need of support.  The implication carried is that something which “slants” is designed thus to do while something which “leans” does so because of some design flaw or unexpected external force being applied so it’s the leaning and not the sloping tower of Pisa, even though the structure has assumed quite a slope.

Slanting Engines

On a slant: Diagram of the mounting of the M194 straight-six engine in the Le Mans winning Mercedes-Benz 300 SL (W194) canted at a 40^o slant (left); the Mercedes-Benz M196 straight-eight engine schematic (centre) and installed in a 1954 W196R "Streamliner" at a 53^o slant (right).  The two large donut-like objects at the front are the inboard, finned brake drums; at the time, the engineers maintained disk brakes were "not yet ready for use". 

There are “slant” engines and they exist in three configurations.  The first is simply a conventional in-line engine (straight-six, straight-eight etc) which, when installed in a vehicle, is fitted with the block canted to the left or right, the objective being a lower hood line which means a better aerodynamic outcome.  A classic example was the Mercedes-Benz W196R Formula One racing car (1954-1955) in which the straight-eight was canted to the right at a 53^o angle, the technique carried over when the same structure was used to produce the W196S (1955) used to contest the World Sports Car Championship.  Rather opportunistically, the W196S was dubbed the 300 SLR (one of which in 2022 became the world's most expensive used car, selling at a private auction for US$142 million) as a form of cross promotion with the 300 SL (W198, 1954-1956) Gullwing then in production, even though the two types shared little more than nuts, bolts and a resemblance.  The 300 SL did however also have its straight-six engine sitting at a slant, this time canted at a 50^o angle and although the factory never published an estimate of the reduction in drag, it’s long been presumed to be “at least several percent”.  Another advantage of the configuration was it made possible the use of “long-tube” runners for the induction system, taking advantage of the properties of fluid dynamics to permit them to be tuned either for mid-range torque or top-end power.  The concept used math which had been worked out in the nineteenth century and had often been used in competition but it wasn’t until 1959 when Chrysler in the US released their picturesque induction castings that the system, imaginatively named the “Sonoramic”, reached a wider audience.

Chrysler Slant Six (170 cid, 1963) schematic.

The “true” slant engines were those with a slanted block atop an otherwise conventional arrangement of components, the best known of which was Chrysler’s long-serving “Slant Six”, produced in displacements of 170 cubic inch (2.8 litre, 1959-1969), 198 cubic inch (3.2 litre, 1970-1974) and 225 cubic inch (3.7 litre, 1960-2000).  The block of the Slant Six was canted to the right at a 30^o and like Mercedes-Benz, Chrysler took advantage of the space created to the left to produce some wide induction runners, the most extravagant those used by the special Hyper Pack option package which used a four barrel carburetor, enabling the engine to produce power which made it competitive with many V8 powered machines.  Although the name “Slant Six” became famous, it was only in the mid-sixties it caught on, Plymouth originally calling the thing a 30-D (a reference to the a 30^o slant), hardly very catchy and something to which only engineers would relate and Slant Six was soon preferred although the aficionados really like “tower of power” and the engine even today still has a devoted following.

Chrysler Slant Six with Hyper Pak in 1962 Plymouth Valiant V-200.

Chrysler didn’t restrict the Sonoramics to the big-block V8s, using it also on the short-lived (1960-1962) Hyper Pak performance option for the both 170 cubic inch (2.8 litre, 1959-1969) and 225 cubic inch (3.7 litre, 1987-2000) versions of the Slant Six, the engineers taking advantage of the space afforded by the canted block to permit the curvaceous intake runners nearly to fill the engine bay.  The Hyper Pak wasn't seen in showrooms but was available as an over-the-counter kit (literally a cardboard box containing all necessary parts) from Dodge & Plymouth spare parts departments and its life was limited because it became a victim of its own success.  Although less suitable for street use because it turned the mild-mannered straight-six into something at its best at full throttle, in the race events for which it was eligible it proved unbeatable, dominating the competition for two years, compelling the sanctioning body cancel the series.

Manifold porn: The Slant Six's angle meant there was much space available to the left and a range of intake manifolds followed, some of which remain available to this day.  Using variations of the sonoramic tuning, manifolds were produced for single, two & four barrel carburetors and between 1965-1968, Chrysler's Argentine operation produced the Slant Six in a version with twin single barrel carburetors.  The use of the properties of fluid dynamics to gain power or torque as desired quickly was adopted by the industry as an engineering orthodoxy.

Some myths seem to have become attached to the Hyper-Pak.  What seems to be true is the original kit, sold in 1960 for the 170 engines used in competition, was a genuine homologation exercise and as well as the intake manifold & Carter AFB four barrel carburetor, it included all the internal parts such as the high-compression pistons, the high-lift camshaft and the valve train components needed to support the consequently higher engine speeds.  Because the competition rules allowed modifications to the exhaust system, on the track the cars ran tubular steel headers which fed an open exhaust, terminating in the racers' preferred “dump pipe”.  After the requisite number of “complete” kits were sold, thus fulfilling the homologation demands, the kits were reconfigured and included only the “bolt-on” parts such as the induction system and a camshaft which, while more aggressive than the standard unit, wasn’t as radical as the one used on the track but could be used in conjunction with the standard valve train and Chrysler’s TorqueFlite automatic, thus expanding the Hyper-Pak’s appeal.

At the same time, the availability was extended to the larger 225 which between 1961-1963 was also available with an aluminum block, thus becoming one of the small number of engines configured with the combination of an aluminum block with a cast-iron head.  US manufacturers were at the time aware the trend was for cars to continue getting bigger so they were interested in ways to reduce weight.  However, despite saving some 70 lbs (32 KG), Chrysler’s aluminum block was, like General Motors’ (GM) 215 cubic inch (3.5 litre) V8, short-lived (though the V8 after being sold to Rover enjoyed a long, lucrative and prolific second life, not finally laid to rest until 2006) for not only were teething troubles encountered with the still novel method of construction, the accountants made clear using cast iron was always going to be cheaper so the industry just accepted weight gain and whenever required, increased displacement to compensate, an approach which persisted until the first oil shock of the early 1970s.

1970 Dodge Challenger (1970-1974) with 225 Slant Six.

Until 1973, both the Challenger & the corporation's companion pony car (the Plymouth Barracuda (1964-1974)) was available with the Slant Six (198 & 225) although the fitment rate was under 10%, unlike the early pony cars (Ford Mustang, Chevrolet Camaro and the early Barracudas) where the six-cylinder versions would at times be close to 40% of production.  Many of the surviving Slant Six Challengers & Barracudas have been "re-purposed" as clones of the more desirable versions with big-block V8s.

Although it was the longer lived 225 version which gained the Slant Six its stellar reputation for durability and the ease with which additional power could be extracted, there's always been a following for the short-stroke 170 because of its European-like willingness to rev, the characteristics of the over-square engine (unique among the slant-six's three displacements (170-198-225)) unusually lively for a US straight-six.  Despite some aspects of the specification being modest (there were only four main bearings although they were the beefy units used in the 426 cubic inch Street Hemi V8), for much of its life it used a tough forged steel crankshaft and high-speed tolerant solid valve lifters; it proved a was a famously robust engine and one remarkably tolerant of neglect.  Despite that, after the Hyper Pak affair, Chrysler in the US showed little interest in any performance potential, knowing the US preference for V8s, something which doomed also Pontiac's short-lived single overhead camshaft (SOHC) straight-six (1966-1969).  A version of the 225 with a two-barrel carburetor (rated at 160 horsepower, an increase of 15 over the standard unit) was offered in some non-North American markets where V8 sales were not dominant and it proved very popular in South Africa, Australia, New Zealand and Central & South America but only when tighter US emission regulations forced its adoption did a 225 with a two barrel carburetor appear in the home market though there it was installed to restore the power losses suffered after the emission control plumbing was added rather than seek gains.

Pontiac Trophy 4 cutaway.

Making a straight-eight or V8 by combining two in-line fours has been done a few times and many have been successful (although Triumph managed to create a truly horrid one for the otherwise lovely Stag).  Less common is making a four from an eight but that’s what Pontiac did when they conjured their 194.5 cubic inch (3.2 litre) four by using one bank of their 389 cubic inch (6.4 litre) Trophy V8 and it was (just about) literally cut in half, meaning the cylinders were canted to the right by 45^o (the V8 obviously in a conventional 90^o configuration.  To emphasize the family connection with the highly regarded Pontiac Trophy V8, the smaller offspring was called the Trophy 4 (although it was at time also dubbed the Indy 4 or Indianapolis 4 which even at the time sounded ambitious).  It did work and the economic advantages for the manufacturer (use of common components and the same assembly line) were compelling but the limitations inherent in a four-cylinder of such a large displacement were apparent in the rough-running and wear on critical parts and it was available only between 1961-1963, only in the compact Tempest.

Diagram showing balance shaft locations.

Large displacement four cylinder engines have been built.  Fiat in 1910 built two of their S76s to contest the world LSR (land speed record) and they were an hefty 28.4 litres (1730 cubic inch), the “Beast of Turin” using its then impressive 290 horsepower (216 kW) to attain a one-way speed of 132.27 mph (213 km/h) but, because it was not possible for the team to make the “return run” (ie in the opposite direction) within the stipulated one hour, the LSR remained with the Blitzen Benz which in 1909 had set a mark of 125.94 mph (202.65 km/h).  On land, never again would anyone build a four with the capacity to match the Beasts of Turin but units with displacements approaching 5.0 litres (305 cubic inch) were not uncommon during the inter-war years.  However, the technology of the internal combustion engine (ICE) greatly advanced during World War II (1939-1945) and one consequence of that was engine speeds rose and less displacement was required for a specific output, both factors which conspired to make the big fours unfashionable.  They did however make a comeback in the 1970s when the clever trick of “balance shafts” enabled the inherently chronic second order harmonic vibrations to be “dampened out” and Porsche between 1991-1995 produced a 3.0 litre (183 cubic inch) range which used the technique.  The balance shaft was invented early in the twentieth century by English engineer Frederick Lanchester (1868–1946) but it was Mitsubishi which in the 1970s patented their “Silent Shaft” system and although Porsche developed their own version, they worked out the Japanese design was superior so used that instead, paying Mitsubishi a small royalty (under US$10) for each one installed.  A balance shaft uses two counterweights (looking something like small hockey pucks with the shaft running through them), set some 1½ inches (40 mm) apart and turns at twice the engine-speed.  With one shaft mounted high on one side of the engine and the other low on the opposite side, the pair counter-rotates, balancing the large reciprocating mass.  

Kammback

Kammback (pronounced cam-bak)

A motif in automotive styling (originally dictated by wind tunnel findings during research into aerodynamic properties) in which rear of the car slopes downwards before being abruptly cut off to terminate in a vertical or near-vertical surface.  The things are known also as the Kamm tail (K-tail).

1950s (the actual design first appearing in 1938): The construct was Kamm + back.  The surname Kamm (related to Kamp) was of Germanic or Jewish (Ashkenazic) origin and translates literally from the German as “comb”.  The German comb was from the Middle High German kamb, kambe, kam & kamme and the Yiddish kam (comb).  Genealogists conclude Kamm was probably an metonymic occupational surname for someone who either made or sold combs, a common tool used for grooming or for textile work such as carding or combing wool.  There’s also the possibility the name of some Kamm clans could have been of topographic origin because in German, Kamm can also mean “ridge” or “crest” of a hill, mountain or some other elevation; it could thus have referred to someone who lived near such a geographical feature.  Less likely is that some arose from nicknames based on physical features or personal characteristics with Kamm used to describe someone with hair resembling a comb or someone with a sharp or distinctive personality.  The surname emerged in the Middle Ages, a time when hereditary family names were becoming more common in German-speaking regions and in addition to the presence in Germany, exists at various scale in areas with a historic patter of German migration (notably the north-eastern US and South Australia.

Back was from the Middle English bak, from the Old English bæc, from the Proto-West Germanic bak, from the Proto-Germanic bakam & baką which may be related to the primitive Indo-European beg- (to bend).  In other European languages there was also the Middle Low German bak (back), from the Old Saxon bak, the West Frisian bekling (chair back), the Old High German bah and the Swedish and Norwegian bak; there are no documented connections outside the Germanic and in other modern Germanic languages the cognates mostly have been ousted in this sense by words akin to Modern English ridge such as Danish ryg and the German Rücken.  At one time, many Indo-European languages may have distinguished the horizontal back of an animal or geographic formation such as a mountain range from the upright back of a human while in some cases a modern word for "back" may come from a word related to “spine” such as the Italian schiena or Russian spina or “shoulder”, the examples including the Spanish espalda & Polish plecy.

Tail was from the Middle English tail, tayl & teil (hindmost part of an animal), from the Old English tægl & tægel (tail), from the Proto-Germanic taglaz & taglą (hair, fibre; hair of a tail) (source also of the Old High German zagal, the German Zagel (tail), the dialectal German Zagel (penis), the Old Norse tagl (horse's tail) and the Gothic tagl (hair), from the primitive Indo-European doklos, from a suffixed form of the roots dok & dek- (something long and thin (referring to such things as fringe, lock of hair, horsetail & to tear, fray, shred)), source also of the Old Irish dual (lock of hair) and the Sanskrit dasah (fringe, wick).  It was cognate with the Scots tail (tail), the Dutch teil (tail, haulm, blade), the Low German Tagel (twisted scourge, whip of thongs and ropes; end of a rope), the dialectal Danish tavl (hair of the tail), the Swedish tagel (hair of the tail, horsehair), the Norwegian tagl (tail), the Icelandic tagl (tail, horsetail, ponytail), and the Gothic tagl (hair). In some senses, development appears to have been by a generalization of the usual opposition between head and tail.  The Oxford English Dictionary (OED) suggest the primary sense, at least among the Germanic tongues, seems to have been "hairy tail," or just "tuft of hair," but already in Old English the word was applied to the hairless "tails" of worms, bees etc.  The alternative suggestion is that the notion common to all is that of the "long, slender shape."  It served as an adjective from the 1670s.  A long obsolete Old English word for tail was steort.  Kammback is a noun; the noun plural is kammbacks.  No lexicographer seems to have listed Kammbackesque, Kammbacklike or Kammbackish as standard adjectives but, given the extent of the deviances from Professor Kamm's original which are still labelled as “Kammbacks”, they might be useful forms.  Who wouldn't want to be able to use terms like the comparative “more Kammbackish” and the superlative “most Kammbackish”?

Some notable Kammbacks

The Kammback (also known as the Kamm tail) was named after German engineer & aerodynamicist Professor Wunibald Kamm (1893–1966) who during the 1930s pioneered the shape, his work assisted greatly by some chicanery within the Nazi military-industrial complex which enabled the FKFA (Forschungsinstituts für Kraftfahrwesen und Fahrzeugmotoren Stuttgart (Research Institute of Automotive Engineering and Vehicle Engines Stuttgart) institute he established in 1930s to secure funding to construct a full-sized wind tunnel equipped with a two-part steel treadmill in the floor and an 8.8 metre (350 inch) diameter axial fan, able to drive air at up to 400 km/h (250 mph).  What the two concentric floor turntables allowed was that as well as enabling turbulence to be studied from the side on the running steel belt, slip angles were also possible.   At the time, it was the most modern structure of its kind on the planet, the very existence of which was owed to the priority afforded by the Nazis to re-armament, especially the development of modern airframes, most of the money eventually coming from the Reichs-Luftfahrt-Ministerium (RLM, the State Air Ministry).

A classic Kammback on a 1970 Fiat 850 Coupé (1965-1973), one of the last of the generation of post-war mainstream rear-engined cars built in Western Europe.

While Professor’s Kamm’s work on automobile shapes continued, increasingly the facility became focused on military contracts, contributing to an extraordinary range of novel aircraft designs, some revolutionary and most of which would never reach production.  All of this ceased in July 1944 when the facility was severely damaged in air-raids by Royal Air Force (RAF) Bomber Command, a costly campaign in which one mission incurred a loss-ration of 20% and it wasn’t until the late 1940s that reconstruction began after it was acquired by Daimler-Benz AG which enlarged and modernized the machinery, the early fruits including the 300 SL (the W194, first gullwing coupé) which won the 1952 Le Mans 24 hour race and the W196R “streamliner” Grand Prix race cars which created such a sensation in 1954.  Although he wasn’t part of “Operation Paperclip” (the US project which secured (by various means including the military “smuggling” them into the country despite many being wanted by those investigating war crimes and crimes against humanity) Professor Kann was acknowledged as one of the world’s leading authorities on turbulence and between 1947-1953 was part of the team working at Wright-Patterson Air Force Base in Dayton, Ohio.  Some of what was undertaken then remains classified but it can be assumed it was all related to military projects and what would later become the space program.

The Kammback which really wasn't: 1976 Chevrolet Vega Kammback.

One often misunderstood aspect of the Kamm tail is that the aerodynamic benefits are realized only if the flat, vertical surface created was no more than about 50% of the total area of the vehicle (as viewed directly from the back).  That’s why even designs which don’t conform to the requirements are often casually referred to as “Kammbacks” and in the US, Chevrolet were cynically opportunistic when the Vega range (1970-1977) included what was nothing more than a two-door station wagon (estate), it was named “Vega Kammback”.  Actually, even the existence of the thing in the US was unusual because at that stage, General Motors (GM) really “didn’t like” small station wagons but many critics did agree the Kammback was the best looking of the Vega’s body-styles.

2023 Ford Mustang coupe (left) and convertible (right).  Three of the Mean Girls (2004) ensemble (Karen Smith (Amanda Seyfried (b 1985)), Gretchen Wieners (Lacey Chabert (b 1982)) & Cady Heron (Lindsay Lohan (b 1986)) in 2023 filmed a commercial for Pepsi Corporation, one of the props a 2023 Ford Mustang convertible.  So ubiquitous has the Kammback become that its now unnoticed (except in its absence), one quirk being that when convertibles are created from such a base, many of the aerodynamic advantages are lost, one reason why (all else being equal which is rarely the case) a convertible will tend to have slightly inferior performance and slightly higher fuel consumption.

The knowledge gained from aero-engine development during World War I (1914-1918) meant even the mainstream engines of the 1920s were developing much more power so the speeds of cars were rising.  Some intrepid types also took advantage of the number of huge, powerful aero-engines being sold cheaply as “war surplus”, installing them is powerboats and racing cars, resulting in some fast machines and not a few fatalities.  However, it became clear the law of diminishing returns applied as speeds rose because while an increase of 100 horsepower might make possible an increase in top speed from 100 to 120 mph, another 100 hp might yield only another 10 mph; wind resistance increasing too much for the power to overcome.  Thus the interest in aerodynamics, then usually called “streamlining” something which, coincidently, produced some memorable art deco designs buy the engineers were interested in higher speeds and lower fuel consumption for a given quantum of energy input (fuel consumption).

2014 Shelby American Cobra 427 50^th Anniversary Edition in aluminium (left) and 1964 Shelby Daytona Coupe (right).

The AC Shelby Cobra (1962-1967) was small, light and powerful which made it an instant success on the race tracks but, ruggedly handsome though it was, its aerodynamics limited the top speed and on the some fast, open European circuits it gave away as much as 50 km/h (30 mph) to less powerful but more streamlined machines.  More power wasn’t the solution but a new Kammback body was and the Daytona duly won its class in the 1965 World Sports Car Championship.  All used the 289 cubic in (4.7 litre) Ford Windsor V8 although one briefly was fitted with a 390 (6.5) FE V8 and the planned 427 (7.0) version (CSX3027, the so-called “Daytona Super Coupe”) was never completed until sold by Shelby some 17 years later in a “rummage sale”.  The Kammback Daytona was the work of US designer Pete Brock (b 1936) and in a macabre coincidence, his namesake, the Australian racing driver Peter Brock (1945–2006) was killed while competing (in retirement) in a replica Daytona Coupe during the now defunct Targa West (2005-2021) in Western Australia.

Before the Kammback, the state of the aerodynamic art was the airship-like "streamliner" which, although it probably didn't cross the engineers' minds, owed something to the train of a bride's gown.  1939 Lincoln Zephyr V12 Coupe (left) and 1937 Mercedes-Benz 540K (W29) Special Roadster (originally delivered to Mohammad Zahir Shah (1914–2007; the last King of Afghanistan 1933-1973) (right).

What soon became clear was that the shape of the dirigible (better known as the “airship” or “blimp”) was close to ideal and needed to be tweaked only by honing it into a “teardrop shape” with a rounded nose, extending to a long, tapered tail, a shape which in the 1930s caught the imagination of designers who rendered some memorable designs although the most famous were impractical and inefficient in terms of packaging, thus suitable only for the then small market niche which sought speed.  It was to try to gain the benefits of streamlining in a shape more suitable for mass production that Professor Kamm and others took their slide-rules to the wind tunnel began to experiment.  The solution which emerged was to terminate the lovely, long flowing roofline with an abrupt end at a surface which was either vertical or close to it, an unexpected benefit being an improvement in high-speed stability, obviating the need for (a usually central) stabilizing fin (a la an aircraft’s tail).  By 1938, BMW had produced a car with a Kammback and although World War II (1938-1945) interrupted development by the late 1940s the shape had begun to appear in showrooms and in little more than ten years it was common in specially bodied racing cars.  That didn’t mean the allure of the teardrop went away because the aerodynamicists (who now had both access to bigger wind tunnels in which higher speeds could be tested and the novelty of computers which could process previously unimaginable quantities of data) could still prove ultimate slipperiness could be attained only with the teardrop.

Pre-Kammback & non-Kammback.  Porsche 917LH (Langheck (long tail)) at Arnage, Le Mans 24 hour, 1969 (left) and 2020 McLaren Speedtail (right).  Such things are now possible.

It was this which convinced Porsche to use such a tail on their revolutionary 917 in 1969 and having encountered no stability issues on their test track, sent the car to the circuits where it proved as fast as expected.  Unfortunately, the size of the Porsche test facility limited the 917 to 290 km/h (180 mph) and when on the long straights of some European circuits when speeds exceeded 320 km/h, it was clear the thing was lethally unstable.  Although the drivers killed at the wheel of the early 917s didn’t die at such velocities, it was understood it would be only a matter of time so the rear bodywork was redesigned.  When in 2018 McLaren returned to the teardrop for the “Speedtail” (a car which sacrificed just about anything not mandated by law in the quest for top speed), it was able to achieve a safe (it’s a relative term) 400 km/h (250 mph) because advances in aerodynamics, computing, materials & hydraulics had made such things possible although the packaging inefficiencies remained, something not significant for the target market.