Horsepower: What It Means & How It Originated

Jan 14, 2024

Horsepower-It'satermthatwehearextensivelywhentalkingaboutcars,butwhatexactlyisit?It'sbasicallyawordusedtodescribethepoweroutputofanengine,generallyreferredtoas'hp'.

Horsepower,however,isn'tusedeverywhere.Thereareothertermstorefertothecar'spower,suchasPS,CV,bhp,andkW.Eachtermhasitsownmeaning:'ps' refersto'pferdestarke'whichjustmeanshorsepower;CVisaFrenchacronymforChevaux-Vapeur,whichagainisequivalenttohorsepower;bhp,oneofthemorecommonlyheardterms,standsfor'brakehorsepower',andisaUKterm;and,finallywehavekW,whichstandsforkilowattandismorecommonlyusedforelectricvehicles.

Whenreferringtobhpandhp,bhpisthepowerfigureatthewheel,andhpisthepowerfigureatthecrankshaft,wherenopowerfrictionalpowerislost.But,thedifferencebetweenthetwofiguresisminute.Itisalmostata1:1ratio,where1hpisequaltojustunder0.99bhp.

Now,afterunderstandinghorsepowerandbrakehorsepower,letustalkabouthowthetermcameabout.Horsepowerwasn'tapropermechanicalmeasurement,itwasamade-uptermbyJamesWatt.

Inthe1760s,whensteamengineswerecomingabout,JamesWaittwantedtocomparethepowerofhisenginestothehorsesthattheyreplaced.

Hehadanideawherehemadeahorselift33,000poundsofwateronefootintheairfromthebottomofa1,000-footdeepwell,inoneminute,andthatresultwas'horsepower'.

Nowadays,luckilypowerofavehicleisnotmeasuredlikethis,butinsteadonaDynamometer,oraDyno!Adynamometerisamachinethatmeasuresthetorqueandpoweroutputofanengine.

Whilemanythinkmorehorsepowerismorespeed,theyaren'tentirelycorrect,noraretheywrong.Itonlymattersinstraight-linespeed.But,alotoffactorscomeintoplaywhentalkingabouthowitworks.

Ingeneral,acarwithmorehorsepowerwillbefasterthanacarwithlesshorsepower.However,therewillbeapointatwhichincreasingthehorsepowerwillnotresultinacorrespondingincreaseinspeed.Thisisbecauseotherfactors,suchasweightandaerodynamics,willstarttobecomemoreimportant.

Anengine'spowerhastwofigures,HorsepowerandTorque.Insimpleterms,torquehelpstopullacar,andhorsepowermakesthecargofast.Inmechanicalterms,torqueistheturningforceofanengine,whilepowerishowhardtheengineworks.

Dieselcarsusuallyhavemoretorqueandlesspower,whereasPetrolcarshavemorepowerandlesstorque.

Althoughthenamewasn'tmadetostick,horsepowerisoneofthemostcommonlyusedtermswhenreferringtopower.Also,morepowerdoesn'tnecessarilymeanhigherspeeds,butitdefinitelybringsabiggergrintotheface,sowhynotgoforit?Afterall-Power,baby,Power!