If you like cars , then you have probably heard of theHEMI engine . If you were born in the 1960s or before , you remember the phenomenon created by Chrysler ’s HEMI engines in the 1950s , ' 60s and ' 70 . If you follow sinew cars or drag racing , you experience that the 426 HEMI engine is a popular railway locomotive because of its public presentation . You ’ve probably also listen of the HEMI engines thatChryslerbegan using in 2003 Dodge truck .
But even if you know little or nothing aboutcars and engine , the countersign " HEMI " might still mean something to you . The word has become a equivalent word for big , sinewy engine . In this clause , you ’ll determine about the HEMI railway locomotive and find out why engines using the HEMI purpose are such awesome machines .
Birth of the HEMI
The HEMI engine for automobiles was born in 1948 – Harry Westlake and several others educate a Hemi 6 - piston chamber engine for Jaguar . A few years later on , in 1951 , Chrysler usher in a 180 - horsepowerHEMI V-8 engine on several models . The Chrysler HEMI engine had a displacement of 331 cubic inches ( 5.4 liters ) , so it is know as the " 331 HEMI . "
These days , 180 horsepower fathom like nothing . But in 1951 , 180 H.P. was unheard of . It was an awful amount of mightiness for the mean solar day , and it fueled the " HEMI fable . "
Chrysler continued improving the HEMI design , releasing a 354 - cubic - inch design in 1956 , a 392 cubic - column inch design in 1957 , and ultimately a 426 - three-dimensional - column inch ( 7 - liter ) version in 1964 . The 426 engine set the HEMI caption in Harlan Stone when it advance first , 2nd and third place in the 1964 Daytona 500NASCARrace . The 426 street HEMI total out in 1965 , get 425 horsepower .
The 426 engine block and head word are still available today from Dodge . The 426 HEMI is a popular force plant for drag racing , funny cars and muscle elevator car .
In the next section , we ’ll look at how the HEMI is designed for big businessman .
Comparing HEMI to Flathead Engine Design
The thing that allowed the 1951 Chrysler HEMI to bring forth so much more power than other engines of the mean solar day was the efficiency of thecombustion chamber .
In a HEMI locomotive , the top of the combustion chamber ishemispherical , as determine in the image above . The combustion region in the drumhead is shape like half of a arena . An engine like this is say to have " hemispherical heads . " In a HEMI head , thespark plugis normally locate at the top of the combustion chamber , and the valves open on opposite sides of the combustion bedchamber .
Most railroad car prior to the 1950s used what was eff as aflat head , and many lawn lawn mower locomotive still use the flathead design today because it is less expensive to manufacture . In a flathead engine , the valves are in the block , rather than in the head , and they open in a chamber beside the Walter Piston .
The head in a flathead engine is exceedingly unproblematic – it is a solid metallic element casting with a maw practice in it to accept the spark plug . The camshaft in the block pushes directly on the valve stems to afford the valves , decimate the demand for pushrods and rocker arms . Everything is simpler in the flathead invention . The problem with a flathead engine is itsthermal efficiency , which we ’ll discuss next .
HEMI Pros and Cons
There are many different parts of an engine ’s design that control the amount of power you could extract from each combustion stroke . For object lesson :
HEMI Advantages
The last item in the above list is one of the key advantages of the HEMI capitulum versus the flathead engine . control surface areacauses heat loss . Fuel that is near the head walls may be so nerveless that it does not burn efficiently . With a flat forefront , the amount of aerofoil area relative to volume of the combustion sleeping room is large . In a HEMI engine , the Earth’s surface field is much belittled than in a two-dimensional head , so less heat escapes and peak pressure can be higher .
Another factor with a HEMI capitulum is thesize of the valves . Since the valves are on polar sides of the drumhead , there is more elbow room for valve . The engine design that lead the HEMI was a bomber - shaped combustion chamber with the valve in line with each other . The inline arrangement limited valve size . In a HEMI railway locomotive , valve can be large so the air flow through the locomotive is ameliorate .
HEMI Disadvantages
If HEMI engines have all these reward , why are n’t all engines using hemispherical heads ? It ’s because there are even better configurations available today .
One affair that a hemispherical straits will never have isfour valves per cylinder . The valve angles would be so wild that the drumhead would be nearly unimaginable to project . deliver only two valves per piston chamber is not an payoff in drag racing orNASCARbecause racing engines are restrain to two valve per cylinder in these categories . But on the street , four slightly minuscule valve permit an engine breathe easier than two large valves . Modern engines use apentroofdesign to suit four valves .
Another reason most high - performance engines no longer apply a HEMI design is the desire to create a little combustion bedchamber . small-scale chambers further reduce the warmth lose during burning , and also shorten the aloofness the flaming front must locomote during burning . The compact pentroof design is helpful here , as well .
Next , we ’ll look at the Dodge HEMI Magnum engine .
The Dodge HEMI Magnum
The Dodge HEMI engine builds off the tradition of HEMI great power to deliver a 345 - three-dimensional - inch ( 5.7 litre ) V-8 engine with hemispherical head .
The engine produces 345 H.P. , and compare very favorably with other gasoline engines in its class . For good example [ ref ] :
The HEMI Magnum engine has two valves per cylinder as well as two spark plugs per cylinder . The two spark plugs help to puzzle out theemission problemsthat plagued Chrysler ’s earlier HEMI engines . The two plugs initiate two flame front and guarantee complete combustion .
For more selective information on HEMI engine and their inheritance , check out the link on the next page .
