What is a Hemi Engine?

Question

All dodge vehicles have a certain "HEMI" engine, what exactly is it and how does it technically differ from conventional IC engines?

Answer 1

Sorry. All Dodge vehicles do not have a "Hemi"engine. Only the Charger, Magnum, and certain trucks.

Hemi (from "hemisphere") or "crossflow cylinder head" is a design of internal-combustion engines in which the cylinder head's combustion chamber is of hemispherical form. The term, "Hemi engine" is a trademark of Chrysler Corporation, though the concept is used by many manufacturers.

The BMW double push rod design, taken over by Bristol Cars, the Peugeot 403 and the Toyota T engine are other well known examples. Harry Arminius Miller racing engines were a more notable example. Stutz had built four valve engines, resembling modern car engines. Chrysler became synonymous with the "Hemi" by building them in such large numbers.

The hemispherical combustion chamber design puts the intake/exhaust valves in-line, rather than side-by-side, allowing for better flow of air through the head (although the inlet and exhaust valves are not simultaneously open and there is no continuous flow). The spark plug in the center of the chamber makes for better ignition of the fuel/air mixture. These aspects help make the hemi-type engine more efficient and powerful, and less prone to engine knock.

The hemispherical cylinder head increases the engine's efficiency through reduced thermal energy loss and increased airflow through the engine. (A hemisphere has the lowest surface area to volume ratio, meaning the most space for combustion while losing the least amount of energy to the engine walls.) Drawbacks such as increased production cost have meant that it has been a rare design. Placing the intake on the opposite side of the engine also reduces the air intake temperature and increases efficiency.

Hemispherical cylinder heads have been used in some engines since they were first used by the Belgian car maker Pipe in 1905. Most applications have been in higher-priced luxury or sporting vehicles, because the hemi design is more expensive to build.

Perhaps the best-known proponent of the Hemi design has been the Chrysler Corporation, which has produced three generations of such engines: the first (the Chrysler FirePower engine) in the 1950s; the second (the 426 Hemi) from the mid 1960s through the mid 1970s; and finally in the early 2000s. Chrysler has used the word "Hemi" extensively in its advertising, to the extent that the word is indelibly associated with Chrysler in North America.

Porsche has also been a notable user of the Hemi design, generating up to 86 hp per liter displacement on production cars (1973 2.4 L 911S), and even more on racing engines (906 Carrera engine). Jaguar used this head design as well on the legendary XK engines, which powered cars ranging from the Le Mans winning D-Type to the XJ6 sedan.

Other manufacturers used the hemispherical design before World War II, including Daimler and Riley.

Answer 2

Dr C certainly knows his Hemis. Today's third generation Chrysler Hemi (the 5.7 and 6.1L engines) has been criticized in the motoring press for not being a "true" Hemi. It is true that the current engine's combustion chambers are not as hemispherical as the first and second generation. Therefore the press is implying that the use of the "Hemi" name is only a marketing ploy to resurrect the imagery of the golden muscle car days!

A little trivia: The first generation Chrysler Corporation Hemi appeared from 1951 through the 1958 model years in an astounding 14 different displacements in a wide assortment Chryslers, Dodges and DeSotos. Generation number two "Street Hemi" was resticted to a few 1966 though 1971 Dodge and Plymouth models and only came in one size: 426. Production expense, weight, emissions and politics doomed the first two generation's Hemis.

Answer 3

maximum folk do no longer comprehend (and ward off would not noise it approximately) that their plenty vaunted "Hemi's" are not. Their heads are in easy terms semi-hemispherical. through fact we are getting technical. "Semi-Hemi" does no longer sound virtually so stable interior the advertisements although. truthfully speaking the semi-hemi layout makes plenty greater engineering sense over a real hemi in a widespread engine layout. I even have an old Harley it rather is a Hemi. If I take a cylinder head off and turn it the other way up i'm able to smartly drop a softball into it and it fits quite much like a glove. Now it rather is a hemi head. humorous Harley by no potential rather stated this returned interior the day. possibly it would have ticked off the ward off human beings. "Hemi" could be trademarked or some thing. in all likelihood additionally why the Toyota human beings by no potential stated plenty with regard to the hemi type heads they used on their autos for like twenty years.

Answer 4

I am a long time MoPar fan and Dr C is right.
I like the "idea" of bringing the HEMI name back, and the new HEMI is similar in many ways to the old, but to me the only true MoPar HEMI engine started back in the '50's and ended in the early 70's with the 426 HEMI.

They were so fast NASCAR Banned them from the track. 'Nuff said!

I will have one for one of my Darts someday, OHH YESSSS, I WILL!! AHHH A HEMI DART.

That's what Dodge should build again, not a four door wanna be "Charger"!

Answer 5

In stead of a flat cylinder head, it uses a hemispherical shaped one. Like a satalite dish or a parabola. Due to the parabola effect, the gasses are focused at the optimal point and you get a much more efficient burn, so more power.

The current Hemi's are a shell of their yesteryear selfs due to emmission requirements.

Answer 6

A hemi is a motor with cleavage

Answer 7

those are hecka fast engine