I used to think the Hemi name was named after some engineer or something, there is a brief explanation in a dealer brochure but it's pretty generic.

What exactly is unique about the Hemi engine?

 

Obviously the hemispherical combustion chambers are defined in the name, but the 5.7L Hemi goes a little further for me.

Everything about this engine is set up for reliability. Only 2 valves per cylinder. A single center-mounted camshaft. The most brutal testing ever performed by the dodge engineers. And after all of that, it still outputs class-leading power, and with MDS (which in itself is a very simple implementation) it gets respectable gas mileage for what it does.

I guess the phrase "reliability and power by simplicity" defines the 5.7L incarnation of the Hemi for me.

 

Yup, as said above.

The name Hemi comes from the hemisherical shape of the cumbustion chambers in the heads. The other easily think to see is the plug goes in the center of the heads through the valve covers. Not on the sides under the valve cover.

 

The plug going in the center isn't unique to the hemi, look at any DOHC engine, they do the same thing I had an 88 Nissan 1.8 liter that was DOHC and had coil on plug ignition on the center plugs). The combustion chambers are the defining thing. As compared to the original 50's version, they are more semi-hemi than a true hemisphere. That engine was originally marketed as the dual rocker shaft engine. Long live the 392!

 

I was referring to v8's, not starter motors.

I think the plug in my lawn tractor is in the middle too. Come to think of it, so is my weed wacker.

And the Hemi of history is the 426, not the 392, Jeeez.

 

LMAO

 

Now THAT was intelligent.....I was giving an example, for starters.....and if not for the 50's design hemi (331, 354, 392), your nascar 426 would never had been born...

Besides, what is "cumbustion"? Or the "easily think to see"

hookt in fonix werkt for me.....

 

the old ford 427 race motors had plugs just like hemis do also. Todays hemis also have 2 plugs for each cylinder

 

ummmm, Hemi's are not unique to Mopar they were just the first to trademark the name.

Lots of engines use hemispherical heads. I think even Toyota! (oh crap, did I just say that outloud???)

To put it in a nutshell, hemispherical heads simply allow a company to pack more crap in there - air, fuel, valves, plugs or anything else they can get to fit - like the broken electrode off an AC spark plug (screw you AC Delco!!) that will then very quickly weld itself to the cylinder wall, destroy your piston and completely ruin a balanced and blueprinted engine!.....but I digress, my therapist said to let it go (in my happy place).

There is more surface area on a hemispherical head than an old(er) flat type head.

 

The early 427 side oilers didn't, but the SOHC (in 4bbl and 8bbl forms) did. Also the Boss 429 was a form of hemi.