He is correct. The name Hemi comes from the hemispherical combustion chambers that were used on the old engines. The new "Hemi's" are only Hemi by name and not by trait. Meaning, they do not have hemispherical combustion chambers.

 

Actually just about every engine out these days are hemi's with a hemispherical chamber.

 

Yes and no lol, combustion chambers are hemispherical but the pistons are not real. The piston are quenched on the sides an not a full dome to match the combustion chambers.

 

It's an opposed valve layout, same as the early HEMI engines, but with different valve angles. It also has the additional spark plug.

The chamber on the 'GEN 3' is not of hemispherical architecture as the previous generations. It's actually a more efficient design. I have a 'GEN 2' (426 style) in my Cuda'. It has a 168cc chamber. I'm not positive, but I think the 5.7 has a chamber in the 85cc range...........which makes for a lighter piston, among other things.

Google it. You'll find some pics that will show the difference in chamber design.

 

Thanks for shedding some light on the technical differences guys. So how does the modern "Hemi" stack up against the "old" one? e.g.. Better, Worse or just Different.

 

Better depends on what you are looking for in your engine. I think its better because its lighter, more efficient, Lasts longer.

 

:i_rolleyes:*sigh*:i_rolleyes:


I got in an argument with a Ford guy about this once- he kept going on about how its not a real Hemi. I asked him what is it then, a wedge head? A flat head? The smirk on his face and lack of response told me that he probably didn't know what the difference was.

The technically correct answer is that the gen 3 Hemis are a polyspherical head engine. The pistons are domed on top except for about the outer 1/4" or so; and the valves are at differing, yet still opposed angles, so the heads look like 2 hemispheres put together with quench bands cut into them:

The 2nd gen Hemi had an actual hemispherical chamber and much more pronounced dome on the pistons (and you should see some of the pistons that drag racers have experimented with:wow:

The 426 Elephant was awesome in its day, and really still is, but the gen 3 Apache Hemi makes more power with only 392 cubes and is more efficient. Because of the era, the power was more accessible in the elephant due to the lack of nannies in vehicles at the time. The main reason for the polyspherical heads instead of true Hemi heads is that even with dual plugs, a truly hemispherical head would not meet modern emissions requirements.

Mopar actually offers a gen 3 426 Hemi crate engine available with a few different cams, that make 600/590, 515/490 565/550 HP/TQ respectively.

They also make a crate 572 Hemi that is a true gen 2 with a carb, and the option to add a 2nd carb. It makes 650/660 HP/TQ, and is a bit more of the traditionalist's option given the distributor and carb setup.


Both the gen 2s and gen 3s are somewhat legendary for their day. The gen 2s for being a legendary muscle car engine that has served as the basis for the overwhelming majority of top fuel drag car engines. The primary drawback in that application is the cost of valvetrain work.

The gen 3 has been even more popular if not as legendary, with the 5.7 alone seeing successful use in everything from sports sedans to SUVs to 1 ton trucks, and you'd be hard pressed to find a gas truck engine with a better track record of longevity and durability in hard use applications. The SRT versions (6.1, 6.2, and 6.4) have their own reputation for being reliable and powerful.

 

The gen 1 hemi was able to produce 1hp per cubic inch which at the time was the benchmark for NA engines few could meet.

 

Gen 2*, the gen 1s were not quite as powerful per displacement and were produced in the '50s. The gen 2s like the 426 did not come out until the mid-60s