Why Hemi??

[Pythonman]

I'm new to Mopars, having had a long time affair with mostly Fords and one '07 Mustang GT. I can appreciate the fine engines in both makes but I am interested in knowing how the Hemi engines in our R/Ts and SRT8s compare with Fords modular performance engines and Chevy's more performance oriented engines. What benefits are there in one make over the other and how do they compare reliability wise? Just curious cause I know there's lots of long time Mopar owners and I'd really like to hear what they have to say. Thanks!

[TinCuda]

Hope this helps...

The Hemi has been around for a long, long time in various forms. Early Triumph motorcycles used this design in 1937 and continued using it up until 1988. Chrysler borrowed ideas for their design from Weslake which built speed parts for Bonneville salt flat racers. Chrysler really utilized it best in automobiles in the early fifties and it's still the all time power king in racing. A drag racing blown hemi produces in excess of 6000 horsepower which is many times what anything else is capable of producing.

The hemi has four main advantages:

1) The spark plug(s) reside directly in the middle and top of the combustion chamber. This makes for a nice, even firing pattern. This is why Hemi engines have spark plug holes right in the middle of the valve covers. Other "wedge" engines like Chevy and Ford V-8's have their spark plugs off-center which is cheaper to build but less efficient.

2) Larger valve size. Draw a circle on a piece of paper. Now draw a line through the middle of it. Now draw two circles on ONE side of that line and you'll see how most ordinary V-8 heads are designed. To draw a Hemi, place one big cirle on one side of the line and another big circle on the other side of the line. Bigger valves mean more efficient and rapid airflow through the engine.

3) Larger combustion chamber surface area. The chamber is of the pentroof design (used by Ricardo in the 1910's) which means it's kinda funnel shaped. More area means more even heat transfer and distribution. More fuel and air can be crammed into the combustion chamber thus producing more power.

4) By placing the valves across from each other, the intake and exhaust flows across the combustion chamber. On a standard wedge head, they enter on one side, turn and cross and turn again to exit the cylinder. That's inefficient. The Hemi is a true flow-through design.

Today, there are numerous manufacturer's who make more efficient designs than the 2-valve Hemi. Most of the DOHC 4-valve designs will easily outflow a Hemi to a point. They have more valve area, however the size of the ports is usually very small increasing intake and exhaust velocity. That's great if you want maximum combustion efficiency but not great if your goal is to move massive amounts of fuel and air through the engine.

For today, the modern Dodge street Hemi is primarily a sales tool. The name, reputation and mystique alone will sell cars. It does produce great power & torque and is definitely an option worth considering.

The term Hemi which is short for Hemispherical simply means half sphere which is what the combustion chamber looks like, with one valve on each side.

[randycat99]

Plus, doesn't it tickle your fancy that not only do you have a v8 unlike most cars on the road, but you have a v8 that isn't like most v8's on the road, as well? It's almost a badge of honor to carry on the torch for a valvetrain and head configuration that set the v8 world on its ear in the 60/70's. It's not just built to be the most dirt simple and cheapest approach to get 2 valves in a cylinder head. It is "special" from the perspective that it is arguably the most elegant and sophisticated engineering approach to put 2 valves in a cylinder head, even if there were no tangible benefits in actual output. It is like the Ferrari of v8's, in a world where nearly any other v8 under the sun is built in a more "commoner" manner. I guess it is like "v8 royalty" in a nostalgic light.

[tony292]

they could have built the new Hemi with some other type of design, but then they couldn't have called it a Hemi, right? Same reason they ressurected the Charger and Challenger names instead of the "Polara" or "Coronet", they just wouldn't sound as cool or sell as many.

[mph]

1. "Bid Daddy" Don Garlits. If I'm not mistaken almost all of his wins came with Chrysler Hemi. He still advertises for Chysler, and has a strip version of the Challenger.
2."The King" Richard Petty. Most of his wins came in a Chrysler powered by a Hemi.
3. The Keith Black Hemi. Damn near a direct copy of the Chrysler Hemi block in aluminum. A butt load of NHRA funny cars and dragsters used that bock for quite some time, if they're not still using it.
4 The Chrysler Hemi is, to the best of my knowledge, the ONLY motor to be banned from NASCAR for a distinct advantage. Even though they didn't really invent it, and every manufacturer at the time had the same opportunity.

Need I say more?

[Pythonman]

Wow! Thanks for the cool Hemi history guys. That's cool stuff I just plain did not know. WHat I do know is the engine in my R/T get's pretty scary powerful at times compared to anything I've ever owned and she strongly reminds me of a hopped up 396 in a 67 Chevelle SS a neighbor of mine once had in pure grunt. Nice for a factory street ride!

[09R/TPony]

Originally Posted by Pythonman

I'm new to Mopars, having had a long time affair with mostly Fords and one '07 Mustang GT. I can appreciate the fine engines in both makes but I am interested in knowing how the Hemi engines in our R/Ts and SRT8s compare with Fords modular performance engines and Chevy's more performance oriented engines. What benefits are there in one make over the other and how do they compare reliability wise? Just curious cause I know there's lots of long time Mopar owners and I'd really like to hear what they have to say. Thanks!

Check out the following link and attached PDF file for some additional information.

Howstuffworks "How HEMI Engines Work"

[Cuda340]

Originally Posted by mph

1. "Bid Daddy" Don Garlits. If I'm not mistaken almost all of his wins came with Chrysler Hemi. He still advertises for Chysler, and has a strip version of the Challenger.
2."The King" Richard Petty. Most of his wins came in a Chrysler powered by a Hemi.
3. The Keith Black Hemi. Damn near a direct copy of the Chrysler Hemi block in aluminum. A butt load of NHRA funny cars and dragsters used that bock for quite some time, if they're not still using it.
4 The Chrysler Hemi is, to the best of my knowledge, the ONLY motor to be banned from NASCAR for a distinct advantage. Even though they didn't really invent it, and every manufacturer at the time had the same opportunity. Need I say more?

You forgot the Sox & Martin Pro Stock 'Cuda and **** Landy Challenger of the late 60s early 70s.

[mph]

Originally Posted by Cuda340

You forgot the Sox & Martin Pro Stock 'Cuda and **** Landy Challenger of the late 60s early 70s.

Hey, I can't think, drink & type ALL at the same time. Now, drinking, drooling & typing I have a better shot at. Your ARE absolutely right though.

[garylee]

One more thing, ALL of the NHRA funny cars and top fuel cars have hemi engines. It doesn't matter if they say Ford, Chevy, Toyota, or DODGE on them. They are all HEMI'S and have between 6000 and 7000 hp. Now, that's something to be proud of.