I have no knowledge of automobile engineering so that is why I am wondering. My Hemi eats more gas than Louie Anderson does food. Can someone tell me why?

 

you said it yourself. . .HEMI


realy and truly, if alot of these emissions BS didnt exist and the refineries would increase the octane rateing across the board to where it was back in the day fuel mileage would be better. but it has mostly to do with emissions.

But to produce power means the need for more fuel. and the more fuel you add to the fire the more power output you get.

 

Do you want the scientific, but written in plain english version. Or the bert and ernie version.

 

I honestly haven't done any research on these new "hemis" we all have, do they actually have hemispherical heads like the old 426's we all grew up dreaming about, or is it a semi rounded combustion chamber with a centered plug that is mostly a marketing ploy? I can't imagine that in todays modern fuel injected engines that a "hemi" head makes even close to the difference it used to. the main reason hemis were so bad ***, at least as I always understood, is because in a carbeurated engine, they allowed better swirl, for better fuel/air mixture, and also had the plug in the center of the combustion chamber, instead of on one side. This meant you got better ignition and a more complete fuel burn, thus more power on your power stroke. With the infinitely better fuel delivery systems of today, and the way better spark plugs/ignition systems, I really can't see it making much of a difference, other than playing to our nostalgia.

Guess I will go google and see if I can find out.

 

In answer to my own questions, here is a very informative link to a page that explains all the intricacies of the modern hemi (which BTW is only a hemi in name, like I suspected.)

http://www.allpar.com/mopar/new-mopar-hemi.html

Pretty cool stuff, and alot in there I didn't have a clue about.

 

Simple physics, more air in requires more gas... on top of that you have a HEAVY vehicle by car standards, and the aerodynamics of a brick.

For comparisons the stock LS-1 in my Vette is the same size engine with identical torque and nearly identical hp, but the car weighs over a half-ton less and spent a lot of time in a wind tunnel. However, set on cruise at 71mph I average 31mpg--and that's by the real fill-up to fill-up math, not the on-board computer.

Engineering and electronic magic will only do so much. Now, am I going to tow my wife's race car with the Vette?

Bring on the hemi, and cash to the pump.

All the best.

 

Commen since tells you, that it takes for gas to keep a bigger engine running. More engine, more gas, more power! Good news, if your concerned about gas milage on a big engine. The new Charger is making one of its engine's where it will shut off 4 cylinders at certain times, when u dont need them to save your gas and you dont have to run the entire engine. However turn it on, when you want to haul ***. If it pulls through, the newers Ram Hemi's could most likely be equiped with the engine as well. Just throwing in my two cents.

 

In the link posted above, that sure looks like a hemi head to me. Oddly enough, the 4.7 has a similar "hemi" combustion chamber to the 5.7.

 

You know me, I'm a Bert and Ernie kinda guy!

 

Here are side by side compares, and you can easily see why the new 5.7 is really only a hemi in name, it is not even close to the hemispherical chamber that used to exist in 426 hemis, as clearly shown in this picture.



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