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What exactly is a HEMI
I'm not trying to ruffle any feathers, but merely see if I am correct in my assumption. Is there something special about a Hemi or is that just the designation Dodge is using for their motors now? I remember in the past it was Magnum and Ford has the Triton and Chevy has the Vortec. To me it just seems like a marketing ploy, make a few changes to a motor and call it some cool name and then add a premium to the cost.
Again, I am not trying to offend any Hemi owners, I was just curious if there is something special about the motor?
They seem quite powerful and fast.
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What exactly is a HEMI
The 5.7 hemi is marketed on the reputation of the old 426 hemi Chrysler marketed years ago in their "pony cars" such as the Barrcuda, Road Runner, Super Bird, etc. The engine cylinder heads were designed in a hemispherical configuration. My opinion is that it is more marketing hype than anything else............besides..............the hemi is for folks who can't handle the power of the Cummins diesel. ;o) just kiddin'!
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What exactly is a HEMI
YEAH, IT'S GOT A HEMIŽ. SWEEEET. Ah, the 5.7-liter HEMI MagnumŽ V8. Best in class power, generating up to 345 hp and 375 lb-ft of torque. HEMI doesn't merely jump over the competition. It leaps. With electronic throttle control. Aluminum cylinder heads. Hemispherical combustion chambers. High compression ratio. And a design that utilizes 2 spark plugs per cylinder to burn fuel more efficiently - and leave the competition eating Dodge dust. That's from their website...and $5K+ less than the Cummins....
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What exactly is a HEMI
Originally the Hemi's of the past with the hemisperical head had more room to put larger intake and exhaust valves. An engines ability to breathe has allot to do with power output. They were able to squeeze more power out especially when you boosted it with a blower for drag racing. The new hemi's are somewhat that way but you are restricted with compression and trying to run regular gas.
The new Ford triton in the 2004 F-150 has 3 valves per cylinder. They have raised the HP rating on the triton but the hemi still puts out more raw HP. The triton is 5.4 while the hemi is 5.7. I haven't compared power and torque curves. I get about 14MPG with my 2002 F-250SD and 5.4 with 2 valves per cylinder. Chief said to expect 12MPG with a 1/2 Dodge. I'm dragging more weight around with a 3/4 ton but still get an edge on mileage. That sounds about right!
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What exactly is a HEMI
In addition to the ability to use larger valves, the hemispherical combustion chamber design can yield more efficient combustion action. Chrysler started working with the hemi concept at least as far back as the fifties, with engines under 400 cubes. The 426 was the culmination of the approach and very few 'stock' U.S. motors could touch it for power. Just about anything Chrysler dropped a 426 hemi into made the top 10 fastest production quarter-mile lists in the sixties. A few other makers (including BMW) used hemi (or multiple hemispherical dome areas, 3 in BMW's case) within the combustion chambers of their head designs for this reason in addition to the valve advantages.
It's not all hype, although it's not the only way to skin that cat.
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What exactly is a HEMI
The old Hemi's had a high domed combustion chamber. The valve's included angle was increased and the valve sizes went larger. To keep the compression ratio high, the piston had to be domed also.
With todays emission standards, this highly domed combustion chamber would not be clean enough. So, they went with a slightly domed chamber with a flat top piston which is the same design as every else. I even read in a magazine article that the new hemi is closer to the GM engines than the old hemi.
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What exactly is a HEMI
WHILE THE SUBJECT CAME UP HOW ABOUT THE
POLY HEMI BOSS 429
AND MY ALL TIME FAVORITE THE LIMITED SOHC/DOHC 427'S
DODGE DID ALSO USE THE THE HEMI HEADED 2.6 L 4CLY MITSUBISHI ENGINE IN NORMAL AND TURBO.
AND I DO RECALL DOING A HEAD GASKET ON A "Z-24" DUAL PLUG NISSAN TRUCK 4CLY ENGINE.
THE IDEA NEVER REALY WENT AWAY.
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What exactly is a HEMI
Don't forget the 426 had spark plugs right down through the valve cover! I haven't looked under the hood of a new Hemi vehicle, but I don't suppose the new ones have that.
Bill
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What exactly is a HEMI
kubotaguy, thanks for bringing the question up, I've been wondering the same thing. The hemi's I remember were from the late 50's and 60's. In 55 Chevy shocked the industry with that little 265 V8, then in 56 put dual quads on it and blew everyone else off the road. That was back in the days of Arkus Duntov, an engeneer form Chevy who knew how to make things go fast. Factory sponsorshp at Daytona was big then, so Ford, and Dodge joined in the horsepower race. The Dodge "Daytona", "Super Bee", and their other Chrysler cars with a "Hemi" were just simply raw horsepower that blew every body away. I had a 61 Chevy with a 348 tripower, four speed that was quite a machine but no match for a "Hemi", I tried to trace it down a few years ago but never found it. I used to really enjoy stock car racing till it went the way of Pro Football' Baseball, and all professional sports that have simply turned from being a sport to being a huge business now with their only intent to generate revenue. I've probably said enough by now to lose every friend I've made on the board, but that's just my honest feelings. Frank.
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What exactly is a HEMI
The Hemi design is the most fluid design for entrance and exit of the compression area needed to run engines. The design gives a better distribution of the material to be burned on both gas and diesel engines. Many of the newer diesels are also going to that design style for it's benifits. At higher RPM's they are at a real advantage over other style heads but there also is a cost factor in making them. Remembering the old chevies with the 265 and 283 engines where a bare block weighed about the same as a head from the old hemi mopars.
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