PDF Tech Link - Late Model Hemi - Specs
& Rebuilding Info
I found this PDF article on the the 'Engine
Builder Magazine' site. Scroll down to the
end of the 'print article' to click on the
link to the full, 16 page PDF format tech
http://www.enginebuildermag.com/Article ... _hemi.aspx
"Rebuilding The Chrysler Hemi"
Chrysler made the Hemi engine famous. They
didn’t invent the hemispherical chamber, but
they were the first to build an engine with a
hemi chamber for an American car back in
By Doug Anderson
Chrysler made the Hemi engine famous. They didn’t
invent the hemispherical chamber, but they were
the first to build an engine with a hemi chamber for
an American car back in 1951. They originally called
it the “Double Rocker Shaft V8,” but it soon became
“the Hemi.” It made a lot more power than the rest
of the car engines that were available at that time,
so some people say Chrysler started the “horsepower
wars” with the Hemi. What made it so good?
• It had better volumetric efficiency because it
had good ports and bigger valves that opened
away from the walls.
• It had a low “surface-to-volume ratio” which
gave it better thermal efficiency so it made
So, with the best chamber, plenty of cubes,
generous ports and better airflow, it was a
winner – except that it was heavy (a 392 cid
Chrysler weighed 737 pounds), more
complicated and more expensive to build – so
it eventually lost out to the big wedge motors
like the 383, 400 and the 440 cid.
Chrysler has built three different families of
Hemi motors since 1951. There were 12
different engines in the first generation that
ranged from a 241 cid Dodge to the 392 cid
Chrysler and spanned almost ten years from
1951 through 1958.
The only engine in the second generation was
the legendary 426 that was built from 1964 thru
1971. It was originally intended to be used for
racing at NHRA and NASCAR tracks, but it
ended up on the street because NASCAR told
Chrysler that they had to sell at least 500 cars
with the “street hemi” to make it legal for the
Daytona 500 that year. It died in ’71 because
NASCAR had outlawed it on the track and the
emissions police frowned on it for the street.
So, it shouldn’t come as a surprise that back
in the late ’90s, when Chrysler realized that
they would need a new engine with more
power and torque for their trucks, they
decided to build the third generation Hemi
for the 2003 Ram pickups. Since then, it’s
been used in their SUVs, Jeeps and RWD cars,
too. There are purists who say it’s not a real
Hemi because it has squish areas on both
sides of the chamber, but it’s close enough
for the rest of us. It has a hemi-shaped
chamber with the valves canted toward the
middle of the cylinder, four rocker shafts
with good valvetrain geometry and generous
ports. And, it incorporates some modern
technology including aluminum heads, dual
spark plugs, roller lifters and a
“multi-displacement system” (MDS) that
deactivates four cylinders under light loads.
So, you can have 345 hp and still get 21 mpg
on the road – at least that’s what I got on my
4WD Hemi pickup on a 100-mile trip with the
cruise set at 68 mph.
So, let’s take a look at this new Hemi including
both the 5.7L and the 6.1L.....
(Click here to download a viewable pdf -
http://www.enginebuildermag.com/Content ... 019776.pdf
Discussion of the 5.7L-6.1L-6.4L HEMIs.
2 posts • Page 1 of 1
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Great stuff there Mart. Thanks!
Owner of the Poor Man's Hemi Cuda
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