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What's so special about a Hemi?

26K views 143 replies 50 participants last post by  DoubleVision 
#1 ·
I know a lot of you people hold a 426 hemi in high regard...why is this? Don't you ythink a comparable built Chevy motor is just as good? I lived in Long Island, NY , for 10 years and have seen a lot of street racing. The talk was always hemi this, and hemi that, mainly because of 1 guy who had a hemi dart i think...it was fast! My buddy had a 67 impala with a stock LS7 he purchased from chevrolet for about 3000$. Fitted with an Offenhauser manifold and a big holly, this puppy ran. Needless to say he made a name for himself and eventually lined up with the hemi. Money was flying, tires burned, and the little hemi that could, lost! They raced 2 more times with the same outcome( 1/2 car lengh ) For a couple of weeks the hemi guy was nowhere to be seen then suddenly in a flash one Friday he reappeared. " He's got a new motor...rebuilt the whole thing. He wants to race the impala again" Supposedly this guy( who was a jeweler in NYC-money to burn) assumed something had to be wrong with his motor and spent 10000$ to get it right....need i tell the rest of the story? He lost again by a car length this time. He just could not understand how. Anybody on this board from LI who watched street racing extensively during the late 80's-mid 90's has seen this big white car pull the front wheels and win some money....for 3000$!!!! go figure

[ August 17, 2002: Message edited by: windmaster ]</p>
 
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#3 ·
Why are Chevy people so whiny? There's a lot more to street racing than just sticking a built motor in something. I'm sure the Chevy only won cause he had higher gears, and some sticky tires or something. :rolleyes:

In my opinion the Hemi is one of the greatest thing to ever come from Mother MoPar. The Hemi is patented isn't it? GM can't build ANYTHING like it. And wasn't Dodge running the Hemi in NASCAR when Chevy boys got whiny about them always winning?
 
#4 ·
PONTIAC!!!! WHOOOOOOOO!!! chugga chugga chugga chugga, WHOOOO WHOOOOOOOOOOO!!!! (that was a train noise) Hmmmm... seems i remember a website that explained the difference between a Hemi and a normal motor, and why they are so good. I would love to have a Hemi in a Charger. Those things are mean. But, lets not start a motor company war here. I like hemi's, but i wouldn't trade in the pontiac 400 in my GTO for one unless it was straight out with no money involved, but i would love to have a mopar with one in it already.
 
#7 ·
Originally posted by Croz:
<strong>you could pay me to take any engine. doesn't mean i will use it, but even a briggs and straton 5 horse could sell for some money, or make something interesting out of, like an elevator so i don't ahve to use the stairs anymore.</strong><hr></blockquote>


If its a Bowtie engine you could use it for a boat anchor.
:D
 
#12 ·
Frog a Hemi is a hemispherical headed engine built by Mopar. Mopar is another name for dodge and the products therin. If you want to see what a hemmi looks like go check out HemmiGremmi's photo album. Other than that, I can't help you much.

Toyota also built a Hemi in the 70's, suprised the sheet outa me, but they did it, not a bad little engine either...for a toy.

HK
 
#14 ·
1> They do make hemi heads still, I have a set in my 98 neon acr.

2> hemi heads had 2 things going for them and a 1 big thing against them. The shape of the combustion chamber was better at burning fuel, don't know why or how I just do. Second the plug was dead center in the chamber, same reason but agin no clue why this was good. The big thing against them was they were real touchy about coming out of tune. You had to be good to keep one going corectly. I had a 70 dart swinger as my first car with a 413 wedge yanked from an old 300 letter car and it moved. I have seen a hemi challanger at the track it sound's evil and moves but......to each his own. They are still a damn fine motor. Although ford 427, chevy LS1, LS6, '70 copo..... I love all cars and all motors it don't matter

Matty

[ August 17, 2002: Message edited by: matty ]</p>
 
#15 ·
As the owner of a built 454 in a pro-street car and 4 early hemis I feel that I can say this with a bit of experience. BB Chevys are great but if they're so great then why are all the top fuel and funny cars built with a variant of Chrysler's hemi.

One reason: There just isn't another motor that can make the kind of HP a hemi can. Take a 454 and a 426 put them side by side, stick the same performance goodies in them and the hemi will pull more HP than the Chevy every time.

If you want good HP on the cheap, buy a Chevy. If you want class, get a HEMI. :p
 
#16 ·
I think that the patent that Dodge had on the hemis only lasted 10 years. Other manufactures would of jumped in on it during the gas crunch era which would of been bad. The early Hemis were not very efficeint and threw alot of raw fuel out the exhaust, so they were to costly to pass the governmet smog regulations. But the hemi is a perfect engine to add a blower to.
I understand the new generation Hemi is much more efficeint. I just proof read this and its sounds like one long winded pile of nothing. :rolleyes:
 
#17 ·
A hemispherical combustion chamber engine has a few properties that make it desirable from a power making perspective;

-A hemi chamber is shaped much like half of a ball, this shape leaves plenty of room for valves of very large diameter. This is good.

-A hemi chamber allows the spark plug to be centrally mounted as Matty has pointed out, this is good.

-A hemi chamber requires a large dome to fill it, thus a piston must have a large popup with valve reliefs cut in for clearance. This makes it hard to build compression without obstructing the valves, it is also much more expensive to fabricate/cast. This is bad.

-The large dome required turns the chamber into a large cresent shaped area which is hard to burn completely, it also has a large surface to volume area. This is bad for efficiency but good for antiknock qualities.

-Since the valves are splayed at large angles the intake and exhaust entry angles are ideal for high flow, but it also makes for an extremely large single casting and a very wide engine width. Good and bad.

-The resultant splayed valves make for a complicated valvetrain that has inherently long pushrods and needs stiff springs to handle the extra valvetrain weight. This is bad.

Many of the bad qualities can be solved by overhead camshafts and sophisticated casting technology in aluminum, but it ain't cheap. Most manufacturers have abandoned hemi chambers and have modified it into a pentroof chamber which still has room for large/multiple valves and a better quench shape for efficiency and added overhead camshafts to solve the valvetrain problem.

Most high performance multivalve engines use this pentroof chamber for these reasons. Virtually every Japanese sport bike has had this since the late seventies.

The Ford Boss 429 had a semi-hemi design and so did various other engines, but for the reasons outlined above the design has been abandoned in favour of the more efficient/cheaper to fabricate pentroof chamber.

I still love the look of the old hemis mind you, there is nothing sexier than a spark plug access tube in a valve cover if you ask me. Except for CG in a swimsuit maybe?! <img src="graemlins/boxing.gif" border="0" alt="[boxing]" /> <img src="graemlins/mwink.gif" border="0" alt="[mwink]" />

Sorry CG, I just have to fit you into every one of my posts if I can. ;)
 
#18 ·
the new Chrysler 300N is going to have a hemi and be rear-wheel drive!

Also, bit of trivia, Way back in the 30's or 40's MotoGuzzi made a 500cc motorcycle with a hemi head. It also had 4valves/cylinder. It was the first non-British manufacturer to win the Isle of Mann race. fyi

so, hemis have been around a long time.

JB

[ August 17, 2002: Message edited by: johnnymopar ]</p>
 
#19 ·
[useless hemi facts] The first production hemi motor, was I believe in the mid 50's. There was a 392 and a 354, or within a few ci of them. The 300 letter cars had the hemi in them. The number 300 stood for 300HP. The letters are the year, the last was the L and then the 300M in the mid 90's. After the hemi was the 413 wedge, I don't think they ever got a 426 in the letter cars. Personally I would take a 440 wedge over a hemi for daily use and drivabilty, but there is NOTHIN in the world like pulling into an ice cream stand an popping your hood, with a stuffed 426 dual quad setup shoved underneath. Correct me if I am off on any of this stuff[/useless hemi facts]

Matty
 
#20 ·
EXCUSE ME i'm a chevy guy and i dont whine. i have an appreceation for all motors and cars.if chevy doesn't win on sunday its ok as long as it was a good race. and i can recall a few years back when i used to go off roading in my blazer i pulled a few broncos out of the mud.. <img src="graemlins/nono.gif" border="0" alt="[nono]" /> <img src="graemlins/evil.gif" border="0" alt="[evil]" />
 
#22 ·
Those who think the small block Chevy introduced the compact modern V8 to the world couldn't be more wrong. It did get a lot of press when the 265 came out in 1955, as though it were the second comming. However, Chrysler was making a 331 hemi as early as 1951. Ford was still surviving with a top-of-the-line flathead and Chevy had it's oil-dipper 253 straight 6. By the debut of Chevy's 265, Chrysler was making a 300hp 354 hemi. (I run a 1952 331 bored to 354 that I will put up against anyone with a 2002 Chevy 350!).
4Jaw gave a pretty good rundown of the hemi. at lower class levels and normal carburation, big Chevies and Fords are competitive. However as you go up in horsepower and need to shove thousands of cubic feet of air and fuel through the engine every second, the hemisperical chamber is the only configuration that will accomodate it. They have been making a hemispherical combustion chamber as long as they have been making engines, from the 1800s. The thing that Chrysler patented was probably the way they got an additional fifth head bolt per cylinder in the 426 hemi. They tried to fit an additional head bolt from the top of the head but couldn't find a spot that didn't interfere with pushrod conduits or intake or exhaust ports. They finally came up with the idea of adding a bolt from the bottom by putting it the valve lifter area, thus it bolts the block to the head rather than vice-versa.
 
#23 ·
All very good responses, except for the fact that ,technically speaking,the combustion chamber is a "semi-hemispherical" (or 1/2 of a sphere). And yes they were "*** kickin" in there day, and continue to be the major contrubutor to the design of every top fuel engine on the track today.
M.F. :cool:
 
#24 ·
What is so special about a hemi?
What is so special about:
Long legs, short skirts?
90 or better on a physics test?
A movie on a really big screen TV?
Pulling a wheel stand?
An old gasser?
A six foot pot plant?
The chase scene in Bullet?
Stevie Ray Vaughn live?

Not everybody's got one or them, and they make people look and want one. Eye Candy! :D
 
#25 ·
I just caught this thread.
Im another good one to give answers to, because I have ran Chevy for a long time and now Im switching to Hemi power.
I love Chevy small blocks and they can run like <img src="graemlins/evil.gif" border="0" alt="[evil]" /> , but I just wanted something different. Not that Im agains sbc's, but I went to a car show today and I bet out of 150 cars that were there, including roadsters, willys, mercs, ect... there was Bowtie engines in 100 of them!
There great and inexpensive, but Im wanting something different. Will I outrun everyone? NO! Will I get all the Chicks with a Hemi? No! But I will get a ton of WOWS just because they are so different and rare.
I saw 2 Hemi's at that show today and thats unusual.
Any car with any engine can beat aqnyone on any givin day, no matter what your driving, but all the 6000 horsepower top fuelers dont drive Hemi based engines for no reason. HG
 
#26 ·
Mrfixmaster; Actually, the term 'hemispherical' is correct for half a sphere. The prefix "hemi" means half as in the 'western hemisphere' or 'northern hemisphere' when referring to geographical location on the earth.

A semi-hemishpere would be a quarter of a sphere which is what Ford and Chevy engines have for a combustion chamber and you know what a pitiful mess they are! <img src="graemlins/mwink.gif" border="0" alt="[mwink]" />
 
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