same went for the six-pack guys too....in my day (early 70's)......lucky for me there were no well tuned 6-paks or even a Hemi car....Chebbies and few Rustangs....easy pickens for a fat kid with glasses a single 4-BBL GTX.
hemi advantage?
- Thread starter MTmopars
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same went for the six-pack guys too....in my day (early 70's)......lucky for me there were no well tuned 6-paks or even a Hemi car....Chebbies and few Rustangs....easy pickens for a fat kid with glasses a single 4-BBL GTX.
I was talking does a hemi have an advantage over the wedge now that we have aftermarket aluminum heads that flow well.
Hersbird
Well-Known Member
It's not the shape, and look at the pictures, not even close to 1\2 a sphere ever. So a 426 has a 4.25 inch bore which means for a true Hemi that center of the dish would need to be 2.125 inches deep. Anyway, what makes the power is the crossflow valves arrangement intake on the intake side and exhaust on the exhaust. That is what NASCAR outlawed.
67Dart273
Well-Known Member
Don't take things so literally. They had to call it SOMETHING for marketing
They could not call it "that big engine with the plugs out the valve covers"
They could not call it a "Eightssphere" or a Threesixteenthssphere
"PartialSpere" would have sounded...........half baked.
Besides, we couldn't say "hemi"
We'd half to say something dumb like, "that thing gotta ThreeSixteenths?"
And just to repeat, anybody that thinks a factory single 4 440 could come close to a hemi is vastly mistaken. I was there. Back then. I owned a -6 car and that thing would come close, and a few times...............very few times...............
moper
Well-Known Member
Nissan did it in the 80s with the 2.4L truck engine. It was fantastic, had EFI, dual plugs, and ran like Swiss watches. But - technology moves forward and now Nissan uses a closed chamber, 4 valve design with a dish and quench ring - because as good as you can get it - the true hemi shape is inefficient in terms of emissions and economy. There's too much real estate in there to really work well. Ford Escorts used to have a really funky piston in the 1.6L which was a semi-hemi to try and get keep the mixture away from that dead space with a big chamber. It worked - but not well.
Hersbird
Well-Known Member
I'm just pointing out to the people who claim the modem Hemi is not a Hemi. Well it is as much as the old one was, it's an opposed valve motor from Mopar just taking what they learned over 50 years and making it better.
Well, I have one. I spent MONTHS reading up on them before I turned a bolt on it. Some of yall on this thread need an education on the Hemi.
From Wikipedia:
"Main article: Chrysler Hemi engine
Perhaps the most widely known proponent of the hemispherical chamber design is the Chrysler Corporation. Chrysler became identified primarily by trademarking the "Hemi" name and then using it extensively in their advertising campaigns beginning in the 1960s. Chrysler has produced three generations of such engines: the first (the Chrysler FirePower engine) in the 1950s, the second (the 426 Hemi), developed for NASCAR in 1964 and produced through the early 1970s, and finally the "new HEMI" in the early 2000s. The "Hemi" engine introduced in 2002 by DaimlerChrysler had a combustion chamber featuring valve and twin spark plug locations markedly different from the second generation 426ci version. The current-production "Hemi" V8, with its pinched chamber, DOES NOT HAVE TRUE HEMISPHERICAL CHAMBERS despite the name; rather, it bears a closer resemblance to the mid-1950s polyspherical chamber, which Chrysler engineers developed as a lower-cost alternative head for their V8 engines. The polyspherical head needed less metal and was narrower due to using only one rocker shaft. This saved costs in material, space, and warranty claims and allowed it to be used in smaller vehicles. Chrysler's Australian-market Hemi-6 of 1970-80 had partial-spherical hemi chambers, though they were only 35% of a sphere."
From Popular Hot Rodding:
Cylinder Head:
"The advantage of a hemi design of combustion chamber is that the valves (and most importantly the intake valve) are always moving away from the shrouding effect of the cylinder walls (Fig 2) as they lift off the seats. However, the new hemi IS NOT ACTUALLY A TRUE HEMI as per its 426-inch predecessor. The hemi style of combustion chamber was put to good use during WWII when the output of supercharged aero engines could basically decide the fate of nations. For a two-valve combustion chamber, the hemi layout not only allows the largest valves to be accommodated but also to have the highest flow efficiency. The downside of a true Hemi configuration is that it does not respond well to a high compression ratio that inevitably requires a combustion-inhibiting, high-domed piston. For an engine with a typical bore/stroke ratio, this means it works great with a supercharger and CRs less than 8.5:1, but not as a normally-aspirated unit with 10:1 or more. To get around this problem the new Hemi has the sides of the true hemi form filled in. With the two spark plugs it is equipped with, this allows all the advantages of a true hemi, including blower capability, along with the ability, if required, to successful utilize high compression ratios."
I can keep going and going and going. They each have their ups and downs, but the new Hemi is NOT a true hemi engine. Period.
Oh and powdered rods SUCK nasty, bug infested rotten dead camel buttholes. They are weak and subject to failure. It is a common failure in the new "Hemi".
famous bob
mopar misfit
rotest: have yet to see anyone that`s full of info. on here say what truly killed the 426 type engines, "other than nhra and nascar killing them". you can not put as big a valve in a hemi as a canted valve head. look at the new hemi that jegs and alan johnson run!-just my 2 centavos----bobmoparlover
Well-Known Member
the real advantage (secret shhhhhh dont tell anyone) was the bottom end. the hemi was designed to go 1000 rpm higher or so. 8-bolt flange on the crank, heavier rods, 1/2" pickup etc. you can put all that into a 440 but then i think the hemi block is stronger lol. the heads had the advantage too, but the real secret is you can run a hemi 8k rpms and still run another race if you build her right. you can put big money into a 440 to run the same.
here's a quote from an old time racer over on moparts:
here's a quote from an old time racer over on moparts:
If you read the articles I posted, it clearly says this is one of the Hemi's advantages. You can put larger valves in them compared to a wedge because the valves are opposite each other rather than next to each other.
The main reasons the Hemi was discontinued was because of all of the motorsports sanctions, rising insurance costs, EPA clean car regulations and just like the 1st generation Hemi, cost of production.
67Dart273
Well-Known Member
I don't even know WTF this is supposed to mean. Nothing I said had anything to do with this???!!?!?!?!??!?!???!?!?!????????????!!!!!!.................................? HU?? H?
Hersbird
Well-Known Member
Rustyratrod, don't you see in your own examples how the modern hemi is an improvement? And I agree the modern hemi doesn't have truly hemispherical shaped chambers but I will say this again for the 100th time, neither did the previous 2 generations! So bashing the new changes for improving the design by saying it's not a "real" hemi is unfair. I agree with everything else you are saying.The new design is also an improvement in emissions as it allows for a better burn, basically the old design wasted fuel and potential energy with poor combustion burn.
jameskernz
duster Man
I had a 68 GTX 4 spd. and a friend had a 69 Roadrunner Hemi Automatic. My GTX put him down several times
I am not arguing it isn't an improvement. It is NOT a true Hemi. THAT is true.
Your friend was a poor driver.
Comparing motor vs motor doesn't tell the whole story either. He said the hemi was auto, his 440 was stick. I'd go out on a limb and guess it had numerically lower rear gear set as well.
How many girls in that hemi? Lol.
moper
Well-Known Member
Ah. gotcha. In that case - I don't think either has an overall advantage. Put enough head on it, configure the pistons to match what you have, match the rest of the combo and they will run similarly.
I think the main advantage a hemi has over wedge is unshrouded valve size for a given bore. And a 426 hemi makes 425 hp at 5000 but I imagine its peak power is much more and at much higher rpm.
For most application aftermarket wedge heads would be very competitive.
For most application aftermarket wedge heads would be very competitive.
Hersbird
Well-Known Member
Again, by your definition neither is the 426. Hemi is a trademark owned by Chrysler and now Fiat that is a marketing term. They own the term and whatever they want to call a Hemi is a Hemi. If Fiat wants to get into the packaged meat business and create a triangular shaped hotdog and call it a Hemi guess what? It's a Hemi. If by Hemi you mean a motor with hemispherical shaped combustion chambers then I don't think any motor has, the more accurate description would be domed shaped chambers.
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