Alfa's Hemispherical chambers and the Dodge Hemi

[Digger]

Greetings,

In re-reading some of my Alfa books, they state, almost casually, that Alfa Romeo used hemispherical combustion chambers in their engines, dating back to the 20s (IIRC)

However, Dodge made a "Hemi" muscle car in the, what? 60s? and a big deal is made about them, even to this day.

Is there something I'm not getting? Or are the terms "hemi" used by Alfa and Dodge two different concepts?

Cheers!

[okiealfaaddict]

Same concept. I can't remember where it was, but when all the latest hemi engines were coming out, I read that back in the '50's or early '60's Chrysler actually had an Alfa Romeo engine in their possession at that time.

[Touringspider]

It is a classic case of marketing and hype trumping the facts. There was another thread on this subject a while back, and IIRC it was determined that the first "hemi" was actually in a Peugeot.

There are a lot of features on modern cars that the ads will have you believe are huge groundbreakers, but have actually been around since before WWII, like pivoting headlights, the folding hardtop/convertible (interestingly again on a Peugeot) etc.

Arno Leskinen
AROC-USA National Concours Chair
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[DaveC]

The big deal on the Chrysler hemi is that its a pushrod engine. It is a big engineering deal to have the valves line up to their respective intake and exhaust ports using pushrods and rockers to open the valves. Its easy with an overhead cam engine.

Dave

[BigSwede]

Yeah, the pushrod is indeed a huge engineering accomplishment...

[Greg Gordon]

Chrysler trademarked the term "hemi" so it's largely a marketing ploy. However the 60's Hemis were the most powerful muscle car engines in the 60s excluding limited edition stuff. They were rare because the Hemi was a very expensive option. The fact that they dominated various forms of racing and the basic design still dominates drag racing certainly helps the image.

Mats, before you knock it, keep in mind the 426 Hemi put out just as much power per cubic inch as a 2.5 or 3.0 Alfa V6, probably more, and it could rev higher! It was a great engine.

[Murray]

Greg I've got to agree with you.Had a friend in the 70's who stuck a Keith Black prepared 426 Hemi in a 65 4-door Dodge Coronet with dog dish hubcaps.That thing could smoke just about anything on the road.If you could find some traction with the Polyglass tires it would pop its front wheels off the ground.The sound was an absolute symphony.I still prefer Alfas however !

[DaveH]

Quote:

Originally Posted by Greg Gordon Mats, before you knock it, keep in mind the 426 Hemi put out just as much power per cubic inch as a 2.5 or 3.0 Alfa V6, probably more, and it could rev higher! It was a great engine.

[Farace]

The 426 Hemi was factory rated at 425 HP, but the story going around was that the factory rated it low for insurance purposes and that it actually got closer to 500 HP in stock form.

[PSk]

Quote:

Originally Posted by DaveC The big deal on the Chrysler hemi is that its a pushrod engine. It is a big engineering deal to have the valves line up to their respective intake and exhaust ports using pushrods and rockers to open the valves. Its easy with an overhead cam engine. Dave

[MALDI]

The new Dodge hemi is DOHC with two plugs per cylinder (sound familiar?)

After some online searching... The 1965 426 in^3 street hemi produced 425 HP (source:http://auto.howstuffworks.com/hemi.htm)

426 in^3 = 6.98 Liters (source: http://www.onlineconversion.com/volume.htm)

So the Dodge produced 60.89 HP/liter

15 years later the 2.5L Alfa V6 produced 154 HP so its specific HP is 61.60 HP/liter.

So the Dodge was eithr ahead of its time or the Alfa was behind the times!

(This does not take into account the change in the way SAE horsepower was measured which occured sometime in the early '70s).

Anyone have the numbers for the Alfa Nord engine?

[PSk]

Quote:

Originally Posted by MALDI Anyone have the numbers for the Alfa Nord engine?

[MALDI]

So I would say the the Dodge hemi was advanced but not extremely far ahead of its time (well in marketing yes, but in engineering no)

[nicke]

Well, look at what happend to the Corvette pushrod 8 at the time the Alfa (half-pushrod) engine was introduced. Exhuast Gas Circulation, catalytic converters, low Ocatne un-leaded and fuel all this really naughty EPA stuff. I don't have the HP graph of the Corvette during the years, but I do remember reading a couple of recent tests of "smog" era cars.

The Dodge Hemi was probably running 10.5:1 - 11:1 compression on 100 octane gas, and no restrictive "cat" on the exhaust. I wonder what the Arese V-6 would do if optimised by the factory for the same fuel/emissions as the muscle car era Hemi?

Also remember that the Dodge engine's HP was measured without exhaust and or axillary systems...

Cheers. Nick

[PSk]

Quote:

Originally Posted by nicke Also remember that the Dodge engine's HP was measured without exhaust and or axillary systems... Cheers. Nick