Why the early Hemis were discontinued (Was The Forward Look)

[dardal@xxxxxxxxxxxxxxx]

Don, in a way both you and Arron are correct.  Yes, the Hemi has inherent 
volumetric efficiency benefits.  However, the displacement requirements of the 
industry were increasing, and the Hemi reached its displacement limits at 392 
CID.  That's what Arron is saying.  Even at 392 CID, it already had a 
relatively long stroke, which will reduce somewhat the volumetric efficiency.  
My guess is that in terms of power per cubic inch, the earlier shorter stroke 
hemis were superior.  In the Chrysler 300's, the 413's ended up being faster 
than the 392's.  However, in the Imperial lower state of tune, it appears that 
the 392's were a bit faster than the wedges, till the 440 appeared much later.

Here is an added point that Arron just toutched.  The main reason that the Hemi 
was designed and introduced for a non-racing car in the late 40's was the very 
low octane available back then.  The central plug location of the Hemi (as 
opposed to the side location of a wedge) allows the engine to use a higher 
compression ratio due to its knock resistance.  It turns out that when you 
increase your compression ratio from say 7:1 to 8.5:1 or 9:1 (remember, we are 
dealing with very low octane numbers here), you get a very serious efficiency 
imrpovement.  Then, in the late fifties, the octane increased sufficiently that 
any wedge could run with 10:1 compression ratio.  It turns out that increasing 
the compression further (say 12:1) does not give as much of an incrememntal 
advantage in efficiency and can reduce durability, so it made no sense for a 
non-racing engine (a racing engine is a different story:  there, even 2 extra 
horsepower can win you the race, and durability is no concern).  So, the main 
advantage of the Hemi for a non-racing car became obsolete.

D^2

Quoting Don Nonnweiler <dnonnwei@xxxxxxxxx>:

> Arron
> I disagree that they were an outdated engine as they were used in racing
>> on and by because they needed a lowline engine for the plymouth and
> lessor
> Crysler cars,but it didn't take long to find out they were inferior to
> the
> wedge in the breathing dept.  By the way the wedge was out in all
> 59 Crown
> ----- Original Message -----
> From: "A. Foster" <monkeypuzzle1@xxxxxxx>
> To: <mailing-list@xxxxxxxxxxxxxxxx>
> Sent: Monday, December 23, 2002 12:10 AM
> Subject: IML: Why the early Hemis were discontinued (Was The Forward
> Look)
> 
> 
> > Don;


> >  No one wants to hear this but by the time Chrysler discontinued
> making
> the
> > early hemis they were an outdated engine anyway. This is not to say
> that
> the
> > Hemispherical concept was outdated, many engines before, during, and
> since
> > were built with Hemi heads, just that the Chrysler design was. By the
> time
> > the RB wedge engines replaced the hemis in 1959, actually in 1958 on
> DeSotos
> > and Dodges, the hemis had been bored and stroked to their practical
> limit.
> > In order to go any further in displacement with any of the early
> Hemis
> they
>