Re: Beginners question sorry

["MO ( Steve Mick)" <micher@xxxxxxxxxxxxxxx>]

Thanks Gary for the poly lesson. I never knew much about them. I just know 
the old 318 ran pretty good !................................MO
----- Original Message ----- 
From: "Gary Pavlovich" <glpavlovich@xxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Thursday, December 10, 2009 11:52 PM
Subject: Re: Beginners question sorry


> Dave,
>
> The  318A "Poly" engine that many refer to is nicknamed a "Poly" because 
> the head design is a Polyspherical combustion chamber with canted valves 
> (angled intake & offset from the exhaust - not in the same plane and side 
> by side as the Wedge chamber) as opposed to a HEMIspherical chamber.
>
> The Plymouth Poly was produced from 1956-66 as a 277, 301, 303, 313, 318, 
> and 326 (1959 Dodge only) and shares many of the same parts as the later 
> 273/318/340/360LA Wedge-head engines.  Sometimes the aforementioned 
> Wedge-head engines are mistakenly called "A" engines which can be 
> confusing.
>
> Interestingly, the modern 4.7 Chrysler engines are a Polyspherical chamber 
> design and not a wedge design; even the new HEMI's are not true 90degree 
> Hemispherical valve layout.
>
> The BMEP, brake-mean-effective-pressure of a Poly engine is far superior 
> to the Wedge chamber and slightly behind the HEMI;
>
> "...the poly engine had one absolutely unique feature: its volumetric 
> efficiency. If the Mopar figures as found in the Plymouth factory manual 
> are to be believed, torque of the poly 318 was 345 lb.ft. Now, take torque 
> and divide it by cubes, then multiply this by 151, and you get brake mean 
> effective pressure (bmep). Try it for your self: bmep for the poly 318 is 
> 164 psi. (Again, that's the figure Plymouth gives). That is near to the 
> theoretical limit for an unsupercharged engine (and that's with the old 
> log-type exhaust manifolds too) and is very close to the 426 hemi's bmep 
> of 173psi, which had all those performance-designed components. The bmep 
> figure purely reflects breathing efficiency (proportional use of the 
> charge coming into the engine), and is a product of the head, as opposed 
> to the block, which just needs to suck/blow as rapidly as possible without 
> flying into little pieces..."
>
> Gary Pavlovich
> ----- Original Message ----- 
> From: "Dave Isle" <mnwildpunk@xxxxxxxxx>
> To: <1962to1965mopars@xxxxxxxxxx>
> Sent: Thursday, December 10, 2009 8:56 PM
> Subject: Beginners question sorry
>
>
> > I see a lot of you guys saying you have a poly this or a poly that. I 
> > know it is a type of engine but which one is it and what makes it a poly.
> >
> >                Thank you for being patient and answering this probably 
> > silly question.     Dave
> > Sent via BlackBerry by AT&T
> >
> >
> > ----
> > Please address private mail -- mail of interest to only one person --  
> > directly to that person.  I.e., send parts/car transactions and 
> > negotiations as well as other personal messages only to the intended 
> > recipient, not to the Clubhouse public address. This practice will 
> > protect your privacy, reduce the total volume of mail and fine tune the 
> > content signal to Mopar topic.  Thanks!
> >
> > '62 to '65 Mopar Clubhouse Discussion Guidelines:
> > http://www.1962to1965mopar.ornocar.org/mletiq.html.
>
>
> ----
> Please address private mail -- mail of interest to only one person --  
> directly to that person.  I.e., send parts/car transactions and 
> negotiations as well as other personal messages only to the intended 
> recipient, not to the Clubhouse public address. This practice will protect 
> your privacy, reduce the total volume of mail and fine tune the content 
> signal to Mopar topic.  Thanks!
>
> '62 to '65 Mopar Clubhouse Discussion Guidelines:


----
Please address private mail -- mail of interest to only one person -- directly to that person.  I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic.  Thanks!

'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.