Re: Fw: LONG RAM MANIFOLDS
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Re: Fw: LONG RAM MANIFOLDS
- From: Dave Casey <dcasey@xxxxxxxxxxxxx>
- Date: Thu, 12 Mar 2009 22:55:30 -0500
Please forgive me for being an engineer:
Because each cylinder only draws air for 1/4 of a combustion cycle, there
are "waves", as it were, in the manifold runners. This pulse of air pressure
will bounce off the back of a closed intake valve an go back up the runner,
hit more air, and get reflected back again. But this time, when it reaches
the valve, there's the air pressure from the first time plus some more from
that which reflected the first pulse. If the valve happens to be open this
time, you get more air than you normally would, and thus you make more
power.
The whole point of the length of the long ram runners is that they've been
tuned to resonate the air charge such that it hits the valve open. Because
of the timing involved, for the long rams this works better at higher RPM
when there are more pulses to sustain the standing wave. (The longer runner
gives a slower charge more time to die out from friction.) The short ram
intake uses runners half as long so it has twice as many pulses at a given
RPM, which helps it do better on the low end.
Tuned intakes are rather common, and the same can be done with exhaust, most
often on 2-stroke engines.
Among some of the crazy tuned intake designs out there inlude one that had a
flapper valve in it to change the length of the runners according to RPM. I
want to say Ford used it, but I can't recall for sure.
If you want to try to better understand the principles, do a google search
for "waveguide" and/or "standing wave". You might get an explanation
pertaining to radio or electronics, or fiber optics. You might also see
stuff about sound. It applies to all of them. After all, sound is just air
pressure. Frequency is proportional to RPM.
Dave Casey
----- Original Message -----
From: "William Lewis" <reatawhippets@xxxxxxxxxxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Thursday, March 12, 2009 10:33 PM
Subject: Re: Fw: LONG RAM MANIFOLDS
I had two buddies in the 1960-61 SF Bay Area, one had a '59 Sport Fury
with 361 single 4bbl Golden Commando and another with a 4dr hardtop '60
Dart with 383 long ram 2 X 4bbl. They raced at Half Moon Bay and Cotati
Drag Strips and though they ran in different classes (Sport Fury NSA and
Dart SSA), the Long Ram Dart could never sport an ET (nor the Trophies) of
the GC '59 Sport Fury. You probably needed Bonneville to get the benefits
of those Long Ram manifolds. Sure looked awesome, though.
Jack Lewis
56 Plymouth Fury
62 Dodge Polara 500
http://home.att.net/~furyjack/wsb/index.html
----- Original Message -----
From: "Jimmy Peavy" <peaver63@xxxxxxxxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Thursday, March 12, 2009 11:13 PM
Subject: Re: Fw: LONG RAM MANIFOLDS
You are right that they weren't used for drag racing.
I might add that they weren't used successfully for drag racing, but I'm
sure a few were tried, and used.
I think it would probably be more accurate statement to say that most
were used on the street.
I remember watching the CBS evening news and seeing a news item on the
long rams, when they were introduced.
They were so unusual that Walter Cronkite couldn't pass on mentioning
their introduction.
They were used to provide massive amounts of torque to the heavy Chrysler
cars, and Plymouths, Dodges in the late 50's and early 60's.
Some may have been used at Bonneville, but I'm not sure that they were
successful.
Most of the talk in the days of Bonneville at that time was centered
around stream liners like Challenger I and II.
I can't remember much written about the stock bodied cars in those days.
There weren't many magazines in those days, other that Hot Rod, Car
Craft, etc.
Most of that coverage was about customs, and drag cars.
Jimmy
Rich Kinsley wrote:
I know what you mean. The shorter ones were higher rpm's I think but I'm
positive the long ones were used on the Bonneville cars and not on drag
racing. I can find pictures I'm sure in my myriads of old magazines.
Rich Kinsley
=====================================================================
Jimmy Peavy wrote:
I thought they were for low end torque?
That by 4500 rpm it was all over on power gains.
I don't think that would be useful in a salt racer application.
Jimmy
Rich Kinsley wrote:
As far as drag racing goes, I'm sure nobody used the long ram. They
were
for top end like Bonneville. Norm Thatcher used them I believe on many
early 60's Mopars and set quite a few records. The old Hot Rod
magazine special, '60 Plymouth?, used them too I believe. The short
ram was the right stuff for dragging. I was talking to an old Timer
who said he was a factory racer in the day and he made his own
manifold at the perfect length, 19" or 20"?, runners. Then he said
they built them that way after his. I was talking to this guy here in
Omaha at a car show about 3
years ago. Take it for what it's worth.?
Rich Kinsley '64 Dodge Polara 4dr 318poly w/goodies
Rich Kinsley '64 Dodge Polara 4dr 318poly w/goodies
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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:
----
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:
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