What cfm rating would provide the most performance on a Magnum engine for a
holley projection Throttle body? Is more always better in this case or are
there other factors? They come in three sizes 660, 700, and 900 cfm and
there all around the same price in summit $380, $396, and $394.
-----Original Message-----
From: Rekker21@aol.com <Rekker21@aol.com>
To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
Date: Tuesday, July 07, 1998 6:57 PM
Subject: DML: V6 w/ a V8 TB
>this is copied from the July '97 issue of Mopar Muscle;
>
>In general, Magnums are under-carbureted (under-throttle bodied?). That's
to
>say, Magnums pick up sizable horsepower gains whenever throttle body
venturis
>are enlarged. Many carb specialy shops enlarge throttle bodies, or sell
you
>new throttle blades (machining required) if you want to increase the flow
of
>your OE unit. Going beyond .080 in the throttle bore is touchy because
you'll
>be close to the end of the OE computers map. Throttle castings start to
get a
>little thin in the venturi past that point. Even at .080, the body will
need
>minor filler in the venruti. V6 owners have another option----install a V8
>throttle body. OE V6 throttle bodies have 1-5/8 inch blades, while the
V8's
>are almost 2 inches. A sixer will need to have the manifold's throttle bore
>holes enlarged to 2 inches (best done at a machine shop) and you're done.
On
>a Mag Six, a V8 throttle body change is worth about a quarter of a second
and
>3 miles per hour!
>Yikes!!! Thats a pretty big jump for that mod!!! Ok read on though, Im
>reading more on the V8 mods and here it is;
>....while your V6/8 Magnum intake manifold is off, the next performance
stem
>is to shorten the runners as much as possible and cut two inches out of the
>plenum divider. This mod will add about 10/12 HP to your engine and raise
the
>shift points about 300 RPM.......Fortunately, both top-and bottom-end
>performance are enhanced. None of these grind/polish/weld V6/8/10
>modifications require a high performance computer (controller) because
factory
>computers require a great deal of latitude to cover everything between lean
>high altitudes to rich seaboard environments.
> .....concerning the lifters. They're real heavy and overcome the
strength
>of the lifter bore casting at high RPM. Spinning a Magnum to 5400 RPM is
>borderline, 5800RPM too much, and above 6000RPM can be the kiss of death.
>What happens is the heavy lifters crack the casting, start to wobble, and
the
>valve train self-destrucks. When the valve train starts to go bonkers,
you'll
>notice an upper RPM vibration, almost like the engine is out of balance.
>Either limit your shift points, buy a Fluidampr, or pray somebody develops
a
>lightweight lifter for the Magnum.
>Ok, heres the awesome setup Im thinking of, remember, this is all out of
the
>Mopar Muscle....:
>If you really want to go Magnum-performance wild, consider Holley's Pro-
>Jextion throttle body (various CFM ratings available) mounted atop onr of
MP's
>manifolds. This is a four venturi throttle body that's had the sprayers
>removed from the upper air horn are and uses the four venturi body as an
air
>regulation unit. This setup seems to work very well in conjunction with an
MP
>computer controllin the timing and fuel delivery rate. You can expect a 40
>plus horsepower increase over you stock setup. They're available from RC
>Performance Engineering. Rc has other Holley based systems for Magnum
ownerw
>who want to dial the cannon past stun and go straight to kill. Hmmmm does
>that make you think of any or all of us on the DML!!!!?
>Conclusion
> The intake manifold is probably the most underestimated piece of
>performance equipment on the engine today. When modified with even simple
>changes, it responds unbelievably well. Though some of these alterations
can
>get quite expensive, a bucks-down performance aficionado can still do quite
a
>bit on a Saturday afternoon's time span. Though the new millennia will
>undoubetedly bring further developments in the intake manifold, onte things
>for sure; as long as the internal combustion engine is around, it will
always
>have need of an intake manifold.
>Ok, thats it, thanks for you time guys, now that my fingers and wrist are
>killing me!!! I hope that has helped atleast one of us!! I did the intake
>mod before the 5.9 instal, and Ill tell ya, I thought it was awesome. Now
>that Ive done the TB its totally awesome!! DUDE!!!!!!! oops, sorry!
Anyway,
>its a lot of work, but it is definately worth it. Good luck all, and you
>should really get this edition of Mopar Muscle, the pictures in it are
great
>for this series of Mods.
>Later guys!!
>Eric
>
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