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With the 9-inch Kinsler ram tubes exchanged for the D,C&O 3.5-inchers, the engine loses a
certain amount of retro bling. But will it run harder? The AIT sensor has been transferred to
the No. 4 ram tube.2000220024002600280030003200340036003800400042004400460048005000520054005600580060002402702101501801209060300300Short TubesLong Tubes, Torque (LB-FT)9-Inch vs. 3.5-Inch Ram Tubes Long Tubes, Power (HP)
284
259
(^273269)
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Above: As this overlay suggests (short-ram tube data on lower
curves of horsepower and torque), with the 3.5-inch ram tubes,
the 4.6 lost 5.3 hp and a whopping 25.7 lb-ft of torque. The area
between the curves represents the lost power. But notice how
the horsepower peak rpm moved up nearly 600 rpm, from
5,370 to 5,933 rpm. This supports years of evidence that shorter
tubes tend to affect high-rpm power.
200022002400260028003000320034003600380040004200440046004800500052005400560058006000
240
270
210
150
180
120
90
60
30
0
300
No Tubes, Torque (LB-FT) No Ram Tubes No Tubes, Power (HP)
248
258
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Above: Without streamlined openings to help straighten the entry
of incoming air, the incoming rush of air impedes flow around the
circumference of the inlets, effectively making them smaller. This
cut cfm and output to 257.9 hp at 5,927 rpm and 248.2 lb-ft at
3,727 rpm, losses of 16.4 hp and 37.3 lb-ft, versus the peak
readings with the 9-inch ram tubes. Just as with carburetors,
flow-straighteners are important with ram tubes.
To work their best, ram-tuned eight-stack FI systems shouldn’t have
flow obstructions; that means air filters. I’ve found that the height
of the 9-inch Kinsler stacks and the law of gravity prevent solid road
debris from reaching their vulnerable openings. That said, I never
follow dump trucks hauling dirt, stay off of unpaved roads, and
avoid jokers with loose change.
What happens when you eliminate the formed ram tube opening?
To see, we removed all eight tubes to reveal the raw 90-degree
edges of the D,C&O 1^15 ⁄ 16 -inch throttle-bodies. In this mode, the AIT
sensor was placed by the firewall to read ambient air temperature.
Before running, ESP’s Dave Brady used a shop vacuum to remove
accumulated road grit from recessed areas of the manifold to
prevent damaging ingestion at WOT.
24 CAR CRAFT AUGUST 2019
fuel-injection manifold from Australia’s
D,C&O via Sean Hyland Motorsports.
Computing power comes from a Holley
EFI system, with extra-length MSD
spark-plug wires to permit in-cabin coil
mounting for a retro Ford 427 SOHC/
Chrysler Hemi vibe.
Homemade fenderwell headers
send exhaust gases through a set of
Dynomax mufflers. A Tremec TKO-600
five-speed gearbox and 3.73 Traction-
Lock 8.8 rear axle round out the drive
line on this street-legal, 2,759-pound,
neo-retro, what-if hallucination.
With the stage set, let’s juggle some
ram-tube lengths and see what effect
it has on engine output.