Chapter
10, Mile Post #12: “Huff and Puff, the Exhaust
Story” (Click here to read Chapter 9.)
Start Date
11-10-08
What ever
flows in must flow out and that is the story of intake
and exhaust in a nut shell. Because we will use a number
of different engine selections in the future sales of
the car, we decided to make the exhaust as universal
as possible. The 80 c.i.d. Harley engine uses a 1-3/4”
dia. exhaust pipe while the 100 c.i.d. Crazy Horse “V”
Power engine uses a 1-7/8” dia. exhaust. If you
ask Harley Davidson tuners and builders they say “don’t
use anything less than a 2” dia. exhaust pipes
and we don’t care about the mufflers, when ever
we use them”. There is always a big discussion
about the tuning of exhaust systems to produce the greatest
power and torque. With a car design like the TigerCat
we will not know until the engine is running what the
required tuning will be. The other question that will
remain unanswered in the beginning will be about the
pipe length of 96” plus a standard Harley Big-Twin
muffler.
After much
input it was decided to use 2” dia. pipe for all
engines selections and create the required “back
pressure” and “flow” using “restrictors”
at the cylinder head and at the muffler connection joint.
The larger 2” dia. pipe also acts like an expansion
chamber for the smaller engines (like the 80 c.i.d.)
which will give good RPM control and engine speed while
not losing any torque. With a car weight of 850 ~ 900
pounds we need to retain as much torque as possible
and this system of restricted pipes should do the job.
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The
2” dia. pipe as it exits the exhaust port
and runs to the down turn at the radius rod joint.
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Motorcycles
designers and builders always spend a lot of time
and money developing good looking “pipes”
and we must do the same. The basic Hot-Rod design
of our car and the exposed “V” Twin
engine allow for a nice shape and flowing lines
for the pipes. Down from the exhaust port, around
the corner of the Firewall, along the level of
the steering radius rods, then tucking down to
run along the lower frame rail and back to the
up-turned muffler. What a great looking exhaust
system. These twin “Sport Pipes” will
accent any paint and graphics works with a look
of power and style. In production the Sport Pipes
will be chrome plated and rubber mounted four
and aft. |
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The
good looking shape of the exhaust pipe as it runs
along the bottom of the frame rail to the muffler.
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In the future
we plan to develop a number of different exhaust pipe
styles,
1: Center crossover connection with simple single muffler
economy style, chrome head pipe and black painted tail
pipes.
2: The left head pipe crosses over to the passenger side
and then runs high and low along the bottom of the body
with short mufflers, chrome plated.
3: Competition style short pipes with simple outboard
turning exhaust tips which will end at the radius rod
joints, painted black and no mufflers.
With the
TigerCat it was easy to see which pipe set we would
use first. The natural line of the Sport Pipes was easy
to fabricate but even so we started out fitting the
1-3/4” dia. pipes to fit the 80 c.i.d. engine.
Then we decided to change the size to 2” but the
shape remained the same.
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First
we started with 1-3/4” dia. exhaust pipe
(as shown) but saw the limit of this size and
then converted to 2” for all engine selections.
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Sport Pipes will have two simple rubber “Lord”
type mounts at two locations on each side, one set just
behind the radius rod joints and one set just in front
of the muffler. The reason for two rubber Lord Mounts
at each location was to guarantee a back-up system. This
strong mounting system should resist bumps and abuse and
still keep the pipes in place and safe. |
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This
photo shows the “double” rubber Lord type
mount connecting the exhaust pipe to the chassis side
rail.
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This “long”
pipe and muffler combination will make driving a pleasure
as the exhaust noise will be well behind the driver and
passenger ears. The owner will also be able to select
a number of different mufflers and still have good looks
and a pleasant sound. The final muffler mount will be
a steel strut secured to the upper tail section and rubber
mounted at both ends. - Carl Myers
Click here to read Chapter 11. |
