Cold Air System

Cool air means more horsepower



The problems
Summer is on the horizon, sunny days, clear skies, and HOT temperatures.
I have had an on going problem, it is three fold #1 my engine modifications have raised my carburetor height about three inches, a 1” Wilson” plastic spacer, a 2” air element, and a K & N open filter top on a 14” air cleaner with a dropped base, this has created a restricted view through the rear view mirror.
#2 even with the open filter on top and a 14” diameter 2” filter on the circumference I suspected at full throttle their was a restriction of air flow taking place, choking my engine.
#3 I have always had a high temperature soak of the carburetor and now I am running 180’s, so this high temperature problem around the carburetor and fuel lines has become even more problematic. (fuel will boil at 200 degrees F.)





The solution
( get to the cool air )


Step #1 started with a new plenum from “Specter”, the dimensions are 15.8” x 7.75” x just 1.9” in height, the unit is welded aluminum and has 4” round inlets on both sides, the manufacture of all components “Specter Products”.

Step #2 was to plumb the 4” openings on booth side of the plenum by way of 4” aluminum tubes to where the cool air is, for my car that would be the side scoops that replaced the rear quarter windows.
This required more than a few measurements of the area between the rear window and the engine cover and from the center of the carburetor to the scoops ( see diagram ).
I decided as I was moving into uncharted territory to go slow (measure twice cut once). Since the routing would be a mirror image of the other side I ordered what one side would require, cut and fitted the components and then ordered the second side components. All tubes are 4”.
The “degree of bend” in the tubes was critical and after checking and re-checking the first leg of tube required a 35 degree bend with a 7” leg this carried the tube from the plenum to above the center side area, measuring from top to bottom.



The next tube was, again, after repeated measuring a 60 degree bend. All the tubes are, through their connection, able to be turned in the direction you want to go, but they are ridged and can not be bent, if you need to make cuts use a hose clamp to guide you hacksaw and keep the cut straight (WD-forty and patience).
The filter element was next, so I turned the 60 down and pointed it to the scoop and a perfect fit was achieved using a 10.5” cone filter, this put the nose of the filter inside the side scoop.

Let me take you through the solutions, # 1, for the very first time, I have a incredible wide open view of what’s behind me.

# 2 How does it breathe? I always say if you can feel it in the seat it’s real, no “dynamometer” yet, but at 5000 to 7000 rpm the difference it startling. It just keeps on pulling.

#3 for every 50 degrees of temperature increase over 100 degrees in your engine inlet air temperature you loose around 10HP, On a hot summer day you can loose as much as 30HP, here’s why, conversely, the colder the air the more dense the charge and the more oxygen can be compressed into the engine ( your engine is a giant air compressor), that’s why you will see drag cars loading ice around the intake prior to a run, or turbo applications where a intercooler is a must to provide a maximum air charge,


hot air is the enemy it robs your engine of hoarse power. I know because where I live the temperature is very temperate, so on a typical summer day when it’s 72 , my car runs perfect, but if I drive to L.A. where it’s 102 the car gets slower and you can feel it!
Since I moved the intake charge to the scoops outside and away from the excessive engine temperatures, my car runs the same at 72 or 102, WOW it really works!

My wife has an Italian word for it MACINA!
The Europeans use this word to describe powerful racy cars, I think it translates to bad ass! (see pictures)