Quote:
Originally Posted by Schurkey
No catalyst before model-year 1975. I think you mean "Thermal Reactors".
Essentially after-burning exhaust manifolds fed with fresh air from the AIR pump or the Pulse Air system. The added oxygen allowed the overly-rich mixture to continue to oxidize.
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Ah, you are an automotive engineer - I say that with no disrespect. So here is the complete info I got this from as the word "catalytic" caught my attention. The topic is headed
AFTERBURNERS. My book source is published 1968 and specific to automotive emissions systems of all the US manufacturers and the diagnosing, troubleshooting, calibrating, and repair of the systems.
"The two types of afterburners that have received extensive development work to date are the catalytic and the flame type. The catalytic afterburner is designed to consume the discharged hydrocarbons by means of
heat developed through a chemical reaction. The units may be positioned at the muffler or in the exhaust manifold. Chemically coated pellets are arranged so that the flow of hot gases activates them; the pellets then promote oxidization of the unburned hydrocarbons. The flow of gases also must agitate the pellets in order to reduce carbon build up in the catalytic bed. Temperatures required to maintain this chemical reaction range from 400 degrees to 1,300 degrees."
So, as you can read, it is exhaust heat activating chemically treated pellets -
not air injection.
However, the same section also describes another system - a flame-type afterburner:
"The flame-type afterburner consumes unburned hydrocarbons by means of an open flame. This system requires the adjustment of the carburetor and distributor to produce, as fuel for the flame, a controlled concentration of the unburned material in the exhaust stream. The exhaust must be kept rich enough or the afterburner will "flame out." If the exhaust is too rich, the unit will burn out from excess heat. Also, the extra gasoline needed to keep the burner going exacts a 3-7 percent fuel consumption penalty."
So both devices/concepts use heat and I fail to see in the description of either anything about injecting air?
The type system you describe has nothing to do with a catalytic system as described above, but the Air Injection Reaction System (A.I.R) is what you reference. For your recollection, and the others who may have never even seen one of these nifty units, I will clarify and describe some basic operations of the system.
"The AIR system consists of an air pump (belt driven) that constantly forces air into each exhaust port immediately after the exhaust valve. Since the exhaust gases at this point are above kindling temperature and have an excess of hydrocarbons, the infusion of oxygen starts the mixture burning and so consumes the hydrocarbons that normally would be expelled into the atmosphere.
The AIR system pump draws air from the air cleaner/air filter canister and forces it through two outlet hoses (one for each side on a V8 engine) through a check valve and into an air manifold, where it is delivered to each cylinder through stainless steel nozzles that project into the exhaust port."
I won't get into the fine points as the system has many features in the event of backfires, pressure changes, high speed pumping, and the like.
