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Do Lesser Emissions Out of The Exhaust Port Result In Higher Power Outputs

by Somender Singh    

Based on my Thinking & Understanding - Air and Fuel in the right proportions are compressed within the cylinder to a desired degree and then ignited to start the process of Combustion. The pressures developed out of the hot expanding gases due to Combustion forcefully pushes the piston down the cylinder to get the engine rotating to idle speeds. Any further increase in engine speeds to accept loads, requires a proportionate increase in the inflow of air & fuel into the cylinder to produce a stronger Explosion to sustain the loads !

If the air/fuel mixture making up the charge were to be consumed efficiently within the cylinder during the process of Combustion , the resultants would probably consist of hot exhaust gases rich in H2O in the form of super heated steam along with a proportionate amount of Carbon Dioxide CO2, while the inhered gas Nitrogen would probably flow in and out of the engine gathering some of the heat derived out of Combustion.

In reality the situation is far more complex than this, as the Oxygen atoms within the charge fail to burn more complete into CO2 & H2O due to improper and erratic Combustion patterns, thus leading to emissions of Carbon monoxide CO (Half burnt gases) and Oxides of Nitrogen NOx, while the unburnt fuel appears in the form of Hydrocarbons HC. (Please Correct me if I am wrong !) To further express my layman's Chemistry, the Hydrogen atoms within the Hydrocarbon fuels are the ones which pop and explode (once ignited) due to the presence of Oxygenated air. Further more this chain forms into a thermal reaction between the two to result in a phenomenon called Combustion !

(Luckily !) Air which aids Combustion of any type is Freely Available on our Planet and is made up of a natural mixture comprising of approximately ; 2/3rds of the inhered gas Nitrogen and 1/3rd of (valuable) Oxygen and a minute proportion of CO2. It is this vital 1/3rd part of Oxygen within the air that actually aids I C Engine combustion of any type on our Planet. Further more Air in a ratio of 14 to 15 parts by weight along with one part of Fuel in the form of Hydrocarbon is assumed to be an acceptable charge that achieve efficient Combustion out of I C Engines. This ideal ratio of air & fuel further contributes to producing efficient Combustion that produces Maximum Torque ! This Torque multiplied by RPM gives us the necessary power required to activate I C Engines of any type, may it be a car or a lawn mower or a truck or two race cars passing each other. All burning up vital oxygenated air in the process to achieve Combustion ! I C Engines come under the category of Air Breathing Engines as the major part of the charge consists of Oxygenated Air which is freely available on our Planet !!!? (How long, is all this going to last, is to be seen, at the rate engines of all sorts seem to be roaring to life and burning up vast quantities of air !)

TORQUE, then should directly relates to efficient Combustion and the outcome of which should lead us to the least emissions out of the Exhaust pipe ! But ! In reality several other design factors and elements such as the Fuel in use, the Density of the charge, the applied Compression, the shape of the Combustion Chamber, the Turbulence in the charge prior to ignition and the location of the Igniter and its Timing - All start to play a vital role to achieve this desired rate of Combustion to delivers & achieve this optimum Torque out of any I C Engine.

All this finally leads us to the insides of the Combustion Chamber ! The Combustion Chamber is the volume of the cylinder at the end of the stroke during which time the trapped air/fuel mixture (in the form of a charge) is compressed to the maximum, while ignition has just occurred to start the rapid process of Combustion ( Not Explosion ! ) in which the ignited Hydrocarbons are aided by the surrounding Oxygenated air to achieve a fast rate of burn within the charge. During these crucial mili seconds minute fuel particles need to meet up with the right proportions of oxygenated air to accomplish a continues even chain of fast burn in the remaining air fuel mixture to produce the required optimum pressures out of Combustion. It is these pressures which act upon the piston to generate and deliver the necessary TORQUE !

Hence this story actually starts at the very source of Ignition which really starts & triggers this quick chain of burn in the conducive compressed surrounding of a volatile charge of air & fuel forming into rapid waves of flame fronts that eventually penetrate and consume the trapped charge within the cylinder by delivering a power stroke in the shortest time frame -To achieve this form of Efficient Combustion , the Air and Fuel mixture consisting of hydrocarbons and the oxygenated air (that includes the 77% of the inhered gas Nitrogen too !) all need to be in a perfect blend & bond & maintaining an equal ratio of 1:15 in the form of a charge and remain so, as the pressures build up within the cylinder prior to ignition and during Combustion !

This leads us to a interesting question, does a premix of air and fuel, forms into a better blend that aids quick burn Combustion - OR - In-cylinder injection of fuel which needs to meet up with vital oxygenated air in its path to form into an efficient burning flame front within the trapped charge during the process of Combustion.(as fuel alone can't burn !) Most often the time available to achieve this perfect blend of air and fuel during the process of Combustion is very short in an expanding cylinder on the power stroke. Thus what is not efficiently consumed result in Emissions !!! Hence turbulence in the air fuel charge is a very essential contributing factor to attain Efficient Combustion. Proven methods are to induce a swirl or tumble motion in the charge that lead to a ideal mixture formation in the charge prior to entry into the cylinder. It is also known, higher compression ratios rob the induced turbulence within the charge further due to the progressive density increases in the air fuel mixtures prior to ignition and during Combustion due to the steep pressure build ups!

At this point of time it is hard to understand how EGR (Exhaust Gas Recirculation) helps to bring down emissions while burnt gases rich in CO2 , CO & NOx are pumped back into the cylinder to form a perfect blend lacking the vital Oxygen in the air fuel charge to derive efficient Combustion that produces Torque ! Moreover the heat in the recycled exhaust gases are sure to drastically reduce the volumetric efficiency in the intake charge further resulting in energy losses required to compress the over heated charge on the compression stroke. The higher temperatures burn lubricating oils & sealents leading to excessive formations of carbon deposits in the internals of the engine and the combustion chamber as well - All contributing to further increases in operating temperatures that could easily lead to instable and erratic burn rates. Over Heated combustion chamber contribute to a single Explosion within the charge resulting in Detonation ! Also known to destroy engines and produce Tons of NOx !!!

If the principles of EGR were that effective, 2 stroke engines ought to have functioned much more efficiently with lowered emissions ! Further more Diesel engines do not feature any form of ristrictor or throttle body valves and draw in more air than necessary during operation i.e breathing in air at a constant ratio in relation to cylinder displacement x RPM. This excess intake of oxygenated air results in wastage and polluting most of the un -utilized air at mid & lower RPMs ! Diesel engines further pump in more fuel than required to accelerate and reach higher RPM's under load. The outcome of this in Diesel engines expel large volumes of polluted air along with soot ! Believe It Or Not !!! The end results of which beautifully contribute to the formation of Smog ! and Acid Rain !!! Which now happens to be a daily occurrence in most Metros spreading into the suburbs!

All in the hope to achieve Efficient Combustion out of I C Engines !!!

Today's Hi-Tech engine management systems rely heavily on external sensors that aid sophisticated computed monitoring devices controlling vital fuel inputs, assisted by variable valve timings and ignition timings backed by dual ignition systems !!! While the real issue of Combustion resides very much inside the internals of the Combustion Chamber where Combustion actually takes place and occurs ! The reflections of this Combustion are measured in TORQUE generated out of the available Charge burning within the cylinder !

Has the Industry or any one else come up with any revolutionary Combustion Chamber Design which actually manages to burn the air fuel charge more complete in-cylinder by producing more Torque out of the same drawn in charge and further discharging the least resultant Emissions of HC, CO, NOx & CO2 out of I C Engine Combustion into the Atmosphere !

Considering the progress made by the Global Industry in the last Century - Is such a concept possible out of the existing 2 & 4 Cycle I C Engine in the near Future ! Incidentally This Happens To Be The Need Of The Hour !!!

We would be grateful Sir, if you could Kindly throw some Light on this subject of Efficient Combustion out of I C Engines which emit the least emissions without the aid of catalytic converters, Which I call - After-Burners !!! And get the maximum utility out of the air fuel charge by burning the remnant HC & CO emission more efficiently inside the cylinder to achieve optimum thermal efficiency out of existing I C Engines !!!

This leads us to an elusive engine, which produces maximum Torque, from the least amount of air & fuel , at the lowest revs, spewing out the least amounts of emissions into the atmosphere without the aid of expensive Afterburners!!!