[hotrod]

You raise some interesting questions. The first point to address is can these systems be used in combination.

To that I would say probably yes.
The question to answer before you get much further into the problem is what is your comfort level for complexity, and how much user intervention do you think you are willing to deal with?

Each time you add an additional system your complexity goes up geometrically, ie. 2 power adders are probably going to be 4x as complex to manage and tune, 3 power adders 9x more complicated. Likewise your probability of failure and bad things happening also goes up very quickly. One of the lessons the space program, the aircraft industry, the computer industry and the nuclear power industry learned is that as the number of components goes up, the mean time between failures goes down. If you have a computer with 1000 componets that have an average failure rate of once every 1000 hours the computer will probably crash every hour.

In a compound system, you will also have systems that sometimes reinforce each other and sometimes work against each other. For example, WI works very well when the air charge is at high temp and low relative humidity. It does not provide nearly as much charge cooling due to evaporation when the intake charge is cool and at high relative humidity. The implication of this is that you will need to consider where in the intake system each system will provide the most cost effective benefit, and at the same time the least negative impact on any system down stream.

As a practical matter any one of the systems you mention alone, can push most engines to or near the breaking point, and I doubt if any common engine could survive long making the type of power available from a successful no holds barred combination of more than two of them.

That said, I am in the early stages of experimenting on a compound system for my car, but am not far enough along to give much useful info.

Here's some food for thought though:

Each system has some characteristics that imply how it might be used.

One concept is that the system that is capable of reaching the lowest intake temps should be the last in the chain (closest to the cylinder).

Pure water injection -- Has some charge cooling effect and modifies the effective octane of the fuel air charge. In large quantities it needs leaner mixtures and more ignition advance to produce max power. It has no significant effect on the effective fuel air mixture (ie does not increase or decrease available fuel oxygen ratio). It is less effective when air charge is cold and at high relative humidities. Can freeze out of the air charge if intake temps go too low, liberating significant latent heat of evaporation and solidification back to the mixture, in effect fighting other super cooling systems as temps go significantly below both the dew point of the mixture and the freezing point of water. There is potential for ice build up due to super cooled water dropplets freezing on contact with surfaces at very low temps.

Water alcohol injection -- Same as above but has higher cooling capacity during high humidity conditions, will reach lower intake air temps, and allows operation at moderate below freezing air temps. Alters effective fuel air ratio. In high concentrations of alcohol, it adds additional fuel to the engines intake charge, but modifies the effective fuel air ratio due to the oxygen content of the alcohol. It in effect changes the effective AFR if you consider the alcohol as part of the fuel load.

Chilled intercoolers -- can reach most any temp your willing to push it to (depending on flow rate of chilling medium). Has no direct effect on fuel air ratio, at high cooling rates slows combustion and will probably require more ignition advance. May ice up at high relative humidities in intake charge passing through the intercooler if super cooling is carried too far.

Propane injection -- Has significant potential cooling, is a pure hydrocarbon fuel with high natural octane. Will richen the fuel air mixture. Flow is not usually modulated by engine rpm in most cases cannot be used at low rpm as it will over supply fuel at low rpm and gradually lean out as rpm increases.

Nitrous injection -- Has significant potential cooling, is an oxygen carrier, DEMANDs high octane fuel to avoid detonation, needs fuel enrichment to utilize the additional oxygen provided, and prevent lean out of mixture, raises combustion temperatures and requires retarded ignition advance to avoid detonation, and prevent excessive combustion pressured due to faster combustion speed. Flow is not modulated by engine rpm in most cases cannot be used at low rpm due to enormus cylinder pressures generated.

As a group super cooling systems can act as though they lean out fuel air mixtures, by pushing the fuel pump, injector system over the edge into static flow --- you will need more head room on your injector and fuel pump sizing to allow for this.


Larry