you should all be aware that when a turbo or superchargercompresses air, heat is a by product of that process. Generally, if you raise the boost pressure higher then 6 pounds, the inlet charge temps raise dramaticly. Once this starts to happens detionation starts to set in and the chances of a molten mass of engine occuring increase every second you detonate.
DETONATION EXPLAIN POORLY:
for those un-knowing... detonation is a process of combustion patterns being deformed/compromised. Instead of an even flame front spreading with in the combustion chambers, an additional flame created from detonation and when these two flame front colide, the cylinder pressures rise dramaticly. Often cracking ring-lands on pistons or far worse such as melted piston, cracked pistons, holed pistons, bent rods, and blown head gaskets.
PREVENTIVE MEASURES:
Theres a few different ways to over come the problems of detonation though, retaring timing is one way, but this method is a rather crude one, as power production is hampered. Increasing the efficiency of the turbo/superchargers compressor or constucting a cold air inlet tract is another, but can be costly. Using a form of intercooling be it water to air or air to air set up, is most likly the best option to go for in a forced inducted engine. But what if you dont have the room or the money to do the above?
WATER INJECTION:
Another way to cool the inlet charge is to inject water into the inlet tract before the ports. This method has been around for many many years even some planes from WWII used basic forms of water injection. Most punters have an understanding that water injection only works in an forced induced set up.... not so,
Water injection (WI) can also be extremely usefull on a natrally aspriated engine, with a higher compression ratio then the norm, as combustion temperatures in this sort of engine is also very high like its forced inducted cousins. Injecting water into the air/fuel mix has the same benefits as it would applying the systems to a boosted applications, However.... the gains are far greater in the boosted aplication. Some people are somewhat baffledas to howe throwing water into an engine can make it run any little bit better. But once they look into the practice their opinions soon change.
THEORY:
When water is sprayed as a fine mist it mixes in with the fuel, during this process, two things happen.
1. When water evaporates it cooles the surface of what it is in contact with. A good example of this is to grab a glass of water and stick your finger into it, take the finger out and blow air on to it. You would feel your finger getting cooler as the water evaporates, therefore when used in an automotive application, as the water evaporates it cooles the fuel and air molecules that the water is attached to.
2. In that process of evaporation, the solid particles of water (H2O) now becomes a gas- 2 parts hydrogen one part oxygen. Its common knowledge the more oxygen that we can cram into the chambers the more fuel we can add, thus creating more power.
But theres important things to take into consideration, like injecting too much water. Taking in too much water can drown out the flame front, add too much water and you get hydralic engine failure. What happens is when the engine takes a big gulp of water rather then air, and as the piston comes up to TDC, the water simply cannot be compressed. As you can imagine, something has to give. Sometimes its the rods bending, other times the pistons give way. or the worst case is the crank snapping. 1989 VN SS Commondore (304 v8) had several known hydraulic failures, due to the engine air pick up being under the front guard, and when driven through a decent sized puddle of water the engine would take in a massive gulp of water.....BANG!!! lol
THE SYSTEM IDEA:
most kits use a windscreen washer bottle and pump assembly, connected to a pipe with the end crimped off, and some pin holes in the end of it to regulate the flow of water, may sound alright now, but have a look at the flow characteristcs of the pin sized holes. they give of big solid dropplets... not what we need!!! A few weeks back a fellow, was having a BBQ out the back of his house, all his guest's were complaining how hot it was. This prompted the fellow to hook up a garden irrigation system, over head from his patio. each water dropping point was fitted with a mistral water fitting. This fitting gives of a very fine mist. The next BBQ that occured he switched on the system, the system gave a beautifull cool refeshing mist over everyone.....better then a cold beer!!!
THE SET UP/INSTALLATION:
Using the same mistrall jet fittings. Fitting then to the inlet tract, as the fittings were made of brass, so they were brazed to a sheet metal strip, which was then rivited to the air cleaner assembly. From the back of the jets, Festo 6mm pneumatic fittings and airlines, connect to a "Y" peice and then to a 12 volt DC solenoid. From the solenoid, flexable airline was run through the car back to a high pressure shurflo water pump. The pump is fed by a plastic jerry can also mounted in the boot/trunk of the car.
the jerry can..
as you can see.. its all done on the cheap, if ur serious.. grab a sheetmetal box to hold the water.
the pnuematic fittings...jets. air cleaner assemblys.
5 and 6: Festo 6mm pneumatic fittings and airlines merge into a "Y" piece before the 12v solenoid
using 2 mistrall irrigation jets to distribute the water. their design ensures a fine mist which easily atomises with the air/fuel mix. made outa brass, they were simply brazed onto a sheet metal strip, then riveted to the air cleaner base.
the Shurflo water pump has a built in pressure switch to prevent over-pressuring the system
a simple microswitch from a NOS set-up was fitted to the carby with a small cam like device used to activate it.
the microswitch then triggers this soleniod
WIRING/CONTROL:
The wiring and control of the system is very easy. The pump has a inbuilt pressure switch set to 3.45 bar (50 psi). the pump is wired directly to the ignition system and starts pumping as soon as the ignition key is turned. Another ignition cable is run to N.O. (normally open) contacts on a microswitch mounted on the carburettor.
From the microswitch, a wire runs to the coil on the solenoid. Naturally the other side of the coil is to ground/earth. A micro-limit switch from a NOS system, a small cam device activates it.
TESTING:
With the system completed, the key was turned. the high pressure pump started pumping as soon stoped onced it reached its preset 3.45 bar. A quick flick of the switch mounted to the carby activated the solenoid and BINGO!! There was a sneeze like mist emmited from the jets. the bennifits of the of the system were isntantly felt with 5 degree's total advance was implemented, and they could go 2 jet sizes bigger in the carby. Although no dyno testing was done, seat of the pants tests confirmed that performance was dramaticly increased.
Next step was adding some methylated spirits to the water at a 50/50 ratio to the water. Old time streeters agree this yeilds some decent gains due to its superior chemical compared to plain water. stick finger in a bottle of methylated spirits, and blow on it and see how much cooler it is compared to water!! Mind you, unlike water.... metho isnt free!!.
EVEN WITH an intercooler fitted, a water injection system can get better results. This CA18DET, is a prime example and thanks to its s14 turbo, front mount cooler,and water injection, it make 142kw at the wheels, with out water injection it detonates it's way to 124kw. The owner devised a system that uses a simple bilge pump, ball valve (to regulate water pressure), hobbs pressure switch, saftey shut of solenoid in case of low water, and a dash triggering switch. Water is injected prior to the throttle body, through a single nozzle and once activated, allows more boost to be dialed in. on a KW per dollar basis its hard to beat.
the below is the scematic of the 180sx install
cheers.joe.
I'll promise to drink water and shut my mouth so you can get a word in edgeways bro'.
