# Water injection



## Nizmodore (May 9, 2003)

No, before your scream "SEARCH" this is not another no clue idiot asking about something that has been talked about quite a few times before....  

Some people here know that my job is building Clubmans (lotus 7 replica's) and we have run Nissan SR20DET's in them. Now these mtors require a intercooler (I know you can wind the boost down and run without, but why would you want to?) and the people who usually get us to build a cluman with a SR20DET want every last drop of performance out of them 

Those of you that have worked on/built (or even seen) the nose of any clubman type (our own designed clubman included) know that there is barely enough room for a decent intercooler (Cripes, there is barely engough room for a radiator!!!!! : rolleyes : ), so as these cars are mostly used for track work, the other idea is water injection (with a small intercooler)

Now I won't go into how it works and pro's/cons, not the best way to get a system rigged up......all I'm looking for is a little feedback etc on what I've done so far and what I'm planning to do......

O.K So I've made the actual injection system, the system consists of a high pressure pump (VL turbo/RB30ET fuel pump) supplying 3 and a half Bar of pressure (around 50PSI) to two Volvo Cold start fuel injectors. The system is pressure regulated by a BMW fuel pressure regulator. The water tank is very small I know, but its just for testing atm. On top of the water tank is a highly modified Alfa Romeo Sud low brake level fluid sender. Screwed into the distributor block is a VL Commodore Oil pressure sender switch. 










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I've gone through 3 versions, from the (highly) dodgy 1st prototype (pic 1) to the second version without any pressure control (pic 2), to the more refined 3rd version (pic 3).......and other idea's just post them on this thread for all to see....

After talking to a few people who tried (and failed) with water injection system, I determined that there where three major problems with their setups:

1. They were causeing hydraulic locks in the motor, by running to corse a spray, so the water didn't vapourise and ran down into the pistons (with direct manifold injection) or if they ran it infront of a turbocharger the spray hitting the compressor blades was like sand blasting them........A system will need to be designed to make sure that the water jets had sufficient pressure behind them so the water droplets would get too corse..... 

2. When they turn off their engines their water injection systems were still running, thus spraying water into the cylinders just as the engine stops.....Now leave an engine like this and bam! Hydraulic lock/rust in the bores

3. They had no auto timeing retard/boost cut when the system ran out of water......

4. Their system were not load sensitive 

Solutions to these problems:

1. The first problem I took care of in my 3rd version of the water injection system, I used a high pressure pump and Volvo cold start injectors, which are designed to give a good (fine!) spray pattern. Also I made a system with a simple transistor bias circuit that read from a VL Commodore Oil pressure sender screwed into the distribution block, that would turn off the injectors if the pressure dropped below 2.5 Bar (at below 2.5 Bar the injector spray patter becomes very corse) The result? a closed system that monitors the pressure and spray pattern and keeps it at its optimum level...if something does go wrong (eg pump failure, lack of water) the system will cut off.....

2. The second problem can be taken care of by useing a turbo timer like system. The water injection sytem is turned off and the engine is run for 5 mins before switching off, the burn/evaporate all the water out of the system ....no hydraulic locks 

3. Well as I'm working with a standard Nissan computer, I ran an output from the water inejectors through a relay, to the engines detonation sender. So if there is any problem with the system or the system is turned off, the detonation sensor is shorted out to earth and the computer winds back the ignition timeing approx 5 degree's. A lack of pressure can trigger this or low water. 

4. Simple run a boost sensor to trigger the Water turn on, or run a line off your air flow meter....I haven't tried the second one, but a airflow meter would be a more accurate measurement of an engines load

What water to use?!?!

Water is water...not.....and while pure water IS the best, the pump in this system requires to be lubricated by fuel (petrol) and in winter the water tank could freeze up ( Not a big problem since I live in South Australia, but the yanks may have a problem with it  ) 

Also I've been hearing Methanol is a good mix with water, since it also provides a handy power boost aswell. Its not as effective as water for cooling, but it does have the added bonus of makeing sure the mixture wont freeze, and more to the point, from my research I've seen people say it "softens" the flame front out, keeping detonation away.....I have no idea if this is true or not....still......

Now cast you mind back to 1944, The Germans with their Bf109G-6 Fighter. This piston engined interceptor was powered by a Daimler Benz DB605A Inverted V12 Liquid cooled 35.7 litre (!) Engine. The engine had provision for 2 engine power boosting systems, the first being the GM-1 Nitros Oxide system and the second being the MW50 Water methanol system. There was also a MW30 system....No wonder with all this power boosting the (heavy and slow accelerating) P51's of the USAF had trouble catching them after they bounced a B17/B24 (B25, Lanc, Halfax, Stirling, Wimpy if you wanna get picky) Formation  

The Nitros Oxide system is of no intrest, but still it weighed over 150kg more than the water injection system, and produced no more power than the water injection system.....but alas, the water injection was not good above 20,000 feet and the Nitros Oxide system wasn't too good below that......

MW50 is made of a Mixture of 50% CH3OH (methanol) 47-49% H2O and 3% of a special lubricant. I can't find any information on this lubricant, but I'd belive it would be some sort of lube to keep the water injection pump and injectors working......

MW30 only has 30% CH3OH (methanol) and 67-70% water, and again 3% of that special oil >:

So what do I use? ran a mixture of 50% Methanol, 47% Water and 3% unleaded through the pump for 4 and a half weeks on and off and I havent had a pump faulure....or the injectors. I belive the unleaded fuel is used to lubricate the pumps....it must be doing its job!

Now I'm a the stage of getting the injector blocks tig welded on to the manifold of my test engine (RB25DE with a blower on it) any thing I've missed? any extra idea's? please? Don't PM me, just post them in this thread....

Thanks


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