PETROL VS GAS VS WATER METH INJECTION

[Roderunner]

I tried injecting water/meth in my previous diesel engine some years ago, using a windscreen washer bottle/pump. 25% meth 75% water worked well, a 50/50 mix resulted in some pretty loud pinging along with an extra 25% more power. Injecting before the turbo usually results in a damaged compressor wheel so after the turbo and intercooler is the recommended place to plumb in the spray nozzle.

[geeves]

how did you control it? Does a windscreen washer pump still spray at full boost?

[MrRevhead]

I don't imagine a washer bottle system would be the best. Not enough pressure to atomise. But could be a good test bed to see if a more exspenive system is worth it

[Roderunner]

how did you control it? Does a windscreen washer pump still spray at full boost?

I used the jet from a petrol carburettor to limit flow, and injected before the turbo as I was only experimenting for a few weeks. If you inject post turbo then a one way valve needs to be placed in the line so that boost pressure doesn't force water/metho back into the washer bottle, if you inject pre turbo then be careful that the water doesn't get sucked into the intake tract (when the system is turned off) by the vacuum created when the engine is revving high. I used a toggle switch to turn the washer motor on, the water/metho was only going to be for short bursts of power when overtaking etc., I did plan on mounting a push button switch on the gear lever knob but decided to save for a professional injection system instead. Here's some interesting info: http://www.dieselpowermag.com/tech/1005 ... ewall.html

[gomulletgo]

Just started learning about this stuff, I find it really interesting.

Most people know that water into a diesel can hydraulic and destroy an engine To think you could get performance gains by just injecting water into the intake is amazing.

I've read a bit about it but one thing that I can't make sense of is this, in physics: energy is never lost only transferred. So when the fine water mist is sprayed into the intake air the water mist absorbs the heat from the surrounding air before it enters the engine, seems fair.....but now the heated mist also enters the engine, as the heat energy has only moved from the air to the water mist the same amount of heat should enter the engine

Intercoolers, radiators etc. All transfer the heat to another area that does not enter the engine intake, which makes sense.

[MrRevhead]

You are introducing water which is much cooler than the incoming air.
What happens when you have a sink half full of hot water and add cold water?

There is a little more to the power gains than just cooling as well

[geeves]

water cools the mixture but also on petrol cars prevents detonation so you can run more advance which is where the power comes from. Dont know how it works on diesels as diesel doesnt detonate without a lot of provocation.

[gomulletgo]

Thanks guys ,

That makes sense, the water would be cooler than the intake charge after the turbo but I can't see water temp being much different to inlet air temp pre-turbo unless the water is cooled somehow. Also I wonder how much heat soak from the manifold to the spray nozzle affects the water temp prior to injection.

I've also read about the cleaning effects of water injection, with the amount of blowby of the 4JB1-T engines I can imagine water getting past the rings, into the crank case, mixing with the oil and making a brown sludge that would make you think you've got a blown headgasket. If this oil/water mixing does happen it can't be good for engine lubrication.

[MrRevhead]

You only inject a tiny amount! No where enough for that

[gomulletgo]

Thanks MrRevhead, from what I read online apparently a lot of water is injected, so much that apparently a 1 Gallon water tank (3.8L-4.5L) can be totally drained on one climb up a hill.

[MrRevhead]

That's masses more water than fuel

[gomulletgo]

It does sound like heaps, perhaps they've got much bigger hills in the states. I think I read somewhere that people had 4-5 Gallon tanks of water to try and last them between diesel fills.