Thread: Water injection

Originally Posted by justinc

Mmm, I stand corrected. It goes against everything I 'know' about high speed objects (Turbocharger compressor blades) hitting a 'solid' as water is deemed to be in a whole 'droplet' form, but I guess water / metho and proper misting nozzles and not just water droplets are a goer then.

JC

You are correct, if the droplets are not small enough or you do not control the shut off (allow the injector to dribble) properly you can cause damage to the blades. Done correctly you can use it to control egt whilst adding power, it will also make the turbo more efficient if injecting pre turbo.

Originally Posted by two up

I am injecting pre turbo and pre inlet manifold, ar a ratio of 50:50 wm. The egts stay noticeably lower, in the vicinity of 100 deg Celsius, this is measured post turbo. One of the largest benefits is that you can control when it starts to inject so you are only injecting when you need it. I would suggest if your egts are going up you NEED to reduce your ratio of meth to 30:70. The increase in power is quite significant.

What is wrong with your tune that you need water injection to control EGT? Do you not have enough boost? Why are you measuring EGT post turbo?

Of course water/meth gives you more power. Methanol is fuel. Diesels also hate fuel being injected into the cylinders before compression.

Originally Posted by Dougal

What is wrong with your tune that you need water injection to control EGT? Do you not have enough boost? Why are you measuring EGT post turbo?

Of course water/meth gives you more power. Methanol is fuel. Diesels also hate fuel being injected into the cylinders before compression.

I am not using it to control the egt, but that is surely a benefit, I am using it to add fuel as my fuel pump is maxed out and I am at a power level I am now happy with, plus my turbo was near its limit, but a new billet wheel and a little machining will fix that problem. I have been measuring post turbo and using the 200 rule because it was easier to do at the time, but when the turbo comes off I will be switching over to pre turbo.

What is your reasoning for saying diesels hate having fuel injected before compression.

There is a couple of additional reasons I did the wm injection. It cleans the engines internals continuously, (reducing carbon build up significantly) lowers engines operating temperatures when pushed hard.

Originally Posted by two up

What is your reasoning for saying diesels hate having fuel injected before compression.

Because diesel combustion pressures and temperatures are high enough to detonate all liquid and almost all gaseous fuels.
The only way to prevent detonation is to only inject fuel when it's needed (which is how diesels normally work).
Any fuel introduced through the intake can detonate. Increasing engine stress far out of proportion with any power gains.

The only thing stopping your methanol detonating is the water in the mix. If you run too much methanol and not enough water, you're in trouble.

Originally Posted by Dougal

Because diesel combustion pressures and temperatures are high enough to detonate all liquid and almost all gaseous fuels.
The only way to prevent detonation is to only inject fuel when it's needed (which is how diesels normally work).
Any fuel introduced through the intake can detonate. Increasing engine stress far out of proportion with any power gains.

The only thing stopping your methanol detonating is the water in the mix. If you run too much methanol and not enough water, you're in trouble.

All the research I have done, and after having spoken to a mechanical engineer who has been using and installing wm in 4wd and large marine diesels for over 20 years, shows that this is only possible once you pass about 75% methanol to water. He said you have a greater chance of quenching the flame front if you use too much water meth at 50:50 .

Done PROPERLY it works well.

Originally Posted by two up

All the research I have done, and after having spoken to a mechanical engineer who has been using and installing wm in 4wd and large marine diesels for over 20 years, shows that this is only possible once you pass about 75% methanol to water. He said you have a greater chance of quenching the flame front if you use too much water meth at 50:50 .

I am a mechanical engineer, that's why I won't use anything like that.
Even if you don't get pre-ignition. You get a much faster combustion which gives the same problems as over-advanced injection timing.
It gives a spike in cylinder pressure which produces far more stress on the engine components (head, pistons, con-rods, crank, crank bearings) than the same power and torque levels on diesel does.

Which ultimately means you can blow head gaskets and crack heads at lower power levels.

Which is why I always ask why people are running methanol in diesels.
Some are running it as a tuning crutch. What they really need is more air through higher boost or better intercooling.
Some run it because they think it makes the engine run cooler. But trading off cooler EGT (which can be managed better with boost) for more engine stress is not good.
Some, like yourself, are running it because they are out of fuel. But as a performance enhancer it has several drawbacks.
- If a nozzle has a bad day it can erode the turbo or even hydraulic the engine.
- You're carrying around a lot of weight in the name of performance. 250cc/min is a low figure. An hour on the juice and you've gone through 15 litres.

But ultimately. Are you producing power figures higher than acheivable on diesel alone?

Dougal my system is controlled by a progressive controller and solenoid's, I am only injecting in high demand situations. For injection to start I need to be making 12lb of boost, and it reaches full injection flow at 20lb. Generally the only time this occurs is on steep hills. I carry 28 litres of fluid, driven sensibly this gives me a range of about 1000kms. On flat roads I could drive for hours without using a drop but I do take your other point,
If a nozzle clogs up yes I could damage a turbo, but as my system is controlled by pressure if this occurs the solenoid's will automatically cut flow to the nozzles.


From my current setup, yes I am producing more power than I could on diesel alone. To upgrade the fuel pump I am looking at a minimum of $2800 ,new turbo $1500 fitting/ dyno tuning $6-700
That will buy me enough methanol to keep me going the next 10-15 yrs.