On J230, the heat, and suitability of the Rotax 912ULS

[Bruce Tuncks]

I'd take that as an experimental find-out thing. As would the quantity of water needed, as the amount consumed can't be too much or the idea is non-viable.

Water injection is still in use for racing engines, and I reckon take-off is similar to drag racing.

My main problem is that it looks too good to be true, so why is it not widely used? Mind you, you can buy a kit for your racing car.

 

[onetrack]

Frank Kleinig of the 1950's and 1960's car racing fame, sold a water injection unit called "Mist-Master" in that period, and advertised it regularly in the Modern Motor magazine of the same era.

His idea was to not only assist with power increase, but also to facilitate clean engine internals and cooler running. The system was also useful for the often poor-quality fuels in that same period.

 

But today, you can purchase a highly refined, high pressure water injection unit from the Germans, in the form of the Snow Performance water injection system. This setup is very effective and well-regulated.

The major problem with water injection is ensuring no traces of water are left in the engine or intake when the engine is switched off.

Modern electronics can ensure that, as compared to Kleinigs relatively crude arrangement that simply relied on manifold vacuum.

 

https://www.snowperformance.eu/en/water-injection/boost-cooler-kits

 

Edited August 19, 2021 by onetrack

[Bruce Tuncks]

Thanks Onetrack. The snow system claim that their thing only uses 160 ml of water per minute, so a couple of litres of water would be enough for any climbout.

[Thruster88]

Water injection without making any other changes to the engine will make it run cooler because it will also reduce power output. Less power equals less heat.

[Bruce Tuncks]

Only if you put the water into the intake manifold onetrack. Applied to the cooling fins

this would not happen.

I think that any power reduction would in any case only apply to a non-supercharged engine.

[pmccarthy]

Wouldn't water on the alloy fins cause accelerated corrosion?

[Bruce Tuncks]

Good point PMC. Rainwater would be better I guess.

This leads one to think the effect should be seen if you fly through rain...  both the cooling and the corrosion.

[facthunter]

It doesn't reduce power output injected into the intake. Water methanol is best and you will get a significant power increase due increase in charge density/mass flow. Set it to operate at only near WOT for normal ops. It acts like an intercooler PLUS.. Your carbon deposits will disappear. Don't use at OAT's well below zero, but that's when you don't need it anyhow. Nev

[Old Koreelah]

20 minutes ago, facthunter said:

... Water methanol is best and you will get a significant power increase due increase in charge density/mass flow. Set it to operate at only near WOT for normal ops. It acts like an intercooler PLUS.. Your carbon deposits will disappear…

Just when I was happy to stop fiddling with my little Baby, you blokes have me almost convinced to do some more modifying! Cleaning out the carbon is the argument-clincher.

Where can I fill up with methanol?

[facthunter]

You can run straight methanol and run cool but you have to  richen it up a lot.   I'm referring to a  pre carb intake spray on a standard  system.. It's been used plenty of times..Nev

[Old Koreelah]

3 minutes ago, facthunter said:

… a  pre carb intake spray on a standard  system…

That would be very easy to install, Nev.

Injecting downstream of the carb would be even easier, because I already have a shut-down oiler setup, which I no longer use.

[facthunter]

I would think it's more effective upstream of the carb in principle. With injector engines even better .. FW 190 had it. Nev

[IBob]

I've been on DC6s that used water injection on very short strips. I was told it was to boost the engine output, while also helping improve cooling.

I would think the combustion pressure in the engine would increase: I would want to be confident the engine could manage that

[RFguy]

just to clarify everyone, we  (well I ....) am not considering water injection into the intake system

 

this is misting of the air mid cooling plenum to cool it down before the heated air hits the rear cylinder fins. the rear fins cop hot air. 

 

Or have droplets hit the rear fins, evaporate the water (instantly) and do the job. 

 

the accelerated corrosion ?, naaa its not doing enough hours for that. The humidity in the air 100% of the time would be a much greater mechanism.

 

 

 

[Old Koreelah]

1 hour ago, facthunter said:

I would think it's more effective upstream of the carb in principle. With injector engines even better .. FW 190 had it. Nev

Late model Japanese fighters also had water methanol injection. Besides the extra power, I assume they were running short of oil because so many of their tankers had been sunk by US subs, but they could produce methanol in quantity.

[RFguy]

humpback whale oil ?

 

[Old Koreelah]

Just as I’ve refined my water/metho injection design ready for installation, it occurs to me that metho is ETHANOL, the plurry stuff we try so hard to keep out of the engine! 

If I spray metho into my Jabiru carb only on wide open throttle, what rubber is downstream to be damaged?

 

 

[RFguy]

flexible silicone gasket compound  on inelt charge plenum pipes

flexible o ring on inlet charge manifold pipes

coupling 4 inch hose, inlet charge plenum to head manifold pipes

coupling hose between carby and inlet charge manifold. 

 

anything else ?

[facthunter]

You can use methanol (speedway  fuel) or ethanol. They sort of mix with water. You're only using it for take off It's not sitting anywhere except it's own tank. After the carby you are pretty safe. injecting before the Carby might get some into it's innards. petrol or mineral oil is no good for rubber.  neoprene would be OK with it. The worst thing about alcohol is it absorbs water and water like that is corrosive of aluminium and magnesium. Nev

[Old Koreelah]

1 hour ago, RFguy said:

flexible silicone gasket compound  on inelt charge plenum pipes

flexible o ring on inlet charge manifold pipes

coupling 4 inch hose, inlet charge plenum to head manifold pipes

coupling hose between carby and inlet charge manifold…

Thanks Glen. If a 50/50 mix of water/metho spray contacted those materials, what would you anticipate to be the worst outcome?

 

56 minutes ago, facthunter said:

You can use methanol (speedway  fuel) or ethanol…

Nev metho (ethanol) is widely available. If I went to the trouble of obtaining some methanol, is it likely to do less damage to sealants and hoses?

 

56 minutes ago, facthunter said:

They sort of mix with water. You're only using it for take off It's not sitting anywhere except it's own tank. After the carby you are pretty safe. injecting before the Carby might get some into it's innards. petrol or mineral oil is no good for rubber.  neoprene would be OK with it. The worst thing about alcohol is it absorbs water and water like that is corrosive of aluminium and magnesium. Nev

For my experimental phase, I plan on mounting a small garden spray bottle in the cockpit, pressurized before takeoff. 
The CHTs might tell me to give the bottle a few pumps during climbing. I can set the release valve to be open only during WOT. That should give at least a few minutes of running to clear out any water/metho residue before engine shut-down.

From my reading an approx 50/50 water/alcohol mix might suffice and be fairly safe in the event I prang the plurry thing.

Next time I light the Rayburn, I can experiment with a small clear measuring cup; we know the combustibility of 100% metho (woof water), so I’m interested to know how much water it takes to remove the “woof”.

 

[facthunter]

metho has something extra to make it taste and smell crook. You should be able to purchase ethanol cheaper than metho.  I'm not sure of the optimum ratio. Kurt Tank used it on the FW 190 and the Fokker F27 (turbo prop) uses it on most take offs.  t's pretty gutless without it.  There won't be any  carbon in the combustion chambers.  Nev

[facthunter]

It's a common thing to do for performance cars  Mix is 50:50. You can buy a pump and tank. Just google it. Nev

[kiwiaviator]

When I was in the RNZAF, we used water/meth mixture on the Hawker Siddeley Andovers. (Rolls Royce Dart 301's) It had a separate tank for this mixture. It made a noticeable difference on short strips and high/hot ops. The correct mixture was 63% water and 37% methanol by volume (tolerance was +- 1%) PPE had to be worn when handling as its extremely corrosive.

[Bruce Tuncks]

Metho is ethanol poisoned with an upper and lower boiling point substance. These are methyl alcohol and pyridine, a bitter oily substance.

The reason for the 2 substances is to make it harder to distil the metho . It is cheaper than ethanol because of tax reasons.

In the 50's, aborigines used to drink metho because they were unable to buy real grog. It did bad things to them.

I don't think that a temporary injection for take-off would harm the intake rubbers too much, but you are right to worry Old K.

Please keep an eye on the rubber hoses in the intake, and tell us the results of your trial.

[pmccarthy]

Not just Aborigines, lots of white metho drinkers back then.