How Do You Make Turbo Engines More Efficient? Just Add Water | Hacker News Reader

How Do You Make Turbo Engines More Efficient? Just Add Water

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The process is actually more efficient with a 50/50 mix of water and methanol. When the water reaches threshold there is additional release of oxygen which at temperature can be consumed by the combustion of methanol, thus reducing overall fuel consumption while increasing efficiency. This has been done in the diesel world for years.

How does that work? Water will dissociate into hydrogen and oxygen at very high temperatures, but the mixture of hydrogen and oxygen so produced is already stoichiometrically balanced. There's no surplus oxygen left to be reacted with additional fuel.

The confusion was on my part, I used release of oxygen but it is probably better explained as intake of oxygen, the cooling effect of the water leads to a higher air density in the mix of atomized air. The water is not releasing more oxygen rather there is more air in the cooler denser mixture of air, water and methanol, the water vaporizes thus creating more volume and then the methanol flashes and consumes the additional oxygen that is brought in via a cooler intake, it is my understanding that this oxygen is only available after the flashing of atomized water into gas, thus I used the term release (which is a poor choice of words for the process). It works similar to an inter-cooler, but unlike an intercooler the mix seems to preserve some oxygen for the methanol combustion cycle so it is more targeted then just forcing more oxygen into the intake via a denser volume of air (e.g intercooling). Sorry for the confusion on what is actually happening, you are correct it is not separating hydrogen atoms from oxygen atoms. If that where the case then as you said, there would be no need for the methanol as it would be generating the additional fuel via hydrogen and oxygen in the generated browns gas to burn it.

Not an engineering expert --- but isn't this the same idea that was being used in aircraft engines to get the max power out of turbine engines?

The B-52 is the classic example (nasty exhaust plume is the hallmark of these water injected engines):

https://youtu.be/xfTdRF66QPo?t=218

edit: I thought they phased this out in the 60's but was surprised to see the video above was from 1989!

Exhaust plume? Silly you, those are chemtrails!

In another interview about this tech, Bosch said that the engine will not be allowed to run as hard if the system detects there is no water - so you basically have a non-water enhanced system when you're out of water.

I'm not an engine expert, but I thought a substantial disadvantage of water injection was incomplete combustion (see for example the billowing smoke here: https://en.wikipedia.org/wiki/File:Boeing_KC-135_J57_wet_tak...

They may be more efficient, but is there a pollution concern?

I'm no expert either, but according to https://en.wikipedia.org/wiki/Water_injection_(engine), it actually reduces emissions.

In turbine aircraft engines that is not the case though.

Injecting water inside turbine engine causes fuel to go unburned, hence the black smoke.

I'm also no expert, but a bit of a hobbyist...

Water injection will reduce the temperature of the combustion chamber. If you take an engine already tuned for the temperature of minimum emissions and inject water, then obviously you will upset that equilibrium.

If you took an engine properly tuned and just add boost (by boost, I mean increasing the pressure of the air at the intake manifold, which allows more oxygen into the combustion chamber), then you will increase engine knocking and raise the temperature of the engine, thus increasing NOx formation. If you then add water injection, that can balance things out again.

Obviously all of the above is an extreme simplification, and in addition, you have to deal with the case where there is no water to inject. Previously this would have been a real concern, but with modern computer controlled engines, it is possible to reconfigure the engine while it is running for some combination of reduced boost, less aggressive timings (including late intake valve timing, if your engine is setup for that; this effectively reduces the compression ratio of the engine), and richer fuel-air mixture.

With modern computers the combustion process can be controlled to such a degree that this is a non-issue, but with that said, see my post above on water methanol mixture, incomplete combustion can be solved by the addition of methanol. As well there is already a ready source of methanol/water mix at every gas station as that is the formula for windshield wiper fluid.

Windshield fluid is made from all sorts of various formulae. In areas with cold winters it may be methylated ethanol, or ethylene glycol. In Southern California, it's mostly water.

People already complain about having to refill AdBlue for their Diesel engines - and you realistically only have to do that every 6-12 months! MotorTrend did a review of that M4 GTS and it worked its way through the 5L water tank very quickly. So how often would the consumer need to refill the tank in a normal, non-sports car?

Fairly certain that BMW is using distilled water, so you can imagine a warranty coming into play using tap water. All those M4's have been spoken for so real BMW enthusiasts will do the right thing.

This system would probably be great for high-end BMW owners (not the regular ones, just the really rich ones buying $100k models), who can be counted on to get their car serviced at the dealership very frequently.

For regular Americans, it'd be a disaster. The tanks would run out and the engines would fall back to their "limping" mode (the safe mode that doesn't need water injection), which would likely have even worse fuel economy than if they had just stuck with regular gas-powered engines without water injection. This would cause the fleet fuel economy to fall greatly.

EVs can't come fast enough. At least almost every American seems to be able to handle plugging in their phone regularly and keeping it charged up.

Actually, if you watch the review of the M4, they very directly say that in case the water runs out the engine performs exactly as the same, non water-boosted engine. So this whole sentence about water-boosted engines that are worse than non-water boosted ones when without water is garbage.

And evs are still not a solution for everyone. There doesn't seem to be any good idea on how to own and charge one if you live in an apartment with a shared parking lot or if you have to park on the street. You say that water-boosting will work great for people who buy $100k cars, but at the moment, it looks like EVs are only usable for people who can afford a house with a driveway.

People barely refill their windshield washer fluid. Asking them to refill a tank with distilled water is a bit of a stretch. Not that I have anything about water injection (I use it).

"People barely refill their windshield washer fluid"

Where are you? I find that cars become pretty much undrivable within a very short time if the windshield washer fluid runs out - particularly in winter.

NB I'm in Scotland.

California native here. What is this 'winter' you speak of?

In all seriousness, it takes about a month or more worth of dust buildup before the view out of my windshield can be considered to have been obscured in any way. Thankfully it rarely gets to that point since I usually clean my windows when putting gas in my vehicle.

Not only that, but the windshield washer fluid you can buy in the Bay Area is NOT the kind that doesn't freeze. Which could lead to a surprise if you head up to Tahoe for skiing. You can buy the anti-freeze kind up there, but you are supposed to "promise" not to use it back in the Bay Area.

I actually discovered this by accident one morning a couple of years ago. We do get the occasional sub-freezing morning temperatures here during winter. One such morning I used my windshield washers and wound up with a nice, blinding sheet of ice on my windshield.

I had to pull into a parking lot and scrape it off with a debit card. Rather dangerous situation for those of us who don't encounter real winter weather often.

I would say 20 minutes for car to become undrivable on a bad day in winter if no windscreen washers.

I know this from bitter experience of letting my washers freeze up and having to stop and clean the windscreen with coffee every few minutes!

Edit: The combination of low winter sun and heavily gritted and salted roads is probably the cause.

My car has been screaming low washer fluid at me for months. Luckily I'm due for an oil change.

You know it's spring in Alberta when you consume more windshield fluid then gas!

Southwest Idaho here. Haven't filled my windshield fluid more than once since I moved here 8 years ago... Very little rain. Very little muck on the roads. Minimal bugs. Park car in the garage every night. When I lived in the Northeastern US I used far more windshield fluid.

I would be afraid to ask some people in the US to refill their washer fluid. It will end up in the coolant or possibly oil. Although some diesel owners can apparently handle refilling the AdBlue tank or the dealer handles it.

The British driving test contains questions with the hood/bonnet up 'where would you add oil?' etc

Most Americans would never pass that test. It's a wonder we can even figure out the gas and brake pedals, and even there we frequently get confused, and then sue the automaker for "unintended acceleration".

My wife got a new car, and I looked up in the owners manual for what kind of oil it takes. The manual's section on changing oil was "To change oil, take car to an authorized Kia workshop." I died a little inside that day.

[edit]

Fortunately there was an "SAE 5W25" indicator on the oil reservoir cap.

You should get a new Mazda. I have one, and changing the oil doesn't get much simpler, though I do need to use tire ramps to get under the car, though I don't think that's too unusual for a car. The bottom is covered in a big plastic cover for aerodynamics, and there's a small access panel that's easily removed for access to the drain plug and filter (which are right next to each other). Take out the plug (you need a big allen socket, not too exotic), drain the oil, and then just reach up and turn the filter to get it off (the filter is mounted with the opening upwards, so it won't spill oil all over when you take it off). Put the new one back, replace the bolt (with a fresh crush washer), replace the access panel, then put 0W-20 in the port that's right on top of the engine. I'm pretty sure the owner's manual just has a section telling you which grades of oil are suitable for which season.

From everything I've seen, if you want a car that you can work on yourself, Japanese is the way to go, and German is the absolute worst. Japanese cars seem to be designed for serviceability much more than other makes. German cars seem to be designed to be as hard to work on as possible without special tools, and American cars seem to be in the middle somewhere, and instead of being intentionally hard to work on, they just didn't think about it too much.

My 2012 Mazda 6 is missing two low beam headlights because replacing them takes removing parts of the wheel well, about 2 hours of labor according to some sources. Modern cars generally aren't that DIY friendly.

It's not that easy on my 2015 Mazda 3 either, but from what I've read you just need to pop out the inner wheelwell lining to get to them. Not super-easy, but not too terribly horrible. Mine has HIDs so the bulbs shouldn't need replacing any time soon.

My wife's 2005 Volvo S40 has really easy-change bulbs though: they look impossible to get to, but the trick is that you slide a metal clip up, and then the entire headlight assembly slides right out.

Modern cars can be very DIY friendly when carmakers design them that way.

Surprisingly, my Cadillac has an easy oil change. Drop-in filter right on top. But changing a light bulb requires disassembling the front-end.

I actually love Mazdas. I currently drive a 2007 Mazdaspeed 3. It's fairly workable, other than the simple fact that there is zero room under the hood.

We have 4 kids and they are large enough now that they don't fit well in my wifes previous car (Mazda 5), and Mazda no longer makes a full-size minivan.

Yeah, the new 3rd-generation 3 has a lot more room under the hood than the 2nd generation. It's nice to see a carmaker going backwards from that whole "cab forward" BS with jam-packed engine compartments.

Did Mazda ever make a full-size minivan? The 5 wasn't; it looked like a slightly larger Fit. If I had to buy a full-size minivan now, I'd get a Honda Odyssey. My mother has one of those (2015 model) and it's great.

The Mazda MPV was a full sized minivan; stopped being sold in 2006 in the US at least.

The 5 is a lot larger than the Fit; it's noticeably longer than my 3, which is already over a foot longer than the Fit.

Make Jiffy-Lube do it every few months. Just like the window fluid :-)

I would stay away from such places. They tend to use cheap oil and filters (but charging for brand name) and shoddy workmanship.

What keeps a reservoir filled up with distilled water from freezing solid in cold weather? I bought a texas car off ebay and had it shipped up north. The day it dipped below freezing was the first day I learned that texas windshield washer fluid is mostly just colored water.

Absolutely nothing. Which means that the distilled water tank would most likely be heated. If you have Bi-Xenon headlamps with washers, they most likely use heated jets already, so it's not an unusual technology in cars.

Nissan has a different take on solving this problem by having variable compression on their new VC-T engines that were on here a few weeks ago. That approach is nice because you don't have to fill any reservoirs and can still get high compression ratios when not running under turbo boost thus increasing efficiency. I really want to see where that one goes, and it is actually in a production car I think this coming year.

Isn't the future electric?

It is - I'm sure of it, but anything we can do to improve the cars people buy across the next 10 years here in the developed world, and likely 25 years in the rest of the world. (Plus the X years people will be driving older cars until petrol/diesel is properly taxed).

Could the need to manually refill water periodically be replaced by a condenser that constantly pulled ambient moisture out of the air? The total amount of water they are talking about is not very much. This seems like it could be solved without constant topping off.

Seems possible in theory, and a car's A/C system already does just this. They'd just have to collect the water that normally drains from the A/C evaporator.

Could be some issues with contamination though - you don't want dirty water being injected into an engine...

Not saying it's impossible, but there is much less water in the air at cruising altitude.

I'm no physicist but wouldn't you lose a bunch of energy running a condenser?

I remember this, and it seems similar. it condenses water at ground level with solar cells, refilling a water bottle:

http://www.jamesdysonaward.org/projects/fontus-2/

https://www.youtube.com/watch?v=aPvXnmBIO7o

Is it possible to replenish the water reservoir from the exhaust vapours? Ideally it would never run out, if the water that gets injected comes out the pipe anyway gets recycled plus what gets generated from combustion.

Here in the UK you could just do it from the rain that runs down the windscreen. Maybe in the US you could run is from condensation from the AC? Or I'd imagine filling it wouldn't be too hard or take too long. In the winter here I probably fill my windscreen washer weekly or fortnightly, and it takes 30 seconds at most (pop bonnet, open the cap (drivers side near the top) pour in 2lt of fluid, close cap, close bonnet - not dirty or difficult to do).

There is nothing new here. Lots of WW2 fighters had water (or water/methanol) injection. All we’ve really learned since then is metallurgy and better control systems (EFI).

Yes, people probably won't want to maintain a water reservoir, but performance enthusiasts might.

That probably comes down to a question of consumption rate, capacity, performance enhancement, and nagging by the car.

This all seems so antiquated when compared with electric cars. They could be flogging a dead horsepower here.

Electric cars are SSDs, ICE cars are HDDs. See what I mean?

I'm contemplating this metaphor, and it really works well. Basically, the driving range is capacity and the acceleration/low end performance is access speed. The only problem is that the kg/kJ stored is not accelerating at the rate that bits/um^2 is accelerating, which makes the time to market domination by the new technology less than stellar.

And if not properly (re)designed, this is also a great way to hydrolock your engine. Water doesn't compress, that's why it effectively increases your compression ratio. That's also why your engine hydrolocks if it gets water-logged. Water doesn't compress = pistons can't move.

You'd have to be a pretty incompetent automotive engineer to inject enough water to cause hydrolocking.

Injecting water isn't done to "effectively increase your compression ratio". If that were the goal, you'd just increase the stroke. Water injection cools the engine, allowing a higher compression ratio. If you injected enough water to meaningfully increase the compression ratio on a 3L engine, you'd run out of water in minutes anyway.

> Water injection cools the engine, allowing a higher compression ratio.

Not mentioned in the article or the comments yet is that the water to steam conversion that takes place increases volume 1700x.

"You'd have to be a pretty incompetent automotive engineer to inject enough water to cause hydrolocking."

Ever hear of a shadetree mechanic? I've had to fix up after many of them. Two hydrolocked engines, rusted out radiator (they put deionized water in the reservoir, straight up) and plenty of failed turbo modifications.

I would not be surprised to see someone try doing this themselves and failing miserably.

No, I've never heard of Bosch or BMW hiring shade tree mechanics to design engines. I'm relatively confident that this isn't a real issue.

I think your concern about weekend mechanics is also unwarranted because most of them aren't morons. The ones who are will be morons regardless and manage to destroy cars regardless.

"I think your concern about weekend mechanics is also unwarranted because most of them aren't morons."

Go to an AutoX competition or two and I bet you'll be changing your mind on that opinion very quickly.

you realize that the engine would get hydrolocked if you pushed too much gas in there as well right?

Somehow manufacturers have solved that problem, I don't think this is an issue.

Manufacturers solved that problem. Now what about the typical mom and pop shop that might try making such a modification or installing such an engine into a vehicle?

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