Taken from Wikipedia, looks like we might actually see some mainstream use of water injection soon, the benefits for emissions and economy are better than I thought...
"
A limited number of road vehicles with forced induction engines from manufacturers such as
Chrysler have included water injection. The
1962 Oldsmobile F85 was delivered with the
Fluid-Injection Jetfire[6] engine, which, incidentally, shares the title of "the world's first turbocharged road car" with the Corvair Spyder. Oldsmobile referred to the water/alcohol mixture as 'Turbo-Rocket Fluid'.
Saab offered water injection for the
Saab 99 Turbo. With the introduction of the
intercooler the interest in water injection to prevent detonation almost disappeared, but recently water injection has also been of interest because it can potentially decrease
nitrogen oxide (NO) and
carbon monoxide (CO) emissions in
exhaust. However the most common use of water injection today is in vehicles with high performance aftermarket
forced induction systems (such as turbochargers or superchargers); such engines are commonly tuned with a narrower margin of safety from detonation and hence benefit greatly from the cooling effects of vaporized water.[
citation needed]
In 2015
BMW has introduced a version of their high performance
M4 coupe, the M4 GTS, that combines water injection with intercooling. The car was featured in the 2015
MotoGP season as the official safety car for the series and was released for the commercial market in 2016.
[7] As per
BMW example, current engine developments featuring water injection seem to concentrate on the effect of “Performance Improvement”. But by the mid 2020s, engine development will shift focus also on improved
fuel consumption, due to the pressure on
CO
2 emissions reduction and related regulations.
[8][9]
Bosch, which co-developed the technology with
BMW, offers a water injection system named WaterBoost for other manufacturers. The company claims up to 5% increase in engine performance, up to 4% decrease in CO
2 emissions and up to 13% improvement in fuel economy.
[10] Similar results
[11] were published by
FEVshowing up to 5,3%
Fuel Efficiency improvement on 2,0L displacement petrol engine and even up to more than 7% in combination with cooled
exhaust gas recirculation, depending of the drive cycle considered.
Water Injection and cooled
exhaust gas recirculation (EGR) could be seen as competitive technologies: it has been demonstrated that at medium load a 40-50 % Water-to-Fuel Ratio (WFR) with Port Water Injection (PWI) has the same effect as an EGR-rate of 10%, which is seen as relatively limited even for petrol engines.
[12]However, Water Injection has some benefits when compared to EGR, especially a better controllability as this is not a closed-loop as EGR, the timing of injection is not linked to other parameters as turbo charger backpressure, limited inertia (PWI timing not linked to engine operation) and combustion delay (as present with EGR). Additionally it does not deteriorate combustion stability significantly. The combustion delay linked to EGR dilution and the necessary adaption of the recirculated gas mass flow to the maximum turbocharger characteristics are typically two limiting parameters of the max. acceptable EGR rate. Therefore, some synergies can be developed when using Water Injection in area of the engine map where EGR is typically not possible (High Load / High Speed).
On-Board Water Generation[edit]
Surveys asking customers about their willingness to regularly fill up an additional operating fluid have demonstrated that the acceptance level is limited.
[9] Therefore, the need for refilling is considered as one of the main barrier for the mass adoption of Water Injection. A key enabler is the development of on-board water generation system to run in close loop system, especially in order to guarantee consistent low level of emissions (engine CO
2 emissions to raise if run without water supply). Three major sources can be investigated:
- Harvesting air humidity from ambient (e.g. by A/C condensate)
- Surface Water (e.g. rain water collected from vehicle body)
- Exhaust Gas Condensate
The first two variants are highly dependent on weather ambient conditions with sufficiently high humidity levels or driver habits (no A/C operation wanted). Consequently, an adequate supply of water cannot be ensured. On the contrary, condensing of water vapour formed during the combustion of gasoline is a reliable source of water: there is approximately a volume of 1L of water vapour in exhaust per each liter of gasoline fuel consumed. In October 2019,
Hanon Systemstogether with
FEV, presented an
Audi TT Sport demonstrator equipped with port Water Injection operating in close systems thanks to an
Hanon Systemsequipment called "Water Harvesting System".
[13] The fully packageable system was able in the most critical cases tested to condensate more than 2 times the water consumed. The quality of the water condensates was presented as being good enough to avoid problems with injectors and potential corrosion issues were not detected during the extensive test drives. the condensates were shown as transparent, without strong odour and color.
Use in diesel[edit]
A 2016 study combined water injection with
exhaust gas recirculation. Water was injected into the exhaust manifold of a
diesel engine and, by opening the exhaust valve during the induction stroke, the injected water and some of the exhaust gas was drawn back into the cylinder. The effect was to reduce
NOx emissions by up to 85% but at the cost of increased soot emissions.
[14]"
