Meningkatkan efisiensi mesin dengan water injection bisa murah dan meriah

Ini adalah trik yang sudah lama diketahui untuk menambahkan tenaga ke kendaraan. Barangkali ada yang tertarik untuk menerapkannya. Teknologi water injection ini sudah ada sejak jaman perang dunia:
A 20 to 50% gas mileage improvement can be yours with … WATER INJECTION WIZARDRY

During the second World War, fighter pilots could push a button and inject a stream of water into the turbochargers of their monstrous powerplants . . . to get extra thrust on takeoff. Some time later, Chrysler (among other auto manufacturers) installed water injection on a number of its large displacement engines . . . again for a performance increase. Indeed, water injection—used to produce power increases—is nothing new.

Sistem ini sekarang sudah banyak dipakai di dunia balap, berikut adalah salah satu merek terkenal, dikatakan bahwa penggunaan water injection bisa meningkatkan tenaga hingga 20%!
THE AEM WATER/METHANOL INJECTION SYSTEM ADVANTAGE

Water/methanol injection for forced induction (turbocharged or supercharged) gas-powered race engines is a proven means for effectively reducing engine inlet air temperatures and suppressing harmful detonation. This allows racers to reliably increase boost and advance ignition timing—without using high-octane racing fuel—for power gains of up to 20%. AEM’s Water/Methanol Injection Systems utilize the most robust hardware combined with more advanced features than any other comparably priced water/methanol system.

Mengapa water injection dapat meningkatkan tenaga? Selain karena bisa menurunkan suhu mesin alasan utama adalah mengurangi pre-ignition:
RSR Pro 1000 PSI Turbo Water Injection

If you want your high output turbo or supercharged motor to avoid engine destroying pre-ignition and detonation you are going to have to employ water injection and the way it has to be done was set in stone a long, long, time ago.

1. Maximum Torque occurs at a 13.2:1 Air Fuel Ratio.
2. Transitional Fueling and Maximum Boost Air Fuel Ratios are about 12.5:1.
3. Water Injection is most efficient with a 50/50 water alcohol (or methanol) mixture.
8. Water to Fuel ratios should be based on weight and not volume.
9. Water weighs 8.33 lb per gallon.
10. Alcohol weighs 6.63 lb per gallon.
11. Air weighs .080645 lb per cubic foot. It takes about 150 cubic feet of air per 100 horsepower. It takes about 12 lb of air per 100 horsepower.
12. Water or Water / Alcohol to Fuel Ratios are between 12.5% to 25%. This means Air to Fluid Ratios are between 11.1:1 and 10.0:1 with water injection.
13. Maximum water delivery should be in higher load low to mid rpm ranges tapering somewhat at peak rpms where load is less.
14. Atomization of the water mixture is directly related to it effectiveness. Finer droplets cool the inlet charge better and with less mass they navigate the inlet plenum easier for more equal water distribution.
15. Don’t flow water through an intercooler.
16. Atomized water, just like fuel, does not like to make turns thus making accurate distribution something to think about. This is why port fuel injection is the norm. Water is a fluid just like your fuel. Using high pressures up to 1000psi for the best atomization and even distribution. Using individual port nozzles is a bit complicated for a large # of cylinders and makes control difficult as nozzles vary in their output.
17. The introduction of water will allow higher boost pressures to be run without detonation. Higher pressures will increase torque. It’s always about torque.
18. Racing high octane gasoline should be used for all forms of competition and for higher than normal boost levels. Water injection as well as charge cooling should be used with racing gas. 91/92 Octane pump gas simply will not cut it. Water spray cooling of the intercooler is a good idea.
19. Fuel Injectors operate in the 1 Millisecond range (.001 second) and are not capable of long term usage for H20 as they will corrode or rust shut in a very short period of time. Unless a solenoid can open as fast as a fuel injector it should not be used to “pulse” water injection events as flow is not directly related to “duty cycle”.
20. Varying voltage to water injection pumps or using similar schemes is a recipe for disaster. You have to eliminate the variables, not increase them.
21. Fuel Injection pumps cannot be used for water injection. Water is conductive. Gasoline is not. Water will corrode an efi pump shut in a very short period of time.
22. Water injection has a cooling effect on the engine head, valves, and cylinder. Exhaust temperatures (EGT) are largely unaffected at recommended water / fuel ratios.
23. The cooling of potential hot spots in the combustion chamber defeats pre-ignition, the most destructive form of uncontrolled or unplanned combustion.
24. Higher static compression ratios will require a higher percentage of water or water / alcohol.
25. No, water does not burn. We are not combusting the hydrogen in the H2O.
26. At around 13.2:1 or fuel air ratios of .75, EGT’s will peak.
27. People will try to selectively edit their way to get you to use water injection by stating “One can basically double the power output of an engine using water/methanol” and “It was used effectively in Formula 1 before being banned for adding too much power”. This is pure bunk. Water or water/alcohol/methanol does not make power…superchargers and turbochargers make power. The cooling effect of the water injection only allows you to run higher boost pressures and leaner mixtures without engine damage. The increased density or higher pressure ratio is what makes the power, not the water. The last time we checked water wasn’t a very good fuel. Water Injection definitely does not give “a 5-15% increase in fuel economy” as some marketers clain.
28. Ferrari suspended water in their fuel during their 1980’s Formula1 period. We don’t recommend that you try this…although Acetone will mix with water.

Dengan berkurangnya pre-ignition maka kompresi mesin bisa lebih ditinggikan, atau bisa menggunakan bensin oktan rendah untuk mesin kompresi tinggi.

Walau cara yang disarankan untuk penambahan sistem water injection adalah dengan pakai spuyer yang dikontrol ECu dan segala macam, kita juga bisa melakukannya secara sederhana dengan memanfaatkan daya hisap dari karburator. Berikut diagramnya:
Rambo1965’s Water Injection Thread

versi lain:
Water Vapour Injector System

Jadi ada versi yang menggunakan hisapan udara vakum dari karbu dan ada yang menggunakan hisapan langsung dari karburator. Daya hisapan dipergunakan untuk menyedot udara dari tabung pembuat gelembung. Disarankan agar keluaran dari tabung tersebut ditampung dulu di tabung pemisah air untuk mencegah air tertumpah ke karburator.

Karena sistem ini mengurangi pre-ignition, efeknya sama seperti penambah oktan. Jadi mesin yang kompresinya tinggi dan diminumi premium akan dapat merasakan penambahan tenaga. Gampang dicoba. Bila ada yang sudah coba, mohon sharing pengalamannya.

Bila masih kurang yakin akan potensi teknologi ini, BMW memperkenalkan teknologi injeksi pada mobil sport M4 nya:
in the near future, BMW M Division will begin production of a model featuring water injection.

Using water injection to increase the knocking limit also helps to largely resolve a familiar conflict in objectives when designing powerful engines. Performance and consumption are not least determined by the compression ratio. This also applies, in particular, to highly charged turbo engines like the BMW M TwinPower Turbo, inline six-cylinder. Thanks to a high compression ratio, this engine is highly efficient and boasts low consumption figures, especially in the partial load range. However, the maximum compression ratio is limited by the knocking tendency when fully loaded. Water injection is also hugely beneficial here, as it reduces the tendency for the engine to knock, whilst at the same time increasing the compression ratio. This way, the turbo engine can achieve optimal performance across a wide range of operating points

The 2016 BMW M4 GTS is a street-legal water-injected track monster, and it’s coming to the US

Even so, performance gets a very marked boost courtesy of that H2O: 493 hp at 6,250 rpm and 442 lb-ft at 4,000-5,500 rpm. Compare that to 425 hp and 406 lb-ft on the regular M4. 0-60 time is down to 3.7 seconds, and top speed is a stated 189.5 mph. Meanwhile, because we’re sure you care, fuel economy shouldn’t take much of a ding (we’re curious to see EPA numbers).