Water/**** Injection VS. Timing Retard for Ping

[Jim Wilson]

There are various size nozzles for water/**** injection. How does one know when to limit the quantity of water/**** injection and turn to retarding timing instead to eliminate pinging?

I would think there is a crossover point to feeding more water/**** into your intake verses pulling timing out for optimal power.

 

[EllowViper]

This is a really good link for W/M info. I'll probably use these guys for my custom W/M system I'm building.
RSR Water Injection Calculator

Here are a few "pearls " from the link....

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.
4. Methanol, as an additive, is not a practical choice as it is prone to pre-ignition in higher than 50/50percentages, is not safe to handle, and is not readily available. It's a good choice, but not necessarily the most practical one when you need some in a hurry. Methanol is usually found where racing fuels are sold.
5. Denatured (ethanol) alcohol, typically 95% pure, is available in paint, hardware, and Home Depot type stores in gallon containers for about $10.00. Expensive but available everywhere. Isopropyl alcohol can be used but it is often 30% or more water by content.
6. Water Injection allows ignition timing to be more aggressive or closer to stock. In other words boost does not automatically mean retard your timing.
7. Excessive amounts of ignition retard will cause a loss of power and overheating.
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. Multiple nozzes, equally spaced in the plenum, although it complicates things, is a superior design.
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 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.
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.
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.

 

[Torquemonster]

a lot was said there - great post!!

being a stirrer I'm going to go left field... and people can laugh it off or think about it

I've seen water burn (as director of a research company) so it sure can in certain circumstances, but that technology is not exactly available right now and has miltary as well as very big OEM and political interest. There are many patents also and not all of them require more power in to what comes out - think latent energy and reaction vs having to use a bunch of energy to get some back.

Water as fuel does create a new set of problems however that modern oils cannot yet address. So future water engines - if indeed we ever do see them in production (instead of just the various prototypes) - will require new lubrication chemistry so the water does not emulsify with the oil.

Water can be used 50% by volume as fuel - that was what Ricardo was doing during ww2. However as said - it must be atomised correctly which typically takes well over 100psi to achieve. Direct port water injection could use a direct port nitrous plumbing setup - but not the jets and solenoids - which should be dedicated for water as mentioned - such as Snows and ERL Aquamist etc... and should be ECU mapped not just dialed in. The old DIY converted windscreen washer units are a waste of time and may hydraulic your motor as solid water cannot compress so something else will.

now for something to think about: what would happen if you employed modern state of art direct cylinder injection technology to a direct water injector - and timed the water to spray directly after TDC as the fuel has been ignited?

clue: think the old stinky trains

You'd suddenly be able to either create a massive increase in power/tq or cut back on fuel 50% to maintain power. You would still have the water/oil issue so a water seperator in the oiling system would be required... but what you'd have is an Internal combustion and steam engine combination. 1 drop of H2O expands explosively if contained under pressure when it converts to steam - harnessing that at the precise point the piston is heading down is all you'd be doing. It'd require injecting water at common rail diesel pressures and at great timing precision.



back on topic - we ran 18psi boost at a true 9:1 cr with 24 degrees timing on 91 octane - with water injection (no ****). We could have run more had we turned up the water volume. We used an ERL Aquamist - it ran great.

another thing about detonation is combustion efficiency... most Vipers have poor quench so will be prone to detonate under boost (or require plenty of retard). The fix is a tight quench piston design, precision build etc.

 

[plumcrazy]

what do YOU think the best quench is for our cars ???

 

[Torquemonster]

With a good piston design and quality engine build/machining - 0.037" is a good start and safe to more rpms than your V10 will ever see. Over .045" you really do not have an effective quench. Stock quench is well over .070" so you do not have any effective quench.

So your gasket compressed thickness will determine whether the piston needs to sit proud of the block or not. The pistons should be designed for tight quench or you may have valve clearance issues esp. on bigger cams.

How do you get the right piston?

Send your heads to CP and tell them what c.r. you want and to set the piston for the desired quench. A steel rod could go tighter - but 0.037 is safe and will get good results... actually DOES get good results. Engine will be better at all rpms, make more power onless fuel and be less prone to detonation.... in fact could run more compression on same octane

 

[Jim Wilson]

Thanks for the replies. The link Ellow provided is very informative. I especially like the photo near the bottom of the link!!!

I'm running the Aquamist setup on one of my cars and it is VERY impressive, and have a spare Shurflo type system, which in comparision is crap.