Direct port injection
 

I'm checking into water injection for a project car and I'm wondering why I can't find a multi-port WI system. Everything seems to be single nozzle. This relies on the intake manifold to distribute water to the cylinders evenly. It does not seem like a good idea to me to rely on a dry flow manifold to flow water properly.

Is there something I'm missing?

TIA,
Brian

Multi-port would be ideal - the biggest hurdle is cost - duplicating a fuel system that handles water. This includes an injection manager, distribution of pressurized water to each port, installation of jets at ports, etc. Certainly an Aquamist 2s can handle this and the guide for the 2s discusses multi-port applications.

While the question of even mixing is always a question with dry flow manifolds with a sufficiently long induction system throttle body injection of water thus far has been at a minimum adequate for most applications.

I already have a standalone EMS that could control an Aquamist HSV so I was leaning towards the 2c. Would that system respond well to a distribution block and 6 nozzles? The smallest available nozzles are apparently .4mm. Is that way too big for a 3 liter six cylinder? Any ideas where I could find a suitable distribution block? I can drill and tap the manifold my self, not a big deal.

Thanks for the quick response BTW, wow! :)

What you propose has been done. The only real issure has been if one nozzle get blocked the engine runs fine but will hurt one cylinder. Even though the intake manifold is not made to flow wet it is the best thing to do.
You will only be injection about 15% of the total fuel flow as water. The air will not be that heavy with liquid.

Heh, this is what I'm worried about with a single nozzle. I'm almost certian that, due to the layout of my intake manifold, #1 and #6 will recieve less water than the rest. I guess the only way to find out is to install 6 egt probes, tune each cylinder to the same egt off of WI then turn it on and see how far they wander. Anyone done that?

No one that I know of. There are a lot of cars running water with the same style of intake that are not having problems in distribution. There is aways a new test to do. Have you used water injection yet?

No I haven't used it yet. I'd prefer my first experience to be a positive one though. :wink: How do folks know they are not having a distribution problem without some kind of per cylinder closed loop monitoring? I'm trying to learn as much as possible. 8) I'm not opposed to a rigorous maintenance regime to keep the system in proper working order. I'd clean the nozzles every week if need be.

I don't know if you have seen what the intake manifold looks like on a 7MGTE but, it just can't be good for wet flow from one nozzle. Too many 90 degree turns for the water to make. I'm trying to decide if WI is a viable alternative for my needs at all. :?

I don't disagree that the set up would not be ideal for wet flow especially for something that needs to as finely metered for instance as fuel. The "water" will be atomized and also is only about 2% of the air/water induction charge prior to the fuel injectors.

Also generally the total concentration of water being injected is more than absolutely necessary for knock suppression. Something like 5% water to fuel is enough to replace the fuel previously used for cooling when leaning from 10:1 to 12.5:1 AFR. So with a 15% target water to fuel flow if a cylinder gets 10% and another gets 20% it should not be harmful. I would not expect that much variability between cylinders though - this is just an example.

Certainly the EGT by cylinder test you propose would identify how much variability there is.

The more concerned you are about mixtures the further down the induction path you should try to inject.

There is a tuner in England testing WI EGTs on 4 cylinders currently with a dry manifold but the runners are long and I expect the mix will be OK.

The other problem with multi port injection is that the amount you are trying to flow is very low on a per cylinder basis - even with a 0.4 mm jet you will be getting into IDCs where you will have lean induction cycles. I think without a very complex and well managed system you may have more rich/lean water conditions than a single jet through a dry manifold.

The intake manifold on a 6 cylinder BMW in has to be the worst. We have been involved in cars making 600hp on pump gas for the street injecting water before the throttle plate with no issues. The biggest issure is trying to inject into a 10/1 air fuel ratio, then power drops.

I'm crazy enough to be shooting for 300 hp per liter and as such, I believe I'm going to wind up with a fairly high strung engine. A little one way or the other could spell disaster. I've already got a fuel system to handle the output. Maybe I'd be better off just running nothing but race gas?

If you are going for that much power your original idea of one nozzle per cylinder make since. The flow will be very high at high rpm and boost. Use only distilled water and methanol if you need to keep it from freezing. Just pring it on a little late and have an over capacity pump. Set up a kit for a quater mile 4 cylinder using two 0.9mm nozzles per running. The car runs on gas and 42psi boost for seven seconds or so at a time.
You could use one nozzle per runner for high boost and a variable flow at the inlet for the less than full power improvement.
There are so many combinations when you know the goal.

Definitely going to be running multiple jets - might as well be looking at each runner. Most likely going to be running multiple pumps or a lot of accumulation.

Hrm... Where does Aquamist have flow rate specs published?

There are listed at www.aquamist.co.uk Go to suppliers list. To the right of the price, in British pounds. Click on the little symbol and the flow ratings for different jet sizes will appear.

Oh wow. I didn't see that yesteday. 8) Looks like 6 .5mm nozzles and 3 HSVs. Eh, hrm, no pump specs?

From the same listing click on the < for the race pump. You would need an accumulator to reach the over 300cc flows keep in mind any duty cycles anticipated when considering jet fuel rates vs. the pump capacity.

http://www.aquamist.co.uk/sl/plist/p...2/jetrate3.GIF

This is the race pump flow then? I thought it was just a representation of how much could be passed thru a single nozzle. Why so low? Was it intended to be used without the HSV?

It is flow of the pump through the different jets. With the smaller jets you get to a point where additional pressure just will not flow more water - it is a jet restriction on flow. With the larger jets it becomes a pump capacity limitation as the jets have the ability to flow more water at higher pressures.

The chart is full on flow of the pump without metering by an HSV. HSV duty cycles change the profile.

For what you are doing you should run two race pumps and at least two accumulator. This should provide for full on for 30sec. The last thing you would want if water flow to slow down at high boost and rpm.

With goals as high as yours, you may need to spend more money to have a failsafe. The FiA2 can be rigged to turn off a boost controller or other device if blocked a blocked jet is detected. Invest in one per cylinder and drive high speed valves and wire up the safety cut off and you will have invested in some insurance for your probably expensive motor.

Philip Bradley

Chevyeater,
My power goals aren't quite as high as yours, and I have been trying to limit my input on these forums to WI or combining it with other systems. That said, you mentioned running racegas (expensive) and as the last poster mentioned, you really want to protect that engine. Have you considered using WI together with Propane Injection? Propane is safer than most people imagine. Hell cars run on it exclusively in many countries ... it is dirt cheap and has an Octane rating of around 110. It would give you extra power, detonation suppression even without WI (probably considerably more with it !!!) and it will definitely reach all cylinders easier.

If you go to General Effects and look at the post headed Water Injection, Cryo Intakes, Nitrous etc (or something like that !!!) myself and a couple of far more knowledgeable guys have been discussing the relative merits and problems of using hybrid systems.

You could come on over, crack open a beer, throw in your two cents and see what comes out. The discussions are really hotting up with some pretty interesting ideas going back and forth.

Thing is the post has been read a lot but not many people are contributing, probably because it seems like a private battle of wits and it was never meant to be like that. Just me trying to get a better idea of where WI really fits in to the big scheme of things, and it sounds to me as if you might be doing that as well.

Paul.

chevy eater....300bhp/l isnt hard at all and is not an unreasonable expectation and if the engine is built properly should be able to be done without WI. even if you want 300whp/l. i would say WI for a little extra security and performance for what you want. but if you start reaching for the 350 to 400whp/l youll need all the help you can get.

Venturi Induction for Water Injection
 

I am addressing the issue at www.aspenesco.com. Drop me a line if you have questions...