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?