So I have been gathering the stuff to put together a custom water/meth injection kit and have come across an interesting question regarding nozzle size and placement. I My idea was to have 3 separate nozzles that are all injecting at 1.5gph at different points, before the supercharger, before the intercooler, and after the intercooler. This is the main idea so far but the other idea was to have them all in the same spot next to each other but off different boost switches to trigger them at different levels of boost. I think either way would be cool but I wanted to know what the more experienced people thought🙃

 

I too, have been thinking a lot about WMI. Less about nozzle placement/size, more about where to put the tank and pump. I figure I could utilize the headlight washer fluid tank since it rarely rains in my area and I use my washers even less but the pump placement is more tricky. Tank and pump in the boot seems better but I'm not too interested in sacrificing the little room there is back there for a 2.5 gallon tank and a pump.

Do you have a tuner for tuning the car for WMI? They usually would suggest a nozzle size and the injection start level and max injection level.

My understanding of WMI is that it is a chemical intercooler for lowering air temperature that the engine is ingesting with a side benefit of increasing octane. With this in mind, I am thinking injection after the intercooler is where I would go. Either in the horn just before the intake manifold (1 or 2 nozzles) or 2 nozzles in the intake manifold spraying directly at the runners into the intake ports spaced between ports 1 and 2 and ports 3 and 4 for fairly even distribution.

I have installed WMI on a Procharged C7 Corvette which has a lot more space to use than an R53. It was the Snow Performance kit where the controller was integral with the boost gauge on the A-pillar. It was technically fairly simple to install - just electrical and plumbing - but the actual work of installing it all was very tedious. Finding where and how to mount the pump, tank, solenoid and gauge/controller and then running electrical and plumbing to everything while trying to conceal it all as much as possible. I had most of the interior stripped for running the wires as the controller must be connected to the tank (level sensor), pump, solenoid and boost pressure sensor. So wires reached all over the car from the A-pillar.

In the case of our R53's, I think it would be best to remove the intake manifold or intercooler horn so that you can drill and tap it to accept the nozzle(s). I used SS braided lines with AN fittings in the Corvette and I think it turned out nice. I haven't spent much time looking in the engine bay of my R53 to imagine how I would run the lines to the nozzle(s) though with the space constraints of our engine compartments. I think WMI would be really good in my climate, but the work involved and then tuning afterward helps me hold off on it until some other time.

 

Yeah, the reason I was trying to figure out the points and stuff like that was mainly because I am waiting to get a tuner so there isn't much else to do lol. I did figure that I would mount the tank and pump in the trunk for now while it's still a daily and then at some point, whenever I can find a way to make a headlight intake, I planned on putting everything where the airbox is now. I'm definitely gonna use stainless steel lines but I just didn't know if I should just get a bigger nozzle size or do multiple injection points. The multi injection point idea only came up since I have 1 1.5gph nozzle and was checking the flowrate of the chart that was recommended. I don't plan on running a crazy mixture either, I was honestly just gonna use windshield washer fluid

 

I've installed a Snow Performance kit with a single 3.5 nozzle. I used the windshield washer fluid reservoir as my water/meth tank. Pump is located in the cowl area next to the ABS pump. Injection is progressive and starts at 9 PSI with max flow at 13 PSI.





I opted for the more expensive kit with the AN fittings & steel braided hoses since the press fittings and nylon hoses on my 335i frequently develop leaks.

 

That was my original plan, however, I can't put the pump there because of my underglow wiring. I had also gotten lucky and got the full snowperformance kit without the controller and I was just going to use the boost switch/switches to control the spray. I would really like to be able to put the tank somewhere in the engine bay but the problem is that it won't be easily accessible unless I move some stuff around. Also, the only reason I was saying 4gph for the nozzle size is because once I get a tuner I'm hoping to sit around 230-240hp.

 

I take it you don't have a headlight washer system, people have used that container before.
And don't forget, nozzle size is determined by boost and injector flow, calculate from there, not attempted HP.

 

I have headlight washers and it actually was my first idea to do that but my whole reason of not doing it from there was simply because of how weird it would be to try and fit everything like sensors into that container. I use my windshield wiper fluid a decent amount, especially right now so I don't want to run the risk of running out like that. If I were to, what would I need to do to hook up a hose to that tank and where could I put the level sensor? Also, is there any way to figure out the flow of the injectors without having a tuner?

 

I installed the water/meth line fitting at the bottom of the windshield washer tank. I use the existing low washer fluid indicator to let me know I'm running low. There's no need for a separate low-level warning circuit.

 

Here's the Aquamist calculation chart, it'll give you a good starting point.


PSI is of course pump pressure.