Ever since I had my 2005 Evo, I’ve wanted to try water injection. Kojima tested it out on his Evo IX back in the day. For the turbocharged 718 Cayman, there are two reasons I wanted to add water injection: mitigate knock from crappy 91 octane fuel during sustained track use and reduce intake air temperatures a smidge. I’m not trying to make more power; I’m trying to reduce power derating from high intake air temperatures and ignition timing correction from knock.
I opted to go with a Snow Performance Stage 2.5 kit. I wanted it modular so that I could easily remove it, so I mounted all the components on a ‘kit’ I fabricated. I bought some plastic, brackets, and fasteners from McMaster-Carr to make the platform. The reservoir, pump, gauge/controller, and boost sensor are all mounted as a unit. To install and remove, there are only 4 connections that need to be addressed: water line, boost line, electrical power lines, and the mounting fasteners.
I used a foam block underneath the water reservoir to help support the weight. There is an optional level sensor you can install into the reservoir, but I decided to leave that out as it’s another potential leak point.
I primed the pump using a 12V jumper pack and checked out the water flow.
I needed a 20-amp switched power source. I tapped into the fuse box in the passenger side footwell using the fuse location for the 12V socket in the footwell that I never use. This location does stay powered for a few minutes after the car is shut off. Make sure to use the proper size cable for sustained 20A current as you absolutely do not want an electrical fire.
The cover goes back on without issues.
11 comments
I know you achieved your goal with just water, but wouldn’t adding a bit of meth to the mix improve things even further?
If Kheim wanted to make more power, he’d tune for 50/50 water and meth and inject after the intercooler with a much bigger nozzle, but Kheim want the car to be perfectly safe if there’s a failure of the injection system.
It could. A few reasons I’m avoiding any meth; I can buy distilled water at any local grocery store or CVS or Walgreens. At my street injection rate, the water flow rate is about 4%-5% of fuel flow rate as I calculated in the table on page 7. When I double that for track use, the water flow rate will be close to 10% of the fuel flow rate. If that were 50/50 meth, that should certainly get its own tune. I do have the reservoir inside the vehicle cabin. I don’t know how prone it is for methanol to evaporate out, but… I’d rather not find out. And lastly, I used regular plumbers tape on the water line fittings and that’s not compatible with meth.
you can also buy meth at any local hardware store… well you can in most of the country, not sure maybe california banned it or something.
I should have been more clear with my question, I meant add meth but keep it to an amount that still doesn’t require a retune… instead of a 50/50 maybe a 20/70? or even less if thats too much for no retune.
strong point on the tank being inside the cabin… I didn’t look too closely and just assumed it was in the frunk. I wouldn’t risk running any mix of meth inside the cabin either. but being inside the cabin… is the pump loud? I’m sure you don’t hear it at full tilt with the windows down at the track, but do you hear it on the street? or do you only turn it on at the track?
This project car has become one of my favorites. Thanks
Thanks! I’m putting in all of the lessons from my previous cars. I have one more round of easy mods. I’ll probably get around to doing the Numeric shifter cables per the recommendations of a reader. I would really like to do an equal length manifold (just coming to market) with a Garrett G25-550 in 0.72 A/R housing (needs custom fab/water lines/oil lines/connections, not bolt on…). The crazy dream would be the DeMan shorter gearing. I really want to do the equal length header because the stock header is really poor design. And I want the G25-550 for that ball bearing goodness. The current Raggdoll Motorsport RENNEN turbo is great for a bolt-on and I expect their equal length manifold alone would improve spool-up 300-500rpm. But gunning for what I consider the ultimate.
Yeah, we love what you are doing here, I can’t find anything to criticize! Lol.
it’s rare where someone only talks about pure water injection, and not a 50/50 (water/meth) setup being used. I love it! It should be advocated more. There are so many cases where if we were not blinded in chasing for more power, but rather improve reliability and safe power; water injection is a great way to go.
Then we also don’t need to worry about special “meth safe,” sealants for the tank or sourcing the proper meth additive that is not a de-icer that slowly gums up screens and nozzles…
I build to be able to drive as hard as I want and not worry about anything breaking! I tried searching for info on pure water injection setups and very few people do it. Of course, there’s the BMW application on their M Competition where they tune for more boost with the water. There’s a bit of chatter about the percentage of water injection vs. air which is why I calculated my values; the implication being that too much water hurts power output due to quenching the combustion. There’s also various research papers on water injection in various engines and relative humidity on the amount of timing advance that can be run.
It’s when I read about the relative humidity impact that I decided to go the direction of injecting water at the turbo discharge. I make sure all the water is vaporized which also gets me the maximum air temperature reduction. And it all made sense, the impact of the mass of water vapor (relative humidity) to reduce peak combustion temperature to reduce knock; similar mechanism to exhaust gas recirculation.
Yeah, overall goal, build the car so that I can drive hard with the least amount of worries.
you can also buy meth at any local hardware store… well you can in most of the country, not sure maybe california banned it or something.
I should have been more clear with my question, I meant add meth but keep it to an amount that still doesn’t require a retune… instead of a 50/50 maybe a 20/70? or even less if thats too much for no retune.
strong point on the tank being inside the cabin… I didn’t look too closely and just assumed it was in the frunk. I wouldn’t risk running any mix of meth inside the cabin either. but being inside the cabin… is the pump loud? I’m sure you don’t hear it at full tilt with the windows down at the track, but do you hear it on the street? or do you only turn it on at the track?
With my pump essentially set to half speed, I don’t hear it at all even with the windows all the way up. I’ll hear the water sloshing in the reservoir once in a while. If the pump is running full speed, then I can hear the pump if the windows are completely up. With the windows even cracked a bit and getting some wind noise, I can’t hear the pump at all, even at full pump speed.