Buy Now, Pay Later
Share This
Through out this article I will be referring to Water/methonal injection as WI. With this entire test and install, we are showcasing this as something anyone can do. There is not a single part of this test that a person should feel scared to do except for the tuning which should be left up to a professional tuner. Water injection has been used in many industries for a very long time. We are finally bringing it to the Mini world! Many have seen our PWI-1 system, and if you read the features from our site, you will be sold on it compared to other systems. This article is not about the PWI-1 system, but about using WI on the Mini cooper. Why would you want to use WI on the Mini? The Intercooler is small, and lacks in the cooling department, smaller SC pulleys increase the charge temps, all these things increase the engine tendency to detonate or knock. So since running race fuel every day is not practical, the next best thing is water/methonal injection! The WI is only on when you are above a certain load point. Meaning only when the engine is about a certain RPM and or boost level. So it only injects it when you need it. This makes the consumption rate very low for normal driving conditions. WI is all about cooling, which in turn controls detonation which allows the engine to make more power, and more power safer. Normally just injecting the mixture nets a loss in power. But with some cars, because of limitations of fuel and how the ECU is tuned, they can gain power. With the Mini some have seen gains with just injecting water/methanol, but with this test we will have to see! Using the wonderful BimCOM software from RossTech, we collected some great convincing data! We started with a customers 2005 Mini Cooper S (which BTW, Mr. Sterns Mini is one of the sweetest Minis around). This car has an ALTA 15% SC pulley, ALTA header, ALTA intake, stock IC, and Invidia 60mm exhaust. As with all Mini Cooper S€™s, or any boosted engine, more boost is the key to making power. Since boost isn€™t going to change much unless we increase the SC speed, by a smaller pulley, or higher redline, the increases are not going to be huge, or are they??


There are a few good places to install the WI system in the Mini, but we chose a place that is both functional and shows off the system. With the install we choose to use the window washer tank (passenger side tank). Because the tank is much lower than the pump assembly, we will have to use a primer pump. We thought we would use the OEM pump assembly to be the primer but the problem is wiring it up, and using diodes to do this wasn't going to be a job for everyone. So we used an off the shelf windshield washer pump from NAPA for about $14. Next was to remove the fender liner to get to the tank. The tank is a little tricky to remove, but once you figure out that there is a hidden connector (below) it comes out very easy. build_methinjection_reservoiremount After drilling an tapping a 1/8NPT fitting into the bottom of the tank we are ready to re-install it back into the car. Next up is the primer pump install. This is a pretty simple job. Drilling a couple of holes to mount it, and connect the tank hose up to it and we are done. Wiring the pump is simple. The PWi-1 has 2 wires ready to go, so all we have to do is extend the wires to the pump. build_methinjection_primerpump With the fender liner back in its time for the pump assembly and and wiring job. The pump assembly fits great in the window cowl area, and it is very easy to get a drill in there for the mounting holes. Besides the normal positive and negative connections, the only tricking connection is the fuel injector ground signal. This connection is important as this is how the PWI-1 picks up fuel injector duty cycle and determines how much water to inject. build_methinjection_ecuwiredup All done! build_methinjection_mountedpump2 The last step in the installation is is the nozzle placement. Normally putting the nozzle before the IC is better, when the IC is in a bad place, or is very small. So the Mini should have the nozzle before the IC. The only problem with putting it before the IC is that there is no good place that will distribute the water over the charged air in the tube equally. Because of the wide opening, if we put the nozzle in the center, much of the water will not affect the outer channels of the air, or the outer channels of the IC. Yes the water will be ingested in the engine, but much of the charge cooling effect will go to waste. build_methinjection_nozzle After the IC was a better choice as it iwas better centered over the boost tube, and would deliver water better to the complete charge. Since it was closer to the cylinders, it would also have better in-cylinder cooling. The only thing it may not effect is the charge temps. But we will have to see!


This is the one part of the whole install that is not for everyone. This requires cutting of ECU wires, and some soldering. Along with the install comes tuning, which needs to be done by a professional. This physical installation isn't very hard. Basically there are 5 wires to tap/cut into and then mounting of the head unit. From there is where it gets tricky. Tuning the ECU is not something for everyone. Besides having a dyno, and the tools to measure things like knock, AFR, and temps, the knowledge needed to adjust parameters is priceless. This is where you need to take your car to someone that knows what they are doing.


During the test we ran multiple runs for all changes. This ensures that the engine temps have stabilized, and proves the changes we were making. First off we did 7 base runs to get a good base number. build_methinjection_davidminibase BASE RUN-shows base power as we might expect from these parts. build_methinjection_davidminiwateron RUN WITH WATER ON- shows that the ECU is happy with WI on, and no tuning. Similar results might be had be race fuel. davidminiwaterontune1 RUN WITH SOME FUEL TUNING- got some smoothing to do, and there is definitely more power to be had. build_methinjection_davidminiwaterontune6 RUN WITH FINAL FUEL TUNING, solid consistent, safe gains.


-Charge temps dropped significantly. During the base, non-tuning runs with no water injection, we saw charge temps (post IC) reach on average 48C. Couple of times we saw 52C. This is with the stock IC of course. With the water on, the charge temps were much more consistent, and much lower. 34C is the highest we saw. Even with back to back, quick runs, we saw the first run peak at 32C, and the second run done 15-20seconds later, we saw, the same peak of 32C!! The charge temps being lowered 20C is a huge gain. 20C cooler charge temps, means less detonation, more ignition timing can be added, and the engine will be running much safer overall. Anyone in hot climates should really look into this as a safety device. -Overall knock energy stayed the same. Normally when you increase power, weather by boost or tuning, the engine will create more noise. Given that there was an increase in power, the noise stayed about the same. When the water turned on (before tuning) the engine noise actually dropped about 20%. Again showing how much safer the car will run with WI. -More power and torque everywhere! That is pretty obvious from the graphs shown above. The most important area where power was gained was at lower RPM. The ECU is tuned very lean here, and with the instant boost. -the ECU liked more timing if the fuel would allow it. The WI proves this, by the fact that turning it on with no tuning nets good power increases. Because of the gains we saw before tuning, the PWI-1 by itself it a great option for more safer power. -With the AFC pulling timing (because we added fuel) at lower RPM, there is still tons of power to be had. -Once again, this combo of parts makes more power than the JCW kit, and it is still far less money.


213WHP and 190ft-lbs of torque is great power for a 15% pulley car. Maybe the best results out there. I would venture to say this is the highest HP 15% mini with no ECU flash (higher redline). Compared to an intake system, or exhaust or anything else, the gains are much better add to that durability, and we have a winner. Normally when you get to this point in €œbolt-ons€, to get a gain like this is not possible. But this is only a small showing of what WI can do. Because we are using the Apex AFC to retune the fueling, we are not able to change timing independently. Because the AFC changes the MAP sensor output, it also effects timing. More fuel = less timing, less fuel = more timing. If we, I should say when we are able to tune fueling and timing separately, we can do far more! I am sure some are seeing this test thinking "Great, WI works, i am just going to go buy one of those cheap systems." One thing to remember with other systems is they do not all deliver the proper fuel/water mixture. Most of them just tune on at a given boost, and deliver the same amount of water through the entire RPM /load band. This is bad as too much water will be delivered at low rpm/load, and not enough at high rpm/load. The progressive nature of our system delivers that 10-20% water vs. fuel everywhere. This is important to making the most out of the WI. David€™s car can gain more power by a couple of things, one being a larger exhaust, like our 2.5€ system, a smaller 17% or19% pulley, larger Intercooler and one of the most important things is a properly tuned ECU. A simple redline change will net an easy extra 10-15WHP with the existing setup. And yes, David is already bugging us about those next parts.

Thank you!

Thank you for signing up.

© 2024 PERRIN - All Rights Reserved
  • Visa
  • Mastercard
  • PayPal
  • Wire Transfer