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      04-11-2011, 04:57 AM   #1

Drives: BMW 335i
Join Date: Oct 2010
Location: Europe

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2008 BMW  [3.12]
Aquamist HFS-2 PWM meth injection system installed - review & pictures

There are 2 important differences between Aquamist and the other meth injection kits used on this forum: it uses a fast-acting electric valve to inject already pressurized water/methanol into the intake manifold - much like a car injector, and it works based on injector duty cycle (IDC) and not boost, keeping a constant fuel-to-water/meth ratio. It can also work with boost if needed.

I just completed the install of my Aquamist HFS-2 kit. I bought it 3 months ago from Howerton Engineering for $600 including the tank, 3 nozzles, 2 nozzle adapters and everything needed (probably the only serious Aquamist distributor - even the Aquamist web site is pretty useless). They modify the original HFS-3 firmware to work on N54 engine. The HFS-2 is plug-and-play upgradeable to HFS-3 (HFS-3 has a flow sensor and a gauge). But since I have a flash, I can't see the point of the failsafe yet unless I will find a solution to dump the wastegate solenoids in case of a flow problem.

I am proud I managed to do the install 100% on my own, including the making of the methanol elbow using an aluminium 45 degree intake tube, some silicone pipe and some JB weld . The tank was installed on the battery side, and the pump was installed beneath the trunk floor, making the install a very clean one. The Aquamist control unit was placed under the glovebox, it's easily accessible and doesn't take up storage space. There were a lot of cables that needed to be routed to the controller. I have routed the fast acting valve cable in the same way you route a boost gauge tube from the engine to the cabin, and I have routed the ECU cable in the same way you route a USB cable for the JB4/Procede from the ECU box to the cabin. There are DIYs on the forum for this. I have intercepted the wires from one of the car's injectors, it's not hard to do it. I did not tap the injector wires, but ordered some pins from the dealer and used those and some wires instead.


When testing, I used some duct tape to glue the Aquamist nozzles to my windscreen to observe the behaviour of the injection while driving. It was a lot of fun It's incredible how responsive the system is, the injection flow follows the accelerator pedal precisely with no delay whatsoever.

For now I couldn't manage to get the GIAC Stage 2 Race to run without timing drops because I didn't have time to test various nozzles, settings and water/meth ratios. But I am confident I will manage this.

On the regular GIAC Stage 2 map things seem to be improved subjectively speaking, the 3rd gear seems more powerful and the 4th gear is really improved. What's interesting is that the throttle response seems improved. Also at high speeds the 5th and 6th gear seems better with improved throttle response and power (maybe from the lower IATs and more denser air ?)

Some pictures from the install below. Feel free to ask any questions if you want to do an Aquamist install yourself
Attached Images

Last edited by tscdennab; 04-11-2011 at 05:15 AM.