WMI Install

I'm currently setting up a water/methanol injection system on a Volkswagen 3.0 TDI with a big turbo @36psi and would love to get some input from anyone who has experience tuning WMI on this platform.

A few specific questions:

1. Activation point – What boost pressure (PSI or bar) do you recommend as a Start and Full injection point for this engine? Is it better to tie activation to boost pressure alone, or would you also factor in IAT (Intake Air Temperature) as a secondary trigger?

2. Target Lambda/AFR – Since this is a diesel application and retuning isn't strictly required, what minimum lambda are you comfortable running when WMI is active? Any specific target to aim for under full load to keep EGTs in check without washing the cylinders?

3. Nozzle sizing – Given the displacement and typical boost levels of the 3.0 TDI, any recommendations on flow rate (cc/min) for a single nozzle setup? Would a staged dual-nozzle approach be worth considering?

4. Mix ratio – Are you running a standard 40/60 water/methanol mix, or have you found a different ratio works better for EGT reduction on this specific engine family?

Any tips or lessons learned from real dyno sessions would be really appreciated.

Thanks in advance!

1. Activation point – What boost pressure (PSI or bar) do you recommend as a Start and Full injection point for this engine? Is it better to tie activation to boost pressure alone, or would you also factor in IAT (Intake Air Temperature) as a secondary trigger? Triggering too early will result in significant engine noise and abrupt power delivery. I usually start around 25 psi and adjust from there on a setup like yours.

2. Target Lambda/AFR – Since this is a diesel application and retuning isn't strictly required, what minimum lambda are you comfortable running when WMI is active? Any specific target to aim for under full load to keep EGTs in check without washing the cylinders? I suspect you'll get dimished returns below 1.1 lambda, it really depends on how efficiently the engine design works.

3. Nozzle sizing – Given the displacement and typical boost levels of the 3.0 TDI, any recommendations on flow rate (cc/min) for a single nozzle setup? Would a staged dual-nozzle approach be worth considering? Start on the small side of the kit recommendations with a single nozzle and go up from there.

4. Mix ratio – Are you running a standard 40/60 water/methanol mix, or have you found a different ratio works better for EGT reduction on this specific engine family? The 40/60 mixes and similar are good for lowering EGT but do not add power anywhere near as well as the -40* washer fluid (90% methanol). If you're looking for power then use the higher methanol mixes. If you're purely looking for temp control, then bias in more water.

The systems are pretty simple. If you go too far on injector sizes or too low on boost activation you'll feel the vehicle hiccup and stutter. Simply raise the activation boost or go to a smaller jet if this happens. The most problematic thing we see in the shop on these systems is poor wiring installation and hacked up installs that result in boost leaks or failure to activate altogether.

Good luck, have fun

Nick