Water-Meth

[L8T]

Anyone tried running water meth as a power adder/mileage improver on their gasser yet? I ran it years ago on a Duramax but have never tried it on an NA engine. I feel with the higher compression and direct injection intake valve build up issues it might be very beneficial at a 30 to 50% meth mixture. 

Edited March 18, 2021 by L8T

[CamGTP]

I see no point on a NA engine.

 

It's already a DI engine, the fuel spray cools the air charge down inside the cylinder.

[L8T]

Not sure if you’re aware or not but WM does more than just cool the air. 

[CamGTP]

I'm well aware of what water/meth does and I see no point on these engines when NA.

 

You are adding in extra fuel as well with the meth, which you don't need. You can't compensate for it with a tune either. Every engine is different but when I took the intake manifold off my DI 5.3 truck with 104,000 miles I was not concerned at all with the build up on my intake valves.

 

At cruising speeds the intake air temp is going be within 5-10 degrees of ambient, then it's going to get cooled by the fuel spray of the injector in the cylinder. What gains do you think you will see if you cool the air down just a smidge further? How will adding water/meth improve fuel mileage in closed loop fuel control?

[Grumpy Bear]

We use to use water as detonation suppression on NA motors when gasoline octane started tanking after TEL was taken from gasoline. Water was quite effective as a charge coolant. It wasn't run continuously but triggered by manifold vacuum. Alcohol was added mostly to prevent freezing but also as an octane booster for stubborn cases.  Yes we have knock sensors but the point of this exercise it to prevent removing timing. 

 

Point of note. A motor with fuel before the valve at part throttle (high vacuum) vaporizes fuel by lowing the boiling point based on absolute pressure in the manifold. Near full throttle this effect is diminished as pressure rises reducing it's effectiveness. Water and alcohol both have lower boiling points than gasoline so it's more effective. 

 

GDI motors inject fuel under crazy high pressure into a cylinder under compression pressure several times higher than atmospheric. The gasoline is atomized not vaporized and does not contribute to charge cooling. Even it's temperature at the injector is quite a bit above its temperature in the tank the result of over 2K pressure.

 

Personally I don't see an advantage in a NA GDI motor and can see a few issues that may arise. For example the sensor that we call the MAP in the GM setup also measures humidity and temperature and adjust fuel accordingly. Adding moisture that is unaccounted for between the sensor and the valve will have an effect on fuel delivery rate. 

 

Anyway my 2 cents of which only one may have any value.