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Water Ethanol Injection

Road Tuning

Discussion and questions related to the course Road Tuning

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I need a little advice on tuning with EU 98 Octane fuel (US 93) and water / ethanol injection.

In my country, methanol is illegal and whiperfluid contains ethanol. Therefore i am using 50/50 water ethanol. (Measured the actual ethanol content to be 50%)


BMW M50 2.8L Inline 6

9.0:1 CR

240 deg 9.7mm - both cams set to 0.5mm overlap at TDC.

Snow Performance injection kit with 625cc nozzle at 25cm before the throttle body.

Precision 6266 AR.81 turbo.

Ecu Master EMU Black

Timing is verified at idle and 6000rpms.


1 bar of boost and 4300rpm the knock limit is 8 deg.

1 bar of boost and 5500rpm and above, 16 deg of timing dosent knock at all. So the timing curve seems strange to me.

I am using both EMU knock detection and knock ears.

Adding the water ethanol injection - lambda drops from 0.78 to 0.7 and i am pulling 22% fuel to get back at 0.78.

When meth is spraying its actually loosing power. 30nm aprox.

Power is picked up again when increasing timing. 6 deg increase from 4500rpm - 12 deg increase at 5500 and above. This was done on a dyno.


It could sound like i am spraying too much?

Does others experience power loss the same way as i do?

Should i increase ethanol content? As the ethanol i am using is 92% before blending with water.

Any tips is much appreciated.


Mustang dyno showed 465WHP / 520WNM @ 1.4-1.5 bar boost.

I did really expect it to make more power than this, comparing other m50s on the 6266.

It is not uncommon for water/alcohol injection to result in lower power before you make adjustments to the tune. The water/ethanol injection can on some engines slow down the burn, meaning you need more spark to get equivalent, and also affect lambda.

I would add spark until you reach whatever you feel is the safe knock limit. Also, you can run a leaner lambda than without the injection. However, you still need to be careful. You can still damage something, and as you add spark or lean out the risk increases.