I got this one.
At 1000 rpm, 30% volumetric efficiency (idle), and an air fuel ratio of 34:1
You need about 2 L per second of E-gas.
With exhaust recycling (25%) and outside air (25%) you can reduce the egas to 50%, 1 L per second.
All speculation until it is done by us ofcourse.
Water to steam is expansion of 1600:1
Water to H and O expansion of 1800: 1 (about)
So 1L of water makes 1600 L of steam and/or 1800 L H2 and O2.
Hope that helps.
Warj1990