Subpage of MembersPage/MarcellGal/PowerAndTraction
We want water injection on this engine. Wether
- the small factory cooler and tubing is bolton
- or if it gets a shiny new cooler with nice tubing
- See the drawing on http://www.vems.hu/gallery/main.php?g2_itemId=41&g2_page=2
To get water into the engine reliably, one needs
- pressure
- on-off solenoid
- It is very important that a solenoid for this is reliable
- a boostcontrol solenoid might suffer corrosion. We don't know
- nozzle(s)
- 2 nozzles have the advantage to supply 3 different amount of fuel at different loads (or 2 different amount if they are equal size, or controlled that way)
Pressure
There are 2 ways to pressurize the system
- pump water
- + small and quiet pump unlike air compressors. Still hard to find for real high (>10bar) pressure, check for ulka coffee machine pumps, http://www.expolygon.hu/files/KVA_Szivattyuk.php
- + ability to produce stable pressure, unlike air-container systems
- + no need for pressurized can (you can reuse even your original windscreen washer can)
- - maybe an 230V inverter necessary for the right pump
- compress air
- this has some huge benefits: if the pump (or the pump supply or relay) fails, some energy is stored in the air so the systems stays pressurized, giving time for the system to lower boost and adjust ignition advance
- easy to store pressure energy for a few minutes of hard running. This would be weight saving for racers. Even for road use, it would be possible to fill with water and air pressure at the same time (it is necessary to fill with water from time to time anyway). This would eliminate any active pumping device
- the air compressor to pressurize air is available for 12 EUR, or even free (tyre compressor on gas stations). However, if one insists on carrying (leaky system?), the air compressor (at least a cheap one) is bigger and more noisy than a water pump
- the "check-valve" (nipple for the tyre-compressor) can be salvaged from an old rim or bicycle tyre
Nozzle
Good nozzles are essential to
- get good spray pattern, nice mist
- good service lifetime (no corrosion)
Nozzles must inject water after the charge cooler, but before the throttle.
It is generally a bad idea to inject water before the charge cooler. Because water cools the charge, injecting water before the charge cooler makes the delta-T smaller, thus the charge cooler can release less heat (bigger charge cooler needed for same effect).
While it is a good idea to spray water to the outside surface of the charge cooler, it is dumb to spray water to the inside surface. So we will certainly inject after the charge cooler.
Number of nozzles
Water mass - compared to fuel mass (or is the literature usually volume/volume?)
10..15% is the minimum, up to 30% might make sense
I have appr 180L/hour available total fuel injector capacity (with 200+ L/h fuelpump). So 20..40L/h water would make sense
Not sure about optimum though (not possible to fine-adjust anyway)... a 0.35 and a 0.45 mm nozzle would probably do it. TODO: more investigation