Water Vapor Injection System - PeachParts Mercedes-Benz Forum

retmil46 · #1 03-25-2012, 04:44 PM

After reading the thread on cheap water injection, I've got an even cheaper water injection system - actually, water VAPOR injection, that you can feed in prior to the turbo - entirely passive and automatic.

All it is is a 1/2 gallon square clear plastic storage jar with screw-on lid for about a $1.50 at Wally World. I drilled two holes in the lid and attached 1/2" ID hose fittings. One I left open right under the lid, the other I attached a piece of 1/2" hose running to the bottom of the jar, to act as a "bubbler".

I'd already routed the CCV hose from the valve cover thru a Provent CCV filter before it went into the air intake boot ahead of the turbo. I plumbed the bubbler jar into the outlet hose of the Provent, so most of the oil vapor was already stripped out - the outlet of the Provent attached to the inlet of the bubbler jar. The outlet of the bubbler jar was routed over to the air intake boot.

The blow-by gases would go thru the Provent and bubble up thru the jar - either distilled water or W/S washer fluid (aka methanol) - evaporating off the water and carrying the vapor to the inlet of the turbo.

I had this rigged up on my first 87 300D. After a few weeks of this, that engine ran as smooth and quiet at speed as a gasser, and I noticed an improvement in fuel economy as well.

The mention in another thread of using the EGR port as a water injection point gave me an idea - you could install a plate with a throttle valve to control air flow, and a check valve to prevent reverse flow of water - and bleed off a portion of the turbo discharge off the intake and use this to feed the bubbler jar, instead of using the blow-by from the CCV hose, for engines that have little or no blow-by. An advantage to this is the air thats been compressed by the turbo will be heated, and aid in water/methanol evaporation.

One added benefit of running the CCV thru the bubbler jar - whatever oil vapor the Provent didn't strip out, the water in the bubbler jar coalesced out - so you had completely oil-free blowby gases being fed into the turbo intake.