Date: Sat, 24 May 2008 23:04:30 -0400
Reply-To: Greg Potts <greg@POTTSFAMILY.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Greg Potts <greg@POTTSFAMILY.CA>
Subject: Re: Water Injection
In-Reply-To: <4838BEAA.50000@charter.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi John,
I tried a water injection experiment in my westfakia last summer. In
July my engine threw a rod through the top of the case and I decided
that water injection might improve the longevity of the next engine, and
improve my milage as well. So I figured I'd give it a try on the
replacement engine.
I inserted a #22 gauge needle into the vacuum line leading to the vacuum
advance on the distributor and connected it to a 2L water bottle with an
air stone as a water filter. During idle it wouldn't draw water, but
above 2000 rpm there was a steady flow, amounting to about 2L per 50L of
gas. I drove about 600 miles this way, and the results seemed to be very
good at the time. Temps were good, and the "seat of the pants" dyno said
that it was running better than a typical 1697cc engine had any right to.
I ran one full tank of fuel through the engine before I put the water
injection system on, and the results on the next tank indicated a gain
of maybe 10% better gas milage. Unfortunately, that's not outside of my
usual standard deviation between fill-ups. I can say that after I
installed the water injection I *really* drove the snot out of it.
But...
After about two weeks the engine seized the rings on the #1 and #2
pistons, and totally lost compression during an extended highway run.
The only time I've ever needed towing on a road trip. I don't know what
the conditions were on that side of the engine, as the CHT gauge was on
the #3 cylinder.
I am not blaming the water injection for this failure, the simple truth
is that this engine was a VWoC rebuild from a 411 that had sat on a
shelf for 18 years before being pressed back into service. The only real
question is why the rings didn't fail a bit sooner. I found out later
that rings are a common failure point on the high-compression 1.7L
engines when stressed. I can say that when we pulled it apart the #1 and
#2 cylinders were as clean on top as any I have ever seen, so the water
must have been getting there.
Since that time I have honed and deglazed the cylinders, lapped the
valves, re-ringed the pistons and added an oil temp guage as well as a
new CHT sender. I also ground off the casting flash from between the
fins, sent the injectors out for flow testing and made sure the entire
cooling system was fully sealed. It's running very nicely since it was
reinstalled in the bus.
I did not reinstall the water injection. I have decided I am better off
to document at least 5000 miles on this engine before any further
experiments. Without any "before" data from this engine, the results
can't be much help to anyone.
I might try this on my vanagon, but I still need a couple thousand miles
of documented fuel consumption before I take this on. I have also
considered using MegaSquirt II to control H2O/methanol injection, but
the task remains to find water-compatible injectors and pumps if I
choose to go that way.
Robt Mann on the type2 list has been a proponent of water injection for
quite a while now.
http://www.dave-cushman.net/misc/mannject.html
We also discussed it last year on the FMBC:
http://fullmoonbusclub.com/e107_plugins/forum/forum_viewtopic.php?66473.60
Happy Trails,
Greg Potts
1973/74/79 Westfakia "Bob the Tomato"
1987 Wolfsburg Weekender Hardtop
www.busesofthecorn.com
www.pottsfamily.ca
a John Rodgers wrote:
> During WW II the Navy F4U Corsair and the Navy Hellcat had radial
> engines that used a water injection system that enabled those engines
> to achieve "Military Power" from the engines or in other words - achieve
> substantial power above the engines design capability for sustained
> maximum power. This water injection system enabled many a pilot to save
> his butt in a dogfight with Japanese pilots.
>
> Does anyone on The List have any knowledge about this, and whether there
> has ever been any effort to try and use the principle to extract more
> power for an automotive engine or increase mileage per gallon?
>
> John Rodgers
> 88 GL Driver
> Pomgranite
>
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