Water injection (was: Re: fuel cooling intake air)

[Axel Rietschin]

----- Original Message -----
From: "Bruce Plecan" <nacelp at bright.net>
To: <diy_efi at diy-efi.org>
Sent: Saturday, July 08, 2000 3:37 AM
Subject: Re: fuel cooling intake air

>> I'm interested in this becuase I just started playing with water
injection, and I am trying to decide where the best place to inject the
water is. I might try some gasoline or alcohol somewhere also when I lift
the boost level.

> Two things, vaporization, adamization.  Vaporization for cooling the
chagre, and adamization for detonation supression.

Cooling the charge by evaporating water before / inside the intercooler?
what for? you'd just displace oxygen with steam :)

Said differently, everything you'd gain from a lower temperature would be
lost because of oxygen displacement. Denser, yes, but that much diluted with
an inert substance.

What you really want to obtain (and the only thing you get) from WI is less
detonation. This could allows more boost pressure and/or more spark advance.
I believe it's better to inject late so water enters the cylinders in liquid
form, and take very little space. You get in-cylinder cooling as expected
and maybe also some extra pressure from water evaporation.

If you are concerned about the charge density, you can also consider to use
a more efficient intercooler and/or spray water on the outside of it. This
will give you a cooler, denser charge, still 100% made of air.

>> I've heard that the serious Rally guys inject before the intercooler when
using water injection.

I've at least one counter example: the Ford Escort Cosworth World Rally Car
has both WI and an intercooler spray system, and water is injected after the
IC.

Just my $0.02

Axel

PS: About spraying FUEL before the IC, I hope you'll never have any
backfire, because the mixture in most of the induction system will be REALLY
flammable, hot and compressed :)




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