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Re: [turbobike] Water injection

John Williamson (john.williamson5@virgin.net)
Sat, 2 Oct 1999 14:36:07 +0100

Injecting water actually reduces power on its own.

Beware of increased power or better fuel consumption claims!

The only way water can increase power is by allowing more boost or
compression at a given boost level.
It reduces power simply because it replaces part of the induction charge, so
less oxygen.
A richer fuel mixture has exactly the same effect as adding water in so far
as it makes it less prone to detonate, and less power.

It can allow more boost / nitrous though at the same compression ratio.

If any of you want to try more boost and detonation is a problem, a simple
water injection system can be made easily.

Run a small (4 to 6mm) tube from the plenum to a sealed (and now pressurised
when on boost) water tank.
This needs to be strong enough for your boost pressure, so alloy is best.
Drill a 1mm hole in the cap, open to atmosphere, (to allow any pressure that
has built up in the airspace to dissipate when you close the throttle - this
is important!
Take a feed from the bottom of the water tank to a needle valve of somekind
(try airline/hydraulic specialists or model aircraft shops) and into your
turbo air intake.
Now the more boost you produce, the more water you get. Fully proportional
and no pumps needed, so it can not fail. Set the needle valve (or fixed jet
if you want) to control flow.
DO make sure that you fit a small non return valve from a car windowscreen
washer or similar one way valve in the pressure line from the plenum to the
water tank, as the motor will suck when the motor is without boost. You
don't want vast quantities of water being drawn into your engine at idle or
on the overrun do you!
The needle valve can be adjusted to give the required flow on full boost.
Best place to do this is on the dyno. You can see it work too!

If you use Nitrous, (turbo or non turbo) the best way to add water injection
is to add 20cc or so to each bottle before you fill it, as water mixes with
the liquid N2O easily and will be injected with the nitrous.

As an aside, water injected engines are always completely carbon free when
the head is removed! not sure what this tells us though...

A mixture of methanol and water is better still or so everyone tells me but
I don't know why..

Adding water only really has the same effect of a richer mixture so you
could just try this instead!

(I sell and build and operate my own dyno systems, build N2O systems from
scratch, and have set up and run lots of turbo / turbo nitrous bikes,
including my own (now dead R.I.P.) Suzuki 1100E with a TO4E Rayjay and MR
Turbo header pipes and manifold / race wastegate etc, and 2 stages of
Nitrous.. One used on the throttle via a microswitch to make power, and spin
the turbo up at low revs for a fast getaway without revving the tits of it
at the line.. This stage switches off at 8 psi boost automatically via a
pressure switch in the plenum.
The other stage is bigger and on the 'button.)


----- Original Message -----
From: Patrick Inniss <inniss@sprynet.com>
To: Turbo Bike Mailing List <turbobike@natvideo.com>
Sent: Saturday, October 02, 1999 7:59 AM
Subject: Re: [turbobike] Water injection

> I think that water injection was used in the old turbocharged Corvair
> Spyder. Water injection was also available on turbocharged fighter
> planes like the Corsair and kicked in when emergency power was needed at
> low altitudes. Some engines actually injected a water/methanol mix. I
> also seem to remember seeing some crude bike installations maybe using
> windshield washer pumps. It does seem like a good idea. Here's some
> stuff I found on the web -
> Here's a company that sells components for water injection systems:
> http://www.aquamist.co.uk/cp/cp.html
> Also http://bert.netcolony.com/members/csdaytona/water.html
> From http://www.rallycars.com/Cars/WaterInjection.html:
> Water injection systems are only needed in turbo charged engines. The
> system has been around for a long time since it was already used in some
> World War II aircraft engines. A water injection system works similarly
> to a fuel injection system only  it injects water instead of fuel. In
> high pressure turbocharged engines the air/fuel mixture that enters the
> cylinders can explode prematurely (before the spark plug ignites,
> effect also known as engine knock) due to the extreme engine environment
> conditions. This situation results in severe engine damage in the long
> run (piston piercing). To avoid damaging the engine, water is injected
> in the combustion chambers in order to provide a  water/air/fuel mixture
> which not only burns more efficiently and avoids spontaneous detonation
> but also provides additional cylinder and piston cooling. There are
> mainly three variations of water injection devices. They are dependent
> on the location of the water injector(s). The first technique consists
> of injecting water at the entrance of the
> intake manifold. The second injects water at the exit pipe of the
> intercooler. The third technique injects water at the entry of the
> intercooler and is only used in competition vehicles. In this latter
> variation most of the in-cylinder detonation prevention is done by
> injecting additional fuel which is used as coolant (i.e. not burned).
>   How water injection works
> The system, usually, is made up of 3 elements. A water injector (similar
> to a fuel injector) a high pressure pump (capable of 3 to 4 bar pressure
> and sometimes even more) and a pressure sensor connected to the inlet
> manifold. The most advanced systems add 3D cartography similar to what
> is used in fuel injection systems.
> When the pressure in the inlet manifold exceeds a certain, predefined,
> value the system starts injecting water. The cartographic based devices
> take into account many more parameters such as inlet air temperature,
> air/fuel ratio, ...
> Copyright 1997-1999 by Tryphon Georgallides, all rights reserved.
> from
> http://www.fortunecity.com/silverstone/morgan/161/how/waterinj.htm:
> Water injection systems are mainly used on turbo-charged engines. It
> works similarly to a fuel  injection system only it injects water
> instead of fuel. In high pressure turbo-charged  engines the air/fuel
> mixture that enters the cylinders can explode prematurely  due to the
> extreme conditions. This situation results in severe engine damage in
> the long run (piston piercing). To avoid this, water is injected in the
> combustion chambers, usually through the intercooler, in order to
> provide a water/air/fuel mixture which not only burns more efficiently
> but also provides additional cylinder and piston cooling. The use of
> water injection seems to have re-emerged in recent times. APS (sellers
> of a performance kit for Subaru WRX's) have included it as part of their
> package and others such as aquamist sell independent kits.
>   There is a great deal of skepticism amongst tuners about the benefits
> and the effectiveness of water injection. However, some of the
> manufacturers, such as aquamist, do have some very comprehensive kits
> that incorporate features such as 3d mapping.
> Good luck,
> Pat Inniss
> inniss@sprynet.com
> http://home.sprynet.com/~inniss/
> ----- Original Message -----
> From: Bob Buehler <ribicf@hotbot.com>
> To: Turbo Bike Mailing List <turbobike@natvideo.com>
> Sent: Thursday, September 30, 1999 9:04 PM
> Subject: [turbobike] Water injection
> > Hi Gang:
> >
> > I need some advice on water injection. I was told or read somewhere
> that water injection was relitively simple and inexpensive and would
> alow for the use compression ratios of 9 or 10 to 1 as is found with
> stock pistons.  I believe it also was supposed to inhibit detonation
> using stock compression ratios even at boost pressures as high as 12 or
> 14 psi.
> ><snip>