[Diy_efi] PW Controlled Sequential Water Injection - It RUNS!

Thu Oct 21 13:49:33 GMT 2004

I am not an engineer, so i might be talking crap here, but according to what i have been reading around, it should be possible to run pretty lean A/F with just an half decent engine management, and without the complication of water injection.

aircrafts engines are routinely run at lean of peak for hours without any problem whatsoever, as long as top power is not required.

knocking at cruise can be easily avoided with a proper ignition map, and i doubt it is necessary to inject a fuel substitute to achieve MPG improvement. 

from the gasoline FAQ. i think the magic word there is "calibrate". i suppose that just squirting some water in the engine is easy, to achieve any advantage is a completely different story.

7.13  What does water injection achieve?.

Water injection, as a separate liquid or emulsion with gasoline, or as a
vapour, has been thoroughly researched. If engines can calibrated to operate 
with small amounts of water, knock can be suppressed, hydrocarbon emissions 
will slightly increase, NOx emissions will decrease, CO does not change
significantly, and fuel and energy consumption are increased [113- Water Addition to Gasoline - Effect on Combustion, Emissions, Performance, and Knock. J.A.Harrington.SAE Technical Paper 820314 (1982).].
Water injection was used in WWII aviation engine to provide a large increase 
in available power for very short periods. The injection of water does 
decrease the dew point of the exhaust gases. This has potential corrosion 
problems. The very high specific heat and heat of vaporisation of water 
means that the combustion temperature will decrease. It has been shown that 
a 10% water addition to methanol reduces the power and efficiency by about 
3%, and doubles the unburnt fuel emissions, but does reduce NOx by 25% [114]. 
A decrease in combustion temperature will reduce the theoretical maximum 
possible efficiency of an otto cycle engine that is operating correctly, 
but may improve efficiency in engines that are experiencing abnormal 
combustion on existing fuels. 

Some aviation SI engines still use boost fluids. The water-methanol mixtures 
are used to provide increased power for short periods, up to 40% more - 
assuming adequate mechanical strength of the engine. The 40/60 or 45/55 
water-methanol mixtures are used as boost fluids for aviation engines because 
water would freeze. Methanol is just "preburnt" methane, consequently it only 
has about half the energy content of gasoline, but it does have a higher heat
of vaporisation, which has a significant cooling effect on the charge. 
Water-methanol blends are more cost-effective than gasoline for combustion 
cooling. The high Sensitivity of alcohol fuels has to be considered in the 
engine design and settings.

Boost fluids are used because they are far more economical than using the 
fuel. When a supercharged engine has to be operated at high boost, the 
mixture has to be enriched to keep the engine operating without knock. The 
extra fuel cools the cylinder walls and the charge, thus delaying the onset 
of knock which would otherwise occur at the associated higher temperatures.

The overall effect of boost fluid injection is to permit a considerable 
increase in knock-free engine power for the same combustion chamber 
temperature. The power increase is obtained from the higher allowable boost. 
In practice, the fuel mixture is usually weakened when using boost fluid 
injection, and the ratio of the two fuel fluids is approximately 100 parts 
of avgas to 25 parts of boost fluid. With that ratio, the resulting 
performance corresponds to an effective uprating of the fuel of about 25%, 
irrespective of its original value. Trying to increase power boosting above 
40% is difficult, as the engine can drown because of excessive liquid [110].

Note that for water injection to provide useful power gains, the engine 
management and fuel systems must be able to monitor the knock and adjust 
both stoichiometry and ignition to obtain significant benefits. Aviation 
engines are designed to accommodate water injection, most automobile engines 
are not. Returns on investment are usually harder to achieve on engines that 
do not normal extend their performance envelope into those regions. Water 
injection has been used by some engine manufacturers - usually as an 
expedient way to maintain acceptable power after regulatory emissions 
baggage was added to the engine, but usually the manufacturer quickly 
produces a modified engine that does not require water injection.

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
Behalf Of David Cooley
Sent: Donnerstag, 21. Oktober 2004 15:27
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] PW Controlled Sequential Water Injection - It
RUNS!

 the MPG improves because you can:
A. Lean out the cruise mixture without fear of detonation and
B. the water injected replaces some of the fuel in the mix, so less fuel per
volume of air is required

-------Original Message-------

From: A list for Do-It-Yourself EFI
Date: 10/21/04 08:43:51
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] PW Controlled Sequential Water Injection - It RUNS!

Hi Daniel,

Would you have some pointers at explanations about cruise mpg
improvement ?

Alexei

"Daniel R. Nicoson" wrote:
>
> It ran. I'm happy and celebrating with a bowl of vanilla ice cream & Oreo
> cookies and a Mt Dew.
>
> I ran it tonight for about 15 minutes, only a few leaks to fix and a
> pressure gauge to wire up Saturday AM. Hopefully dyno time over the
> weekend. I can't claim any blazing performance improvement based on
> tonight's run. I still have to load the appropriate tune into the EEC to
> take advantage of the system. The EEC Tuner list was helping me with that
> tune today.
>
> What is it?
> 8 separate 14# injectors with their own "water feed rail", water pressure
> regulator referenced to intake vacuum (actually a 1994 Mustang 5.0 fuel
> regulator), a 6 gallon supply tank in the trunk with a Sureflo diaphragm
> pump. Water flows up to the feed rail through your basic 300 psi air
> compressor hose and the return flow through the same. I built an analog
> controller that is triggered by the respective fuel injector pulse width,
> the water injector is delayed a set amount of time and then fires for the
> remainder of the pulse width. This delay is adjustable giving me the
> ability to change the percentage of water injected. I have 30# fuel
> injectors. I also use the EEC Tuner which gives me full control over my
> fuel tables and spark tables. The injector drivers are proper P & H if I
> ever need to run lo impedance injectors. Right now just running Crown Vic
> 14# high impedance injectors.
>
> What's it supposed to do on a NA 1994 5.0 Mustang?
>
> Two things, provide detonation resistance at WOT (two T-3 turbos waiting
for
> an install...) and POSSIBLY improve highway cruise mpg.
>
> Theory:
>
> WOT operation you guys all know. Cooler intake charge; also water replaces
> the extra fuel normally used to cool the cylinder during the combustion
> event. I'll be experimenting with pretty lean mixtures at WOT (13:1 even
> 14:1 AFR).
>
> Highway cruise. Based on some WWII research reports - they were running up
> to 50 parts water to 100 parts fuel at high load, achieving great power
> gains AND achieving about 10% improvement in efficiency. My thoughts were
> that 50% water at low LOADs probably would be too much but if I built the
> controller with some adjustability I could EXPERIMENT and see if a lesser
> amount of water would help at highway cruise.
>
> Most of the ideas I used were from you guys on these lists. A lot of
people
> from various lists have contributed. I think we started discussing pulse
> width controlled sequential water injection back in July 2003. I've been
> working on it ever since. I had to learn all about the electronics and
> spent most of this 15 months getting all that working right. My wife jokes
> that I could open a Radio Shack store with everything it took to finalize
> the circuit (most of it came from Mouser and Digi Key). The fabrication to
> mount the extra injectors under my Trick Flow manifold took over a month.
> The feed rail is welded stainless steel (Dustin where I work is a wizard
> welder!). The wiring harness in the car was a LOT of work.
>
> This is an EXPERIMENT! Eventually I will write all this up, post some
> circuit diagrams etc. Right now I have about 30 days before the snow shuts
> me down, I want to get some data during that time. I am also concerned how
> long the injectors will last. I ran straight water tonight. After the
> leaks are all resolved, I plan to run 80% water & 20% methanol that has 1
oz
> of Klotz - Uplon fuel lube per gallon of methanol. The Klotz is supposed
to
> provide upper cylinder lube for alcohol fueled vehicles AND provide rust
> protection for the fuel system. My only corrosion concerns are the
> injectors, pressure regulator and pressure sensor. Everything else is
> stainless, rubber or plastic (boat fuel tank).
>
> Its an EXPERIMENT, I'm having fun! Worst part is I'll be traveling for
work
> the next two days and won't get back to the project until Saturday AM.
>
> Fire away!
>
> Dan
>
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