DIY_EFI Digest V5 #718 - knock sensor / Autospeed articles / water injection / dynos etc

Thu Sep 6 02:38:21 GMT 2001

Some hidden pearls and yes.

On the WI, I just don't see some of the ways for what they did.

They compare I/C to ambient air temp.  Why, it's a matter of MAT temp., that
reflects the potential for detonation, if your just working on the WI end of
things.
MAT as a first stage sound meaningful.
I'd think, a K/S input would be alot more beneficial.

I'm more then convinced there is no such thing as too much WI pump pressure.
If someone really wants to use a low pressure pump system, seems like
referencing the tank to the manifold would be manditory.

12v Tire pump, to an accumulator (pressure switch set to maintain 150 PSI)
air tank then NOS solenoid to presureize the water supply would seem ideal
to me.

Bruce

----- Original Message -----
From: "Hugh Keir" <hugh at sol.co.uk>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, September 05, 2001 7:34 PM
Subject: Re: DIY_EFI Digest V5 #718 - knock sensor / Autospeed articles /
water injection / dynos etc

> Just read the Autospeed articles by Tim White which are based on his
> Bachelor of Engineering thesis presented in November 1999 to the
University
> of New South Wales School of Mechanical and Manufacturing Engineering.
>
> Any one know if copies are available from Tim or the University or are in
> the public domain so we can speak about them?
>
> The title of his thesis is:- "The Effect of Spark-Knock on the Performance
> of a Modern Spark-Ignition Engine'.
>
> The first page of each of the three parts of the article can be found at
the
> following links. To see the remainder of each part you have to subscribe
to
> Autospeed.
>
> http://www.autospeed.com/A_0587/page1.html
>
> http://www.autospeed.com/A_0594/page1.html
>
> http://www.autospeed.com/A_0601/page1.html
>
> The article talks about the types of sensors used in his tests.
Conclusions
> are drawn in a number of areas including whether power is still rising in
> high compression engines at the onset of knock.
>
> The article also presents a table that shows amongst other things the
number
> of °C effect of intake temperature etc that = 1 octane of fuel, allowing
you
> to estimate the cost of reducing the various temperatures etc versus
higher
> octane fuel and the cost of the modifications ( intercooler, water inj
etc )
> to your car.
>
> On a turbocharged car ( well mine anyway ) where you are tuning for more
> power you will at some point want to increase the boost and optimise the
> ignition and fuel. This will have obvious consequences on inlet
temperature
> and the dreaded " knock ".
>
> The site http://www.aquamist.co.uk/dc/technic/technic.html shows a graph
> that backs up many of the results found by Tim White in the Autospeed
> article. The lines on the graph show cylinder pressure against crankshaft
> angle. It caught my eye that the area under the curve for the water
injected
> ( blue line ) setup was significantly greater than the detonating ( red
and
> yellow ) and the non detonating ( green line), which must mean
significantly
> more power from a water injection setup.
>
> Water injection has now become a must have on my shopping list.
>
> The following articles show a DIY water injection kit:-
>
> http://www.autospeed.com/A_0527/page1.html  part 1
>
> http://www.autospeed.com/A_0534/P_1/article.html  part 2
>
> http://www.autospeed.com/A_0574/P_1/article.html part 3
>
> http://www.autospeed.com/A_0578/P_1/article.html part 4
>
> http://www.autospeed.com/A_0589/P_1/article.html part 5
>
> http://www.autospeed.com/site/autospeed/images/0574_00.jpg shows a picture
> of the board
>
> http://www.autospeed.com/cgi-bin/browse.cgi?category=705&product=1280 -
buy
> the kit for AU$ 107.25 = US $58
>
> The DIY-WB has given me and I am sure others ( as soon as the boards and
> group buy parts are ready ) a fantastic opportunity to have a real go at
> optimising the performance ( don't know if my soldering is good enough yet
> but I'm sure gonna find out ) of our vehicles in a way that was previously
> never possible.
>
> Mix in a little of one of the following pieces of dyno ( sorry but I just
> don't want to do it on a rolling road, I want to do it myself )  software
or
> possibly a datalog from my as yet unpurchased ECU.
>
> On Track Dyno       http://www.ontrackdigital.com/generic.html?pid=4
> Road Dyno            http://www.charm.net/~mchaney/roaddyno/dyno.htm
> Revtrigger
http://www.students.tut.fi/~eppu/bin/rev.html#Updates
>
> I have also found this self build datalogger
> http://www.geocities.com/93notch/EMS/ , though not sure how useful it
might
> be.
>
> Only one thing missing in my life , ( well that I can admit to )  a
> .......... DIY KNOCK SENSOR .......... any thoughts possibly a modified
> version of the SAAB unit
http://www.geocities.com/tv41mxa/tweakyourapc.html
> or
> http://web.inter.nl.net/users/turbo-team-europe/apc.htm or
> http://www.users.qwest.net/~qed/volvoapc/index.html
>
> With all the individuals that want to spoil the party and seem unable to
say
> thanks to the DIY_WB team and abide by their rules,  its hard to believe
> that there would be enough enthusiasm to do a DIY knock sensor, but maybe
> just maybe.
>
> This is a long post to get to the point that I am passionately interested
in
> tuning my vehicle not because I race or want to show off or have any
> commercial interest, but because I care about how well I have made it run
> with tools available to me.
>
> Bruce and the team I take my hat of to you for your selfless efforts to
> bring the DIY-WB project to it's conclusion.
>
> I hope that I can do you justice by building the boards myself and
reporting
> on how I have improved things on my vehicle.
>
> I also hope I may have some skill that you will find useful in the future.
>
> Hugh
>
>
> ----- Original Message -----
> From: "Mark Agnello" <m_agnello at yahoo.com>
> To: <diy_efi at diy-efi.org>
> Sent: Wednesday, August 29, 2001 8:57 PM
> Subject: Re: DIY_EFI Digest V5 #718 - knock sensor
>
>
> >
> > > > TVS wrote:
> > > > >
> > > > > I assume the frequency has some dependence on
> > > variables
> > > > > like bore diameter and combustion chamber shape,
> > > but is the knock detection
> > > > > circuitry likely to 'listen' for a wide range of
> > > frequency's or just a
> > > > > narrow band?
> > > >
> >
> > These are just educated guesses, but I suspect they
> > apply.  Detonation is closely coupled to the pressure
> > wave in the combustion chamber.  The pressure wave is
> > an acoustic event.  As such, it should be influenced
> > by the geometry of the combustion chamber at the
> > instant of the event.  The dominant mode's wavelength
> > will probably be proportional to the cylinder bore.
> >
> > If the event timespan is too short to propagate
> > laterally, then the dominant mode will probably be
> > related to the combustion chamber height at the time
> > of the event.  Even if there is a lateral mode, I
> > wonder if the high frequency content in a knock signal
> > is due to the vertical mode(s)?
> >
> > WRT the cylinder head and/or block structure
> > influencing the dominant frequencies, I agree there
> > will be some interaction.  Unlike the 10 Hz bell
> > analogy, I don't believe there will be a dominant
> > vibrational mode of the engine structure.  These
> > structures are too complex to have a primary mode and
> > I'll bet auto manufacturers spend a lot of time
> > designing engine structures that don't have
> > significant vibrational modes.  I know aircraft engine
> > manufacturers do this.  If they didn't, the life of
> > the engine mounted fuel pumps, actuators, sensors, and
> > accessories would be severely shortened.
> >
> > What do y'all think?  Remember, I'm just a lonely old
> > EE that likes to read SF.;)
> >
> > Autospeed published an article based on an Aussie grad
> > student's research into engine knock earlier this
> > year.  Does anyone have a copy and does it shed light
> > on this issue?
> >
> >
> > =====
> > Mark Agnello
> > Washington Crossing, PA (USA)
> > 88 Toyota Celica All Trac Turbo (restoration project)
> > 92 Toyota Celica All Trac Turbo
> > 96 Honda VFR
> > 89 Honda Hawk GT (restoration project)
> >
> > __________________________________________________
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> > http://im.yahoo.com
>
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