DIY_EFI Digest V4 #696
Bobby Radomirov
supra90t at prodigy.net
Wed Dec 15 20:25:04 GMT 1999
The O2 sensor varies the voltage constantly. Abouth 8 times per sec on a
good one and 4 times per sec one old one. The perfect 14.7-1 mixture is
about .480V anything that is under is Lean anything over is Rich. The
Max power range is abouth 10:1 - 12:1 mixture. You can cheat on the O2
sensor my puting small resistor in series with the circuit you will have
some initial voltage drop accross it and will cause the Computer to
richen the mixture. Althou I dont see why you would do that Because at
WOT teh computer doesnt receive input from the O2 sensor and it will run
at teh best preprogramed mixture for teh particular engine. The point is
in making other sensors like temp sensor, air temp sensor, AFM to read
denser air and colder temperatures. That added the resistor accross the
O2 wire will richen the mixture. But it might afect performance as well.
Richer mixture doesnt neseseraly means that you will have more HP or
Torgue. It all depends on the engine design
DIY_EFI Digest wrote:
>
> DIY_EFI Digest Wednesday, December 15 1999 Volume 04 : Number 696
>
> In this issue:
>
> CFM vs. lb/min
> re: Pulse Wdith.
> Re: DIY_EFI Digest V4 #695
> Re: 4 links
> Max injector size?
> Re: ECU pulse width calculations
> RE: Airflow Measurement
>
> See the end of the digest for information on subscribing to the
> DIY_EFI or DIY_EFI-Digest mailing lists.
>
> ----------------------------------------------------------------------
>
> Date: Tue, 14 Dec 1999 15:37:02 -0500 (EST)
> From: William T Wilson <fluffy at snurgle.org>
> Subject: CFM vs. lb/min
>
> On Tue, 14 Dec 1999, DIY_EFI Digest wrote:
>
> > Can someone tell me why cylinder heads, intakes, throttlebodys, etc.
> > etc. airflow numbers are quoted in CFM? Would it be better if they
> > were given in lbs/min? Why or why not? I understand why compressors
> > are rated this way just not why other engine componets are not.
>
> Because CFM is the same regardless of ambient pressure, but lbs/min is
> not.
>
> ------------------------------
>
> Date: Tue, 14 Dec 1999 14:16:01 -0800
> From: "John Dammeyer" <johnd at autoartisans.com>
> Subject: re: Pulse Wdith.
>
> >John Dammeyer <johnd at autoartisans.com> wrote:
> >
> >>If it's a standard O2 sensor why not replace it with a pot that provides
> >>0..1.0V and set the output to 0.5V which is supposed to be 14:7:1. Then,
> >>because the O2 is telling the ECU that the mixture is perfect it won't keep
> >>screwing around with the mixture pulse width and you can see the real result
> >>of your tuning.
> >
> >I have little experiance in these things, but don't OEM controllers richen the
> >mixture until they see the O2 sensor make a "transition" from low to high, and
> >then they lean the mixture until the voltage goes back down.
> >
> >Holding the O2 sensor voltage constant would have an unpredictable effect.
> >Possibly the computer would flag it as faulty and use some sort of backup
> >system.
>
> I don't believe that's true. The HEGO sensors have a voltage output of 0.5V at
> 14.7:1 and then the voltage changes rapidly on either end and so the sensor
> appears to have a on/off value. Perhaps some engine controllers do just use a
> simple go/nogo approach but I doubt it. I can adjust the mixture so the O2 puts
> out 0.55V or 0.6V etc. I have no clue if 0.55V is 14.1:1 or 10.1:1 but I do
> know that with a properly set up engine with an Ellison Throttle carb. or else
> an SU carb that at maximum Torque the O2 sensor is at about 0.75V. I've set my
> fuel injection to be roughly the same. Exhaust Gas Temperature and a Post Run
> check of the spark plug colour all confirm the mixture is 'about' right.
>
> Cheers,
>
> John
>
> ------------------------------
>
> Date: Tue, 14 Dec 1999 17:28:28 -0500
> From: Scott_Hay at toyota.com
> Subject: Re: DIY_EFI Digest V4 #695
>
> 4 Links
>
> Van, The length and distance apart are only a small portion of the equation.
> What are their angles relative to horizontal and are they parallel? I assume
> that this car is for the road as opposed to drag racing (completely different
> setup). The instantaneous center is the point where the torque of the wheels
> will act upon the body. This is determined by the angles of the links. If this
> projected point is too low (significantly below the CG) the front of the car
> will have tremendous lift on acceleration. Too high, and not enough weight will
> transfer to the back and wheelspin (if you have that much HP). As to the
> lengths that you are working with, that will probably be determined more by
> space availability more than anything else.
>
> There are some very good books like HP's "How to Make Your Car Handle" it is a
> starting point that goes into most of the questions that you need to ask.
>
> Scott
>
> Date: Tue, 14 Dec 1999 05:24:47 EST
> From: DemonTSi at aol.com
> Subject: Non- DIY EFI: question about four link/bar rear ends...
>
> Hi folks, I was hoping to get some info from someone who has experience with
> fabricating a rear 4 link or 4 bar suspension setup. I'm working on designing
> and fabbing a 4 bar for my datsun roadster and was just wondering if there
> were any optimum lengths for the links, and distance between them that I
> should try and stick to. Right now I have the links at about 10.5-11" long,
> and 5" apart, center-to-center. Any help/advice/tips/comments would be great!
> Thanks in advance.
>
> Van
>
> ------------------------------
>
> Date: Tue, 14 Dec 1999 17:30:16 -0500
> From: David Brode <dbrode at hereintown.net>
> Subject: Re: 4 links
>
> Hello all,
> Finally something I know a little about![humor]. I've done a bit of
> chassis fabricating and help a friend with a 4 link equipped 3040 lb
> B-1 Dart that carries the wheels 90 ft and runs 9.20's @ 149
> [through the muffs].
> Short "bars" will cause your pinion angle to change a bunch during
> travel. Most race car equal length "links" are 20" C/L to C/L.
> Unequal length deals are usually 20" on the lower bars and shorter,
> but as long as possible on top. For a street only car, Spread them
> out as far as possible to prevent bad body roll, and make them level
> front to rear. You can run them parallel to car's C/L, but you'll need a
> diagonal link or a panhard bar. Another option is to run the top bars
> [or all] at an angle, like many factory 4 bar setups. You could copy
> most any factory design. Running at least the tops at an angle will
> enable you to get away without a locator [panhard/track locator]
> Fyi - Chevettes had a 4 bar set up that could be cheaply adapted.
> You can cut and re-weld them too.
>
> Now, if I could just get someone to tell me if 80's turbo 2.2 Chryslers
> had low or high impedance injectors.
> Good luck.
> Dave Brode
>
> >
> > From: DemonTSi at aol.com
> > Subject: Non- DIY EFI: question about four link/bar rear ends...
> >
> > Hi folks, I was hoping to get some info from someone who has experience with
> > fabricating a rear 4 link or 4 bar suspension setup. I'm working on designing
> > and fabbing a 4 bar for my datsun roadster and was just wondering if there
> > were any optimum lengths for the links, and distance between them that I
> > should try and stick to. Right now I have the links at about 10.5-11" long,
> > and 5" apart, center-to-center. Any help/advice/tips/comments would be great!
> > Thanks in advance.
> >
> > Van
> > - - http://members.xoom.com/BADROC
> >
>
> ------------------------------
>
> Date: Tue, 14 Dec 1999 17:50:46 -0500
> From: "Jesse R. Ortiz" <jro at tampabay.rr.com>
> Subject: Max injector size?
>
> Is there a formula to figure out the maximum injector size, while still
> allowing for a good idle. I'll be using a Haltech so idle pulse width can be
> adjusted. The engine is 2.6L.
>
> Thanks in advance.
>
> Jesse.
>
> ------------------------------
>
> Date: Tue, 14 Dec 1999 16:55:06 -0600
> From: "G. Scott Ponton" <gscottp at ix.netcom.com>
> Subject: Re: ECU pulse width calculations
>
> <unlurk>
> There is a lot of good information in the archives about how the OEM
> systems use the o2 sensor. As the OEMs implement it it is used more as a
> switch than anything else. This has been an ongoing disagreement for some of
> us. The O2 sensor is capable of being used as an analog device if it is not
> connected to the OEM computer system.
> The problem with it is that it has a very narrow operating window. It
> won't read AFRs much either side of stoich. So using it in a manner other
> than it was intended by the OEM system isn't necessarily going to give you
> the info you always want.
>
> <relurk>
> Scott
>
> ------------------------------
>
> Date: Tue, 14 Dec 1999 18:15:27 +0000
> From: Ade + Lamb Chop <alaw at mrc.soton.ac.uk>
> Subject: RE: Airflow Measurement
>
> At 05:00 14/12/99 -0500, DIY_EFI Digest wrote:
> >
> >Date: Mon, 13 Dec 1999 22:38:40 -0600
> >From: pcs74 <pcs74 at swbell.net>
> >Subject: Airflow Measurement
> >
> >Hello,
> >
> >Can someone tell me why cylinder heads, intakes, throttlebodys, etc. etc.
> >airflow numbers are quoted in CFM? Would it be better if they were given in
> >lbs/min? Why or why not? I understand why compressors are rated this way
> >just not why other engine componets are not.
> >
> >Thanks Chris Skarzenski pcs74 at swbell.net
>
> Don't think it really matters as long as everbody uses the same units for
> comparison purposes. Also air changes density so a lb of air changes it's
> phisical dimentions. However a Cubic foot of air will always be a cubic
> foot of air.
>
> Whether this is a good thing of not I don't know :-) It probably stems from
> some acient ritural that us brits came up with :-)
>
> Ade
>
> ------------------------------
>
> End of DIY_EFI Digest V4 #696
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