DIY_EFI Digest Friday, May 21 1999 Volume 04 : Number 297 In this issue: TEST (Ignore me!) Re: alternative engines, now Hemi Re: 1227749 Re: alternative engines, now Hemi Re: O2 Volts Re: alternative engines, now Hemi Re: Mr Helmholz - simple model Re: alternative engines, now Hemi Re: Supercharged 440 Re: O2 Volts Re: Mr Helmholz - simple model Re: Mr Helmholz - simple model Re: alternative engines, now Hemi Re: alternative engines, now Hemi Re: alternative engines, now Hemi Re: alternative engines, now Hemi Re: O2 Volts Re: alternative engines, now Hemi Re: O2 Volts Re: O2 Volts Re: O2 Volts Re: O2 Volts Re: O2 Volts Re: Mr Helmholz - simple model Re: Mr Helmholz - simple model Simple Injection Questions See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Thu, 20 May 1999 17:13:08 -0400 From: "C. Brooks" Subject: TEST (Ignore me!) Told ya so :) ------------------------------ Date: Thu, 20 May 1999 14:26:13 -0700 (PDT) From: Squash Subject: Re: alternative engines, now Hemi - --- "Todd....!!" wrote: > I'll probably use a RAT ROASTER when I inject my > twin turbo 426 Hemi, What is a RAT Roaster?? Is this a mopar anti-chevy slang term? Andy _____________________________________________________________ Do You Yahoo!? Free instant messaging and more at http://messenger.yahoo.com ------------------------------ Date: Thu, 20 May 1999 17:26:09 -0400 From: Frederic Breitwieser Subject: Re: 1227749 > HOW in the world didi ya find out when and where this auction was going > to be? I dunno, this was back in the early 90's, but they have them every so often. Read the papers, car mags, etc, sometimes they advertise in the back. Those "Jeep for $10" government ads are information about auctions... waste of 10 bucks really, but thats your worse case scenario. We should prolly take this offline too since its a carb based truck at the moment, and I don't have the time to EFI it, too many other EFI things going on. > I'd pay $700 for a hummer shell! Yeah, that goes without saying. I really wasn't in the market for one at any price, however I was visiting a friend in LA, he was going, I tagged along, I found this carcass, and couldn't help myself. > Did ya use the caddi transaxle and make IT a mid engine! or is it setup > in the normal front engine rear wheel drive, or 4 wheel drive or what? 4wd using hummer diffs, 5 speed out of a commercial GM box truck of some sort (junkyard), engine/trans adaptor. > Hope I can find this e-mail when your firewall's fixed! Remind me every few weeks. ------------------------------ Date: Thu, 20 May 1999 14:46:58 -0700 From: Bill Edgeworth Subject: Re: alternative engines, now Hemi Hemi's do not use siamesed intake ports like the B engine heads. Most stuff from the bottom end is interchangeable i.e..) timing chain or gear drive, timing cover, water pump, oil pump, NOT the cam, oil pick up on hemi is 1/2" instead of 3/8" pipe (can be changed on 440 block to Hemi specks), cranks, NOT main caps, NOT blocks. Bill Edgeworth "Todd....!!" wrote: > Would your FI setup for the 440 intake bolt onto the 426 Hemi's intake? > (i.e. are the runners located in the same position? I know the intake > bolts are verticle on the hemi vs. the 440 has the angled intake bolts, > but other than that, I've never noticed any diff? > > I'll probably use a RAT ROASTER when I inject my twin turbo 426 Hemi, > how bout you? > > If ya think ya want some Hemi parts go to my link page at: > http://www.c-com.net/~atc347/toddlnk.htm > and go to the Swapmeet stuff, there's quite a bit of VERY TRICK HEMI > stuff there for sale! Like Hemi Alum rods, 8 titanium keepers or > retainers, can't remember which, gear drive, etc.. Some of this stuff is > usable on our NON hemi BB Mopes... > > LATER! > > Todd....!! > > Frederic Breitwieser wrote: > > > > > Anyhoo.. I believe ya, the Hemi heads really flow alot, even in stock > > > form, add that to the shape of the combustion chamber and where the > > > > They also look cool and sound cool. However, they suck gas. Good > > candidate for EFI :) > > > > -- > > > > Frederic Breitwieser > > Bridgeport CT 06606 > > > > 1993 Supercharged Lincoln Continental > > 1989 HWMMV w/turbocharged 500cid Caddy > > 1975 Dodge D200 Club Cab soon to have 431 stroker + turbos > > 2000 (I hope) Buick GTP (Mid-Engined Sports Car) ------------------------------ Date: Thu, 20 May 1999 18:00:11 -0400 From: "Bruce Plecan" Subject: Re: O2 Volts Now, to me rather than go on,, with further testing while it might settle a curiousity, it doesn't help with what my goal is. If you think about it, there are so many variables that on any one day, you can ask, where are things?. ie O2 level, in the atmosphere varies day to day, along with other "rare" chemicals. that might contaminate the results. In the oem applications they supply a reference voltage which as to effect the ionization, and performance of the O2 v generating strategy. The useful facts as I see them are: In cold weather, a none heated O2 sensor can go open loop. due to the O2 sensor being too cold. A heated O2 develops enough heat so that it can "properly sense" the needed gases to operate. The O2 sensor, as tested responds to HC rather than O2. While you might be able to change things, or define other operating modes, I know that if I mount the sensor far enough away from the engine that being heated is neseccary, then I know what gases matter, and thus what the sensor is seeing. Grumpy > Varying the amounts of HC, CO, > >CO2, and NOx don't affect the sensor. Only O2 quantity in relation to > >the sensor's reference changes voltage. TPS senses TP whether output > >voltage increases or decreases with increased throttle angle. Why do > >you think an "inverted" output from the O2 sensor makes it a Not O2 > >sensor? > A TPS has a supply voltage that can be modulated in either increasing or > decreasing fashion with increasing throttle angle, but the O2 sensor has to > make its own voltage. My simple logic led me to the conclusion that the > compound that is being actually being sensed must be the one that provides > this positive voltage. > Then I remembered that the O2 sensor is actually a differential sensor, like > you said: it provides voltage based on the differential between the outside > reference air and the gases in the exhaust. So my new hypothesis is that > the sensor is sensing O2, but it actually produces voltage from the > reference oxygen; when it is compared to an oxygen-poor environment in an > exhaust stream, there is a voltage differential across the ion-sensing > electrodes, and the voltage produced at the reference side goes up the > signal wire. When the O2 is even on both sides, no voltage is produced. > Of course, this would only apply to the zirconium type O2 sensors, the > titanium dioxide ones do actually use a reference voltage and act as a > variable resistor. > So now what I want to see is someone test a sensor using sealed chambers > for both reference and exhaust sides, using O2, HCs, an inert gas such as > argon, and another gas containing negative ions (maybe one of the halogens) > as a control. :-p > Soren ------------------------------ Date: Thu, 20 May 1999 15:03:19 -0700 From: Bill Edgeworth Subject: Re: alternative engines, now Hemi Us mopar guys cannot be held responsible for what edelbrock named the manifold. It is a manifold with a huge plenum area with a removable top. Tops are available in 1X4 and 2X4 the manifold design allows for all kinds of playing around with air dams inside the manifold to tune for specific applications. there was also two bases one for drag racing and one for nascar. It is a ram tube design but fits under the hood unlike a tunnel ram. I prefer beating Rats as opposed to cooking them. Bill Edgeworth Squash wrote: > --- "Todd....!!" wrote: > > I'll probably use a RAT ROASTER when I inject my > > twin turbo 426 Hemi, > > What is a RAT Roaster?? Is this a mopar anti-chevy > slang term? > > Andy > _____________________________________________________________ > Do You Yahoo!? > Free instant messaging and more at http://messenger.yahoo.com ------------------------------ Date: Thu, 20 May 1999 16:37:55 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: Mr Helmholz - simple model >I was thinking ( rare but it does happen) when a standing wave is set up >the exhaust would be moving slowwer (higher pressure). Hey--in the flow of a compressible fluid, higher pressure = higher temp, without even worrying about contact time. Just the way it works. Greg > >where the standing wave was there would be more of a heat buildup > due to a slightly longer time in contact with the pipe. ------------------------------ Date: Thu, 20 May 1999 19:21:54 -0400 From: "David A. Cooley" Subject: Re: alternative engines, now Hemi At 02:26 PM 5/20/99 -0700, you wrote: >--- "Todd....!!" wrote: >> I'll probably use a RAT ROASTER when I inject my >> twin turbo 426 Hemi, > >What is a RAT Roaster?? Is this a mopar anti-chevy >slang term? The Rat Roaster was a big flat intake I believe had Dual quads on it. One in the rear right and the other in the front left (If I remember right... may have been reversed). Just the name it was given. =========================================================== David Cooley N5XMT Internet: N5XMT@xxx.net Packet: N5XMT@xxx. Member #7068 Sponges grow in the ocean... Wonder how deep it would be if they didn't?! =========================================================== ------------------------------ Date: Fri, 21 May 1999 11:35:14 +1200 From: Simon Quested Subject: Re: Supercharged 440 Hi Jason Sounds like a nice engine! > Rob at Force fuel injection told me that i better add enrichment fuel to > the top of the blower (roots have low efficiency you know) to provide some > additional cooling so I'm working on that now. I have a EFI supercharged (roots) 2L pinto engine in my Capri. To fix the problem off charge heating I used a very simple DIY water injection set up. It is a PWM 555 circuit controlling a windscreen washer pump that injects in to the TB, the water injector is mounted in the air filter. The amount of water injected is adjustable on the dash. I just increased the water until the detonation stopped. The whole set up cost about US$25 The only hassle with water injection is all the extra hardware like the water tank pump and plumbing. > I dunno how is the best way to drive the additional injectors though - any > ideas on an inexpensive additional injector driver would be appreciated I forget who suggested it but the easy way is to use the pulse to the injectors, feed the injector signal in to 1 input of a 2 input AND gate the other input is controlled by a hobbs switch, the out put goes to an injector driver. This way when the boost reaches the set point the extra injector comes on and it is triggered / controlled by the ECU. Cheers  Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested Computer Engineer, Silicon Graphics & Windows NT Support LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A person who smiles in the face of adversity .....probably has a scapegoat. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ Date: Thu, 20 May 1999 16:41:41 -0700 (PDT) From: Orin Eman Subject: Re: O2 Volts > The useful facts as I see them are: > In cold weather, a none heated O2 sensor can go open loop. due to the O2 > sensor being too cold. A heated O2 develops enough heat so that it can > "properly sense" the needed gases to operate. > The O2 sensor, as tested responds to HC rather than O2. > While you might be able to change things, or define other operating modes, > I know that if I mount the sensor far enough away from the engine that being > heated is neseccary, then I know what gases matter, and thus what the sensor > is seeing. There are a couple of things I'd like to throw in the mix here. The heater on the heated sensor is a helper to get the sensor up to temperature... it's probably still relying on hot exhaust gases to be at working temperature... it may not be hot enough when testing with room temperature gases. There is a catalyst on the electrodes which may well promote the combustion of gaseous hydrocarbons with the O2 that diffuses thru the sensor, hence the reaction to gaseous hydrocarbons. The sensor itself, when hot enough senses the relative concentrations of O2. This is not necessarily the O2 concentration in the exhaust gases as measured by other means due to the catalytic action of the sensor electrode... Orin. ------------------------------ Date: Thu, 20 May 1999 18:49:51 -0400 From: "Gary Derian" Subject: Re: Mr Helmholz - simple model Todd, what did your mph do in the 1/4 when the octane boost increased power so much your ET's got longer? Maybe some dew condensed onto the track, or someone blew their engine. Gary Derian > > I then proceeded to not EVER gain traction for the rest of the > night, about 5 runs in all with the octane boost in the tank, E.T. NEVER > even dropped to mid 14's again! Due to wheel spin.... > ------------------------------ Date: Thu, 20 May 1999 18:52:12 -0400 From: "Gary Derian" Subject: Re: Mr Helmholz - simple model If one has a sliding clutch, it should be set to hold the engine at max torque rpm, not max power rpm. Gary Derian > > The rpm's aren't held constant unless you have some sorta newfangled > clutch setup like the top fuelers have that hold their rpm's at PEAK > power the whole run! THAT would be nice!! > ------------------------------ Date: Thu, 20 May 1999 19:02:08 -0400 From: "Gary Derian" Subject: Re: alternative engines, now Hemi Actually, the plug location in a Hemi is bad because it is off to one side. Its the best you can do with a Hemi but its still bad. As a result it needs lots of ignition advance and high octane for a given compression. Now the Dick Landy twin plug heads really hastens the combustion and makes an already strong engine much stronger. Other mfgs have used twin plugs since then. Gary Derian > Anyhoo.. I believe ya, the Hemi heads really flow alot, even in stock > form, add that to the shape of the combustion chamber and where the > spark plug(s) are located within the cylinder and you have one power > packin pachyderm! > > > Todd.... ------------------------------ Date: Thu, 20 May 1999 17:50:19 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: alternative engines, now Hemi >Hemi's do not use siamesed intake ports like the B engine heads. Most stuff >from the bottom end is interchangeable i.e..) timing chain or gear drive, >timing cover, water pump, oil pump, NOT the cam, oil pick up on hemi is 1/2" >instead of 3/8" pipe (can be changed on 440 block to Hemi specks), cranks, >NOT main caps, NOT blocks. > >Bill Edgeworth > Yep--the 2,3, &4 caps are cross bolted on a Hemi. Cranks do not interchange either. Greg ------------------------------ Date: Thu, 20 May 1999 16:54:13 -0700 From: Bill Edgeworth Subject: Re: alternative engines, now Hemi "David A. Cooley" wrote: > > > The Rat Roaster was a big flat intake I believe had Dual quads on it. One > in the rear right and the other in the front left (If I remember right... > may have been reversed). Just the name it was given. That was actually the 426 Race Hemi Super Stock Cross Ram. It was kind of similar to the Rat Roaster as you could also perform application specific modifications inside of it. Bill Edgeworth ------------------------------ Date: Thu, 20 May 1999 17:10:02 -0700 From: Bill Edgeworth Subject: Re: alternative engines, now Hemi Greg Hermann wrote: > > Yep--the 2,3, &4 caps are cross bolted on a Hemi. Cranks do not interchange > either. > > Greg You can use the Hemi crank in a RB engine however there is the issue of balance (the Hemi has heavier stock rods) and a 8 bolt flange on the Hemi as opposed to a 6 bolt on the RB engine. Both the 440 and 426 have 3.75 stroke. However the Low block (383-400) has smaller mains and you cannot use the Hemi crank without cutting down the mains. Bill Edgeworth ------------------------------ Date: Thu, 20 May 1999 20:33:42 -0400 From: "Bruce Plecan" Subject: Re: O2 Volts I *added* heat with the lighter earlier, and no changes were noted. On the cars being used in really cold temps, the exhaust on several models the tubing would not crack spit. Meaning while over 210dF, was not really hot. On some vettes, the O2s are probably 4' away from the ports. On a really cold day, at idle, with mechanics gloves (nomex type)(none operative cat) you can hold the exhaust back there. If the temp was a major concern why is't there a true strategy to compensate for it?. This when hot enough, is this the 800-900dC temp?. When does an average engine reach an EGT of that?. When speaking of a catalyst, fine, but without knowing what it is, and what it's properties are, is gets again rather mute, as I see it. By the way, in all my testing I was using a strategy where by I know to some degree what the actual heater temperature is. So I can duplicate this on car, and then see what is going on. Without quessing. While oems, are doing this O2 work as a emission law mandated issue, I'm just trying to figure out enough to do what I want to do. Other issues don't matter, other than as a point of interest, or maybe concern for others. Grumpy > > The useful facts as I see them are: > > In cold weather, a none heated O2 sensor can go open loop. due to the O2 > > sensor being too cold. A heated O2 develops enough heat so that it can > > "properly sense" the needed gases to operate. > > The O2 sensor, as tested responds to HC rather than O2. > > While you might be able to change things, or define other operating modes, > > I know that if I mount the sensor far enough away from the engine that being > > heated is neseccary, then I know what gases matter, and thus what the sensor > > is seeing. > There are a couple of things I'd like to throw in the mix here. > The heater on the heated sensor is a helper to get the sensor up to > temperature... it's probably still relying on hot exhaust gases to > be at working temperature... it may not be hot enough when testing with > room temperature gases. > There is a catalyst on the electrodes which may well promote the > combustion of gaseous hydrocarbons with the O2 that diffuses thru > the sensor, hence the reaction to gaseous hydrocarbons. > The sensor itself, when hot enough senses the relative concentrations > of O2. This is not necessarily the O2 concentration in the exhaust > gases as measured by other means due to the catalytic action of the > sensor electrode... > Orin. ------------------------------ Date: Thu, 20 May 1999 18:35:00 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: alternative engines, now Hemi >Us mopar guys cannot be held responsible for what edelbrock named the >manifold. It is a manifold with a huge plenum area with a removable top. >Tops are available in 1X4 and 2X4 the manifold design allows for all >kinds of playing around with air dams inside the manifold to tune for >specific applications. there was also two bases one for drag racing and >one for nascar. It is a ram tube design but fits under the hood unlike a >tunnel ram. >I prefer beating Rats as opposed to cooking them. > >Bill Edgeworth Well--'tis true that rats end up rather FLAT (and do not run very well at all) after an elephant has stepped upon them!! Greg > >Squash wrote: > >> --- "Todd....!!" wrote: >> > I'll probably use a RAT ROASTER when I inject my >> > twin turbo 426 Hemi, >> >> What is a RAT Roaster?? Is this a mopar anti-chevy >> slang term? >> >> Andy >> _____________________________________________________________ >> Do You Yahoo!? >> Free instant messaging and more at http://messenger.yahoo.com ------------------------------ Date: Thu, 20 May 1999 20:40:58 -0400 From: Shannen Durphey Subject: Re: O2 Volts soren wrote: > So now what I want to see is someone test a sensor using sealed chambers > for both reference and exhaust sides, using O2, HCs, an inert gas such as > argon, and another gas containing negative ions (maybe one of the halogens) > as a control. :-p > > Soren Soon, if time allows, I hope to try some tests. I'll attempt something similar to this, based on the gasses present around the shop. Shannen ------------------------------ Date: Thu, 20 May 1999 21:05:21 -0700 From: rr Subject: Re: O2 Volts Jay Wallace wrote: > > At 02:03 AM 5/20/99 -0400, you wrote: > >rr wrote: > >> > >> >> Bruce Wrote: > > snip... > > >> Response's to different gases: > >> > >> propane: rapid and long lasting, > 850mv. > >> R12: light response, quick to return to nominal, ~475mv. > >> acetylene: rapid and long lasted, > 750mv. > >> hold breath, breath through tube into can: no effect... > >> argon: light response, very short lived: ~70mv. > >> contact cleaner: medium response, ~650mv. > >> (tricloroethane + diclorodifluoromethane) > >> > >> (couldn't find any butane) > >> > >> Thinking about this, it makes sense. Once you reach stoich (450mv), > >> how can you go higher? Only if the excess hc takes it there... > >> > >> The argon response, or lack thereof, is interesting. > >You didn't report on the duration of the gas "shot". Not sure it > >matters, but I would have left whatever gas "running" for a fixed > >amount of time in the can. Or better yet, continously until end of > >test. Methinks I may have been motivated enough to do my own > >experiments. > >Shannen > > I wouldn't be surprised if Shannen is on the right track here: Ar > is heavier (denser) than air so it would sink to the bottom of > whatever container that it is flowing into. You would need to flow > long enough to displace all of the air before the tip of the sensor > was surrounded by Ar. > > One more thing that should be emphasized: a standard oxygen sensor > is just an electrochemical cell with the output voltage > proportional to the difference in oxygen concentration between the > inside and outside (for a constant temperature) as long as the > zirconia is hot enough to conduct. The output voltage is given by > the Nernst equation. I _think_ that all of the experimental > observations are consistent with this. > > Jay If I got an instant response, I really didn't run the gas much longer. But for say, the argon, with a slow response, it was run for a while, easily 30 to 60 seconds. Not real scientific, but I'm on a limited time budget. Another thought, in the back of my mind, I believe that o2 sensors are built with a very thin film of platinum on the sensor cone. This would act like a cat-con, burning any HC's and robbing the porous cone of any o2. Including that o2 that has permated the cone material. This may help explain the rapid reaction to hc's. BobR. - -- ------------------------------ Date: Thu, 20 May 1999 21:08:14 -0700 From: rr Subject: Re: O2 Volts soren wrote: > > Varying the amounts of HC, CO, > >CO2, and NOx don't affect the sensor. Only O2 quantity in relation to > >the sensor's reference changes voltage. TPS senses TP whether output > >voltage increases or decreases with increased throttle angle. Why do > >you think an "inverted" output from the O2 sensor makes it a Not O2 > >sensor? > > A TPS has a supply voltage that can be modulated in either increasing or > decreasing fashion with increasing throttle angle, but the O2 sensor has to > make its own voltage. My simple logic led me to the conclusion that the > compound that is being actually being sensed must be the one that provides > this positive voltage. > Then I remembered that the O2 sensor is actually a differential sensor, like > you said: it provides voltage based on the differential between the outside > reference air and the gases in the exhaust. So my new hypothesis is that > the sensor is sensing O2, but it actually produces voltage from the > reference oxygen; when it is compared to an oxygen-poor environment in an > exhaust stream, there is a voltage differential across the ion-sensing > electrodes, and the voltage produced at the reference side goes up the > signal wire. When the O2 is even on both sides, no voltage is produced. > Of course, this would only apply to the zirconium type O2 sensors, the > titanium dioxide ones do actually use a reference voltage and act as a > variable resistor. > So now what I want to see is someone test a sensor using sealed chambers > for both reference and exhaust sides, using O2, HCs, an inert gas such as > argon, and another gas containing negative ions (maybe one of the halogens) > as a control. :-p > > Soren Check out the SAE articles that were pointed too, this is the kind of thing that the epa was doing: http://vehicle.me.berkeley.edu/~markw/efi/SAE920289/ http://vehicle.me.berkeley.edu/~markw/efi/SAE930352/ They are interesting reading. BobR. - -- ------------------------------ Date: Thu, 20 May 1999 21:35:20 -0700 From: rr Subject: Re: O2 Volts Bruce Plecan wrote: > > Now, to me rather than go on,, with further testing while it might settle a > curiousity, it doesn't help with what my goal is. > If you think about it, there are so many variables that on any one day, > you can ask, where are things?. ie O2 level, in the atmosphere varies day > to day, along with other "rare" chemicals. that might contaminate the > results. > In the oem applications they supply a reference voltage which as to effect > the ionization, and performance of the O2 v generating strategy. > > The useful facts as I see them are: > In cold weather, a none heated O2 sensor can go open loop. due to the O2 > sensor being too cold. A heated O2 develops enough heat so that it can > "properly sense" the needed gases to operate. > The O2 sensor, as tested responds to HC rather than O2. > While you might be able to change things, or define other operating modes, > I know that if I mount the sensor far enough away from the engine that being > heated is neseccary, then I know what gases matter, and thus what the sensor > is seeing. > Grumpy > I think your right on here, I've two observations that run the same course. a. A engine temperature based, o2 sensor output correction table in ecm's. b. 2.8l/3.1l f-body's, that get real bad fuel mileage in cold (<50f), wet weather. The o2 sensor is mounted low, at the 'y' pipe joint, about one-and-a-half feet from the head exhaust port. (one wire, it cools off). I want to confirm this one with a scanner, once the weather gets cold again, then try a heated sensor, if so. BobR. > > Varying the amounts of HC, CO, > > >CO2, and NOx don't affect the sensor. Only O2 quantity in relation to > > >the sensor's reference changes voltage. TPS senses TP whether output > > >voltage increases or decreases with increased throttle angle. Why do > > >you think an "inverted" output from the O2 sensor makes it a Not O2 > > >sensor? > > A TPS has a supply voltage that can be modulated in either increasing > or > > decreasing fashion with increasing throttle angle, but the O2 sensor has > to > > make its own voltage. My simple logic led me to the conclusion that the > > compound that is being actually being sensed must be the one that provides > > this positive voltage. > > Then I remembered that the O2 sensor is actually a differential sensor, > like > > you said: it provides voltage based on the differential between the > outside > > reference air and the gases in the exhaust. So my new hypothesis is that > > the sensor is sensing O2, but it actually produces voltage from the > > reference oxygen; when it is compared to an oxygen-poor environment in an > > exhaust stream, there is a voltage differential across the ion-sensing > > electrodes, and the voltage produced at the reference side goes up the > > signal wire. When the O2 is even on both sides, no voltage is produced. > > Of course, this would only apply to the zirconium type O2 sensors, the > > titanium dioxide ones do actually use a reference voltage and act as a > > variable resistor. > > So now what I want to see is someone test a sensor using sealed > chambers > > for both reference and exhaust sides, using O2, HCs, an inert gas such as > > argon, and another gas containing negative ions (maybe one of the > halogens) > > as a control. :-p > > Soren ------------------------------ Date: Thu, 20 May 1999 21:25:39 -0700 From: rr Subject: Re: O2 Volts Orin Eman wrote: > >???? wrote: > > The useful facts as I see them are: > > In cold weather, a none heated O2 sensor can go open loop. due to the O2 > > sensor being too cold. A heated O2 develops enough heat so that it can > > "properly sense" the needed gases to operate. > > The O2 sensor, as tested responds to HC rather than O2. > > While you might be able to change things, or define other operating modes, > > I know that if I mount the sensor far enough away from the engine that being > > heated is neseccary, then I know what gases matter, and thus what the sensor > > is seeing. > > There are a couple of things I'd like to throw in the mix here. > > The heater on the heated sensor is a helper to get the sensor up to > temperature... it's probably still relying on hot exhaust gases to > be at working temperature... it may not be hot enough when testing with > room temperature gases. > > There is a catalyst on the electrodes which may well promote the > combustion of gaseous hydrocarbons with the O2 that diffuses thru > the sensor, hence the reaction to gaseous hydrocarbons. > > The sensor itself, when hot enough senses the relative concentrations > of O2. This is not necessarily the O2 concentration in the exhaust > gases as measured by other means due to the catalytic action of the > sensor electrode... > > Orin. Yes, this makes sense. I was thinking that there is a very thin layer of platinum deposited on the sensor cone during manufacturing. Can't remember where I got the info from. So, my brains cells didn't fail me... BobR. - -- ------------------------------ Date: Thu, 20 May 1999 21:45:08 -0400 (EDT) From: William T Wilson Subject: Re: Mr Helmholz - simple model On Thu, 20 May 1999, Gary Derian wrote: > If one has a sliding clutch, it should be set to hold the engine at max > torque rpm, not max power rpm. I disagree, because of the effects of gearing. A hypothetical engine makes 300 ft.lbs at its torque peak of 4000 RPM. At that RPM it makes 228.5 HP. Let's say it makes 201.3 ft.lbs at its HP peak of 6000 RPM. At that RPM it makes 230 HP. This is an engine that could probably use a new cam. :} Even so, once gearing is taken into consideration, it is better to use the HP peak. You can have a 33% lower gear ratio at the higher RPM, which - more or less by definition - outweighs the decrease in torque at the HP peak. Once we gear this engine down by 1/3 it makes the same 300 ft.lbs of torque that it did at its torque peak. But let's say we have an engine that doesn't have its torque fall off so badly. Let's say, instead, the engine makes 220 ft.lbs at 6000 RPM, instead, for an HP rating of 251.3. This engine, when gearing is taken into consideration, can generate an effective 328 ft.lbs of torque - a noticeable improvement. This is why engines are rated mostly in HP. Torque is of course the most important component in acceleration, but what RPM the torque is generated at is just as important. HP is a better measurement of torque at RPM, although of course a full printout of the torque curve is the best :} ------------------------------ Date: Thu, 20 May 1999 22:40:43 -0400 From: "CLsnyder" Subject: Re: Mr Helmholz - simple model - ----- Original Message ----- From: Gary Derian To: Sent: Thursday, May 20, 1999 6:52 PM Subject: Re: Mr Helmholz - simple model > If one has a sliding clutch, it should be set to hold the engine at max > torque rpm, not max power rpm. > Gary Derian > > > > The rpm's aren't held constant unless you have some sorta newfangled > > clutch setup like the top fuelers have that hold their rpm's at PEAK > > power the whole run! THAT would be nice!! > > >On a snowmobile it holds at max HP rpm at wide open throttle. With a 2 stage helix it can hold max torque atpart throttle. > > ------------------------------ Date: Thu, 20 May 1999 23:42:04 -0700 From: Christopher J Beasley Subject: Simple Injection Questions Hi, I've been lurking for a little while and have a couple of questions. It seems this list is very detail oriented, my questions are more specific. I would like to know how to make a very simple injection system, possibly the simplest available design, with the caveat that it must be closed loop, and have reasonably good performance. My current plan revolves around a 68HC11 or '332 with an O2 sensor. This will be targeted at a 650cc single cylinder motorcycle engine. I assume I will also need a tach sensor, throttle position sensor, and some kind of manifold sensor. What is the minimum subset of sensors that you need? What kind of manifold sensors exist? Do I have to take over ignition as well? What's the cost/benefit of this integration? I already know that this particular engine lacks a rev limiter so I'd want to incorporate that feature. It seems the list focuses mostly on control systems. I'm wondering where to buy things in small quantities like throttle bodies with TPS, mass flow sensors, pumps regulators, injectors. In short, all the goodies I don't already have ( computer guy if you hadn't guessed). Thanks folks! Beez ------------------------------ End of DIY_EFI Digest V4 #297 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".