DIY_EFI Digest Thursday, 12 September 1996 Volume 01 : Number 270 In this issue: RE: Water Injection for power? RE: Ancient History RE: Re; Ancient History RE: O2 Sensor-Leaded gas RE: Water Injection for power? Re: DIY_EFI Digest V1 #269 group buy pcb& chip water injection Altitude Compensation Re: Altitude Compensation Re: Altitude Compensation Re: Altitude Compensation Re: Altitude Compensation Re[2]: O2 Sensor-Leaded gas Re: Playing... Re: more water injection New subscriber Re: Altitude Compensation Re: Re[2]: O2 Sensor-Leaded gas Re: Re[2]: O2 Sensor-Leaded gas Re: Altitude Compensation Re[2]: Re[2]: O2 Sensor-Leaded gas More Water Injection RE: Playing... RE: Altitude Compensation EFI332 home page See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Mark Pitts Date: Wed, 11 Sep 1996 10:34:36 +-200 Subject: RE: Water Injection for power? Cant remember if I mentioned this... but I learned to drive in a Citroen = 2CV (you know those things... the ones that dont get chrome door = handles.. and after you see one corner you realize why) But.... 1 got 10 = miles an hour (85 instead of 75) flat out, on a cold and misty morning, = to a fine and clear one... call it atmospheric water injection!=20 So I recon there is a lot to be said for water and density!! (bear in = mind this 4 seater car only had 600cc!). Mark. - ---------- ------------------------------ From: Mark Pitts Date: Wed, 11 Sep 1996 10:18:56 +-200 Subject: RE: Ancient History So I way in at 122 lbs but.. I can lift my engine!... I can also lift my = chassis with the G'box in it, and I can lift the whole Body shell with = the interior in it up!... so I reckon the whole car could be picked up = by about 5 of me... now drop 120 BHP into a 15 foot by 4'10 car at that = weight... Is still quick.. not fast.. but QUICK.. (also allows very = quick 'S' bends, as the body doesn't roll.. never had it so the body was = on the piss still from the last bend when entering the next one.. helps = against the more powerful slugs! Mark (who still wants to build a 2.2 litre v8 to put in it) - ---------- From: Markus Strobl[SMTP:eusmsrt@xxx.se] Sent: Tuesday, September 10, 1996 9:40 PM To: diy_efi@xxx.edu Subject: RE: Ancient History > Its =3D > a real shame only having 1.5 litres (but my body weight is so low I = =3D > still get performance enough to scare me down the little lanes). >=20 > Mark I thought having *negative* body weight was in violation of the laws of physics?=20 :-) - ------- Markus '96 Z28 w/ mods. Proof that OBDII is not the end of performance. ------------------------------ From: Mark Pitts Date: Wed, 11 Sep 1996 10:22:49 +-200 Subject: RE: Re; Ancient History Hey tin man... you didnt call just to wash your head at us, so whats the score. (Zaphod... to Marv just before carpark in Milliways... where they found it... big black, and steeres like a cow.) Mark... Hitching right off thread ;-) Sorry.. promise not to do it again! - ---------- From: Matthew Lamari[SMTP:mlamari@xxx.com] Sent: Wednesday, September 11, 1996 4:14 AM To: diy_efi@xxx.edu Subject: Re: Re; Ancient History At 09:05 AM 9/11/96 est, you wrote: >>I believe the point that is trying to be made is that if HP = Torque >>only at 5252 (which is agreed). Then this is the only place where >>they CAN both be a maximum. Not that they are a maximum. But that >>this is the only point where they can both be a maximum at the same >>time. > >OK, now try the calculation in kW and N.m and see if you come to the >same conclusion! > That's where the lines cross for those units; but hp does not equal torque as their units are different. You could say two powers are equal, or two torques are equal, or two areas. . . . Yeah, I was having a strange time believing that 5252 was some sort of universal constant, when everyone knows the answer to life, the universe and everything is 42!! Matthew "References to Hitchiker's Guide to the Galaxy are purely irrational" Lamari ------------------------------ From: Mark Pitts Date: Wed, 11 Sep 1996 10:11:37 +-200 Subject: RE: O2 Sensor-Leaded gas Nope... not just the puss that dies... Pb kills the o2 as well... which = is a shame, cos I like lead... unless any body out there knows of an o2 = that can cope with lead. Mark=20 - ---------- From: Mark Eidson[SMTP:mark.eidson@xxx.com] Sent: Tuesday, September 10, 1996 7:21 PM To: diy_efi@xxx.edu Subject: O2 Sensor-Leaded gas Is the O2 sensor affected by leaded gas or is it just the cat conv? me *************************************************************************= ** * Mark Eidson Voice: (602)752-6513 = * * Staff Design Engineer Fax: (602)752-6000 = * * Manager System Integration and = * * Verification E-Mail: mark.eidson@xxx.com = * * VLSI Technology, Inc. = * * 8375 South River Parkway = * * M/S 265 = * * Tempe, Arizona 85284 = * *************************************************************************= ** ------------------------------ From: Mark Pitts Date: Wed, 11 Sep 1996 09:44:53 +-200 Subject: RE: Water Injection for power? My exhaust system has a 'sump' in it, and on a really cold start (-10c), = it condenses in the pipe, and fills up. I know this, because while manouvreing out my works car park (after = leaving the car there for a night due to snow), I blew enough shit out = on a quick blip to completely drench wis white BMW in black water! I recon I got about 1/4 pint of water out after it had been warming up = for 20 mins on full choke! (looked like a glass full in quantity). Mark (who is no longer employed by the above BMW driving boss) ;-) - ---------- From: Arnaldo Echevarria[SMTP:aec@xxx.net] Sent: Wednesday, September 11, 1996 1:24 AM To: diy_efi@xxx.edu Subject: Re: Water Injection for power? >I Remember two relevant curves - holding fuel constant, power went up=20 >linearly with water on a percent by percent basis. 100% fuel 10% = water,=20 >+ 10% power etc. until a practical limit of about 50% was reached. > >Holding power constant, each percent of water displaced a percent of >fuel until about a 50 50 ratio was reached. So if I went out to my car and fed my 455ci engine a 50/50 mix of water/ fuel I'd get the same power? I have a hard time believing this at full throttle - plus I cant afford that much water :(, but will it work for = part throttle, ie cruising, speeds? =20 I think I can get around the mineral buildups with a weekly trip to the = track w/ high octane gas..... >WTF does it work? 70% plus of chemical energy released by combustion >leaves the engine as excess heat. Absorb any of that EXCESS heat and >turn water to steam and you gain either power or fuel economy or both. But won't the added water particles reduce the ability to create a = complete combustion? > >PS Ever wonder what is really going on during combustion. Check the >pressure temp curves of the three major gasses present after = combustion. >CO2, N2 and H2O. Check out how much partial pressure each contributes >to the mix. Then remember, that as a rough approximate, one gallon of >gasoline makes 2 gallons of water in the exhaust.=20 That much water comes out of my tailpipe? Arnaldo ------------------------------ From: talltom Date: Wed, 11 Sep 1996 03:57:39 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #269 >------------------------------ > >From: Chuck Tomlinson >Date: Wed, 11 Sep 1996 01:25:43 -0400 >Subject: Re: Ancient History > >>I believe the point that is trying to be made is that if HP = Torque >>only at 5252 (which is agreed). > >True. If power is measured in hp and torque in lb-ft, then the >torque and power curves must cross at 5252 rpm. No exceptions. Oh I don't know about that! If you go down to the local hot rod shop often you'll find some product there with dyno charts for their product that show that torque and hp aren't the same at 5252.! These guys should use just a little more sense when they draw there performance curves, but I always appreciate the clue! ------------------------------ From: pfontana@xxx.it (fontana pasquale) Date: Wed, 11 Sep 96 13:23:07 +0200 Subject: group buy pcb& chip HELLO TO ALL I want to know where ,also how (by credit card it's possible?) , I can purchase the pcb, for the efi ecu 68332 based cpu and relative BDM , the 'special chip': MC68332acfc20 AM29f010-120JC 5v eeprom 821949-5 - bottom part of 68332 socket 821942-1 . It's possible by a group if exist? Thanks for "those helpers" . PASQUALE *** ** \||/ * * ('') ------------------------------ From: Frank_Mallory@xxx.com (Frank Mallory) Date: Tue, 10 Sep 1996 23:08:09 -0400 Subject: water injection d>Within the last few months I read an article about recent d>efforts to perfect an agent to maintain naptha and water d>as a stable colloid. In addition to being useful as a d>fuel, the criteria for acceptability include multiple d>transitions from high to low temperatures without d>separation. d>The magazine may have been MACHINE DESIGN. I believe that d>the University of Arizona and Caterpillar were both d>mentioned. d>Did any one else see the article? I would like to read it d>again. Caterpillar is supposedly working with a guy named Gunnerman to develop this "wonder fuel". I'll believe it when I see it. d>--- FIDOGATE 3.9.7 ------------------------------ From: "Robert J. Harris" Date: Wed, 11 Sep 1996 11:24:43 -0700 Subject: Altitude Compensation >From what I read and hear, the Air Flow sensor used in production EFI's at best compensate for temp and density changes in the intake air mass. Then the oxygen sensor is used to fine tune the mixture to a rich power setting - I.E. no uncombined oxygen Does anyone do any altitude compensation? Because, as altitude increases, not only does the air mass density decrease, but the percentage of oxygen decreases (simple physics - check books before questioning or flaming) and the oxygen decrease is independent of the density decrease. Basically, this means that to maintain a constant fuel /oxygen mixture (which is what counts because the rest of the air is meaningless for combustion) for a given power, more air most be ingested and a leaner fuel/air mixture used or it becomes overrich. Incidentally, why you lean out a piston aircraft engine at altitude is more to avoid a cool burning overrich mixture slowing carboning up and fouling out your engine than just enhancing economy. Basically, as I understand it, the oxygen sensor corrects this after the fact. Is there any sensors that compensate the air flow value for the altitude related decrease in oxygen? Note that this is not a problem on excess oxygen engines such as diesels and gas turbines and why they do not loss power in the mountains like gasoline engines do. Remember the Reichstag - ---------- ------------------------------ From: "David M Parrish" Date: Wed, 11 Sep 1996 16:35:57 +0000 Subject: Re: Altitude Compensation > From: "Robert J. Harris" > Does anyone do any altitude compensation? Because, as altitude > increases, not only does the air mass density decrease, but the > percentage of oxygen decreases (simple physics - check books > before questioning or flaming) and the oxygen decrease is independent > of the density decrease. Okay. I'll bite. What's your source for this simple physics? (Remember Brownian motion and diffusion.) On cars with MAF sensors, it's automatic, since you're measuring the Mass of air and X mass of air needs Y mass of fuel. Speed density systems measure pressure and temperature to calculate the mass. - --- David Parrish Carbs and aircraft injection are a whole 'nuther ballpark. ------------------------------ From: Markus Strobl Date: Wed, 11 Sep 1996 15:55:56 -0500 Subject: Re: Altitude Compensation > Does anyone do any altitude compensation? Because, as altitude > increases, not only does the air mass density decrease, but the > percentage of oxygen decreases (simple physics - check books > before questioning or flaming) and the oxygen decrease is independent > of the density decrease. The PCM in my '96 GM car has barometric pressure as an input, so it seems it's used. - ------- Markus '96 Z28 w/ mods. Proof that OBDII is not the end of performance. ------------------------------ From: Chuck Tomlinson Date: Wed, 11 Sep 1996 17:27:14 -0400 Subject: Re: Altitude Compensation Robert J. Harris wrote: > >Does anyone do any altitude compensation? Because, as altitude >increases, not only does the air mass density decrease, but the >percentage of oxygen decreases (simple physics - check books >before questioning or flaming) and the oxygen decrease is independent >of the density decrease. OK, I did a little research on the Web; everything I saw that described atmospheric composition said that the composition of the troposphere is roughly constant (up to ~10 km) because of thorough convective mixing. This makes sense to me, and since the highest roads I know of are lower than 5 km (16,000') and subject to winds that travel from valleys to peaks, I'd expect the air composition to be essentially the same as sea level (but less dense, of course). I'm not flaming you; I'm just curious about *why* the percentage of oxygen would change from sea level to 5 km, and if it does, by how much. Thanks. - -- Chuck Tomlinson. ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Wed, 11 Sep 1996 17:36:33 -0500 Subject: Re: Altitude Compensation >> Does anyone do any altitude compensation? Because, as altitude >> increases, not only does the air mass density decrease, but the >> percentage of oxygen decreases (simple physics - check books >> before questioning or flaming) and the oxygen decrease is independent >> of the density decrease. > >The PCM in my '96 GM car has barometric pressure as an input, so it >seems it's used. > seems to me that that's what BAP (barometric atmos. press.) as opposed to (or in addition to ??) MAP (manifold atmos. press.) does. also, supposedly EGO feedback accomplishes this within certain limits ?? tom cloud ------------------------------ From: Johnny Date: Wed, 11 Sep 1996 15:51:20 -0700 Subject: Re[2]: O2 Sensor-Leaded gas There was a thread a few months ago that covered this topic pretty well. I would have sworn that someone had mentioned knowledge of a sensor out there that was supposed to be able to deal with lead. I have searched through all my old archives and can't find that old thread. Does anyone else remember this or am I just losing it? Darrell??? do you remember this thread? - -j- At [Wed, 11 Sep 1996 10:11:37 +-200] Mark Pitts wrote: saxon> Nope... not just the puss that dies... Pb kills the o2 as well... which is a shame, cos I like lead... unless any body out there knows of an o2 that can cope with lead. saxon> saxon> Mark saxon> saxon> ---------- saxon> From: Mark Eidson[SMTP:mark.eidson@xxx.com] saxon> Sent: Tuesday, September 10, 1996 7:21 PM saxon> To: diy_efi@xxx.edu saxon> Subject: O2 Sensor-Leaded gas saxon> saxon> Is the O2 sensor affected by leaded gas or is it just the cat conv? me saxon> *************************************************************************** saxon> * Mark Eidson Voice: (602)752-6513 * saxon> * Staff Design Engineer Fax: (602)752-6000 * saxon> * Manager System Integration and * saxon> * Verification E-Mail: mark.eidson@xxx.com * saxon> * VLSI Technology, Inc. * saxon> * 8375 South River Parkway * saxon> * M/S 265 * saxon> * Tempe, Arizona 85284 * saxon> *************************************************************************** saxon> saxon> saxon> ------------------------------ From: jengel@xxx.net Date: Wed, 11 Sep 1996 18:22:44 +600 Subject: Re: Playing... Mark, I'd thought about doing something of the sort. The reason I didn't is that a MAF from the junkyard is going to be a lot less expensive unless your attempt is pretty close on the first try (or unless your time isn't worth much). Didn't it take Edison 119 trys to make the first electric light? On the other hand, you could learn a LOT about MAF during the process. And don't they use platinum ($$$) wire? je > From: Mark Pitts > To: "'DIY EFI'" > Subject: Playing... > Date: Tue, 10 Sep 1996 10:14:07 +-200 > Reply-to: diy_efi@xxx.edu > Is ther any reason why I cant build my own mass meter wth some nichrome wire, and a foot of 6" drain pipe? > > Cos what I've seen of them thats about it. > > Plus a burn off circuit, and a bridge for doing the current measurement. > > Like, I think the Idea is: Keep the current constant, measure the voltage across to get that current, have another bit of wire as a reference, and an absolute air temp/ atmospheric pressure reading, > and away you go? > > > Yes... no ... who cares I got mine from the breakers....? > Any comments really? > > (I'll even take 'Dont be stupid' for this one!) > > Mark ------------------------------ From: jengel@xxx.net Date: Wed, 11 Sep 1996 18:39:43 +600 Subject: Re: more water injection Dirk, The problem is keeping the water mixed with the gasoline. "Dry Gas" is generally an alcohol-based product that attaches the water and gas on a molecular level (I forget whether gas is polar or non-polar, but water is the opposite. Alcohol has a polar end and a non-polar end, so it attaches to both). I doubt that a significant amount of water mixed with gas would have any postitive long term effects on fuel injectors, though. je > Date: Tue, 10 Sep 1996 09:23:55 -0400 (EDT) > From: Dirk Wright > To: diy_efi@xxx.edu > Subject: more water injection > Reply-to: diy_efi@xxx.edu > OK, here's a really dumb (but interesting to me) question: If water > injection is so great, why is water in the gas considered so bad? Why > bother with products like "dry gas" if water in the cylinders is a good > thing? Why do most engines run so bad (I think) when there's water mixed > in with the gas in the tank? > > I can understand the freezing bit in winter, which could be cured with > added alcohol of glycol, but if water injection is so good, it seems that > you could save yourself a bunch of hassle by just adding water to the gas > in the gas tank. Is it possible that you only want water injection under > certain circumstances, like WOT? If so, then I could understand the need > for dry gas and a separate water injection system. Otherwise, what's the > deal? > > > **************************************************************************** > Dirk Wright wright@xxx.gov > "I speak for myself and not my employer." 1974 Porsche 914 2.0 > "A real hifi glows in the dark and has horns." 1965 Goodman House > **************************************************************************** > > ------------------------------ From: Craig Eid Date: Wed, 11 Sep 1996 11:32:15 -0800 (PDT) Subject: New subscriber Hello all - I'm new to the group so I'll give you my background and interests. I'm an electrical engineer working for HP in northern California. I've done a fair amount of digital and analog circuit design in the past - the last three years have been spent bringing new products out of the lab. I own two vintage Mustangs (a '65 coupe and '66 fastback) and have dropped a 1994 4.6 litre, 4 cam V8 into the '65 coupe. I've played around with the EEC-IV SEFI system a bit on the dyno and believe there are some hidden ponies waiting to be unleashed. However, the EEC-IV system is a bit awkward to work with. My interest is in getting more performance from the FI system (as always) at a reasonable cost. I don't want to pay the price for the ACCEL/DFI system but would like to help develop an SEFI system that's much more user friendly and easier to customize. I've searched the first 15 archives and haven't been able to find the FAQ. If it exists, could someone point me to it? Thanks, CRaig - -- Craig Eid Manufacturing Development Engineer Microwave Instruments Division, Hewlett Packard e-mail address craige@xxx.com ------------------------------ From: James Weiler Date: Wed, 11 Sep 1996 17:19:04 -0700 (PDT) Subject: Re: Altitude Compensation On Wed, 11 Sep 1996, Markus Strobl wrote: > > Does anyone do any altitude compensation? Because, as altitude > > increases, not only does the air mass density decrease, but the > > percentage of oxygen decreases (simple physics - check books > > before questioning or flaming) and the oxygen decrease is independent > > of the density decrease. > Ford's EEC-IV system (speed density) utilizes a MAP sensor that also doubles as a Barometric sensor. It switches to this other function at every start up and at wide open throttle. I don't know when this type of sensor started to be used but I would guess early '80's and definitly up and including 1987. The older EEC-III speed density systems used a separate Baro. sensor as well as a MAP. cheers jw ------------------------------ From: Frank F Parker Date: Wed, 11 Sep 1996 21:23:02 -0400 (EDT) Subject: Re: Re[2]: O2 Sensor-Leaded gas > There was a thread a few months ago that covered this topic pretty well. > I would have sworn that someone had mentioned knowledge of a sensor > out there that was supposed to be able to deal with lead. I have searched > through all my old archives and can't find that old thread. Does anyone > else remember this or am I just losing it? > > Darrell??? do you remember this thread? > > -j- All sensors are affected by lead but the Bosch LSM-11 sensor used in the Bosch LA-2 a/f meter is less affected by lead. Sheet shows after 500 hours exposure to 0.5 gm/gal , the sensor shows <0.02 lambda change. That is not alot of lead, but 500 is lotsa hours. Bosch says they can be renewed if not too dirty by running in unleaded engine for awhile. Sensor costs about $160 so cheap 3 wires may be cheaper in long run. Frank Parker ------------------------------ From: Darrell Norquay Date: Wed, 11 Sep 1996 21:09:09 -0700 (PDT) Subject: Re: Re[2]: O2 Sensor-Leaded gas At 03:51 PM 9/11/96 -0700, you wrote: >There was a thread a few months ago that covered this topic pretty well. >I would have sworn that someone had mentioned knowledge of a sensor >out there that was supposed to be able to deal with lead. I have searched >through all my old archives and can't find that old thread. Does anyone >else remember this or am I just losing it? > >Darrell??? do you remember this thread? Yeah, I remember the thread, I think it was someone in NZ who brought it up, since they still use leaded gas. It was someone whose name I haven't seen around lately. All I remember was that they had found some stock sensor that lasted longer than most others, but I don't recollect which it was. I also recollect that they'd wake up if you used unleaded gas for a while... I'll check through some of my old folders and see if anything shakes out... BTW, I think you're like me, have an excellent memory, but short... regards dn dnorquay@xxx.com ------------------------------ From: Darrell Norquay Date: Wed, 11 Sep 1996 21:09:06 -0700 (PDT) Subject: Re: Altitude Compensation At 11:24 AM 9/11/96 -0700, RJH wrote: >>From what I read and hear, the Air Flow sensor used in production >EFI's at best compensate for temp and density changes in the >intake air mass. Then the oxygen sensor is used to fine tune >the mixture to a rich power setting - I.E. no uncombined oxygen >Does anyone do any altitude compensation? Because, as altitude Most production systems use barometric compensation in one form or another. Some systems take a baro reading from the MAP sensor after the ignition key is turned on, but before the engine starts, and store this as a reference. This can also be updated at WOT, since manifold pressure is essentially = baro pressure at this point (with some flow related pressure drop). Some systems have a separate baro sensor in addition to MAP. Some MAPs are not absolute sensors at all, but differential sensors, referenced on one side to atmospheric, so as the baro changes, the MAP reference point changes as well. Some compensation is possible with the fuel pressure regulator, since it is usually referenced to manifold pressure and thus atmospheric indirectly. And, some systems have none at all. Remember that most carbs have no baro comp, and they worked for the last 100 years or so... As you mentioned, the O2 sensor can compensate somewhat at steady state conditions. regards dn dnorquay@xxx.com ------------------------------ From: Johnny Date: Wed, 11 Sep 1996 21:54:56 -0700 Subject: Re[2]: Re[2]: O2 Sensor-Leaded gas The cheapy's add up pretty quick. I have been able to get unreliable sensor output in a matter of a few hours when running with avgas. Even the 100LL screws them up fairly quickly. Not totally shot, but incorrect and inconsistent enough to be rendered useless for closed loop.I guess it won't matter after avgas is made leadless... but until then I guess there's always the trim pot on the dash. ;-) - -j- At [Wed, 11 Sep 1996 21:23:02 -0400 (EDT)] Frank F Parker wrote: fparker> All sensors are affected by lead but the Bosch LSM-11 sensor used in fparker> the Bosch LA-2 a/f meter is less affected by lead. Sheet shows after fparker> 500 hours exposure to 0.5 gm/gal , the sensor shows <0.02 lambda change. fparker> That is not alot of lead, but 500 is lotsa hours. Bosch says they can fparker> be renewed if not too dirty by running in unleaded engine for awhile. fparker> Sensor costs about $160 so cheap 3 wires may be cheaper in long run. fparker> fparker> Frank Parker fparker> fparker> ------------------------------ From: Jim Steck <72614.557@xxx.COM> Date: 12 Sep 96 02:54:09 EDT Subject: More Water Injection >> OK, here's a really dumb (but interesting to me) question: If water >> injection is so great, why is water in the gas considered so bad? Why >> bother with products like "dry gas" if water in the cylinders is a good >> thing? Why do most engines run so bad (I think) when there's water mixed >> in with the gas in the tank? > >Gasoline is lighter than water, and hence "floats" on top of it. You >fuel tank pick-up is located in the bottom of the tank. You add water to >the tank and all you'll be injecting into the engine is water. If you read Ricardo experiments with water injection he also states that water dissolved in the fuel . . . with some mutual solvent like acetone . . . is even more effective than water injection. Jim Steck AutoComponenti ------------------------------ From: Mark Pitts Date: Thu, 12 Sep 1996 09:43:34 +-200 Subject: RE: Playing... Thanks for the note on Platinum, if you go to your local hobby store, = you will find they sell glow plugs, for model airplane engines, with a = small coil of .... You guessed it Platinum wire, as the element (and = they survive for about 40 hours running red to white hot in the = combustion chamber.. so the wire must be ok).. If I cant get enough, il = phone a manufacturer, and see if they have any off cuts, ends of reels = etc. PS Plugs are only a couple of bucks each. Mark ;-) - ---------- From: jengel@xxx.net] Sent: Wednesday, September 11, 1996 8:23 PM To: diy_efi@xxx.edu Subject: Re: Playing... Mark, I'd thought about doing something of the sort. The reason I didn't=20 is that a MAF from the junkyard is going to be a lot less expensive unless your attempt is pretty close on the first try (or unless your time isn't worth much). Didn't it take Edison 119 trys to make the first electric light? On the other hand, you could learn a LOT about MAF during the=20 process. And don't they use platinum ($$$) wire? je > From: Mark Pitts > To: "'DIY EFI'" > Subject: Playing... > Date: Tue, 10 Sep 1996 10:14:07 +-200 > Reply-to: diy_efi@xxx.edu > Is ther any reason why I cant build my own mass meter wth some = nichrome wire, and a foot of 6" drain pipe? >=20 > Cos what I've seen of them thats about it. >=20 > Plus a burn off circuit, and a bridge for doing the current = measurement. >=20 > Like, I think the Idea is: Keep the current constant, measure the = voltage across to get that current, have another bit of wire as a = reference, and an absolute air temp/ atmospheric pressure reading, > and away you go? >=20 >=20 > Yes... no ... who cares I got mine from the breakers....? > Any comments really? >=20 > (I'll even take 'Dont be stupid' for this one!) >=20 > Mark ------------------------------ From: Mark Pitts Date: Thu, 12 Sep 1996 09:51:19 +-200 Subject: RE: Altitude Compensation The point is even tho' the density drops, if you compress that air to = sea level density, there is less oxygen in it, thus you need to lean out = at altitude. Sorry to go back to my model airplanes, but for the glider tugs (which = ran 120cc petrol engines, with electronic ignition) we had to solder an = arm on the end of the needle so that we could fit a servo and adjust = mixture in flight, otherwise we lost so much power, we couldnt pull the = glider any higher. And we are only talking 5000' Like a mile or so up! At ground level the tugs would climb out at about 45 degrees, with = anything on the back.. Mark - ---------- From: David M Parrish[SMTP:dmp@xxx.EDU] Sent: Wednesday, September 11, 1996 6:36 PM To: diy_efi@xxx.edu Subject: Re: Altitude Compensation > From: "Robert J. Harris" > Does anyone do any altitude compensation? Because, as altitude > increases, not only does the air mass density decrease, but the > percentage of oxygen decreases (simple physics - check books > before questioning or flaming) and the oxygen decrease is independent > of the density decrease. =20 Okay. I'll bite. What's your source for this simple physics?=20 (Remember Brownian motion and diffusion.) On cars with MAF sensors, it's automatic, since you're measuring=20 the Mass of air and X mass of air needs Y mass of fuel. Speed density systems measure pressure and temperature to calculate=20 the mass. - --- David Parrish Carbs and aircraft injection are a whole 'nuther ballpark. ------------------------------ From: M HILL Date: Thu, 12 Sep 1996 09:18:09 GMT0BST Subject: EFI332 home page Has something happened to the server for the efi332 homepage? I have been trying to get there for the last few days with no success. Martin ------------------------------ End of DIY_EFI Digest V1 #270 ***************************** 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".