DIY_EFI Digest Wednesday, 20 November 1996 Volume 01 : Number 352 In this issue: Re: Air Flow Measurement - Formula 1 Re: Air Flow Measurement Lantastic... Re: Air Flow Measurement RE: Air Flow Measurement Air flow & such RE: Air Flow Measurement re: Air Flow Measurement re: Air Flow Measurement Electromotive TEC-II? RE: Air Flow Measurement re: Air Flow Measurement Re: Air flow & such Diff between theory and practice re: Lambda Readings New member Re: Lambda Readings See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: dzorde@xxx.au Date: Wed, 20 Nov 96 11:45:33 Subject: Re: Air Flow Measurement - Formula 1 From what I've seen the injectors aren't even mounted in the heads, but above the throttle body and spray straight down into the ram tubes onto the throttle blades, more along the lines of throttle body injection. Can anyone verify this, I'd imagine indy cars use a similar setup. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: Air Flow Measurement - Formula 1 Author: diy_efi@xxx.edu at INTERNET Date: 11/20/96 11:16 AM On a related note, how do the Formula 1 guys measure air flow? From pictures of their engines they don't seem to have any hot wires or anything. I would guess that they are just using Throttle position, RPM, and air temp. jeff ------------------------------ From: Dave Zug Date: Tue, 19 Nov 1996 22:31:33 -0500 Subject: Re: Air Flow Measurement kleenair@xxx.com wrote: > > > Can someone guide me to descramble this? i tried xferpro,(a mail-format de-scrambler, a must when transferring thru some services) all formats with no luck. sorry. ------------------------------ From: Donald Whisnant Date: Tue, 19 Nov 1996 22:18:34 -0600 Subject: Lantastic... This isn't EFI related (not directly anyway), but since alot of the list members have jobs at places where networks are used, let me ask this question... Is there anyone out there using Lantastic for Windows 95?? If so, email me privately... Thanks... Donald Whisnant dewhisna@xxx.com ------------------------------ From: Dave Zug Date: Tue, 19 Nov 1996 23:26:42 -0500 Subject: Re: Air Flow Measurement tom cloud wrote: > > >> Specifically, I am wondering if anyone has looked into using a > >differential-pressure manometer to calculate air flow. This manometer > >could be located in the same location as GM puts its heated-wire > >mass-air-flow sensor. Any thoughts/comments? > > > >>(FYI - Air flow could be calculated from a differential pressure manometer (.....) > >You still need a measure of density to determine mass flow rate, even > >if you know the > > > >begin 600 WINMAIL.DAT > >M>)\^(@,2`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$(@ <` > >M& ```$E032Y-:6-R;W-O9G0@xxx.;W1E`#$(`0V ! `"`````@`"``$$ > >MD 8`9 $```$````,`````P``, (````+``\.``````(!_P\!````8P`````` > > Anthony, can't you speak English ? I'd like to read this ... it's > like watching 'X' files and having it TO BE CONTINUED !! > > Tom Cloud c'mon, you can't read that?, thats the first message i CAN read and understand! after having 68hc11 code burned into the back of my brain, this is REAL easy on the eye... Our experience in the HVAC CONTROLS industry is that a cost effective air flow measuring station (one that low-bidder can sell), using hot-wire, or static and total pressure, becomes REAL inaccurate at the low end, as was mentioned in a previous responce. mass of air must be assumed, and the duct runs must be of a certain minimum STRAIGHT distance before and after the flow station (no turbulance?). as the price of these stations goes up, honey-comb inserts can be included to mix and straighten the air out as it comes around a bend in the duct. (try that in a 4"dia twisting steel tube). with more cash, you can matrix anamometers or combo pressure pickups in a duct in a grid that samples the pressures at 9,12,16... points. granted, HVAC doesnt have to be as exacting, but a blade-position sensor produces such a non-linear percent open-to-flow relationship, that to use it, you have to FLOW the setup to get a curve to track. (ie 10% open=35%flow). as you add "fixes" to a simple manometer setup to correct for ??? the price goes up and up and you've lost the bid and your broke cause you spent all your wad on the blueprints and lunch for the engineer and your jobs on the line...... sorry, i drifted out of EFI and into rat race there. just another airflow view from another airflow angle. lucky ECM designers get decent budgets for the controllers or we'd still be cranking that spark-retard knob. - ---------- ~Dave. @:-)-I--< - ---------- ------------------------------ From: pantera@xxx.com (David Doddek) Date: Tue, 19 Nov 1996 22:53:17 -0600 Subject: RE: Air Flow Measurement >If you knew velocity and area, you could calculate >volumetric flow rate. This assumes that average >velocity measure you have adequate represents the >real velocity profile over the area. You still to >know density to determine mass flow rate. > >>If you know BAP and MAP, you know delta-P across opening -- granted, >the opening size varies with throttle position, but you've got TPS >for that -- seems that air flow could be rather accurately determined >without much hassle????? > >OK, now you've added barometric pressure (and you had >temperature above), so you can figure out ambient air >density. And you're transforming throttle angle >to area, so presumably you can get mass flow rate. >(Assumption: flow coefficient of throttle (or orifice for >that matter) is known.) > >But is it any less of a hassle than using a MAF sensor? >I don't see a huge advantage of one system over the other. > >Anthony Tsakiris With all of this talk about air flow, could some one please just give me the actual working equations for calculating the quantity of fuel required based on either the MAF or MAP or TPS methods. I need something to work with. David J. Doddek |pantera@xxx.com Owner SGD Electronics & Development Engr for Caterpillar |h 309 685-7965 Formula SAE Team Sidewinder 94-95 |w 309 578-2931 89 T-bird SC, 69 Fairlane w/SGD EFI |fx 217 428-4686 74 Pantera w/Electromotive Tec-II Twin turbos and Nitros | Hey, If you are going to go fast, go REEEAAL FAST. | ------------------------------ From: DRM Date: Tue, 19 Nov 1996 00:21:32 -0800 Subject: Air flow & such OK... I've been reading this list for several weeks and am still not ready to "CLEP" for my degree in engineering, but the topics are getting closer. I don't know about the American car systems but based on playing with Bosch L-Jet on a Alfa Race car... The way I understand it, the flapper type AFM provides a bias voltage to the ECU (with a range of something like 1v. to 5v.) through a wiper resistor inside the AFM. The ECU in turn controls injector period or duration based on air flow. I have wanted to get rid of the restrictive flapper type in favor of the hot wire or film type used on the Motronic and others, but people are telling me, you can't because it's "Digital" and the L-jet is "Analog". What is the difference between a "Digital volt" and an "Analog Volt", or did I miss something in Mr. Kelly's basic electronics course? On a roadrace car, that spends most of it's time (hopefully) with the throttle either wide open or completely closed, how critical is the measurement at part throttle in this application. BTW, when opening the throttle fully from idle on the Alfa, you can hear the flapper SLAM open. Does it close back partially after the initial change in pressure and follow rpm with load, or does it remain open? If it remains open, then it must only have a linear effect under part throttle acceleration, which we try to avoid on the race track. I'm not done, but that's enough for now. Be gentle, it's my first time. Dave Miller Deltona, Florida USA ------------------------------ From: Robert McElroy Date: Wed, 20 Nov 1996 00:35:37 -0600 Subject: RE: Air Flow Measurement If you want to measure airflow using BAP, MAP, and TPS, you would also need to account for the pressure drop across the air filter and through the duct work leading from the air filter to the throttle body. If you don't, you won't get a correct pressure differential. I'm also not sure how the shape of the air flow path (such as through the throttle plates in your example) affects the calculated air flow. All of the examples I have seen used a circular cross-section flow meter. Have you tried calculating air flow using BAP, MAP, & TPS? I would be very interested in learning how well that method works, as it would be much simpler to implement than what I suggested. - ---------- From: tom cloud[SMTP:cloud@xxx.edu] Sent: Tuesday, November 19, 1996 11:12 AM To: diy_efi@xxx.edu Subject: Re: Air Flow Measurement My long-standing question -- precisely ...... 'cept I think I've one-upped you (?? tell me what's wrong with this concept ??). If you know BAP and MAP, you know delta-P across opening -- granted, the opening size varies with throttle position, but you've got TPS for that -- seems that air flow could be rather accurately determined without much hassle????? Tom Cloud ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 20 Nov 1996 14:36:02 est Subject: re: Air Flow Measurement >This is achievable, the only problem is any restriction in the air >intake reduces peak air flow to the engine, so its not the best >method for power. the beauty of the venturi is that most of the pressure drop that you use to measure the volume flow rate is recovered, compared with say an orifice plate where it isn't. Andrew Rabbitt ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 20 Nov 1996 14:39:26 est Subject: re: Air Flow Measurement >what's IAT ? inlet air temperature ------------------------------ From: dg@xxx.com (David Gould) Date: Tue, 19 Nov 1996 23:00:30 -0800 (PST) Subject: Electromotive TEC-II? Perhaps this is not truly diy, but... I autocross a 1.8 liter Mazda Miata. I am allowed by the rules I run under to replace the entire intake and exhaust systems, but not to modify the engine internals. Some of the other competative cars (Miatas, RX7s, CRXs) are using the Electromotive TEC-II system to control fuel and ignition. I have looked at the Electromotive manuals and it looks like a reasonable system to me, but I am not an expert and have little to compare it too. Since this car is both a race car and a daily driver in CA, I will have to face the smog check every two years. It looks like the simplist solution would be to replace the original system, get the smog cert, and put the Electomotive back on every two years. Bummer. Given all of the above, is the Electromotive a reasonable system? I am vaguely aware that there are others (Motec etc) out there, but am under the impression that they cost quite a bit more. Is there another system I should look at? Is there anything especially good or bad about the Electromotive? I noticed in the manual that it does not have some of the frills that the stock system has like idle control adjusted for electrical loads, EGR control, purge canister control. Do I need all this stuff? I suspect not, except for the purge control. How do I do the canister purge without the stock ecu? Will there be drivability problems with the Electromotive? What about weather and altitude changes? Again, the stock ECU looks more sophisticated, but then cars ran on carburators (a french word meaning 'don't mess with it') which were even less sophisticated than the Electromotive. Any experience with Electromotive as far as reliablity of the system? Do they support the product and handle repairs etc well? Any special gotchas or neat hints for this application? Thanks for any and all advice. - -dg David Gould dg@xxx.6383 Informix Software (formerly Illustra) 1111 Broadway #2000 Oakland, CA 94607 - A child of five could understand this! Fetch me a child of five. ------------------------------ From: Robert McElroy Date: Wed, 20 Nov 1996 01:06:52 -0600 Subject: RE: Air Flow Measurement The main reason I don't want to use an existing MAF sensor is that I don't have one to play with. Also, I am under the impression that most heated-wire MAF's output a frequency signal. Since I am a mechanical engineer and don't have much knowledge when it comes to A/D conversion techniques, I would prefer to use a sensor that will output a voltage signal (something I am slightly familiar with.) (Nobody that I know is completely happy with MS Exchange. However, at work interoffice e-mail is sent through MS Mail, so using MS Exchange (or MS Mail client software) is the only choice available to us.) - ---------- From: Anthony Tsakiris[SMTP:atsakiri@xxx.com] Sent: Tuesday, November 19, 1996 2:38 PM To: 'diy_efi@xxx.edu' Subject: RE: Air Flow Measurement Knowing velocity and area allows the determination of volumetric flow rate. (This assumes the velocity measurement adequately represents the real velocity profile over the entire flow area.) Density must still be known to determine mass flow rate. Density can be determined if barometric pressure and temperature are know. At this point though, is it any less of a hassle than a MAF sensor? (Again, sorry for the lack of context. I'm completely underwhelmed by Microsoft Exchanges abilities.) Anthony Tsakiris ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 20 Nov 1996 14:57:22 est Subject: re: Air Flow Measurement >> What's wrong with speed-density? And what exactly do you do to it? >>I thought it was just found by Air=K*MAP*RPM (where K is a magic >>constant), but I'm naive. Am I going to get into trouble using >>this? > >There is nothing wrong with speed-density, especially if you are not >worried about emissions certification. I get upset whenever somebody maligns the humble MAP sensor and speed density calculation! :) Let it be known that the ULEV Honda Accord uses a MAP sensor and speed-density airflow calculation. After trying to get a MAF to work with a reasonable error over the speed-load map, I'd gladly toss it out and use a MAP sensor except that you can't MAP and EGR at the same time. I think if most people who swear by MAF had a reference airflow measurement to compare it to, they'd be horrified! ------------------------------ From: "Bosch, AN, Andrew, Dr" Date: Wed, 20 Nov 1996 10:20:42 UTC-2 Subject: Re: Air flow & such I have wanted to get rid of the restrictive > flapper type in favor of the hot wire or film type used on the Motronic when opening the > throttle fully from idle on the Alfa, you can hear the flapper SLAM open. > Does it close back partially after the initial change in pressure and > follow rpm with load, or does it remain open? If it remains open, then > it must only have a linear effect under part throttle acceleration, which > we try to avoid on the race track. Hi! I also want to get rid of that flapper: I've seen postings on this list from someone that, if I remember correctly, described a way that the hot wire system can be made to work in place of the flapper system: the problem I guess is to get the signals matched, and the problem with THAT is that the flapper has a weird change in resistance as you sweep across. Unfortunately, although I kept the posting, it seems to have been deleted sometime. As far as I know, the flapper initially overshoots a bit, which acts as a sort of acceleration enrichment. But its wide open from about 3- 3500 rpm, anyway. Anybody? Sincere;y Andrew Dr A. N. Bosch Physiology Department/ Sports Science Institute University of Cape Town Medical School P. O. Box 115 Newlands 7700 South Africa ------------------------------ From: jon hanson Date: Wed, 20 Nov 1996 09:50:08 +0200 Subject: Diff between theory and practice hopefully someone can explain the following deviation from theory to me The engine is a 1985 USA spec Toyota 4age 16 valve twin cam. the factory engine management system has been removed and replaced with a programmable system (controls fuel and ignition timing). The Toyota TVIS flaps have been removed from the intake manifold (the new ecu cannot control them). The O2 sensor is removed and the system is always open loop. the system uses a MAP sensor and a TPS. Peak torque occurs at 4800 rpm acc to spec. I recently had the car on a dyno and was adjusting the fuel myself. At 4800 rpm I had a WOT fuel no of 155 to achieve a CO reading of 3.5%, at 6000 rpm I had a fuel no of 170 to get a CO of 3.5%. Accoarding to my limited knowledge peak volumetric efficiency coincides with peak torque. I would have expected to have the highest fuel no at around 4800 rpm and then seen them drop slightly as revs got higher but the opposite happened. I'm a great believer in doing something and seeing the results for yourself. Can anyone explain why this is so, I'm curious to know. Jon Hanson Johannesburg South Africa. ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 20 Nov 1996 16:33:56 est Subject: re: Lambda Readings >14.7 only produces good power if you have excellent air / fuel >mixing. As others have commented, theoredically you should get more >power going slightly rich, because the vaporization of the extra >gasoline should cool the charge down. you probably won't get any power increase by going rich unless you advance the ignition as well. ------------------------------ From: PiJay@xxx.de (Peter Juergens) Date: Wed, 20 Nov 1996 09:36:21 -0800 Subject: New member Let me say hello to you fuel-spitters out there! Just signed the list and feel fine, due to the massive information coming with the traffic. The reason why I came on is to design( if it's not allready done!) a small and cheap ignition and later on a EFI for Triumph TR's. Probably most of you (especially you down under and on the other side of the pond :) ) don't know the destructive Tax regulations here in Germany. We have to change to catalyser or we'll be punished! Well Fellows, let me steel your hard earned buckeroos! Is there anyone who did something similar? My first attemt will be a 68hc11 driven ignition, because I allready worked with the '11 during study. Any help and info is really appreciated! TIA and - -- BFN Pete _____ 1962 TR4 daily -- - - / <> \ __,@_\____ Peter Juergens - --- '--0--'~~'--0-----0-> PiJay@xxx.de !! Only the one with the fastest toy wins !! Dortmund/Germany ------------------------------ From: Doug Robson Date: Wed, 20 Nov 1996 20:50:17 +1100 Subject: Re: Lambda Readings RABBITT_Andrew@xxx.au wrote: > > >14.7 only produces good power if you have excellent air / fuel > >mixing. As others have commented, theoredically you should get more > >power going slightly rich, because the vaporization of the extra > >gasoline should cool the charge down. > > you probably won't get any power increase by going rich unless you > advance the ignition as well. very astute point i think im learning something now - -- |===============================================================| | When I die, | | I want to go in my sleep, like my grandfather, | | not screaming like the passengers in his car. | |---------------------------------------------------------------| | Doug Robson (H) mailto:doug@xxx.au | | (W) mailto:Doug.Robson@xxx.com | | Sydney, Australia http://www.cia.com.au/doug | |---------------------------------------------------------------| | Club Car Racing Register of NSW | Thank God | | 1992/93 Under 2 litre State Champion | for | | http://www.cia.com.au/doug/ccrrnsw.html | Gravity | |===============================================================| ------------------------------ End of DIY_EFI Digest V1 #352 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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