DIY_EFI Digest Thursday, 29 February 1996 Volume 01 : Number 060 In this issue: RE: Blow off valve Hi-resolution Crank angle sensor Boost control Re: T-Coupe Intercooler RE: Blow off valve Re: Intake runner sizing.. Re: spark and MAP Re: Non-turbo turbo Re: Unreadable Posts RE: Microsoft exchange & bloated attachments Re: spark and MAP Re: spark and MAP Re: Hi-resolution Crank angle sensor Re: New EFI reference Re: T-Coupe Intercooler re: Re: spark and MAP RE: Binary attachments RE: Hi-resolution Crank angle sensor Re: Injector driver chips? Where? FW: re: Re: spark and MAP Re: Hi-resolution Crank angle sensor Re: Hi-resolution Crank angle sensor Re: Injector driver chips? Where? RE: Ducted Fan Engine See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Brad Martin Date: Wed, 28 Feb 1996 07:16:27 -0500 Subject: RE: Blow off valve At 08:28 PM 2/27/96 -0600, you wrote: >Sounds like a quickie HKS EVC. The EVC I've got uses Fuzzy Logic to program [chop] >begin 600 WINMAIL.DAT >M>)\^(CH"`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$-@ 0` Whats with the binary attachments? I've seen quite a few of these lately... Hope it's nothing devious... - -Brad ------------------------------ From: einarp@xxx.no (einarp) Date: Wed, 28 Feb 96 12:17:06 CET Subject: Hi-resolution Crank angle sensor >Yes, if you can get a 200 tooth wheel. Not necessary. Add one sensor instead. * x _ _ _ _ _ _ _/ \_/ \_/ \_/ \_/ \_/ \_ Where * is the original sensor, and "x" is the additional one. Run the signals through an or gate, and the output will give the same result as having twice as many teeth. And, it will be a true position, not interpolated like what you could do in software. The extra sensor could be placed anywhere on the periphery of the wheel, but must be between two teeth at the same time the original sensor is at a tooth. That is; if the wheel is not the missing tooth type. You could extend further to triple the resolution and so on. And yes, the starter gear on the flywheel is a good source, in most cases around 150 teeth, and (hopefully) no missing tooth. - -- einarp@xxx.no ( Maserati Biturbo Spyder ) ------------------------------ From: einarp@xxx.no (einarp) Date: Wed, 28 Feb 96 12:00:38 CET Subject: Boost control Jim, The function you describe was called APC by Saab, and MABC by Maserati back in 1985 or so. Not user programmable though, as the pot's were inside the box. This means you can get the solenoid from these sources. The parts used by Maserati (including the control box) are made in Sweden, make your own guesses here :-) In the MABC the solenoid is pulse width modulated with a pulse frequency of 14Hz. It's an analog box where Boost pressure signal, knock amplifier output and RPM increase are taken into account. It will lower boost if knock occurs, or preset boost pressure is exceeded. During rapid acceleration it will allow more knock. The parts used in it are cheap and readily available. On a DIY basis it would be very cheap. The solenoid and pressure sensor will probably cost more than the control box. If you are building an ignition controller, put this functionality in there. That's what Weber did for Maserati from 1988. It basically tries to avoid knock first by retarding ignition. If that doesn't help, it turns down the boost. The signal level from the knock sensor that will be interpreted as knock, is dependent on RPM and defined in a table. It also has a "rabid dog" mode that goes into effect if RPM rises fast. - -- einarp@xxx.no ( Maserati Biturbo Spyder ) ------------------------------ From: Corey Cole Date: Wed, 28 Feb 1996 09:29:48 -0700 (MST) Subject: Re: T-Coupe Intercooler On Tue, 27 Feb 1996, Bill Sarkozy wrote: > Could anyone tell me where I can find a Thunderbird Turbo-Coupe Intercooler? > Any and all information would be greatly appreciated. Thanks. > > Bill > Sarkozy > Kala > mazoo, MI > > I'd try Racer Walsh in (I believe FL). They usually have ads in the back of MM&FF and SuperFord magazines. I was looking at their stuff to hot rod my 1.6 L Escort...(pretty funny), but they sell all kinds of goodies for the Turbo'd 2.3. I know for sure that they sold a killer intercooler. Corey Cole colec@xxx.edu '65 Skylark "Knowledge is power...but cubic inches help." Go #24!!!!! I was drunk the day my mom got out of prison and I went to pick her up in the rain. But before I could get to the station in my pick up truck, she got runned over by the darned old train... David Allen Coe Steve Goodman ------------------------------ From: Kent Sullivan Date: Wed, 28 Feb 1996 09:37:31 -0800 Subject: RE: Blow off valve If the attachment isn't an obvious separate file (a GIF, a MS Word doc, etc.) then it's probably caused by the Microsoft Exchange email client. For every address in an Exchange user's personal address book, there is a checkbox labeled "Always send to this recipient in Microsoft Exchange rich-text format". If it is checked, two copies of the message are sent: one is plain ASCII text (which any mail program can read) and the other is RTF that has been uuencoded (I think). It's usually a good idea to uncheck this box for Internet mail addresses unless the sender knows that the receiver uses the Exchange client. - --Kent >---------- >From: Brad Martin[SMTP:btm@xxx.net] >Sent: Wednesday, February 28, 1996 4:16 AM >To: diy_efi@xxx.edu >Subject: RE: Blow off valve > >At 08:28 PM 2/27/96 -0600, you wrote: >>Sounds like a quickie HKS EVC. The EVC I've got uses Fuzzy Logic to program >[chop] >>begin 600 WINMAIL.DAT >>M>)\^(CH"`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$-@ 0` > >Whats with the binary attachments? >I've seen quite a few of these lately... >Hope it's nothing devious... >-Brad > > ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Wed, 28 Feb 1996 13:52:12 +0500 Subject: Re: Intake runner sizing.. "Also, c is not equal to the speed of sound exactly, but the sonic speed of the inlet gases." c is, in fact, the local speed of sound, which is dependent on air temperature, which depends on where you measure it. For this equation, local means IN the intake manifold, and can be determined by the following formula: c = sqrt(gamma*R*T) where sqrt means square root gamma for air is 1.4 R for air is 287 T is temperature in Kelvin, which you get by adding 273 to the temperature in Celsius. 27 degrees Celsius is the same as 300 Kelvin. Thus, c for air @xxx. "Is Vswept the volume swept by the piston?" Yes, actually it is. The formula posted divides this in half and accounts for compression ratio to derive mean cylinder volume. "When I worked it out I got the inverse of units of length %-( So I'm not too sure what's up with that. I'm going to ask my professor about it." The formula that was posted will give you frequency because it has c in the numerator. The formula in the ASME paper(page 3) does not have c in the numerator(one of Engleman's mistakes) and will give you the inverse units of length. "And it is still very 'iffy', because it really only works for tubular intakes, and designs where you can accurately measure all lengths and volumes." My earlier post states other restrictions(included below) for this formula, but it defintely WILL work for non-tubular intakes. As far as accurately measuring lengths and volumes, what you can measure with your tape measure will be good enough for members of this list, and the frequencies you calculate will be ball park. Suffice it to say, this is as accurate as anyone can expect who doesn't have access to engine modelling software which can account for wave propogation, Navier-Stokes solutions, unsteady flow, blah, blah, blah. Have fun with it! Snipped from my earlier post: "Somone later posted the correct equation(referred to in the industry as the Helmholtz method). For mean cylinder displacement, divide the cylinder displacent in half regardless of whether it's a piston or rotor. CAUTION: This only works for 4 cylinders or less, and will approximate the rpm where volumetric efficiency will peak, not how high the peaks will be. If you're good and select the right combination of lenghts and areas, you will get two peaks. The SAE paper where this can be found is 900680. The original which this paper is based on is an ASME paper by H.W. Engelman "Design of a Tuned Intake Manifold". The latter is a great tuned intake primer for this list, the first has a sample calulation. ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Wed, 28 Feb 1996 14:02:10 +0500 Subject: Re: spark and MAP "...keep in mind that a flame in the combustion chamber takes about 3 ms to burn. Hence, timing has to be advanced with increased rpm..." That is mostly correct, except that above a certain rpm, the flame speed(or burn rate) actually rises with rpm. It turns out that if your measure flame speed in crank degrees instead ms, you'll discover that it takes the same number of crank degrees to burn at 3000rpm as it does at 6000rpm. That is why distributor advance mechanisms and most spark maps "top out" and have nearly identical spark advance at the two rpms: | s| p| a| r| ********************************** k| * | * a| * d| * v| * |* ____________________________________________ rpm The point at which spark advance tops out varies from engine to engine. ------------------------------ From: Mitsu16v@xxx.com Date: Wed, 28 Feb 1996 15:04:46 -0500 Subject: Re: Non-turbo turbo In a message dated 96-02-26 06:28:14 EST, you write: >Re: Electriaclly driven supercharger. > >>This motor would also put quite a load on the electrical system on the >>car. The size I'm thinking is a small starter motor, for the torque. >>Would have to spin at a low speed, to stop itself from flying to bits. > >Alfa Romeo used two "turbos" where the turbine side were replaced >by hydraulic motors. There was a hydraulic pump driven directly >by the engine. They were said to give boost right from low RPM. >And with no need for regulation (like a wastegate on a turbo). >This was done back in 196. > > Hmmm.. how interesting... I seem to have reinvented the wheel... I have thought of using either a model jet airplane ducted-fan engine, or highspeed constant duty electrical motors through gear reduction, to turn a turbo on my Eclipse... There I go re-inventing the wheel again I suppose :> Not bad for someone with no formal engineering school though, eh?? :::tooting my own horn shamelessly:::::::: Soooo.. whad'ya think?? ------------------------------ From: Mitsu16v@xxx.com Date: Wed, 28 Feb 1996 15:05:39 -0500 Subject: Re: Unreadable Posts If you get an answer about Winmail.dat, Please let me know :> Thanks! And yup.. the DIY_EFI Digest IS the one it's coming from .. Later! ------------------------------ From: Doug Rorem Date: Wed, 28 Feb 1996 14:09:50 -0600 Subject: RE: Microsoft exchange & bloated attachments >---------- >>From: Brad Martin[SMTP:btm@xxx.net] >>Sent: Wednesday, February 28, 1996 4:16 AM >>To: diy_efi@xxx.edu >>Subject: RE: Blow off valve >> >>At 08:28 PM 2/27/96 -0600, you wrote: >>>Sounds like a quickie HKS EVC. The EVC I've got uses Fuzzy Logic to program >>[chop] >>>begin 600 WINMAIL.DAT >>>M>)\^(CH"`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$-@ 0` >> >>Whats with the binary attachments? >>I've seen quite a few of these lately... >>Hope it's nothing devious... >>-Brad > >If the attachment isn't an obvious separate file (a GIF, a MS Word doc, >etc.) then it's probably caused by the Microsoft Exchange email client. >For every address in an Exchange user's personal address book, there is >a checkbox labeled "Always send to this recipient in Microsoft Exchange >rich-text format". If it is checked, two copies of the message are >sent: one is plain ASCII text (which any mail program can read) and the >other is RTF that has been uuencoded (I think). > >It's usually a good idea to uncheck this box for Internet mail addresses >unless the sender knows that the receiver uses the Exchange client. > >--Kent I had worked with someone on this problem (we use Sun workstations here and are thankfully immune from generating this stuff). When they first turned off RTF (rich text formatting) they got rid of the MIME encoded attachment : Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IiQEAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAENgAQAAgAAAAIAAgABBJAG AGQBAAABAAAADAAAAAMAADADAAAACwAPDgAAAAACAf8PAQAAAGMAAAAAAAAAgSsfpL6jEBmdbgDd AQ9UAgAAAABkaXlfZWZpQGNvdWxvbWIuZW5nLm9oaW8tc3RhdGUuZWR1AFNNVFAAZGl5X2VmaUBj ....... but then their mailer started uuencoding the WINMAIL.DAT attachment. begin 600 WINMAIL.DAT M>)\^(CH"`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$-@ 0` ..... I certainly hope Microsoft has this stuff OFF by default. I guess there should be a FAQ in every list on the net as to how to turn it completely off. It creates large attachments which really have no utility on Internet mailing lists (i.e. who cares if their 3 line message is formatted with fancy fonts?) It certainly creates a lot of needless extra overhead when you figure that stuff is being sent out to every subscriber on the list. - -- Doug Rorem University of Illinois at Chicago (312)-996-5439 [voice] EECS Department RM 1120 (312)-413-1065 [fax] 851 S. Morgan Street (708)-996-2226 [pager] Chicago, IL 60607-7053 rorem@xxx.edu ------------------------------ From: Bohdan.L.Bodnar@xxx.com Date: Wed, 28 Feb 1996 14:30:15 -0600 Subject: Re: spark and MAP - ---------------------------- reference material --------------------------- "...keep in mind that a flame in the combustion chamber takes about 3 ms to burn. Hence, timing has to be advanced with increased rpm..." That is mostly correct, except that above a certain rpm, the flame speed(or burn rate) actually rises with rpm. It turns out that if your measure flame speed in crank degrees instead ms, you'll discover that it takes the same number of crank degrees to burn at 3000rpm as it does at 6000rpm. That is why distributor advance mechanisms and most spark maps "top out" and have nearly identical spark advance at the two rpms: | s| p| a| r| ********************************** k| * | * a| * d| * v| * |* ____________________________________________ rpm The point at which spark advance tops out varies from engine to engine. - ---------------------------- reference material --------------------------- I can see the burn time being a function of a/f mixture (rich mixture => reduced burn time). I don't understand why rpm alone will cause the flame burn time to vary unless there's a significant contribution from heat of compression. What's the involved mechanism? Regards, Bohdan Bodnar ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Wed, 28 Feb 1996 16:58:56 +0500 Subject: Re: spark and MAP "I can see the burn time being a function of a/f mixture (rich mixture =>reduced burn time).I don't understand why rpm alone will cause the flame burn time to vary unless there's a significant contribution from heat of compression. What's the involved mechanism?" First, rich mixtures do not burn faster. True, just slightly rich of stoich is where you get the fastest burn rate. Burn rates drop as you get leaner or richer than that, something to consider since most DIY A/F ratios at WOT are not tightly controlled, especially with SD based systems(oops, there I go again). This means your spark advance changes not only with rpm and load, but with A/F ratio. Control, that is to say, fix A/F, and you can eliminate one variable. The reason that burn rates rise with rpm is that charge motion increases, and the faster the mixture is swirling/tumbling around, the faster it burns. There are lots of things affecting burn rate, but above a certain rpm, charge motion is dominant. Another variable is heat, as you guessed, which also rises with rpm. It isn't dominant, but it does make for faster burn rates. Incidentally, high swirl/tumble combustion chambers with their fast burn rates tend to keep the fire lit after you spark it. This is one of the biggest design criteria for lean burn engines. It's hard enough to light these lean mixtures(and very rich ones), but half the problem is preventing the fire from going out. That's usually the #1 reason that certain engines have a rough idle: slow moving charge, slow burn rates, fire may get lit but then it goes out. ------------------------------ From: pjwales@xxx.net (Peter Wales) Date: Wed, 28 Feb 1996 18:06:39 -0500 Subject: Re: Hi-resolution Crank angle sensor >>Yes, if you can get a 200 tooth wheel. > >Not necessary. Add one sensor instead. > > > * x > _ _ _ _ _ _ >_/ \_/ \_/ \_/ \_/ \_/ \_ This doesn't make sense. For every peak there will be a trough and each sensor will detect the same thing. >And yes, the starter gear on the flywheel is a good source, >in most cases around 150 teeth, and (hopefully) no missing tooth. That makes much more sense. Why didn't I think of it :) Peter Wales President Superchips Inc Chairman Superchips Ltd "Timing is everything" Superchips home page with all the answers http://www.superchips.com ------------------------------ From: Jerry Wills Date: Wed, 28 Feb 1996 15:30:12 -0800 Subject: Re: New EFI reference Probst, C.O., "How to Understand, Service and Modify Ford Fuel Injection and Electronic Engine Control", Robert Bentley, Cambridge, MA, ISBN 0-8376-0301-3, 1993. Covers basic engine control theory and Ford systems to 1988. Excellent book on topic. Similar to author's other work on Bosch systems. Available from SAE for $30 (order B-584) - ----------------------------------------------------------------------- This is a good book for Ford people, but it is for 1988 to current ^^^^^^^^^^^^^^^^ 1993 was the publish date and it has a SVO part # M-1832-Z1 enjoy, Jerry Wills I'll have enough POWER when I can spin the tires at the end of the straight! 89 FJ DERSLYR, DoD#500 KotF(Flag) Mark Donahue, about 917's USC/Information Sciences Institute (USC/ISI) SoCal (310) 822-1511 x 236 90's cowboys, ride iron horses, and punch Deer!!! You done violated Physics, BOY! Assume the position..... (Rider 5/92) ------------------------------ From: jengel@xxx.NET Date: Wed, 28 Feb 1996 19:05:53 +600 Subject: Re: T-Coupe Intercooler > From: Bill Sarkozy > Subject: T-Coupe Intercooler > Could anyone tell me where I can find a Thunderbird Turbo-Coupe Intercooler? > Any and all information would be greatly appreciated. Thanks. I have a stock one that I may not need. It depends whether my car will pass a breathalyzer test or not. For a non-stock 'cooler: I'm very happy with a Spearco unit for the SVO Mustang (T'bird engine / Mustang chassis). They may make a kit for the T'bird as well. Spearco: (818) 901-7851. je ------------------------------ From: SRavet@xxx.com Date: Wed, 28 Feb 96 17:36:53 CST Subject: re: Re: spark and MAP Bohdan.L.Bodnar@xxx.com Wrote: | I can see the burn time being a function of a/f mixture (rich mixture => | reduced burn time). I don't understand why rpm alone will cause the flame | burn time to vary unless there's a significant contribution from heat of | compression. What's the involved mechanism? Increased turbulance creates a better mixture, which causes it to burn faster at higher RPMs. The ignition time is constant, that's what the rpm advance is for. Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: Andrew Dalgleish Date: Thu, 29 Feb 96 11:42:00 S Subject: RE: Binary attachments On Wednesday, 28 February 1996 7:16, owner-diy_efi-outgoing wrote: > At 08:28 PM 2/27/96 -0600, you wrote: > >Sounds like a quickie HKS EVC. The EVC I've got uses Fuzzy Logic to program > [chop] > >begin 600 WINMAIL.DAT > >M>)\^(CH"`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$-@ 0` > > Whats with the binary attachments? > I've seen quite a few of these lately... > Hope it's nothing devious... > -Brad > Microsoft Exchange mail client stores it's rich-text formating in an attachment WINMAIL.DAT if UUENCODED, or section "application/ms-tnef" if MIME. If the recipient is using Exchange, it converts it back again. Note to all Exchange users - you can modify this your address book by setting/clearing the check-box in the "tools.address box.properties.SMTP address" dialog. But if you're *replying*, exchange guesses the state of this flag, often incorrectly. Regards, Andrew Dalgleish Axon Research, Pty Ltd 6 Wallace Ave, Toorak, VIC 3142 AUSTRALIA Tel +61-3-9826-5538 Fax +61-3-9824-0083 ------------------------------ From: Andrew Dalgleish Date: Wed, 28 Feb 1996 21:02:23 -0500 Subject: RE: Hi-resolution Crank angle sensor On Wednesday, 28 February 1996 18:06, owner-diy_efi-outgoing wrote: > >>Yes, if you can get a 200 tooth wheel. > > > >Not necessary. Add one sensor instead. > > > > > > * x > > _ _ _ _ _ _ > >_/ \_/ \_/ \_/ \_/ \_/ \_ > > > This doesn't make sense. For every peak there will be a trough and each > sensor will detect the same thing. > > >And yes, the starter gear on the flywheel is a good source, > >in most cases around 150 teeth, and (hopefully) no missing tooth. > > That makes much more sense. Why didn't I think of it :) > > Peter Wales > President Superchips Inc > Chairman Superchips Ltd "Timing is everything" > Superchips home page with all the answers http://www.superchips.com > > Ever seen Vernier calipers? Quadrature encoders use the same principal. For one extra sensor the spacing should be at (n +/- 0.25) tooth ++++++++++++++++ ----____----____ Sensor 1 --____----____-- Sensor 2 __--__--__--__-- Exclusive-or ++++++++++++++++ Regards, Andrew Dalgleish Axon Research, Pty Ltd 6 Wallace Ave, Toorak, VIC 3142 AUSTRALIA Tel +61-3-9826-5538 Fax +61-3-9824-0083 ------------------------------ From: "Andrew Dennison" Date: Thu, 29 Feb 1996 13:16:06 +1000 Subject: Re: Injector driver chips? Where? On 27 Feb 96 at 11:57, Brad Sheridan wrote: > For the full data sheets, you have > to use the Motorola fax service. Not that it really matters, as it > won't be available for quite some time. Plus, as someone else > pointed out, it doesn't appear to be the peak/hold circuit I was > under the impression that it was. If you want I can set up the data > sheets for ftp. If you have WWW access you can download .PDF versions of most motorola data sheets. Get the free viewer from Adobe. The viewer is now a Netscape 2.0 plugin so you can view datasheets directly. ------------------------------ From: jac@xxx.us (john carroll) Date: Wed, 28 Feb 96 19:29:06 PST Subject: FW: re: Re: spark and MAP Increased RPM does not increase the burn time. A first order consideration is that increased RPM requires that the spark be initiated at an earlier crank position in order that combustion be finished at the the desired crank location. A second order consideration is that because the spark is initiated earlier, the flame front must travel through both a larger volume and a lower density charge. jac@xxx.us john carroll >Bohdan.L.Bodnar@xxx.com Wrote: > >| I can see the burn time being a function of a/f mixture (rich mixture => >| reduced burn time). I don't understand why rpm alone will cause the >flame >| burn time to vary unless there's a significant contribution from heat of >| compression. What's the involved mechanism? > >Increased turbulance creates a better mixture, which causes it to burn >faster at higher RPMs. The ignition time is constant, that's what the rpm >advance is for. > > > >Steve Ravet >sravet@xxx.com >Baby you're a genius when it comes to cooking up some chili sauce... > - ---------------------------------------------------------------------------------------- jac@xxx.us john carroll ------------------------------ From: dn Date: Wed, 28 Feb 96 21:32:09 MDT Subject: Re: Hi-resolution Crank angle sensor > >Not necessary. Add one sensor instead. > > > > > > * x > > _ _ _ _ _ _ > >_/ \_/ \_/ \_/ \_/ \_/ \_ Peter Wales wrote: > This doesn't make sense. For every peak there will be a trough and each > sensor will detect the same thing. Ah, but the key is in the phase difference between the two sensors. This will only work if the tooth is asymmetrical, ie the peak is much narrower than the trough. Assuming that this is the case, sensor waveforms will appear like this: _ _ _ _ Sensor A _____| |_____| |_____| |_____| |_____ _ _ _ _ _ Sensor B _| |_____| |_____| |_____| |_____| |__ _ _ _ _ _ _ _ _ _ A + B _| |_| |_| |_| |_| |_| |_| |_| |_| |__ (logical OR of the two) Voila, double the output frequency. This is very similar to the system used in optical encoders, but in the encoder the two waveforms (A and B) must be 50 % duty cycle, and separated by a phase difference of 90 degrees. It is then possible to discern rotational velocity, relative position, and direction by determining whether A or B occurs first. Of course, you are not interested in direction, if the engine starts turning backwards you've got other problems :) This brings up an interesting point... Hewlett Packard makes a chip specifically for reading optical encoders, which may work great with this type of system. Assuming you can get the 50% duty cycle waveforms as mentioned above, (you could have some sort of sensitivity adjustment on the sensors so it picks up the tooth halfway up and down each ramp) the chip takes care of the quadrature decoding and has a built in 16 bit counter which will totalize pulses until you read it. As an added bonus, it multiplies the resolution of the system by 4 because it counts each rising and falling edge from each sensor. Thus, on your 150 tooth ring gear, you could get 600 pulses per revolution, and eliminate interrupting your processor for each tooth and save a lot of software overhead. Just read it on a fixed time basis, and the CPU could easily calculate rotational velocity based on the number of pulses per unit time, and position based on the number of counts. You cannot, however, determine absolute position based on this approach, so you would have to have a third sensor which would interrupt the processor once per revolution to keep things synched up. It should be easy to predict when the next spark event will occur by calculating the difference between the latest count and the previous count. The chip I am referring to is the HCTL2000 (newer version is the HCTL2016) and is around 15$. I have used these in a position sensing application and they are a piece of cake to interface to. You'd only have to read it once per second and you'd be able to keep up with about 6500 RPM. Of course, you'd want to read it a lot more often to keep up with things, but it would take a big load off the processor in any case. regards dn - -- - --------------------------------------------------------------------- Darrell A. Norquay Internet: dn@xxx.ca Datalog Technology Inc. Bang: calgary!debug!dlogtech!darrell Calgary, Alberta, Canada Voice: +1 (403) 243-2220 Fax: +1 (403) 243-2872 @ + < __/ "Absolutum Obsoletum" - If it works, it's obsolete -------------------------------------------------------------------- ------------------------------ From: masmith Date: Wed, 28 Feb 1996 22:30:40 -0800 Subject: Re: Hi-resolution Crank angle sensor At 06:06 PM 2/28/96 -0500, you wrote: >>>Yes, if you can get a 200 tooth wheel. >> >>Not necessary. Add one sensor instead. >> >> >> * x >> _ _ _ _ _ _ >>_/ \_/ \_/ \_/ \_/ \_/ \_ > > >This doesn't make sense. For every peak there will be a trough and each >sensor will detect the same thing. > chop > >Peter Wales >President Superchips Inc >Chairman Superchips Ltd "Timing is everything" >Superchips home page with all the answers http://www.superchips.com > think about which sensor fires when - they are (hopefully) 180 deg out of phase -> like having twice as many teeth twice as close Matt Smith masmith089@xxx.com Mailer Eudora 1.5.2 ------------------------------ From: masmith Date: Wed, 28 Feb 1996 22:30:42 -0800 Subject: Re: Injector driver chips? Where? At 01:16 PM 2/29/96 +1000, you wrote: >On 27 Feb 96 at 11:57, Brad Sheridan wrote: > >> For the full data sheets, you have >> to use the Motorola fax service. Not that it really matters, as it >> won't be available for quite some time. Plus, as someone else >> pointed out, it doesn't appear to be the peak/hold circuit I was >> under the impression that it was. If you want I can set up the data >> sheets for ftp. > >If you have WWW access you can download .PDF versions of most >motorola data sheets. Get the free viewer from Adobe. The viewer is >now a Netscape 2.0 plugin so you can view datasheets directly. > > ditto national semiconductor Matt Smith masmith089@xxx.com Mailer Eudora 1.5.2 ------------------------------ From: ducharme@xxx.com Date: Thu, 29 Feb 96 03:25:57 EST Subject: RE: Ducted Fan Engine Mitsu16v@xxx.com wrote: >Hmmm.. how interesting... I seem to have reinvented the wheel... I have >thought of using either a model jet airplane ducted-fan engine, or highspeed >constant duty electrical motors through gear reduction, to turn a turbo on my >Eclipse... >There I go re-inventing the wheel again I suppose :> >Not bad for someone with no formal engineering school though, eh?? >:::tooting my own horn shamelessly:::::::: >Soooo.. whad'ya think?? As far as using a ducted fan engine is concerned, forget it! These engines run 15% - 25% nitro content alcohol-based fuel at 2-3 ounces per minute, consume glow plugs (one per ten minute flight), have a nasty habit of flaming out, and if not carefully cleaned up after each session, develop rust deposits in their crankshaft bearings that often lead to catestrophic engine failure. A constant-duty electric motor would be a better choice - provided your electrical system can handle it. Cliff Ducharme ------------------------------ End of DIY_EFI Digest V1 #60 **************************** 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".