DIY_EFI Digest Wednesday, 18 September 1996 Volume 01 : Number 277 In this issue: Haltech E6 EFI Re: Why run it hot? Re: Timing - again, ceramic Re: Kinsler fuel injection catalog?? Looking for a price/supplier for a Honda F2 EFI Re: Why run it hot? Re: Looking for a price/supplier for a Honda F2 EFI Re: Kinsler fuel injection catalog?? Microcontroller shielding questions Timing - Ignition Re: Looking for a price/supplier for a Honda F2 EFI Re: Timing - again Re: steam! Re: Haltech E6 EFI Re: Microcontroller shielding questions Re: Dyno Stuff GM Coolant sensor Re: steam! Re: Math Question Re: GM Coolant sensor Re: Microcontroller shielding questions Re: Timing - Ignition See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Jeremy Pronk Date: Tue, 17 Sep 1996 20:22:28 +1000 (EST) Subject: Haltech E6 EFI Hello all, I just purchased a nice alfasud which has been converted to haltech efi. I am having a little trouble tuning the system using the software that came with it. The haltech software has a function call "QuickMAP" which will generate some ruff fuel maps from a few simple inputs. Now I put the standard inputs in, but the map created seems to be much to rich. The standard inputs are 2.3ms injector time at idle, ~10ms at full power... I think these are wrong? The air/fuel ratio is display in volts? Any help is greatly appreciated! I would like to hear from anyone who runs Haltech E6 in there car as well. (Forgive my ignorance, but I have only ever played with carbies up until now, even though I have been on this list for a while, I dont seem to have picked up to much)... Jeremy, Sydney AUSTRALIA '69 510 4dr (for sale!) '83 AlfaSud Ti (Haltech E6 EFI) ------------------------------ From: Dirk Wright Date: Tue, 17 Sep 1996 08:02:34 -0400 (EDT) Subject: Re: Why run it hot? On Mon, 16 Sep 1996, Thor Johnson wrote: > > A lot of traffic relating to ceramics/keeping exhaust hot has been > passing through... Why would I want to do this? Is it just for > TurboCharging, or is it useful in other respects?I thought gas blew up > best when cold... enlighten me f I'm wrong. > Hotter exhaust gas translates to higher gas velocity, which aides scavanging during the exhuast stroke. It's a racer trick to get a little more power out of the engine. Also, using an insulating header wrap reduces temperatures under the hood, which also helps to make a little more power by keeping fuel lines cooler. As Todd has pointed out, things aren't always what they seem, and a good idea can lead to serious consequences depending on the application. **************************************************************************** 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: Dirk Wright Date: Tue, 17 Sep 1996 07:57:39 -0400 (EDT) Subject: Re: Timing - again, ceramic On Mon, 16 Sep 1996, Todd Knighton wrote: > Beware of Ceramics!!! > Especially on internal engine parts, i.e. pistons, combustion chambers, > valves, exhaust ports. Does this include Jet Hot Coatings? They have pictures of coated valves and piston tops inthier brochure. I can understand this might be a problem in air cooled engines, where the parts expand more due to the higher operating temperatures. > Coating headers as well tends to make the material run much hotter, > thus disintegrates quicker, especially on mild steel. If you just go to > a good stainless steel header, the coefficient of thermal heat transfer > is so slow, the heat transfer is practically better than a mild steel > header ceramic coated. Yeah, that's the idea behind stainless steel valves for air cooled engines, they run cooler that way. **************************************************************************** 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: Matt Sale Date: Tue, 17 Sep 1996 07:21:56 -0500 (EST) Subject: Re: Kinsler fuel injection catalog?? > > Hi, > > I saw a tiny advert in a magazine for Kinsler fuel injection in Troy, > Michigan (usa), and apparently they have a catalog with about 100 pages > of cool stuff in it. > > Has anyone got this catalog, & if so how can the rest of us get one? > > Cheers, > Craig. > pugsley@xxx.au > Yes I have one, but I don't know whether they can ship overseas or not. They have quite a few parts, but they aren't cheap. Their EFI info is useful, even if its a little dated. Their original claim-to-fame was mechanical FI systems for race cars. - -- Matthew D. Sale, IC Development Engineer, Delco Electronics Corp. msale@xxx.com/~msale '69 Mustang 351W 5-spd (13.656@xxx. All responses are my own and should not be mistaken for those of Delco Electronics or General Motors. ------------------------------ From: Thor Johnson Date: Tue, 17 Sep 1996 08:43:33 -0400 (EDT) Subject: Looking for a price/supplier for a Honda F2 EFI One the reqs for sr design is to evaluate the build/buy decisition (though I like building things). So I am looking for an aftermarket Honda F2 (599 cc, 13000 rpm motorcycle) EFI unit. Any sources? TIA, Thor Johnson johnsont@xxx.edu http://falcon.mercer.peachnet.edu/~johnsont Have you seen the WarpMap lately? http://falcon.mercer.peachnet.edu/~johnsont/warpmap ------------------------------ From: Chris Howard Date: Wed, 18 Sep 1996 00:41:14 +1000 Subject: Re: Why run it hot? At 08:02 17/09/96 -0400, you wrote: >On Mon, 16 Sep 1996, Thor Johnson wrote: > >> >> A lot of traffic relating to ceramics/keeping exhaust hot has been >> passing through... Why would I want to do this? Is it just for >> TurboCharging, or is it useful in other respects?I thought gas blew up >> best when cold... enlighten me f I'm wrong. >> > >Hotter exhaust gas translates to higher gas velocity, which aides >scavanging during the exhuast stroke. It's a racer trick to get a little >more power out of the engine. Also, using an insulating header wrap >reduces temperatures under the hood, which also helps to make a little >more power by keeping fuel lines cooler. As Todd has pointed out, things >aren't always what they seem, and a good idea can lead to serious >consequences depending on the application. > Actually the main reason to do this is to increase the thermal efficiency of the engine. For a theoretical reversible (Carnot) engine, thermal efficiency is given by: Tl n = 1 - -- Th where n = thermal efficiency Tl = temperature of low temp. reservoir ( Atmosphere in this case ) Th = temperature of high temp. reservoir ( Combustion temp ) "The thermal efficiency of actual heat engines can be maximized by supplying heat to the engine at the highest possible temperature (limited by material strength) and rejecting heat from the engine at the lowest possible temperature." Source: Cengel y, & Boles M. Thermodynamics: An Engineering Approach Get hold of any elementary thermodynamics textbook for more info. Chris Howard Computer Science University of New South Wales (was Mech. Eng @ Sydney University) email: s2184002@xxx.au Web: http://www.usyd.edu.au/~choward ------------------------------ From: Brian J Hanson/OIIS/EKC Date: 17 Sep 96 11:08:43 EDT Subject: Re: Looking for a price/supplier for a Honda F2 EFI >One the reqs for sr design is to evaluate the build/buy decisition >(though I like building things). So I am looking for an aftermarket >Honda F2 (599 cc, 13000 rpm motorcycle) EFI unit. Any sources? I might look in a junk yard for a recked bike to get this off of. Honda parts are quite expensive(believe me, they steal a bunch of $$ everytime I need to do maintenance on my F3). Another source might be to look at the Vance & Hines upgrade system. It isn't a Fuel Injection system tho(These are carbed engines). The V&H computer gives you variable timing with the turn of a dial and I believe it's in the $350 range(Don't remember exactly tho..I might be way off) ------------------------------ From: Ennis Bragg Date: Tue, 17 Sep 1996 11:40:27 -0400 (EDT) Subject: Re: Kinsler fuel injection catalog?? > I saw a tiny advert in a magazine for Kinsler fuel injection in Troy, > Michigan (usa), and apparently they have a catalog with about 100 pages > of cool stuff in it. > > Has anyone got this catalog, & if so how can the rest of us get one? Here's some info out of an ad in SCCA's Sportscar magazine.(Sept.96,pg43) Kinsler Fuel Injection 1834-K Thunderbird Troy, MI 48084 Phone: 810-362-1145 Fax: 810-362-1032 Send check or money order. no COD or credit cards are accepted for catalog Catalog Price: $12.00 (US) "Our 92 page handbook/catalog is the bible on RACING FUEL INJECTION." This is all straight from their add. hope it helps Ennis - -- Ennis Bragg gt9803a@xxx.edu http://www.cc.gatech.edu/people/home/gt9803a/ ------------------------------ From: iii@xxx.) Date: Tue, 17 Sep 96 09:14 PDT Subject: Microcontroller shielding questions Hi All, I am designing a small (2"x2") controller board for use in the automotive and robotics industries. The board is based on the MC68HC16Z1 microcontroller. Since the engine compartment of a car is filled with EMI we are attempting to make the board as resistant as possible to the effects of the EMI. Since I don't know the specifics of the sources of EMI a an automobile I would appreciate anyone who could help me with the following questions and maybe give some extra advice on things I have not asked about but are of concern in this type of design. What are the frequency and voltage levels of noise present in the typical automobile (EFI, and carburettor type)? What is the strength of the magnetic waves created by spark plugs and/or distributors? What is currently done to protect against it? What type of wire is used to connect a controller to the rest of the system (shielded, unshielded, twisted pair)? Can anyone give me some information on how to determined the type of shielding to use (box type and thickness, feed through type and value)? What is necessary? What is commonly used and what is affordable? Thanks in advance, Wade Barnes, Electronics Tech. - -------------------------------------------------------------------- MC68HC16 Embedded Controllers and Software Development Tools | WebPg http://www.islandnet.com/~iii | - -------------------------------------------------------------------- Intec Inoventures Inc. Phone 604-721-5150 | 2751 Arbutus Road Fax 721-4191 | Victoria BC V8N 5X7 | Canada | - -------------------------------------------------------------------- ------------------------------ From: "Robert J. Harris" Date: Tue, 17 Sep 1996 10:25:23 -0700 Subject: Timing - Ignition Subject: Ignition timing in conjunction with EFI There appears to exist a number of sensors to build an excellent self tuning EFI, yet the only sensor that anyone talks about for ignition timing is a knock sensor that just tells me - oops too much - self destruct sequence initiated. Factory curves and random published curves are all that most without dynes have to work with. Back in the bad old days, (pre computer) the killer secret for street tuning was to advance the static initial timing watching rpm and vacuum, until you got the max you could get and still start the engine, then put a sping kit in adjust the mechanical until the total was the same as what ever your guru of choice had dicated. Look for ping or knock, then put some more in. It works but had too much PFM (Pure F___ng Majic) to be reliable for all engines. Since then, many bandaid seem to have appeared. Since we now have computers, we should be able to monitor something other than self destruct imminent and tweak and peak the timing in conjunction with the fuel to get optimum power and economy. I truly hope that there are some good ideas out there. Remember the Reichstag - ---------- ------------------------------ From: "Mike Fahrion" Date: Tue, 17 Sep 1996 14:50:48 +0000 Subject: Re: Looking for a price/supplier for a Honda F2 EFI > >One the reqs for sr design is to evaluate the build/buy decisition > >(though I like building things). So I am looking for an aftermarket > >Honda F2 (599 cc, 13000 rpm motorcycle) EFI unit. Any sources? > > I might look in a junk yard for a recked bike to get this off of. Honda parts > are quite expensive(believe me, they steal a bunch of $$ everytime I need to do The closest thing I can think of would be Yamaha's GTS1000. Good luck finding one in the junk yard though. This FI 4cyl 1000cc wasn't a big seller. A friend has a '93 and isn't exactly impressed with its warmup characteristics considering its injected. There is also a FI harley and BMWs I believe, but those probably wouldn't do much for you. If this was a real life adventure I think I'd personally stick with the method honda chose - pretty hard to improve upon if emissions aren't a critical factor. Good Luck - -mike ------------------------------ From: "Woodd, Michael" Date: Wed, 18 Sep 1996 09:09:00 +1200 Subject: Re: Timing - again > Well it's time for me to challenge some with more edu than me, but I'm {snip snipetty snip} >if you can agree on why this is? I was going to mention a guy who makes engine computers here in NZ, who I talked to once - I asked how he set spark on the dyno before customers took their "hotted up" cars away, and he said that it was mainly guesswork maximising torque etc, but you could sometimes look for a reduction in torque as spark advanced, prior to knock. (he has worked on many different types of cars, including jap) I was going to mention him, but Todd blew my words away - if you're new to this list it wont take long to figure out who to listen to... I will mention talking to Robbie Francevic, who told me that when he was driving turbo Volvos in touring cars, they got max power when knock was just starting, and infact when they stuck a scope down the plug hole you could see the tiny pock marks in the top of the piston around the crown. Are turbo engines different to normally aspirated in this regard, due to any reason apart from c.chamber design etc., I wonder? Mike Woodd (wooddm@xxx.nz) Anybody need a race car driver? ------------------------------ From: Doug Rorem Date: Tue, 17 Sep 1996 17:30:43 -0500 Subject: Re: steam! >From: "Robert J. Harris" > .... >What you will have is the problems of external combustion and water >recycling to have sufficient range. Railroads had water towers at frequent ***** >intervals to avoid carrying more than a couple of hundred tons of water and >coal at a time. > .... That's exactly what I've heard for the reasons of the demise of steam locomotives.. Roughly 100 miles range between water stops. There's also the pollution problem of soot from the burning coal, but I imagine that could be overcome today. I believe the maintenance issues of steam are also more costly than with diesels. - -- 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: pantera@xxx.com (David Doddek) Date: Tue, 17 Sep 1996 18:45:44 -0500 Subject: Re: Haltech E6 EFI Jeromy wrote: (clip) >The haltech software has a function call "QuickMAP" which will generate >some ruff fuel maps from a few simple inputs. Now I put the standard >inputs in, but the map created seems to be much to rich. The standard >inputs are 2.3ms injector time at idle, ~10ms at full power... I think >these are wrong? These numbers depend greatly on the injector sizes. But at these times, your injectors would have to be almost too small for the engine. Try 8ms at full throttle and 1.5 to 1.8 ms at idle. You will just have to experiment to get a close value. Remember the bigger the injector, the smaller the on time at idle. Full throttle time depends on the engine hp cabability. 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: dzorde@xxx.au Date: Wed, 18 Sep 96 08:25:05 Subject: Re: Microcontroller shielding questions Get hold of the European EMC standards, they have a section specifically on automotives. ie, the levels you have to test too for compliance. I guess that if you can design to pass these levels, you'll be OK. Give someone like the UK consulate a call, they should be able to help you with the relevant section of the standards and any other info you want. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: Microcontroller shielding questions Author: diy_efi@xxx.edu at INTERNET Date: 9/17/96 9:14 AM Hi All, I am designing a small (2"x2") controller board for use in the automotive and robotics industries. The board is based on the MC68HC16Z1 microcontroller. Since the engine compartment of a car is filled with EMI we are attempting to make the board as resistant as possible to the effects of the EMI. Since I don't know the specifics of the sources of EMI a an automobile I would appreciate anyone who could help me with the following questions and maybe give some extra advice on things I have not asked about but are of concern in this type of design. What are the frequency and voltage levels of noise present in the typical automobile (EFI, and carburettor type)? What is the strength of the magnetic waves created by spark plugs and/or distributors? What is currently done to protect against it? What type of wire is used to connect a controller to the rest of the system (shielded, unshielded, twisted pair)? Can anyone give me some information on how to determined the type of shielding to use (box type and thickness, feed through type and value)? What is necessary? What is commonly used and what is affordable? Thanks in advance, Wade Barnes, Electronics Tech. - -------------------------------------------------------------------- MC68HC16 Embedded Controllers and Software Development Tools | WebPg http://www.islandnet.com/~iii | - -------------------------------------------------------------------- Intec Inoventures Inc. Phone 604-721-5150 | 2751 Arbutus Road Fax 721-4191 | Victoria BC V8N 5X7 | Canada | - -------------------------------------------------------------------- ------------------------------ From: "John Faubion" Date: Tue, 17 Sep 1996 17:48:48 -0500 Subject: Re: Dyno Stuff > Just might be useful to look at as an absorber for a dyno. Of course > Mr. Thermodynamics and other anally retentive types will quote me > physics books saying its impossible - and the fact it is in production > by a major heavy truck parts manufacturer will make little difference. Robert, I guess you weren't reading the thread a while back about using a "Telma" (another brand name for the device you describe) as a dynamometer. This has been mentioned but no one has posted many details for using one. It is an interesting idea though. John Faubion jfaubion@xxx.net ------------------------------ From: peter paul fenske Date: Tue, 17 Sep 1996 16:45:03 -0700 Subject: GM Coolant sensor Hi All Here is some more sensor data for you guys. Gm used the same sensor as a coolant sensor, a air temp sensor, and a oil temp sensor. GM TEMP SENSOR DATA TEMP(C) RESISTANCE VOLTS 100 177 1.29 90 241 1.8 80 332 2.24 70 467 2.6 60 667 3.0 50 973 3.6//1.0 45 1188 1.2 40 1459 1.28 35 1802 1.45 30 2238 1.85 25 2796 2.05 20 3520 2.4 15 4450 2.88 10 5670 3.1 5 7280 3.35 0 9420 3.5 - -20 28680 4.4 - -40 100700 4.9 The kink in the curve is because GM uses a 348 ohm pullup above 50 degrees. Below it uses a 348 ohm in series with a 3.65K resistor as a pullup. A temp range of -40 to 151 degrees gives a range of 0-255H. GL: peter ------------------------------ From: John Napoli Date: Tue, 17 Sep 1996 21:06:04 -0400 (EDT) Subject: Re: steam! Good luck with your project. Sounds intriguing. John On Sun, 15 Sep 1996, Robert J. Harris wrote: > Remember the Reichstag > > ---------- > > From: talltom > > To: diy_efi@xxx.edu > > Subject: Re: steam! > > Date: Saturday, September 14, 1996 11:59 PM > > > > > > Allright! Anybody got any good ideas about how to reclaim the water > when it's > > been thru the engine?(Water isn't as plentyful as it used to be) Short of > making > > a deal with wppss(Another conceptually and financially bankrupt govt. - > > washington public power supply system.) on a unused cooling tower that > is.? > > > If you are truly interested in steam engines, the late 40's Americans seem > to > represent the height of the technology. The south Africans used condensers > and recycled the water on some of their steam engines. On many tender > mounted booster engines the low pressure exhaust steam was vented directly > back into the water supply. > > With a steam piston engine, transmissions are totally useless. Cut of > steam = > parked, stopped - no need to idle. Move valve to "forward", go forward. > Move > valve to reverse, go backwards. Change direction by changing how steam > admitted. RPM limit is the destruction limit of engine. Torque limit is > by PSI > and size of piston. Think of how small loco pistons were in comparison to > the 10,000 plus ton loads they sometimes carried. Also, road locomotives > were almost universally limited to 300 PSI or less. > > What you will have is the problems of external combustion and water > recycling > to have sufficient range. Railroads had water towers at frequent > intervals to > avoid carrying more than a couple of hundred tons of water and coal at a > time. > > If they told you about 1200 PSI steam and the power from it, remember that > it is made at half the temperature reached in an IC engine. For the > skeptics, > remember - 1cc of liquid water state changed to vapor (boiled) makes about > 1800 cc of vapor. Not a bad little expansion ration. > > What I am tying to do is first build a self tuning controllable EFI for > petrol fuels > and then, inject a precisely metered amount of additional H2O to get the > power > of steam from the excess heat and avoid all the external combustion > hassles. > > No it would not be as efficient as an external combustion engine, but it > would > be far simpler and I believe could develope a lot more power than the same > amount of fuel in a straight IC engine. > ------------------------------ From: John Napoli Date: Tue, 17 Sep 1996 21:15:11 -0400 (EDT) Subject: Re: Math Question This issue of thermodynamic efficiency is one of my hot points (ouch). Fossil fuel plants use every trick in the book to recapture all the 'waste' BTUs that they can. If you neglect the power used to run their pollution devices (a parasitic loss), their overall efficiency is pretty good - I recall numbers in the mid-40s. Our gasoline engines in our cars do nothing to utilize the energy in the waste heat. Arre they 10%? 20% efficient overall? I doubt 20% but lets go with that number. If we were able to utilize a third of the waste heat, wouldn't that make a big difference? Instead of raising CAFE with smaller and lighter cars, we would raise it by being more efficient. I doubt that all the EFI software in the world will make much more MPG than we see right now. I would like to see something intelligent about using the waste heat. John On Mon, 16 Sep 1996, Robert J. Harris wrote: > Remember the Reichstag > > ---------- > > From: RABBITT_Andrew@xxx.au > > To: diy_efi@xxx.edu > > Subject: re: Math Question > > Date: Monday, September 16, 1996 7:06 AM > > > > > > >The point was, is, and always will be to try to combine the sheer > > >power of a steam engine with the simplicity of an IC engine. > > > > You can't get something for nothing. If you have 'sheer power' then > > you're also burning a lot of fuel too. Bear in mind that most > > stationary steam plants are working at about 35% thermal efficiency > > (unless they're combined cycle plants), which a good IC engine can > > approach too! Therefore just adding water to fuel in an IC engine is > > not going to give you vast increases of power. What it might allow is > > to extend the characteristic limits of an engine by a small amount. > > (ie the knock limit) > > > > > > Let me see if I get this thermodynamic thing right. I burn fuel, convert > between 20 and 30 percent to mechanical energy, heat up cooling > water and oil to 200 plus degrees, and throw away 50 per cent or > more of the energy as heat at 1300 plus degrees exhaust temperature > - enuff to send water boiling at 3600 psi - and there is only a little > teeny > tiny amount of excess heat to convert water to steam in the chamber - > as an antidetontant? I'm convinced. > > I guess I just don't get the big picture. Maybe water knows that it is > about to be injected into an engine and presto magic changes > characteristics and doesn't boil at 212 degrees or expand 1800 times > when it turns to steam when that happens in a combustion chamber. > It just stops making 600 psi at 440 degrees so that heaven forbid any > of that wasted heat might get converted to power. > > Thank you for the thermodynamic and magic lesson. > > ------------------------------ From: dzorde@xxx.au Date: Wed, 18 Sep 96 11:44:15 Subject: Re: GM Coolant sensor Does anyone know if there's a positive curve temp sensor around, ie. increasing voltage for increasing temp. Would make life a lot easier for analogue circuitry. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: GM Coolant sensor Author: diy_efi@xxx.edu at INTERNET Date: 9/18/96 10:52 AM Hi All Here is some more sensor data for you guys. Gm used the same sensor as a coolant sensor, a air temp sensor, and a oil temp sensor. GM TEMP SENSOR DATA TEMP(C) RESISTANCE VOLTS 100 177 1.29 90 241 1.8 80 332 2.24 70 467 2.6 60 667 3.0 50 973 3.6//1.0 45 1188 1.2 40 1459 1.28 35 1802 1.45 30 2238 1.85 25 2796 2.05 20 3520 2.4 15 4450 2.88 10 5670 3.1 5 7280 3.35 0 9420 3.5 - -20 28680 4.4 - -40 100700 4.9 The kink in the curve is because GM uses a 348 ohm pullup above 50 degrees. Below it uses a 348 ohm in series with a 3.65K resistor as a pullup. A temp range of -40 to 151 degrees gives a range of 0-255H. GL: peter ------------------------------ From: Darrell Norquay Date: Tue, 17 Sep 1996 22:12:20 -0700 (PDT) Subject: Re: Microcontroller shielding questions At 09:14 AM 9/17/96 PDT, Wade Barnes wrote: >I am designing a small (2"x2") controller board for use in the automotive >and robotics industries. The board is based on the MC68HC16Z1 >microcontroller. Since the engine compartment of a car is filled with EMI >we are attempting to make the board as resistant as possible to the effects >of the EMI. >Can anyone give me some information on how to determined the type of >shielding to use (box type and thickness, feed through type and value)? >What is necessary? What is commonly used and what is affordable? Sorry, I can't quantify any of the EMI/RFI effects that you mentioned, I'd be surprised if anyone could. Mebbe stick the car in a Faraday cage and see what you get. As far as processor shielding, you would at least need a good metal enclosure, some of the commercially available die cast aluminum boxes would be ideal. All wiring entering or leaving the box should run through a feedthrough RFI filter. The RFI filtered feedthrough DB style connectors from Conec are very good. They have a ferrite core through which all pins run, some also have feedthrough capacitors. The important thing here is to have the bypass caps grounded to the box right where the wire comes through the box. Bypass caps on the circuit board are not enough. Even an inch of unbypassed wire in the box is enough to radiate RFI sufficient to scramble the processor. Panasonic and Phillips make nifty little RFI filters which are essentially a feedthrough capacitor with a ferrite bead on each side of the through line, forming a pi filter. They are very effective. Filtering on the supply lines is a must, both power and ground, as well as protection against transients and load dump. Signal lines will also require transient protection as well. Use differential inputs on analog leads wherever possible, this will minimize the effects of common mode noise and ground differentials. Shielded leads on all inputs are also a good idea, but remember not to use the shield as a current carrying conductor and only ground it at one end. Use hard pullups on digital signals, and generally keep impedances low to minimize noise pickup. Take a tip from the OEM's and use the body as shielding, ie mount the computer on the passenger compartment side of the firewall. You'll generally find that the protection and filtering circuitry that you need will take up more board space than the controller itself, you'll have a hard time fitting all this on a 2x2 board... Consider making the system building block style, with the controller as a piggyback module on the signal conditioning board. In this way, you can keep the controller generic, and just make different signal conditioning boards for different applications. Some of the stuff I have suggested may seem like overkill, but it's much better to overdesign the first time for any contingency. A few dollars worth of extra components will save many hours of dinking around later. Good luck, and keep us posted. regards dn dnorquay@xxx.com ------------------------------ From: M HILL Date: Wed, 18 Sep 1996 09:11:06 GMT0BST Subject: Re: Timing - Ignition > Since we now have computers, we should be able to > monitor something other than self destruct imminent and > tweak and peak the timing in conjunction with the fuel > to get optimum power and economy. > > I truly hope that there are some good ideas out there. By monitoring the pressure in the combustion chamber you can judge how well the ignition system is working, the problem with this is the price of the probes and the charge amplifiers required. Another method is the spark ionisation. Add another spark around 15 degrees after TDC. The cylinder pressure should be at a peak around here. Then measure how long it takes for the ionisation current to decay from the spark. This will tell you how much burning mixture there is at the time. This is currently what I am looking at. Another one you could try is looking at crankshaft acceleration. Again something I will look at in the near future. By measuring the max and min speed of the crankshaft you can tell which cylinders are firing better than others and hopefully sort out the timing and fuelling for them. There will be problems with noise from the drivetrain however. So there are ways, it is just a case of time and money and having the right equipment to measure what is happening and see if it will be useful. Martin ------------------------------ End of DIY_EFI Digest V1 #277 ***************************** 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".