DIY_EFI Digest Friday, 27 September 1996 Volume 01 : Number 289 In this issue: Re: Digital Software Design Re: Chip operating temperatures Re: Combustion chamber heat RE: Digital Software Design INFO to develop a software Wires and such RE: Chip operating temperatures Re[2]: Chip operating temperatures Re: Combustion chamber heat Re: Wires and such Re: Chip operating temperatures Re[2]: Chip operating temperatures Re: Re[2]: Chip operating temperatures Re: Combustion chamber heat RE:Re: Chip operating temperatures AC Delco See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: prebuf@xxx.uy (Pablo Rebufello - CECAL - ) Date: Thu, 26 Sep 96 09:15 GMT-3:00 Subject: Re: Digital Software Design Hi! Some weeks ago I sent a mail asking for information to develop a software to manipulate and visualize the data and the states of all these "sensors", but I didn't receive any message back. I got a degree in Computer Science and I'm trying to get the information I need just to develop a good soft. I agree with you, and you can count with me in the development, as well as in informatic things. Pablo Rebufello Uruguay e-mail: prebuf@xxx.uy ------------------------------ From: iii@xxx.) Date: Thu, 26 Sep 96 06:23 PDT Subject: Re: Chip operating temperatures > ...The 68332 chips bought in the >group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). I'm sure >these are ok for prototypes, but is anyone concerned about them lasting 50-100 >k miles in a real environment ? You may want to check the specs on the 68332. According to my book, the MC68332FC is rated for -40C to +85C. While a car left in the hot sun can do serious damage to poor Fido (rated at 0 to 40C) locked inside, it is unlikely to get up to +85C. However, less than -40C in North Overshoe, Saskatchewan is not unlikely. And when you go to start it up in the morning, the interior is probably colder than the engine compartment. Incidentally, vinyl coated automotive wire from Wal-Mart or the likes, is rated up to 75C. It is darned tough getting flexible wire with a higher temperature rating, short of going to fiberglass insulated oven wire. Bob Furber - -------------------------------------------------------------------- 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 Harris" Date: Thu, 26 Sep 1996 06:38:37 -0700 Subject: Re: Combustion chamber heat Any particular mechanically efficient engine combination has a sweet spot of advance, generally at the onset of detonation, where maximum power is made. If they are not close, such as the case with early FE heads, it means you have either room for more mechanical improvement (e.g. more compression) or your chamber has gotten crapped up - dome shape etc. Richening a mixture "cools" a mixture because more low evaporative temperature components vaporize prior to combustion, absorbing more latent heat from the air and cylinder, thus favorably changing the time/pressure/temperature detonation (ping/knock/big bang whatever) relationship. Air cooled engines run hotter cylinders and heads, thus because of temperature, not mechanical compression, run closer to detonation than an identical engine that is water cooled. Richening the mixture again cools the mixture, allowing more mechanical compression prior to detonation and thus more power out of the engine. Aluminum heads absorb more heat during compression, keeping the mixture cooler, allowing higher compression than iron heads. Both air cooled and aluminum heads have the disadvantage of after ignition of rejecting more heat to the cooling system and thus are somewhat less efficient than iron heads. Changing to aluminum heads from same design iron heads generally involve adding a few degrees lead to compensate for the additional cooling of the charge by increased cooling system loss's. Ceramic's work by vaporizing more fuel during compression, but more importantly retaining significantly more heat within the cylinder to make working pressure after combustion. Lower cooling system loss's directly translate to power at the flywheel. Ignition must be retarded several degrees to compensate for the higher initial charge temp, and faster flame spread because of reduced heat loss's. All of the above comparisons are based on the impossibility of mechanically identical engines except for the changes noted. Please note an earlier writer's statement that a highly turbo'd mega output engine made peak power at 18 degrees advance - about half of what aluminum headed street V-8's like. IMHO, the more mechanically efficient (chemical energy converted to mechanical energy) an engine is, the less total lead it will take to make maximum power. Just keep in mind that firing the mixture before top dead center, i.e. spark advance means initially building pressure OPPOSING the pistons upward movement to build maximum pressure about 15 degrees past top dead center. - ----- Cut here - personal comment follows ----- Q: What's the difference between Jane Fonda and Bill Clinton? A: She had the balls to go to Viet Nam Robert Harris - ---------- > From: talltom > To: diy_efi@xxx.edu > Subject: Combustion chamber heat > Date: Thursday, September 26, 1996 1:45 AM > > > I've noticed a little discrepency here in relation to combustion chambwer > heat. > It seems that some say it's necessary to go over rich to cool and prevent > preignition/detonation. Others say that thermal barrier coatings are the > neat trick, ------------------------------ From: Mark Pitts Date: Thu, 26 Sep 1996 16:51:26 +-200 Subject: RE: Digital Software Design Sounds like a very good Idea to me. I'll let you go first.. see if anybody follows Mark - ---------- From: Robert Harris[SMTP:bob@xxx.com] Sent: Thursday, September 26, 1996 8:27 AM To: diy_efi@xxx.edu Subject: Digital Software Design Anyone up for opening a thread to deal with developing a simple software algorithm following good engineering practices - i.e. blatantly stealing anything that works? Have worked out some ideas, but would like to open a forum and reach a consensus. I'm sure many of us have fragments that we could put together and make a great program. - ----- Cut here - personal comment follows ----- Q: What's the difference between Jane Fonda and Bill Clinton? A: She had the balls to go to Viet Nam Robert Harris - ---------- ------------------------------ From: prebuf@xxx.uy (Pablo Rebufello - CECAL - ) Date: Thu, 26 Sep 96 12:18 GMT-3:00 Subject: INFO to develop a software Hi! This is exactly the mail I send some weeks ago. Pablo - ------------------- start --------------- Hi! I'm new in this list. I got a degree in Computer Science, and my brother works as a mechanic. I'm planning to develop a software to manage and visualize the data (I/O) to full control the EFI, and everything else that could be read from a computer. But I need information about de EFI, and any electronical sensor. I know it depens on the car, but at least I have to try with just one at the beginning. What I need is: - - protocol of comunication from/to the devices. - - how the data is transmitted from/to the device, as well as description of the data to send/receive from/to the device to be read/write from/to the computer. I know I'm asking for a lot of information, so anything will help. Source of information such as books, internet address, etc will help much. Thank you!! Pablo Rebufello prebuf@xxx.uy URUGUAY - South America - ----------------------------------- end --------------------- ------------------------------ From: Kalle Pihlajasaari Date: Thu, 26 Sep 1996 17:20:58 +0200 (sat) Subject: Wires and such Hi, > Incidentally, vinyl coated automotive wire from Wal-Mart or the likes, is > rated up to 75C. It is darned tough getting flexible wire with a higher > temperature rating, short of going to fiberglass insulated oven wire. Silicon Rubber and Teflon coated wires are also an alternative. Your local airfield may have a workshop you could call and ask where they buy their engine compartment wires. The aircraft stuff is overengineered on top of over specked. The wires also usually have a second insulation layer for mechaniocal protection. Cheers - -- Kalle Pihlajasaari kalle@xxx.za Interface Products Box 15775, Doornfontein, 2028, South Africa +27 (11) 402-7750 Fax: +27 (11) 402-7751 ------------------------------ From: Mark Pitts Date: Thu, 26 Sep 1996 17:11:05 +-200 Subject: RE: Chip operating temperatures Thanks for the comment about oven wire, I was wonderin' what to do about = the temp sender wire that lies accross my cylinder head.. hadnt thought = of that! Mark (who is now happy ;-)) - ---------- From: Intec Inoventures Inc.[SMTP:iii@xxx.com] Sent: Thursday, September 26, 1996 3:23 PM To: diy_efi@xxx.edu Subject: Re: Chip operating temperatures > ...The 68332 chips bought in the = >group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). = I'm sure=20 >these are ok for prototypes, but is anyone concerned about them lasting = 50-100=20 >k miles in a real environment ? You may want to check the specs on the 68332. According to my book, the MC68332FC is rated for -40C to +85C. =20 While a car left in the hot sun can do serious damage to poor Fido = (rated at 0 to 40C) locked inside, it is unlikely to get up to +85C. However, = less than -40C in North Overshoe, Saskatchewan is not unlikely. And when you = go to start it up in the morning, the interior is probably colder than the engine compartment. Incidentally, vinyl coated automotive wire from Wal-Mart or the likes, = is rated up to 75C. It is darned tough getting flexible wire with a higher temperature rating, short of going to fiberglass insulated oven wire. Bob Furber - -------------------------------------------------------------------- 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: "Al Grippo" Date: Fri, 27 Sep 96 00:30:50 EST Subject: Re[2]: Chip operating temperatures >>You may want to check the specs on the 68332. According to my book, the >>MC68332FC is rated for -40C to +85C. You're right about the 68332, as I found out just a few minutes before getting this post. However, the SRAM I was planning to buy (from DS) is only rated 0 to 70C unless the IND suffix is used, which gives -40C to 85C. Al Grippo ------------------------------ From: Dirk Wright Date: Thu, 26 Sep 1996 09:40:36 -0400 (EDT) Subject: Re: Combustion chamber heat On Thu, 26 Sep 1996, talltom wrote: > > I've noticed a little discrepency here in relation to combustion chambwer > heat. > It seems that some say it's necessary to go over rich to cool and prevent > preignition/detonation. Others say that thermal barrier coatings are the > neat trick, > which would make the combustion chamber hotter, and to me more knock prone. I have no hard facts to back me up, but I would agree that using a thermal barrier coating on the pistons/combustion chamber/valves would create a situation where detonation/knock would be more likely. Since less heat would be abosrbed by the engine, as the flame front progressed through the cylinder onthe power stroke, the remaining unburned fuel would be heated more rapidly. I think there would indeed be a penalty in that the spark would ahve to be retarded more, and the mixture enriched to prevent this. Another alternative of course, is water injection, which I am more and more convinced is a good thing for air cooled engines at least, which tend to run hotter. I think, though that you could get away with coating the exhaust and intake ports without any penalties. The idea behind using coatings in the first place was to reduce heat in the engine and thus extend its life. Likewise with the exhaust header. For the intake port, the charge would stay a little cooler before entering the chamber. For the exhaust port, the exhaust gases would stay hotter, leading to better scavanging at the expense of running the exhaust valve hotter. Everything's a tradeoff, it seems. **************************************************************************** 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: cloud@xxx.edu (tom cloud) Date: Thu, 26 Sep 1996 15:07:53 -0500 Subject: Re: Wires and such >Hi, > >> Incidentally, vinyl coated automotive wire from Wal-Mart or the likes, is >> rated up to 75C. It is darned tough getting flexible wire with a higher >> temperature rating, short of going to fiberglass insulated oven wire. > >Silicon Rubber and Teflon coated wires are also an alternative. > >Your local airfield may have a workshop you could call and ask where they >buy their engine compartment wires. The aircraft stuff is overengineered >on top of over specked. The wires also usually have a second insulation >layer for mechaniocal protection. Buy your wire from Newark, Mouser, Digi-Key, etc. I'd stay away from the wire from auto parts houses and Wal-Mart -- unless I needed it that instant. I'd also buy from any of the above before I'd buy from Rat-Shack. [ Rat-Shack's wire, like the rest of their stuff, is the cheapest construction possible: lo-temp insulation, large strands (makes it less flexible than wire with more but smaller strands), and is not plated (bare copper will oxidize, even up under the insulation).] The catalogs will list the temp rating of the insulation (generally, the higher the temp, the stiffer it is). Be sure the wire is plated and get the highest/smallest number of strands so it'll be flexible. ** Don't ** use solid wire !!! It'll break. Don't drape the wire across exhaust manifolds, exhaust crossovers, EGR, etc. Cover the ends with heat shrink or such to keep crud from wicking up under the insulation into the wire. Really ought to avoid crimp connectors. Should solder all connections. If you want to use the crimp connectors, buy a quality grade that will take solder. Then you can solder them if you want to (many crimp "fast-on" connectors won't take solder, if they look sorta chrome or shiny, they probably won't solder. If a magnet will attract them, they probably won't take solder. If they have a dull, solder-looking sheen to them, and/or are non-magnetic (i.e. made of copper) they'll probably solder. Note that the magnetic ones (i.e. steel) will eventually corrode and rust. ------------------------------ From: "Brian Warburton, c/o Turbo Systems Ltd" Date: Thu, 26 Sep 1996 21:44:25 Subject: Re: Chip operating temperatures > It does not usually get much over +40C here so the top end of the >temp range is not much of a concern. BUT, winter IS comming. It is already >going down to +3C at night, and -40C is not that unusual. > > Wayne ( I really need to find a more moderate climate ) Braun >Wayne Braun Product Support Services Develcon Electronics Although ambient might rarely reach 40 degC, I would imagine that the temperature inside your ECU box/enclosure is well over that. Just think of the power dissipation from four coil drivers at say 40% dutycycle at 6000 rpm (dwell = 4mS/Wasted-Spark) and say eight injector drivers at 75% dutycycle at 6000 rpm (Fuel p/w = 15mS/SEFI) Typically, a 4 cylinder ECU can be sucking up to 10 Amps when the engine's really revving, I don't have figures to hand for 8 cylinder systems and of course all these figures depend on coil/injector type and so on, but we're still talking about passing a lot of current through the system. 120 watts can have pretty serious heating effects on the box especially if it's mounted in an area of static airflow. I would suggest that you would be advised to only use Industrial or Automotive spec parts where available, especially if your car's intended for serious day-to-day use. Failing that, mounting the ECU in the A/C outlet trunking might prove advantageous ... :^) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Brian Warburton, "Still searching for the perfect curve....." email: bwarb@xxx.net Advanced Automotive Electronics Ltd, Van-Nuys House, Scotlands Drive, Farnham Common, England. SL2-3ES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ------------------------------ From: dzorde@xxx.au Date: Fri, 27 Sep 96 08:39:19 Subject: Re[2]: Chip operating temperatures Just my few cents worth. Any of you lot out there ever heard about spaghetti strand (a common name). Comes in long tubes like heatshrink, except its woven fibreglass and it doesn't shrink. This is ideal for containing bunches of wire (or a single wire) in hot places (like engine bays). There is a very noticable temp difference between the inside and outside of the tube when this is used. Use it with standard automotive wire, you can basically run those wires across the extractors if you want to, and the wires will still survive. Just a thought, its a lot cheaper than buying oven wire, at least down under. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: RE: Chip operating temperatures Author: diy_efi@xxx.edu at INTERNET Date: 9/27/96 1:13 AM Thanks for the comment about oven wire, I was wonderin' what to do about = the temp sender wire that lies accross my cylinder head.. hadnt thought = of that! Mark (who is now happy ;-)) - ---------- From: Intec Inoventures Inc.[SMTP:iii@xxx.com] Sent: Thursday, September 26, 1996 3:23 PM To: diy_efi@xxx.edu Subject: Re: Chip operating temperatures > ...The 68332 chips bought in the = >group pcb buy were rated 0 deg C to 70 deg C (32 deg F to 158 deg F). = I'm sure=20 >these are ok for prototypes, but is anyone concerned about them lasting = 50-100=20 >k miles in a real environment ? You may want to check the specs on the 68332. According to my book, the MC68332FC is rated for -40C to +85C. =20 While a car left in the hot sun can do serious damage to poor Fido = (rated at 0 to 40C) locked inside, it is unlikely to get up to +85C. However, = less than -40C in North Overshoe, Saskatchewan is not unlikely. And when you = go to start it up in the morning, the interior is probably colder than the engine compartment. Incidentally, vinyl coated automotive wire from Wal-Mart or the likes, = is rated up to 75C. It is darned tough getting flexible wire with a higher temperature rating, short of going to fiberglass insulated oven wire. Bob Furber - -------------------------------------------------------------------- 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: iii@xxx.) Date: Thu, 26 Sep 96 20:10 PDT Subject: Re: Re[2]: Chip operating temperatures > You're right about the 68332, as I found out just a few minutes before >getting this post. However, the SRAM I was planning to buy (from DS) is only >rated 0 to 70C unless the IND suffix is used, which gives -40C to 85C. You might want to consider buying SMOS SRAM, available from Future and a number of other suppliers. The SRM20100LC70 (128K x 8) SRAMs that we use in their plain vanilla flavour are rated at -40C to +85C and they are competitively priced. There may be other similarly rated plain vanilla SRAMs. Bfn, Bob Furber - -------------------------------------------------------------------- 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: Shaun Brady Date: Thu, 26 Sep 1996 21:59:08 -0700 Subject: Re: Combustion chamber heat At 09:40 AM 9/26/96 -0400, you wrote: >On Thu, 26 Sep 1996, talltom wrote: > >> >> I've noticed a little discrepency here in relation to combustion chambwer >> heat. >> It seems that some say it's necessary to go over rich to cool and prevent >> preignition/detonation. Others say that thermal barrier coatings are the >> neat trick, >> which would make the combustion chamber hotter, and to me more knock prone. > >I have no hard facts to back me up, but I would agree that using a >thermal barrier coating on the pistons/combustion chamber/valves would >create a situation where detonation/knock would be more likely. Since >less heat would be abosrbed by the engine, as the flame front progressed >through the cylinder onthe power stroke, the remaining unburned fuel >would be heated more rapidly. > Unforutunately, current practice in everything from Formula 1 to stationary diesels refutes this reasoning. My seat of the pants rationalization is that the coatings reduce the likelyhood of hotspots and thus reduce the likelyhood of detonation, or don't affect the ignition event at all and enhance the expansion. I use thermally reflective coatings in my motorcycle racing engine, but didn't have a good baseline prior to applying them and don't have hard numbers on the improvement. Vizard feels that they are worth a 5-10% power improvement. The coatings are relatively cheap(about $15 per surface) when compared to what must be spent for similar improvements. They are more of a messy pain in the ass & scheduling hassle than an expense really. I can't think of another modification (other than electronic engine management) that improves both power and economy in equal measure. I'm also from the school of thought that the amount of ignition advance required for max power is a direct reflection on the efficiency of the combustion chamber. 34-36 degrees is a pretty typical number for an amazingly wide range of applications. Max power at 32 degrees would indicate to me that trying to improve the combustion efficiency would be a waste of time. 40 degrees would suggest the chamber is pretty pathetic. Mismatches between dynamic compression ratios and fuel octane will skew this, of course. If the combustion chamber is working well, and the fuel is matched to the application, power will fall off several degrees before detonation. These numbers are based on working with naturally aspirated motors with power peaks from 5000 to 12000 rpm and specific outputs from 1-2.5 hp/cid. These are just my generalizations based on a narrow range of experiences from a huge range of possibilities, so don't take them too seriously. Be carefull, detonation will kill a motor far faster than anything you can do with the fuel curve. SBrady ------------------------------ From: Krister Wikstrom Date: Fri, 27 Sep 1996 09:47:32 +0200 Subject: RE:Re: Chip operating temperatures >Just think of the power dissipation from four coil drivers at say >40% dutycycle at 6000 rpm (dwell =3D 4mS/Wasted-Spark) and say eight >injector drivers at 75% dutycycle at 6000 rpm (Fuel p/w =3D 15mS/SEFI) >Typically, a 4 cylinder ECU can be sucking up to 10 Amps when the >engine's really revving, I don't have figures to hand for 8 cylinder >systems and of course all these figures depend on coil/injector type >and so on, but we're still talking about passing a lot of current >through the system. 120 watts can have pretty serious heating effects >on the box especially if it's mounted in an area of static airflow. =20 I think the 120W is not dissipated at the driver location, most goes to = the injectors. If the driver sinks 10A and drops maybe 0.6V, the "warming" power is 6W - right? Using some low = RDSon MOSFETs etc. may have even lower voltage drop and power = dissipation. I've been repairing some (low cost) car audio stuff, and there seems to = be a lot of 0-70 C components used. This is a matter of cost, and those seem to survive/work at least on cold. On = the other hand, they _did_ broke down... (usually by too low speaker impedance or shorts, cheap stuff seem to = have no good protection circuits). Krister Wikstrom kwi@xxx.fi ------------------------------ From: walter.kaufmann@xxx.ch (Walter Kaufmann) Date: Fri, 27 Sep 1996 09:47:58 +0200 Subject: AC Delco Hi! Someone on the list works by AC Delco. I have some question.... Please send me the mailaddress. Thanks Walter ------------------------------ End of DIY_EFI Digest V1 #289 ***************************** 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".