DIY_EFI Digest Saturday, 24 August 1996 Volume 01 : Number 244 In this issue: Re: DIY_EFI Digest V1 #243 Re: DIY_EFI Digest V1 #241 Re: Camshaft/crankshaft sense Subscription Out of Date ? Re: Data Logging Re: Djetronic EFI: was ZEV / REV See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: steve.powers@xxx.COM (Steve Powers) Date: Fri, 23 Aug 1996 15:44:49 +0000 (BST) Subject: Re: DIY_EFI Digest V1 #243 Einar suggests: > > >The biggest problem with almost any dyno is getting rid of the heat > >generated. For a 200HP engine, that's more than 500,000 BTU/hr. > >That's enough to boil off 523lbs of water per hour, or 65 gallons. > > Hook it up to your hot water tank, spa or swimming pool. No, I'm not > joking. They are ranging from large to huge in heat storage capacity, > and you can enjoy the heat before it dissipates. hot water heaters work expectionally well, I can attest to that. We had a massively parallel power distribution system to test. It consisted of 44 power supplies (300 VDC in/48 VDC out), each having 4 300 watt bricks each. Feeding these supplies was another parallel system which consisted of 3 paralleled lab supplies (300V/50A each). I needed to see the effect of fully loading the 3 lab supplies, so purchased a used water heater for $25 and bought the largest elements I could find. I opened the bottom drain and connected a running hose through it. With 45KW to dissipate, it was too much to let it simmer. With full power applied and the water running through it was just warm to the touch. steve powers ... '95.5 S6 ... '95 620RX/C ... '91 K100RS-16V ... '88 R100S spowers@xxx.com * stratos product development group * seattle, washington "I must tell you that these are strong Bavarian beer-carrying horses, not the smaller ones of Italy." (Ferdinand Piech) ------------------------------ From: Kalle Pihlajasaari Date: Sat, 24 Aug 1996 02:25:37 +0200 (sat) Subject: Re: DIY_EFI Digest V1 #241 Hi Bob, > Now we're getting somewhere, and good point about the u-joint angles, > btw. If I had so much as a modicum of artistic talent (ascii or otherwise), > I'd draw the completely-portable, pins-together, axle-driven dyno now > rolling around in my head. I don't, so use your imagination. Differentials > attempt to rotate under load, hence the need for traction bars, perhaps some > means of measuring this action could be converted to HP. Problem with a hub coupled dyno is that you could very easily get a resonance to occur in the left to right hum connecting drive train, (you could not just lock one hub, diffs (especially limited slip) are not meant to run at full slip for that long. Cheers - -- Kalle Pihlajasaari kalle@xxx.za Interface Products Box 15775, Doornfontein, 2028, South Africa +27 (11) 402-7750 Fax: +27 (11) 402-7751 ------------------------------ From: John Dammeyer Date: Fri, 23 Aug 96 21:29 PDT Subject: Re: Camshaft/crankshaft sense At 07:47 PM 22/08/1996 -0700, you wrote: >In the designs I've read for an electronic ignition system, there is >usually a missing notch in the sense wheel to sense one full rotation of >the sense wheel. My question is, to do the initial calibration for the >electronic ignition controller, does the controller take (up to) one >rotation to make sure that its assumptions about TDC are correct before >starting to fire the plugs? Actually it should take only a couple of teeth if the tooth and the gap are symetrical. try it this way: Wait for opposite polarity of tooth sensor. ie: look for edge. and then start a counter accumulating some frequency until opposite edge occurs. Save counter and start again till first edge happens again. The two counted values should be roughly equivilent. If the one interval is three times the other - two gaps and a missing tooth - you've already found TDC. Otherwise treat this like a UART looks at bits in the bit window. Use half the previous interval time to count from an edge into the middle of the next tooth time and you should find another tooth. (Logic high?) otherwise you've found TDC if ( ToothSensor != TRUE) { TDC = TRUE; } else { TDC = FALSE; // keep counting till edge and use half of that count to check for presence of the next tooth }; > >A second question is, does anyone sense crankshaft and camshaft positioning >separately? This sounds silly, but it would let one sense timing >belt/chain failure almost instantly, so one could inhibit plug firing which >might save some bent valves. In theory, you could sense belt/chain wear, >but I don't think you'd want to spend the money on that level of precision. Engine would do at least enough revs through momentum of flywheel or manual transmission coupling through clutch that bent valves are a fact of life. John Pioneers are the ones, face down in the mud, with arrows in their backs. Automation Artisans Inc. Ph. 604-544-4950 6468 Loganberry Place Fax 604-544-4954 Victoria BC CANADA V8Z 7E6 ------------------------------ From: "Brian Warburton, c/o Turbo Systems Ltd" Date: Fri, 23 Aug 1996 05:56:17 Subject: Subscription Out of Date ? Having not received anything from this conference over the last 10 days, has it gone into limbo or has my subscription expired ? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: rickydik@xxx.com (RD Rick) Date: Fri, 23 Aug 1996 23:30:52 -0700 Subject: Re: Data Logging Skog scribbled: >Have you guys ever looked at >http://proffa.cc.tut.fi/~k124775/revpro.html >It's a program for estimating your HP and torque for the Amiga. You >simply hook a tape recorder to the ignition coil and record it. Then you >sample it in your computer and it calculates the torque. >I've tried it on a few cars and it seems to give a pretty correct result. >Maybe he will hurry up with the PC version if a lot of people shows >interest in it. Bugg him:) >Hope this helps! Thanks for the tip. I just checked the site, and it flashes a screenful saying NO PC VERSION DON'T BUG ME! He's working on it, but no timeline. I have been collecting data on tape from off the tach lead in my 914, but hadn't got around to using the awkward setup in our shop. The direct input to my laptop would be wonderful. RD ------------------------------ From: rickydik@xxx.com (RD Rick) Date: Sat, 24 Aug 1996 00:28:38 -0700 Subject: Re: Djetronic EFI: was ZEV / REV Kalle wrote: >Are there any technical sources on the EFI systems used in older >MB 450 engines, they have analog brain which is a Bosh unit I think >and a friend of mine has asked if I can modify this to generate timed >injection for the V8 as at the moment it is a proportional system with >only 2 phases for all 8 injectors. Is there any point and do I just >take the pulse width for the current revolution and delay the start >until the correct injectors turn has come and then hold the injector >open when the valve is open for the same time it would have done anyway ? > >I was told that there were 2 pulses on each set of 4 injectors per rev >(or was it one per 2 revs) is this right or is it a random unsynchronised>dutycycle that just meters/proportions the fuel? I have the Bosch D Jetronic EFI on my two Porsche 914's, and also have a tester for the Djet. It will test the Merc 450, but I have never looked at a Mercedes, as I don't much like radiators and hoses and waterpumps. The D stands for Druck, or pressure. The later Ljet is for Luft, or air(flow). The Djet uses a Manfold Pressure sensor, which is a transformer with a core that is pulled against a spring by vacuum. It also uses a pair of trigger points located in the base of the distributor (dizzy to you in SA). In the 4 cyl VW and Porsche, the trigger points start the injection for each pair of cylinders on every other revolution. It would fire four at a time in the V8. There is apparently no real advantage to squirting fuel toward an open valve, as they could have done it and didn't. The Djet is the grandfather of EFI. It was patentd by Bendix in 1952 after they reportedly stole it from some guy who developed it in his garage. Bendix licensed it to Bosch in the sixties, at the request of VW. Its first use was in the '68 Fastback/Squareback. As with all electronics of the era, it is primitive by today's standards. However, it does an outstanding job in a stock engine. I am working on mods to it so the hiperf engine in one of my 914 will idle below 2000, and still get enough fuel at 6000. RD 81 VW Vangon aircooled four with Ljet EFI 76 Porsche 914 stock commuter with Djet 73 Porsche 914 hiperf commuter with Djet 46 Bellanca Cruisair with 165 hp Franklin (Aircooled Motors) engine 34 Franklin Olympic sedan with 100 hp aircooled upright six Except for some boats and ships, all engines are aircooled anyhow. Why bother with water? ------------------------------ End of DIY_EFI Digest V1 #244 ***************************** 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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