DIY_EFI Digest Friday, 20 September 1996 Volume 01 : Number 281 In this issue: re: Maths Question Re: Diesel Injectors.... How do they work? Re: Math Question Re: DIY_EFI Digest V1 #277 Learning Systems Acceleration of Vehicles See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: RABBITT_Andrew@xxx.au Date: Fri, 20 Sep 1996 08:42:14 est Subject: re: Maths Question >> >> 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. > > >In a relatively old textbook that I have on heat engines (40's or >50's era) there's a discussion of the idea of following an IC with a >gas-turbine. >The context wasn't like that of a turbocharger, but rather with the >turbine shaft connected though a mechanical drive to the driveshaft, >hence combining the output of the two for useful work. Curtis-Wright did this on their Turbo-Compund aero engines of the 40's and 50's. It gave more power, better power-weight, but not sure about thermal efficiency though. Now they use gas turbines made by GE, Pratt&Whittney and RR :) ------------------------------ From: Doug Rorem Date: Thu, 19 Sep 1996 21:08:26 -0500 Subject: Re: Diesel Injectors.... How do they work? >> >>Not quite EFI, but while looking for Injectors, I met a good friend at >>NOPI, and he showed me alot of injectors... I noticed that the Diesel ones >>had Fuel in, and two little ports on the sides. How do these injectors >>know when to fire? >> >> Thor Johnson Thor, The injection pump ramps up the fuel pressure very high (roughly 2500 psi) and the injector 'fires' when it's breaking pressure is reached. For VW diesels there is a moveable pintle in the nozzle that is spring loaded which determines the 'breaking' pressure. There are shim washers that are used to adjust the spring force and thus the pressure for firing. When the right pressure is reached, the pintle nozzle moves up into the injector body and fuel sprays out. When the pressure drops, the spring shoves the pintle back into place which cuts off fuel flow, readying the injector for the next cycle. The two ports on the side of a VW injector are for excess fuel flow which goes back to the fuel tank. - -- 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: "George M. Dailey" Date: Thu, 19 Sep 1996 21:19:04 -0500 (CDT) Subject: Re: Math Question At 12:46 PM 9/19/96 -0400, you wrote: >Unless some real efficient heat/electric device was available, and used to >drive the car, not much of a gain will be seen. >Power plants have 2 advantages. THey don't move. So weight of the extra >equipment isn't a problem. And they are amortized over something like >thirty-five years. Helps with the costs. Now while some of us might have >overweight project cars that never move and just eat dollars, that is not >the point! :) > >So I expect that this issue will remain pretty much a sore point unless >somehow we figure out how to use the waste heat to perform mechanical >work. Your car just does not use enough electrical power to gain much by >eliminating the alternator, although of course it is a step in the right >direction. > >John I agree John, but if over 60 percent is waste heat energy out of the radiator and tail pipe it seems simple enough to catch at least 20% of the wasted heat. Read the excerpt from my response to talltom's initial request. The turbine could be substituted for a large vane type air motor couppled to the engine. I think the materials are available to make it happen. ...snip...Think about this, a low pressure turbine connected between the rear axle and tranny (to assist the engine). Hot water from the engine is routed to water jacketed exhaust manifolds for 'super heating'. This steam is then routed to the drive shaft turbine. Low pressure steam leaves the turbine and enters the radiator or back to the engine to be condensed or heated again. And, don't forget the water purification unit right before the turbine. I'm sure there is a simple reason why this will not work, besides cost. I don't know it. Let's see what the thermodynamic experts say. GMD BTW, we use similar unit to generate power with >50% effiency. We essentially vent the exhaust of a gas turbine generator into conventional fossile boiler. Some plants have simply decomissioned a burner and stuck the ass end of the turbine/generator there. The supercritical plant where I work achieves 9,400 - 10,200 btu/killowatt-hour with just a super critical boiler and generator. ------------------------------ From: "John Faubion" Date: Thu, 19 Sep 1996 22:13:09 -0500 Subject: Re: DIY_EFI Digest V1 #277 > All kinds of stuff! 84 Datsun z cars had a factory g-meter on board, although > limited to .5 g's.(A good hard launch at the strip is at least 3g's.) You won't see 3g's from any thing driven on the street! My Gas dragster only pulled 2.6g's and we were running the quarter mile in the 7's! I was running a 355 inch small block with an 8 inch converter. I released the trans brake with the tach at 5400 RPM! The ProMod guys are pulling that but then again you find many of them on the street either! John Faubion jfaubion@xxx.net ------------------------------ From: David Crocombe Date: Fri, 20 Sep 1996 14:38:15 +1000 Subject: Learning Systems In my last job I used to service a tape recorder synchroniser that would learn the performance of each tape recorder so that it could control it in the most efficient way. It would do a few fast forwards, rewinds, stops and measure the dynamics. Each time it would get a bit better at controlling the machine so that if for example it wanted to go to a particular position on the tape it would know how far before that point it had to go into braking from fast forward to be able to stop slightly ahead of the required point and then drop into play mode to find the exact point. This was very impressive to watch its performance get noticably better as it learnt the dynamic performance. It would be interesting to play with this kind of learning in relation to cars. The vehicles could then be self tuning depending on environment, load, parameter drift, wear or whatever. I guess traction control and antilock brakes are a step in this direction of making cars more intelligent. David Crocombe, Sydney, Australia. - --------------------------------------------------------- Reply Seperator - --------------------------------------------------------- >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. /cut/ The only thing stopping you having a computer tweak the engine parameters for you is that you have to have *accurate* *results* from your measuring system. It seems to me with an accurate performance measure- ment system, anything is possible, but building an *accurate* system is a bit of an ask. /cut/ Use some fuzzy logic to try to improve things over multiple acceleration runs, hey presto, self tuning car. /cut/ record multiple instances of the same speed/RPM/TPS for different spark/fuel parameters, historical EGO info... My idea is to have this running for a race track environment, where the car is doing multiple acceleration and speed runs, repetitively, and I think given a baseline spark/fuel curve, it could quite quickly approach the perfection asymptote... ------------------------------ From: David Crocombe Date: Fri, 20 Sep 1996 15:41:39 +1000 Subject: Acceleration of Vehicles I was wondering how you measured the acceleration of your dragster. This is something I was planning to do with an Analog devices accelerometer. Any information would be appreciated. Thanks, David Crocombe, Sydney, Australia. ------------------------------ End of DIY_EFI Digest V1 #281 ***************************** 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".