DIY_EFI Digest Thursday, 20 June 1996 Volume 01 : Number 172 In this issue: Re: Re: your mail Re: 1/4 Wave Tuning Bosch Motronic Questions Re: Home-grown 5th wheel project--wheel lacings Re: DIY_EFI Digest V1 #171 Re: Bosch Motronic Questions Re: Bosch Motronic Questions Re: Bosch Motronic Questions -Reply fuel pickups & filters? Re: Anybody build their own 5th wheel? Re: fuel pickups & filters? Re[2]: Anybody build their own 5th wheel? AUX. MEM. PORT See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Bosch, AN, Andrew, Dr" Date: Wed, 19 Jun 1996 11:12:48 UTC-2 Subject: Re: Hi! I'm not sure that this is going to be of much help, but in case it is I'm replying to you re your question about fuel enrichment. As far as I'm aware, something like 8:1 is way too rich. I would suggest that you connect up a rich/lean indicator, and then set up your injection system to run rich, around 12:1. Then drive the car, either on the road if your measuring equipment permits, or on a dyno. You will then be able to grdually lean out the mixture until you get max power, listening for detonation all the time as you do so. Running 15 psi boost, on an intercooled, 8:1 CR motor and using 93 octane (R+M/2) octane fuel should give peak power at an AFR of about 13:1 or just under. Adjustment of this ratio based on air temp would be useful, as otherwise you could run too lean as the air temp drops. Hope this helps. Let me know how you go if you have the time. Andrew Dr A. N. Bosch Physiology Department/ Sports Science Institute University of Cape Town Medical School P. O. Box 115 Newlands 7700 South Africa ------------------------------ From: Frank Parker Date: Wed, 19 Jun 1996 07:53:14 -0600 (EDT) Subject: Re: your mail > Hello, > I am building a simple MAP controlled system for a 2litre turbo. It > is micro-controlled and basically fires each injector with the spark > signal, and the duration is based linearly on the MAP output. There > is also a 3d correction table which gives a correction factor for RPM > and MAP (to adjust mixture, and to compensate for changes in > volumentric efficiency with rpm & boost). This works quite well, but > I dont know what mixtures should be used theoretically at boost. I > have assumed a 14:1 mixture at light loads (about 1/2 bar absolute) > and 12:1 at 1 bar (absolute). Presumably I should keep enrichening > the mixture as boost increases, but what to!!! (I am ignoring > volumetric efficiency changes with rpm at the moment) My aim is 1 bar > boost pressure, so does anyone know approx. what mixtures you should > use at this level with an intercooled motor. It must level off at > some point (maybe 8 or 9:1). I have heard that turbo motors like very > rich mixtures under boost. > Any help appreciated. > Mark. > I think it depends on whether you have good intercooler now. If so and inlet temp is within 20 deg or so of air temp, then you do not have to use fuel as an intercooler as some mfr have done. They also do for warrenty reasons. I do believe 12 to 12.5 a/f is best for power and can run down to about 10 to 1 for cooling. Below that, I believe more fuel can actually make detonation worse. Also a good knock control system like an J&S helps you be able to run closer to best power a/f frank parker ------------------------------ From: Donald Whisnant Date: Wed, 19 Jun 1996 11:18:19 -0400 Subject: Re: 1/4 Wave Tuning > From: Chuck Tomlinson > Date: Tue, 18 Jun 1996 14:05:41 -0400 > Subject: Re: 1/4 Wave Tuning > > The module is called a Helmholtz resonator, and its primary (I think only) purpose > is noise reduction near a particular frequency. > > According to the Bosch Automotive Handbook, > > Volume = (Sm/l)*(c/omega)^2, where > > Sm = avg. cross-section area of the runner > l = runner length > c = speed of sound in air > omega = resonant frequency = 2.pi.f, for f in Hz. > > AFAIK, it adds no power (maybe reduces power slightly), and the shape does _not_ > matter. I don't know why the GM manual calls them "1/4 wave" modules, because > the volume (not the length) is the important parameter for a Helmholtz resonator. > Chuck Tomlinson > tomlinsc@xxx.com > Thanks Chuck... I thaught that maybe they called it a "1/4 Wave Module/Box" because it had something to do with the 1/4 wave of the frequency of concern ... I was also trying to figure out if it had some function as a "reservoir" for the air that could maybe provide for a smoother air induction from the filter box into the intake... Since I retrofitted this engine into an older car, I of course had no such "1/4 wave box". Instead I did some fiberglassing to modify an air cleaner box, and used an industrial/aircraft grade 3" duct (as the intake opening measured 2-7/8") to run between the aircleaner box and the intake. The result looks rather "different" -- as I had to route this large Carolina Blue duct in a long circular fashion (it is about 4-5 feet long) to clear the cooling fan (which I had to switch the an electric unit) and to clear the belt and many pulleys... I would like to find a "1/4 wave box" (or something similar) used for that engine off of a truck or something just to clean things up and make it look a little neater .... Though right now it is most definitely a true cold air induction system -- plus as smooth as the inside of the duct is, there should be no turbulance at all from "ripples" in the sidewalls (since this duct uses a hard plastic core wrapped external to the inner wall) --- I'm almost afraid that switching to such a box may even hurt the effecientcy/performance... Thanks again... Donald Whisnant dewhisna@xxx.com ------------------------------ From: Brad Anesi Date: Wed, 19 Jun 1996 10:46:06 -0600 Subject: Bosch Motronic Questions Two questions for the collective... 1) I've been told that it is possible to lessen the spring force on the door of the Air Meter by moving the spring back a few notches, which may somewhat lessen the throttle lag issue. I've tried to get to the spring by removing the bottom plate of the meter, but apparently access to the spring is from the top. My question.... How do you get the black plastic top off without destroying it in the process? I'd also be interested in hearing from anybody who has experience with this modification. 2) What blank E/PROM chip do I need to order for the ECU? (I've got access to a chip programmer and wanted to make back-up copies of my current chips). Also, any suggestions on sources? Thanks, Brad (banesi@xxx.com) '86 Porsche 911 Coupe '91 Alfa Romeo 164 ------------------------------ From: tom sparks Date: Wed, 19 Jun 1996 12:18:33 -0500 Subject: Re: Home-grown 5th wheel project--wheel lacings As your sensor gets closer to the hub though the spoke spacings get less regular--that is, the spokes are not spaced exactly 10 degrees apart, half of the intervals will be more than 10 degrees and half will be less. If this won't cause any problems, great, but if it does you may have to lace up the wheels in a radial pattern. This requires shorter spokes and a bit of skill to get right. The 2X, 3X, and 4X patterns are used to transmit torque better and to bear more load. Those are not great concerns here so I'd give radials a go. Besides, a radial pattern just looks slightly more exotic. Better yet, why not use a rear wheel hub with threads for the freewheel already built in. Then you can fabricate a circular plate to mount your magnets that will screw onto to those threads--you can even use off the shelf locking rings to lock it in place. It would be much more secure than trying to get a reliable mount to a 14 gauge spoke. Unless of course you use aero bladed spokes. Or why use magnets at all if you have a stable plate. drill small holes in the plate at regular intervals and use an optical system. Any machine shop that cuts gears should be able to keep the intervals regular. Or, here's another approach: Use an aero disc (flat not lenticular) and mount anything anywhere. You might be able to get a used one for not much money, many cyclists are going to DuPont or Spinergy 3 and 4 spoke style wheels anyway so a nice flat disc could be found on the used market. Best regards, Thomas Sparks At 21:20 6/18/96 -0400, you wrote: >Thanks Bruce, Orin, Dan and Peter for the wonderful input. I'll zip over to the >bicycle shop and get an idea of what the mag pickup looks like. I might be able >to do just as you suggested and mount a small magnet onto every other spoke. >There seem to be approx. 36 spokes on a typical wheel so that would be 18 >positions >which is one every twenty degrees. Based on my initial calculations using >36 spokes >on a 26 inch O.D. tire/rim combo, I would get a 1000 Hz signal at approx. >129 MPH. >Thus, with only 18 spokes, I should get a 500 Hz signal. > >I did a quick check on how much time a .100" thick spoke would break my >light beam >if I was monitoring near the edge of the rim. (20.5" dia.) I found that the >spoke >would obstruct the beam for only 60 microseconds at 129 MPH!! I'd have to >widen that pulse width by either using a 1 shot timer, or by moving the >sensor closer to the >hub. > > The research continues. > > BTW, I like the idea of correlating the data via integration of >the accelerometer data. I'll probably load it all >into MATLAB and crunch it in just that fashion. > >Cheers! > --Dan. > > > > ------------------------------ From: steve.powers@xxx.COM (Steve Powers) Date: Wed, 19 Jun 1996 10:24:57 +0000 (BST) Subject: Re: DIY_EFI Digest V1 #171 Orin asks: > > Have you used an Avocet recently? I used to have one and it didn't work very > well, had Audi battery contacts I think, I had to wedge bits of paper in > there to make sure it didn't lose power. > > Orin. about every other day. I'm currently doing alot of bicycle training. I have used Avocets since they came out and wouldn't use any other. I had a Cateye Solar which was a POS. I think I've got about 4 of the li'l buggers. Most magnets are just one pulse per rev. More pulses require more magnets which brings more mass. Avocet uses a magnetized ring similar to a hall effect encoder magnet. Their ring has 20 pole reversals over its circumference. COnsequently, they are more accurate due to more information for the speed averaging algorithm. The diameter and mass are small. Folks on the BMW list report that they do quite well at speeds over 100. 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: atsakiri@xxx.com Date: Wed, 19 Jun 96 13:45:40 -0400 Subject: Re: Bosch Motronic Questions > 1) I've been told that it is possible to lessen the spring force on the door > of the Air Meter by moving the spring back a few notches, which may > somewhat lessen the throttle lag issue. I've tried to get to the spring by > removing the bottom plate of the meter, but apparently access to the > spring is from the top. My question.... How do you get the black plastic > top off without destroying it in the process? I'd also be interested in > hearing from anybody who has experience with this modification. I thought vane meters worked by correlating the momentum of a stream of air against the rotational position of the vane. Doesn't changing the spring force alter that relationship? Sorry, I can't help on the disassembly question. Anthony Tsakiris - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: Land Shark Date: Wed, 19 Jun 1996 13:21:21 -0600 Subject: Re: Bosch Motronic Questions At 10:46 AM 6/19/96 -0600, you wrote: >1) I've been told that it is possible to lessen the spring force on the door >of the Air Meter by moving the spring back a few notches, which may >somewhat lessen the throttle lag issue. I've tried to get to the spring by >removing the bottom plate of the meter, but apparently access to the >spring is from the top. My question.... How do you get the black plastic >top off without destroying it in the process? I'd also be interested in >hearing from anybody who has experience with this modification. Possible .. yes .. advisable .. NO!! The relationship of air flow to volts out is finely calibrated ... Since your address is novell.com, are you in Provo?? I'm in salt lake city.. >2) What blank E/PROM chip do I need to order for the ECU? (I've got >access to a chip programmer and wanted to make back-up copies of my >current chips). Also, any suggestions on sources? WHat do you want to do with your car .. i have the sourcecode to the Porsche Carrera 1 ... Jim ------------------------------ From: Brad Anesi Date: Wed, 19 Jun 1996 18:06:52 -0600 Subject: Re: Bosch Motronic Questions -Reply Hi Werner- >If you loosen the spring about two notches (about 2% point AFR) it >should help the hesitation if there is any. But if you use a O2 sensor >normal running will not change. Thanks for the reply - so far, you're the only one who has been bold enough *not* to suggest I should committed to an institution for trying to touch anything inside that box! I am using an O2 sensor, so I also believe normal running will be unaffected. My sole objective is to get the "barn door" to open more quickly, enabling the air/fuel mixture to enter the combustion chamber a split-second quicker. BTW, what do you mean by 2% point AFR? Thanks again, Brad ------------------------------ From: Mark Reichert Date: Wed, 19 Jun 1996 21:47:11 -0400 Subject: fuel pickups & filters? This is "just barely" diy-efi related... Can anyone recommend a source for an in-tank fuel pickup suitable for EFI use? I need something that would fit at the end of a 3/8"ID fuel line in the tank. I'd like to find something with a screen on it to keep out the larger pieces of garbage that might somehow find their way into my tank. Similarly, the typical Bosch FI setup has the fuel filter after the pump. Does anyone out there run a "pre-filter" before the pump to protect it? Thanks, Mark Reichert markr@xxx.com ------------------------------ From: Darrell Norquay Date: Wed, 19 Jun 96 19:06 PDT Subject: Re: Anybody build their own 5th wheel? At 02:07 PM 6/17/96 -0400, you wrote: > > The second two are going to come from a 5th wheel that I want >to make from 10 speed bicycle tire. Has anyone had any experience with >making one of these? > > Does anyone have any suggestions or comments on how I can improve >this design? Any suggestions for an LED/Photo-receptor package that is not >influenced by stray light? I think you would be much better off going to a "photo interrupter" type system than a reflective sensor. These are sometimes called "slotted optoswitches" and come in several different flavors. As long as you use infrared emitter/detector pairs, ambient light should not affect it too much, other than possibly direct sunlight. A small "hood" should take care of this. The interrupter style sensor could even be used with the original equipment sprocket and hub, a much more practical arrangement for what you have in mind than either magnetic reed switches or reflective optos. As some people have stated, detecting a spoke at 120+ MPH would be a real challenge, and I don't think a magnetic reed switch will activate that fast either, although a hall effect sensor might work. The bicycle speedo approach may also work, but they are not really rated for those speeds, and you may end up missing pulses. When was the last time you saw a bicycle doing 120 MPH? :] regards dn ------------------------------ From: dzorde@xxx.au Date: Thu, 20 Jun 96 11:14:05 Subject: Re: fuel pickups & filters? You bet ya. I use the standard tank and pick-up running to a 5L surge tank, this uses a standard electric pump with a pre-filter (before pump). The FI pump then runs from the surge tank into the FI filter and on to the engine. I don't think FI pumps like filters before them since they are push type pumps and don't like the restricted inputs. I initially had a standard filter before the FI pump (didn't use a surge tank back then and wanted to protect the pump from crap), and boy oh boy did the FI pump sound like it was working hard, and it got very hot. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: fuel pickups & filters? Author: diy_efi@xxx.edu at INTERNET Date: 6/20/96 10:46 AM This is "just barely" diy-efi related... Can anyone recommend a source for an in-tank fuel pickup suitable for EFI use? I need something that would fit at the end of a 3/8"ID fuel line in the tank. I'd like to find something with a screen on it to keep out the larger pieces of garbage that might somehow find their way into my tank. Similarly, the typical Bosch FI setup has the fuel filter after the pump. Does anyone out there run a "pre-filter" before the pump to protect it? Thanks, Mark Reichert markr@xxx.com ------------------------------ From: dzorde@xxx.au Date: Thu, 20 Jun 96 11:21:10 Subject: Re[2]: Anybody build their own 5th wheel? I know for a fact the bike pick-up works very well at 120mph, as a matter of fact, so does the rest of the bike computer mounted in the race car I run. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: Re: Anybody build their own 5th wheel? Author: diy_efi@xxx.edu at INTERNET Date: 6/20/96 10:58 AM cut As some people have stated, detecting a spoke at 120+ MPH would be a real challenge, and I don't think a magnetic reed switch will activate that fast either, although a hall effect sensor might work. The bicycle speedo approach may also work, but they are not really rated for those speeds, and you may end up missing pulses. When was the last time you saw a bicycle doing 120 MPH? :] regards dn ------------------------------ From: pfenske@xxx.ca (peter paul fenske) Date: Wed, 19 Jun 1996 23:02:05 -0700 Subject: AUX. MEM. PORT Hello to everyone: Am just wondering if anyone besides GM has tried to acess the auxiliary memory port on the 730 ECM. It appears that by pulling one pin low on the test connector , ported memory driven by a PC could be attached. This could allow custom fuel calibrations ect. This is a little bit easier than borrowing very very expensive eprom emulator. Also wondering if anyone played with redundant fuel device.(RFD) Also can someone confirm that the extra two chips in the calpak are resistor networks designed to drive the RFD. I always thought that the software which hooks at 6000 was located here. Well tnx for help GL all: peter ------------------------------ End of DIY_EFI Digest V1 #172 ***************************** 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".