DIY_EFI Digest Tuesday, 27 August 1996 Volume 01 : Number 248 In this issue: Re: Re[2]: real time dyno? Re: Strain gages on the drive shaft for torque measurement Re: speaking of displays & DPM re: Re: Digital EFI How? Newer VATS Vehicles Re: Newer VATS Vehicles Re: Fuel Pump Return line Re: speaking of displays & DPM See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Michael D. Porter" Date: Mon, 26 Aug 1996 20:25:33 -0700 Subject: Re: Re[2]: real time dyno? wmcgonegal@xxx.ca wrote: > > If you can manage to put a strain gage on you drive shaft and get it > calibrated, .... Of > course, constructing and calibrating such a monster is not a trivial > task. Will makes a good point which has plagued me over the years... how does one go about calibrating a home-made dyno? To some degree, a strain-gauge sensor has some attraction, since its resistance change with strain is a known quantity, but one must still be able to equate that strain to torque, which depends on the mechanism and the position of the strain gauge. And while there may effective ways to absorb power by other means, the measurement of the absorbed power still seems devilish. Any ideas on means, or does anyone have knowledge of how the commercial dyno manufacturers do calibration? Cheers. - -- My other Triumph doesn't run, either.... ------------------------------ From: Darrell Norquay Date: Mon, 26 Aug 1996 19:57:27 -0700 (PDT) Subject: Re: Strain gages on the drive shaft for torque measurement At 12:38 PM 8/26/96 EST, Will McGonegal wrote: >At out facility we have several torque measuring devices. To get the >excitation voltage to the rotating strain gage and the signal back to >the signal conditioner, a non-contact rotary transformer is used. One >set of coils rotates near a stationary set. Excitation voltage is fed >through one set of coils and the signal voltage is fed back through >another set. The excitation voltage is an AC signal (3kHz). The >signal coming back to the signal conditioner is also AC with an >amplitude proportional to the torque. > >There are a few chassis dynamometers at our lab that have in-line >torque transducers that use this type of set up to measure torque. >The transducer is mounted between the dynamometer power absorption >unit and the rest of the dynamometer. There is also a car, here, >equipped with "torque wheels" that uses rotary transformers to get the >signals to and from the strain gages. Instead of having the strain >gage on the drive shaft, this car has an adapter plate that bolts >between the hub and the tire (one for each of the drive wheels). The >plates have the appropriate strain gages so that torque can be >measured. Gee Whiz Will, can we come over and play at your place? ;) regards dn dnorquay@xxx.com ------------------------------ From: Darrell Norquay Date: Mon, 26 Aug 1996 19:57:29 -0700 (PDT) Subject: Re: speaking of displays & DPM At 10:55 AM 8/26/96 -0600, you wrote: >>At 08:23 AM 8/26/96 -0500, you wrote: >>>>LCD displays also don't work very well when they are hot. All the crystals >>>>polarize. There are a number of LCD video projectors and they have to be >>>>chock full of fans to keep the LCD cool enough to remain useful. >>>> >>> >>>No, LCD displays don't work well when they're cold. The temp extremes >>>inside a car is fine for LCD -- except very cold days. >>> >>>tom cloud Older LCD panels were easily destroyed by temps in the +40C range. Newer technologies are better, but they still suffer from "freezup" when the temp goes below zero. You can get extended temp range LCD's, but generally they are optimized either for high temp extremes or low temp extremes, but not both. Lowest operating temp I have seen on a LCD panel is -20C. Ever wonder why auto manufacturers don't used LCD's in the dash? Now you know. regards dn dnorquay@xxx.com ------------------------------ From: Darrell Norquay Date: Mon, 26 Aug 1996 19:57:25 -0700 (PDT) Subject: re: Re: Digital EFI How? At 10:24 AM 8/26/96 CDT, Steve Ravet wrote: >| specifically designed for it. Might be something to look into. Neural >| networks would be a bit overkill, though, IMHO. >Why? Once you train it to run the engine, you could then train it to drive >the car for you. It'd get great repeatable 1/4 mile times, and would >probably be great on the road course also. Yeah, all you need is a few Intel Hexium Processors, a Gig of RAM, and a terabyte hard disk or two... regards dn dnorquay@xxx.com ------------------------------ From: john spears Date: Mon, 26 Aug 96 22:42 EST Subject: Newer VATS Vehicles More and more GM vehicles are using VATS. The newer units are still a separate module, but the frequency is now 50 Hz. It can still be defeated by either using the original module with the key resistance just soldered in with a fixed resistor, making a VATS module with a 555 timer, or changing the bit in the EPROM from VATS to NO VATS. John Spears Speartech F. I. Systems ------------------------------ From: peter paul fenske Date: Mon, 26 Aug 1996 22:16:17 -0700 Subject: Re: Newer VATS Vehicles At 10:42 PM 8/26/96 EST, you wrote: >More and more GM vehicles are using VATS. The newer units are still a >separate module, but the frequency is now 50 Hz. It can still be defeated by >either using the original module with the key resistance just soldered in >with a fixed resistor, making a VATS module with a 555 timer, or changing >the bit in the EPROM from VATS to NO VATS. > > > John Spears > Speartech F. I. Systems Hi all The above is true for all GM vehicles except!!! new vettes. In this beast the CCM does a measure of the key resistance and then this info is sent to the ECM via common serial data line. FYI info the key resistance is in fifteen values ranging from 394 to 12,036 ohms. This translate to codes between 0 - 255 in the ECM Mind you normal people with F bodies don't have to worry. Just the unfortunates trying to tangle with vettes. Also simply disabling the VATS bit in the eprom doesn't always work. You also have to disable the error code mask if you don't want a Vats error. GL : peter ------------------------------ From: "Robert J. Harris" Date: Tue, 27 Aug 1996 00:10:18 -0700 Subject: Re: Fuel Pump Return line Remember the Reichstag - ---------- Fuel Line return - ancient history Hilborn type mechanical fuel injection had solution 30 years ago Used a small (1 to 2 gallon) holding tank mounted higher than mechanical pump (made it self priming). Return fuel went to holding tank (may be referred to as make up tank also). Fuel was fed by electric pump from main tank to holding tank. Used modified holly 4 barrel float bowl to regulate level of fuel in make up tank. Same Idea would work very well. Make-up fuel = fuel actually used by engine. Could use off shelf carborated engine after market fuel economy measuring system. 1 to 2 gallons (like original) avoids problems of directly returning to pump. Works on engines up to 3000+ hp so can't be all bad. Now if anybody knows about where I can get pulsed injectors that will work with liquid propane? ------------------------------ From: Kalle Pihlajasaari Date: Tue, 27 Aug 1996 01:58:53 +0200 (sat) Subject: Re: speaking of displays & DPM Hi, > >Maybe I have an odd LCD pannel (2x20, I doubt it). Mine turns black when the > >car warms up in the sun. > > Don't know -- only know what specs I am familiar with -- maybe something > new ?? Don't think so, but maybe. LCD specs (that I read umpteen years > ago) say they don't work as well in the cold, get sluggish and go blank. I was led to believe that the most sensitivity to temperature until the very extremes was in changes to the bias/contrast voltage requited. There are various automatic and software methods in use that measure the temperature and change the contrast voltage to keep the display in a useable mode for most of the temperature limits. At the extremes of temperature the display will go either blank or dark depending on the failure mode (which I don't know) but is reversible until the liquid freezes or boils I think. Using a thermistor to check temp and then using a single pin to generate a dutycycle PWM output for the voltages is a practical solution if the operator cannot be trusted with tweaking a knob. Cheers - -- Kalle Pihlajasaari kalle@xxx.za Interface Products Box 15775, Doornfontein, 2028, South Africa +27 (11) 402-7750 Fax: +27 (11) 402-7751 ------------------------------ End of DIY_EFI Digest V1 #248 ***************************** 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".