DIY_EFI Digest Tuesday, 27 August 1996 Volume 01 : Number 247 In this issue: Re: DIY_EFI Digest V1 #246 Re: real time dyno? Re: speaking of displays & DPM Re: Strain gages on the drive shaft for torque measurement Re: speaking of displays & DPM re: Re: Digital EFI How? Parts buy Re: Strain gages on the drive shaft for torque measurement Re: speaking of displays & DPM Re: Slide Throttles Re: Slide Throttles Re: DIY_EFI Digest V1 #241 Re: speaking of displays & DPM Re: real time dyno? Re: EFI Conv. Re: speaking of displays & DPM Fuel Pump Return line Dyno's and way's to rid HP Fuel Pump Return line Re: Fuel Pump Return line Re: real time dyno? Re[2]: real time dyno? Re: Fuel Pump Return line Re: Strain gages on the drive shaft for torque measurement Looking for more EFI details.... Re[2]: speaking of displays & DPM Re: EFI Conv. Re: Fuel Pump Return line Re: Fuel Pump Return line See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: talltom Date: Mon, 26 Aug 1996 04:22:10 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #246 - ----------------------------- > >From: "John Faubion" >Date: Sun, 25 Aug 1996 10:43:03 -0500 >Subject: Re: EFI musings > >> -> Well Dave with some prudent shopping you could have done it cheaper >> -> too. I picked up a GM #730 ECM, harness and most of the sensors from >> ... >> -> especially if you can adapt factory parts. Ford and GM already spent >> -> the money to make them reliable, why not use them? >> >> What do you intend to do about reprogramming the ECM? >> > >Actually very little. The programming for the '90-'92 F-bodies is a speed >density system. By sizing the injectors correctly you can adjust for the >size difference between the engines. For example, the factory 5.7L used a >Lucas #5207011 injector that flows 20.73 lb./hr at 44 psi of fuel pressure. >My 427 is 427/350 = 1.22 or 22% larger. If I maintain the same RPM range of >idle-5000 RPM that the factory used, then I would need to use an injector >that flows 22% more fuel to maintain the same injector pulse width. So my >injectors need to be 20.73 x 1.22 = 25.29 lb./hr. in this case I could use >the injectors from a Nissan 300ZX (Lucas #5206004) and adjust the fuel >pressure. These flow 24.73 lb./hr at 37psi. To get 25.29 lb./hr I need to >use 25.29/24.73 = 1.02 x 37 = 37.84 psi of fuel pressure. By sizing the >injectors this way and maintaining the same injector pulse width, the ECM >fuel maps should be close. With the learning ability built into this ECM, >it should be able to compensate for the small variances. > >If you are using a V8 that had the same type injection you want to use, >(i.e. your going to TPI and running a 350 small block) then your >programming is easy. Even if you have modified the engine with aftermarket >pieces such as a cam, headers, better heads etc., just contact someone that >already programs PROMs for these. Get information from them about their >chips on a version that would be close to what you have already built. If >like me you are building something the factory never even considered like >port EFI on a 427 big block, this could still be an option. You only need a >chip that will support the gear ratios, rear axle ratio, approximent >weight, type of injection (TPI, MPI, TBI) and most importantly RPM range. >Since I will probably not maintain the same RPM range (my 427 is built for >1500-6500 RPM) I would need a stage 3 or 4 chip from Hypertech. This will >also require an increase in the size of my injectors to support the >horsepower level of this engine. Even if I buy an aftermarket chip, I'll >still be under $400 for my total project. > >The factory systems are much easier to adapt than to build your own >controller. I like to idea of building my own but I just don't have the >money to sink into the project. I'm also trying to decode the factory ROM >as well. I have access to the hardware to do this but as I'm sure everyone >knows, this is not a simple undertaking. Until then though, there are >several options open. > >John Faubion >jfaubion@xxx.net > Well that's all fine but what does this system do when MP>29.9"? You all can say I'm halucinating, but I say something that looks like it would really have some potential. It was an electro-mechanical gadget that sensed MAP and regulated fuel supply pressure as a derivative of MAP. Now if we could come up with a good o2 sensor reasonable this thing could provide enrichment as a function of MAP and o2 sensor that would allow one to use stock injectors on artificially insemenated engs.(oops, I meant aspirated.) Seemed cheap, easy, programable, and most importantly universal. With this the programing of the ecu wouldn't play much of a role, would have the limp mode, and be monopoly proof! ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 08:04:31 -0500 Subject: Re: real time dyno? > >All this dyno talk has me wondering.... > >The strain gauge on the driveshaft sure seems like a interesting way >to measure torque (at least relative) in real time, although wiring >problems would seem to preclude it. .......... but how/where to get the torque reading? The motor mount >suggestion sounds feasible, anyone care to elaborate? Can anyone see >any fatal flaws in the concept? >Mike Fahrion mfahrion@xxx.com/ Mike, I've thought about this off and on for a long time. Still think, for most, acceleration is what you want to know. But, compression / expansion of motor mounts results from torque and hp from torque over time. To work best, one would have to machine some mounts. Typical load cells are "S" shaped with a pair of strain gages to detect their combination elongation / narrowing. Could put load cell / motor mount on both sides of engine and "add" the outputs to get greater voltage with engine twisting (torque). I would think the error from the transmission mount would be reasonable constant and could be factored out. How would it be calibrated??? tom cloud ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 08:23:48 -0500 Subject: Re: speaking of displays & DPM >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 ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 08:45:19 -0500 Subject: Re: Strain gages on the drive shaft for torque measurement >In regards to the message about placing strain gages on the drive shaft: > >Don't just rule out slip rings by saying they are "complicated". Most >modern slip rings use brushes on gold contacts, where the contacts >are mounted on a spindle of only a quarter inch diameter. The angular >velocity is therefore very low. Hence, brush noise is minimal. > --Daniel Burk Gad, consider a practical application: the slop (sic) ring would have to be mounted to both the rotating, bouncing shaft and the chassis. Imagine the mechanism required to do that alone. Plus, you'd have to figure out how to keep dirt, water, grease, etc out of the rings, not counting the cost of making them and getting an unbroken ring pressed onto shaft (else would wear the brush or generate noise). Sounds okay for the lab -- not very practical for the road. tom cloud ------------------------------ From: Fred Miranda Date: Mon, 26 Aug 1996 08:32:07 -0700 Subject: Re: speaking of displays & DPM Maybe I have an odd LCD pannel (2x20, I doubt it). Mine turns black when the car warms up in the sun. 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 > > > ------------------------------ From: SRavet@xxx.com Date: Mon, 26 Aug 96 10:24:05 CDT Subject: re: Re: Digital EFI How? Darrell Norquay Wrote: | | At 08:38 PM 8/22/96 +0100, Jonathan Lloyd wrote: | | >reading some detail recently about neural networks implemented on some | >fairly complex tasks on some pretty ordinary hardware. I like the idea | >of a system which is programmed to do no more than "learn how to make | >the car run best and then do it". Presumably with the correct | >parameters for definition of "best" one could rely on the system to be | >self correcting to the extent that a "limp home" was inbuilt and ageing | >taken care of. | | Seems to me engine controllers would be a prime candidate for fuzzy logic | controllers. Especially the EGO system. There are fuzzy logic tools | available for most microcontrollers these days, along with some controllers | 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. :-) :-) - --steve | | | regards | dn | dnorquay@xxx.com | | Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: Wayne Braun Date: Mon, 26 Aug 1996 10:27:02 -0600 Subject: Parts buy I received my parts over the weekend ( picture a silly person with a REALLY foolish grin jumping up and down ). I guess I now have no excuse ( well maybe a significantly less number of excuses ) for not getting on with trying to get the hardware up and running. Thanks Mike, your efforts are very much appreciated. Regards Wayne Braun ------------------------------ From: wmcgonegal@xxx.ca Date: Mon, 26 Aug 96 12:38:04 EST Subject: Re: Strain gages on the drive shaft for torque measurement >There exist slip ring assemblies that allow one to gage up a drive >shaft. 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. Will McGonegal Electrical Engineer Mobile Sources Emissions Division Environment Canada wmcgonegal@xxx.ca ------------------------------ From: Corey Stup Date: Mon, 26 Aug 1996 12:46:12 -0400 Subject: Re: speaking of displays & DPM Fred Miranda wrote: > > Maybe I have an odd LCD pannel (2x20, I doubt it). Mine turns black when the > car warms up in the sun. Sounds more like the components used for adjusting contrast are changing values due to the heat... ------------------------------ From: Todd Knighton Date: Mon, 26 Aug 1996 09:32:07 -0700 Subject: Re: Slide Throttles tom cloud wrote: > Okay, Todd: > 1 - I didn't yell at you about Radio Shack, sorry you felt like > I did. I buy 'stuff' there too, just thought the newbie > ought to be forewarned. No Problem, I wouldn't have suggested it had I not done it already. > > 2 - What do you call the little round, tubular slides that were > in my Triumph and Honda motorcycles ?? They're constant venturi type carbs. They actually use a typical butterfly as a throttle plate with these tubular sliding things to maintain a very high velocity. As well as the movement of the sliding part is attached to a tapered needle and seat arrangement that regulates the fuel flow. They actually work very well, and are probably one of the best carburetors I've ever seen. Todd Knighton Protomotive Engineering ------------------------------ From: Todd Knighton Date: Mon, 26 Aug 1996 09:38:44 -0700 Subject: Re: Slide Throttles SRavet@xxx.com wrote: > > Todd Knighton Wrote: > | > | SRavet@xxx.com wrote: > | > | > OK, what is a slide throttle? I thought it was simply a "cover" that > | > slides over a "hole". But that wouldn't tend to stick closed. so what > is > | > it? > | > > | > | It is just a plate over a hole, but try this. Put a ruler on the > | ground and move it around, easy right. now have someone stand on it, a > | little more difficult. Same idea, because of the great pressure > | differential caused by turbo motors and supercharged motors on surge, > | the plates have an enormous amount of pressure placed on them. They > | tend to deflect and stick in the tracks because the tracks are precision > | machined for a good seal and no rattle in the vertical direction. Apply > | a bit of curvature in a linear track, uhnt wallah, we have schticking. > > Doesn't the wastegate vent that pressure? > A wastegate vents the pressure from the exhaust system to decrease the energy potential of the exhaust entering the turbine. The turbocharger however maintains quite a bit of momentum / intertia due to it's 130,000 rpm's and mass and does not slow instantaneously upon throttle closure. Thus, you get surge. The throttle closes, the air flow continues from the turbocharger to the point where the pressure overcomes the flow and the flow then reverses through the compressor, being that it's not a positive displacement blower like a roots type blower. And depending on the application, you'll see from 25 to 100 psi in the intake before flow reversal occurs. That's hard to deal with. A blow off valve decreases the problem, but loses pressure in the intake and creates turbo lag between shifts. Cure one problem, create another. > Next, what is a barrel throttle? > Some one earlier described it well. Take a tube a lay it across your port. Put another tube inside it, but make this one solid. Punch a hole through both tubes. Now when you rotate the inside tube you can open and close the port. Todd Knighton Protomotive Engineering ------------------------------ From: Todd Knighton Date: Mon, 26 Aug 1996 09:44:53 -0700 Subject: Re: DIY_EFI Digest V1 #241 Robert Van Zant wrote: > > >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. We use a waterbrake type dyno to work with 600-700 hp turbocharged engines. Typically, for break in and light throttle calibrations, we run the water in an closed configuration.. We have a 500gallon water tank out side that feeds the pump and brake, then recirculates through a radiator to the tank. When power testing short runs can be done in this recirculating method, but power testing engines at this level, not much beyond 30 sec. to 1 minute are done. So cooling still is not a problem. For extended runs, the system is open and the tank just drains, albeit very rapidly at 75 gallons / min to dissapate this kind of power. Then refilled with cool water. The water output from the dyno is regulated to be under 140-160 deg F, if it is getting too hot, we open the output orifice and flow more water with less pressure for the same power level and cool the brake better. Todd Knighton Protomotive Engineering ------------------------------ From: Wayne Braun Date: Mon, 26 Aug 1996 10:55:49 -0600 Subject: Re: speaking of displays & DPM At 08:32 AM 8/26/96 -0700, you wrote: >Maybe I have an odd LCD pannel (2x20, I doubt it). Mine turns black when the >car warms up in the sun. I don't know if the new, fancy, latest technology displays do this but this is typical of some of the standard alpha-numeric displays. In a previous life, I worked at a company that used LCD displays. The first time that the guys ran into this it caused quite a bit of consternation. They were calibrating an instrument outside during the summer and it was about +30C. They thought that they had destroyed the unit. As it turned out, all that was needed was to let things cool down and the everything was fine. > >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 I guess this would depend on where you are. If you are in a place like England where you typically don't see extreme temperatures then you could be OK. Here on the other hand we see temperatures ranging from +40c in the summer down to -50c in winter. We don't always see these extremes ( except for last winter ) but you do need to account for them. Unheated LCD's tend to get a little slow at -40. For general testing purposes, you will likely run into very few problems but if you are going to permanently mount this you should look for one that is designed for use in this environment. Regards Wayne Braun ------------------------------ From: Todd Knighton Date: Mon, 26 Aug 1996 09:50:07 -0700 Subject: Re: real time dyno? > > > The strain gauge on the driveshaft sure seems like a interesting way > > to measure torque (at least relative) in real time, although wiring > > problems would seem to preclude it. My meager mind has trouble > > comprehending accomplishing the resolution necessary with hall > > effect sensors. > All this stuff about real time dyno's seems to have a problem. You're not taking into account the fact that you are accelerating the car and not steady state. You're torque will always be low unless you calc in all your masses and wind resistance and frictions and try to calc out the lost torque. As well as try to get a repeatable condition. Up hill, down hill, up wind, down wind, etc. etc. etc. We used to try to calibrate cars on the road, what a disaster, you're always nervous about the law, as well as ons and off's and people jumping across the road at you. Almost been killed way too many times by women in vanagons putting on lipstick at 80 mph going down the highway not paying attention. No thanks! Give me my engine dyno back. I can sit in safety in my little room and calibrate to my hearts content. No worries at all. Todd Knighton Protomotive Engineering. ------------------------------ From: Todd Knighton Date: Mon, 26 Aug 1996 09:53:44 -0700 Subject: Re: EFI Conv. > >From what I understand, the ECM designed for the peak and hold type can use > the saturated injectors with out problems but not vice versa. However from > the looks of it should be a simple process to design a board to use a peak > and hold injector driver to take the signal from the ECM and fire the > injectors. This way we won't hurt the ECM and you could use either injector > type. > Yeah, we've had to do that. Good injectors beyond 36#/hr arent available in 15 ohm. As well as at high pressure (above 5 bar) they stick close because of the limited driver type. They're slower, not repeatable, etc etc etc. We had to make drivers that would invert the output of the computer, then drive a typical peak and hold circuit. The trick was, on late model OBD I and II cars, they look for faulty injectors, so you need to place a load resistor on the output. Not much, but just enough that the computer still thinks theres an injector out there. Otherwise the drivers work great. Todd Knighton Protomotive Engineering ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 14:33:10 -0500 Subject: Re: speaking of displays & DPM >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 have experienced the problem you speak of -- think it must be an artifact of type of LCD or manufacture process ?? But that seems to only be isolated to certain displays. I use LCD's in my car with no problem -- not even in 'cold' (except when in mountains in N.M. when it got into the teens -- then they went blank). ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 14:52:27 -0500 Subject: Fuel Pump Return line >Matthew Lamari wrote: > >I was just thinking of your idea (quite good) for the return line to a pump >going to the back of the pump (thus saving further butchery of the fuel tank >area.) > >I was wondering, though, that, in the flow circuit, it is possible for the >pump to end up pulling fuel through the regulator. I guess this would >depend on the flow resistance between the fork and the tank, and the pump >and the return fork. > >Since it was your idea (don't want to take credit) I was wondering if you >could mention it to the group and see if anyone has tried it or shoots it >down for some reason. > >It sounds like a cool way to add such a thing; but I was wondering if it had >any hazards I should know about. > >thanks, >Matthew. > Okay, here goes: On the Holley EFI system (Matt, you could call Holley tech. support at 502-781-9741 about this), a return petrol line is required from the pressure reg which is located at the TBI. The fuel pump runs continuously with the excess fed back to the tank. I understand some other systems do this as well. Matt wanted to avoid installing a return line (I put mine into the filler neck). I suggested perhaps putting a tee into the pump intake and feeding back to there. Then, if no fuel being used by car, the fuel would circulate in loop from pump to TBI back to pump. Only fuel drawn from tank would be actual amount used. The way the return line system works, the fuel is constantly circulated through the tank, its filter sock, and whatever other filters are in line. Any comments? Any reason why this wouldn't work? tom cloud ------------------------------ From: Sandy Date: Mon, 26 Aug 1996 13:06:38 -0700 Subject: Dyno's and way's to rid HP No one as yet has mentioned a plentiful souce for getting rid of LOTS of HP. I would guess that they can be had for not much $$. The old Berkley Jet that was the HP succker for many boats. They are really simple, and take all the hp that you can make (and then some). All you have to do is figure out what to do with all the water, and some way to control the load. Sandy ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 15:13:29 -0500 Subject: Fuel Pump Return line >Matthew Lamari wrote: > >I was just thinking of your idea (quite good) for the return line to a pump >going to the back of the pump (thus saving further butchery of the fuel tank >area.) > >I was wondering, though, that, in the flow circuit, it is possible for the >pump to end up pulling fuel through the regulator. I guess this would >depend on the flow resistance between the fork and the tank, and the pump >and the return fork. > >Since it was your idea (don't want to take credit) I was wondering if you >could mention it to the group and see if anyone has tried it or shoots it >down for some reason. > >It sounds like a cool way to add such a thing; but I was wondering if it had >any hazards I should know about. > >thanks, >Matthew. > Okay, here goes: On the Holley EFI system (Matt, you could call Holley tech. support at 502-781-9741 about this), a return petrol line is required from the pressure reg which is located at the TBI. The fuel pump runs continuously with the excess fed back to the tank. I understand some other systems do this as well. Matt wanted to avoid installing a return line (I put mine into the filler neck). I suggested perhaps putting a tee into the pump intake and feeding back to there. Then, if no fuel being used by car, the fuel would circulate in loop from pump to TBI back to pump. Only fuel drawn from tank would be actual amount used. The way the return line system works, the fuel is constantly circulated through the tank, its filter sock, and whatever other filters are in line. Any comments? Any reason why this wouldn't work? tom cloud ------------------------------ From: MSargent@xxx. Sargent) Date: Mon, 26 Aug 1996 16:42:40 -0400 Subject: Re: Fuel Pump Return line > The way the return line > system works, the fuel is constantly circulated through the tank, > its filter sock, and whatever other filters are in line. One reason use the fuel tank recurculation method is that it keeps the fuel cool. If you continually circulate a small quantity of fuel through the pump, it will heat up quickly. Perfromance problems will occur if you're lucky, and a fuel fire will occur if you're damned. +--------------------------------------------------------------------------+ | Michael F. Sargent | Net: msargent@xxx.com | Phone: 1(613)721-0902 | | Gallium Software Inc.| | FAX: 1(613)721-1278 | +--------------------------------------------------------------------------+ ------------------------------ From: "Mike Fahrion" Date: Mon, 26 Aug 1996 16:09:48 +0000 Subject: Re: real time dyno? > All this stuff about real time dyno's seems to have a problem. > You're not taking into account the fact that you are accelerating the > car and not steady state. You're torque will always be low unless you > calc in all your masses and wind resistance and frictions and try to > calc out the lost torque. True - but for me this is what peaks my interest (obviously not a performance vehicle). Numbers like torque required to maintain cruising speeds, effects of trailers, cargo and such. More of an efficiency thing. Some of the (very interesting) ideas on sensors for this application sound very worth trying, but I'm wondering about their linearity/accuracy at lower levels (say 10bhp cruising?) - -mike mfahrion@xxx.com ------------------------------ From: wmcgonegal@xxx.ca Date: Mon, 26 Aug 96 17:54:04 EST Subject: Re[2]: real time dyno? >> > The strain gauge on the driveshaft sure seems like a interesting >> >way >You're torque will always be low unless you calc in all your masses >and wind resistance and frictions and try to calc out the lost >torque. >As well as try to get a repeatable condition. Up hill, down hill, up >wind, down wind, etc. etc. etc. If you can manage to put a strain gage on you drive shaft and get it calibrated, you do not need to consider wind resistance, tire losses etc., if you are only concerned with power output from the transmission. This value should not be much less then engine power output on a vehicle equipped with a standard transmission. You will always be able to read the power being transmitted to the axle uphill, downhill, accelerating, steady state on windy or calm days. Of course, constructing and calibrating such a monster is not a trivial task. To measure acceleration is much easier, but then you must consider all the above mentioned power losses to get the actual engine power. Most of the aerodynamic and friction losses can be determined by coasting in neutral and measuring deceleration. Occasionally we have to do this type of coast down measurement when setting up vehicle road load for emissions testing on the chassis dynamometers. It may take a while to find that perfect, straight, flat, secluded stretch of pavement to do acceleration/power measurements. But maybe you just want to know if you can accelerate faster down the same stretch of road after a slight modification under similar weather conditions after installing a new performance part. Sure better then the seatofthepantsometer. Will McGonegal Electrical Engineer Mobile Sources Emissions Division Environment Canada wmcgonegal@xxx.ca ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 26 Aug 1996 16:49:03 -0500 Subject: Re: Fuel Pump Return line I suggested perhaps putting a tee into the pump intake >and feeding back to there. Then, if no fuel being used by car, >the fuel would circulate in loop from pump to TBI back to pump. Only >fuel drawn from tank would be actual amount used. The way the return line >system works, the fuel is constantly circulated through the tank, >its filter sock, and whatever other filters are in line. > >Any comments? Any reason why this wouldn't work? > >tom cloud > This is dumb -- I'm responding to my own post! It has struck me that there might be a recirculating air problem -- air bubbles would be purged if recirculated back into tank, but not if recirculated around to the pump inlet ? tom ------------------------------ From: Thor Johnson Date: Mon, 26 Aug 1996 18:43:27 -0400 (EDT) Subject: Re: Strain gages on the drive shaft for torque measurement How does this strike you: Use a flexible coupling (or possibly a small shaft that can stand the torsion/power), and mount a disc (with a slit) at each end so that they are in-line with each other at rest. Mount some optical sensors (that will detect the slit) on a stationary (relative to the shaft) beam. Your torque should be related to the time difference of the signals from the slits. Bear in mind these are the ramblings of an EE type with little/no mechanical expertise... FWIW. Thor Johnson johnsont@xxx.edu http://falcon.mercer.peachnet.edu/~johnsont Have you seen the WarpMap lately? http://falcon.mercer.peachnet.edu/~johnsont/warpmap ------------------------------ From: Thor Johnson Date: Mon, 26 Aug 1996 18:55:37 -0400 (EDT) Subject: Looking for more EFI details.... Hi all! I've been conscripted into designing/building/modifying an EFI system for our Formula SAE car. Unfortunately, I know little about the combustion process and even less about EFI/O2 sensors. I've looked at the DIY EFI homepage, and a couple references on O2 sensors, but want to know more (especially using the tried and true technique of borrowing/modifying another design). TIA! Thor Johnson johnsont@xxx.edu http://falcon.mercer.peachnet.edu/~johnsont Have you seen the WarpMap lately? http://falcon.mercer.peachnet.edu/~johnsont/warpmap ------------------------------ From: dzorde@xxx.au Date: Tue, 27 Aug 96 08:33:07 Subject: Re[2]: speaking of displays & DPM You'll find that as LCD's heat up you need to reduce the contrast voltage (and it's not linear either). Once you actually hit about 65?C the LCD will turn blue due to the heating of the crystals. The easiest way to overcome any problems is to keep the LCD out of direct sunlight and use a display with external contrast adjustment, set up a compensation curve in the CPU and drive the contrast through a digital pot and an opamp circuit. Dan dzorde@xxx.au ______________________________ Reply Separator _________________________________ Subject: Re: speaking of displays & DPM Author: diy_efi@xxx.edu at INTERNET Date: 8/27/96 6:37 AM >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 have experienced the problem you speak of -- think it must be an artifact of type of LCD or manufacture process ?? But that seems to only be isolated to certain displays. I use LCD's in my car with no problem -- not even in 'cold' (except when in mountains in N.M. when it got into the teens -- then they went blank). ------------------------------ From: "George M. Dailey" Date: Mon, 26 Aug 1996 19:33:00 -0500 Subject: Re: EFI Conv. At 12:22 PM 8/25/96 -0500, you wrote: Blah blah blah >> Oh and tnx for VATS info. Changed a bit in code to defeat Vats in my >> 730 project. Have confirmed data on timing, idle parms, and fan control. > >And you didn't send me any info on it?? If you don't mind I'd like to >get the info. > >John Faubion >jfaubion@xxx.net > Here is a copy of what was sent to the group. The CIA must have intercepted your copy.:) At 09:11 AM 6/11/96 -0700, you wrote: (snip) A description of the (VATS) system is in order. >>First off gm has a resistor embedded in their keys. TRUE This can >>have one of 15 resistance values. When five volts is >>applied to that resistor one of fifteen voltage values results I beg to differ my good man. While installing the '89 350 TPI into my '58, I had to crack the VATS enigma. What I found out was that the resistor in the key provided a voltage to the VATS module. The VATS module would then send about a 30hz signal to the ecm to say "a-okay". The ecm would then allow the injectors to fire. I built my VATs defeater from a 555 timer. Configured it to go +5v to groung. The ECM will provide the +5v, you just need to ground it at about 30hz. >>The older ones >>used a separate VATS module which makes life easier. No info on the newer units. I was told they use a 40hz signal with a module. Good luck, and keep us informed. GMD ------------------------------ From: john carroll Date: Mon, 26 Aug 1996 18:02:08 -0600 Subject: Re: Fuel Pump Return line Dumping the bypassed fuel back into the inlet side of the pump is a bad deal. The sudden depresurization and turbulance encourages the lighter fractions to bubble out of solution. After a few passes through the regulator and engine compartment the fuel warms up, compounding the problem. A friend did this despite being warnined. He is alive, his airplane is bent. Put it back into the tank. john carroll jac@xxx.us At 03:13 PM 8/26/96 -0500, you wrote: >>Matthew Lamari wrote: >> >>I was just thinking of your idea (quite good) for the return line to a pump >>going to the back of the pump (thus saving further butchery of the fuel tank >>area.) >> >>I was wondering, though, that, in the flow circuit, it is possible for the >>pump to end up pulling fuel through the regulator. I guess this would >>depend on the flow resistance between the fork and the tank, and the pump >>and the return fork. >> >>Since it was your idea (don't want to take credit) I was wondering if you >>could mention it to the group and see if anyone has tried it or shoots it >>down for some reason. >> >>It sounds like a cool way to add such a thing; but I was wondering if it had >>any hazards I should know about. >> >>thanks, >>Matthew. >> > >Okay, here goes: > >On the Holley EFI system (Matt, you could call Holley tech. support >at 502-781-9741 about this), a return petrol line is required from >the pressure reg which is located at the TBI. The fuel pump runs >continuously with the excess fed back to the tank. I understand >some other systems do this as well. > >Matt wanted to avoid installing a return line (I put mine into the >filler neck). I suggested perhaps putting a tee into the pump intake >and feeding back to there. Then, if no fuel being used by car, >the fuel would circulate in loop from pump to TBI back to pump. Only >fuel drawn from tank would be actual amount used. The way the return line >system works, the fuel is constantly circulated through the tank, >its filter sock, and whatever other filters are in line. > >Any comments? Any reason why this wouldn't work? > >tom cloud > > john carroll jac@xxx.us ------------------------------ From: Mark Eidson Date: Mon, 26 Aug 1996 18:11:03 -0700 Subject: Re: Fuel Pump Return line It should work but you won't save much since the recommended pump location is back at the gas tank. I'm in the process of installing a Holley 4DI system and added a return line next to the source line just to be sure. me At 03:13 PM 8/26/96 -0500, you wrote: >>Matthew Lamari wrote: >> >>I was just thinking of your idea (quite good) for the return line to a pump >>going to the back of the pump (thus saving further butchery of the fuel tank >>area.) >> >>I was wondering, though, that, in the flow circuit, it is possible for the >>pump to end up pulling fuel through the regulator. I guess this would >>depend on the flow resistance between the fork and the tank, and the pump >>and the return fork. >> >>Since it was your idea (don't want to take credit) I was wondering if you >>could mention it to the group and see if anyone has tried it or shoots it >>down for some reason. >> >>It sounds like a cool way to add such a thing; but I was wondering if it had >>any hazards I should know about. >> >>thanks, >>Matthew. >> > >Okay, here goes: > >On the Holley EFI system (Matt, you could call Holley tech. support >at 502-781-9741 about this), a return petrol line is required from >the pressure reg which is located at the TBI. The fuel pump runs >continuously with the excess fed back to the tank. I understand >some other systems do this as well. > >Matt wanted to avoid installing a return line (I put mine into the >filler neck). I suggested perhaps putting a tee into the pump intake >and feeding back to there. Then, if no fuel being used by car, >the fuel would circulate in loop from pump to TBI back to pump. Only >fuel drawn from tank would be actual amount used. The way the return line >system works, the fuel is constantly circulated through the tank, >its filter sock, and whatever other filters are in line. > >Any comments? Any reason why this wouldn't work? > >tom cloud > > > *************************************************************************** * Mark Eidson Voice: (602)752-6513 * * Staff Design Engineer Fax: (602)752-6000 * * Manager System Integration and * * Verification E-Mail: mark.eidson@xxx.com * * VLSI Technology, Inc. * * 8375 South River Parkway * * M/S 265 * * Tempe, Arizona 85284 * *************************************************************************** ------------------------------ End of DIY_EFI Digest V1 #247 ***************************** 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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