DIY_EFI Digest Wednesday, 28 August 1996 Volume 01 : Number 249 In this issue: Re Propane injectors Re: Real time dyno RE:re:newer VATS vehicles Re: Re[2]: real time dyno? Re: Newer VATS Vehicles Re: Real time dyno Re: Re[2]: real time dyno? Re: Re[2]: real time dyno? DIY_EFI Digest V1 #248 -Reply Re: Re[2]: real time dyno? Re: Real time dyno Re: DIY_EFI Digest V1 #248 -Reply Re: Re[2]: real time dyno? Re: Data Logging Re: My DIY EFI Re: DIY_EFI Digest V1 #248 -Reply real time dyno Strain gage based dyno numbers Calibration of commercial dyno load cells Re: Driveshaft slip rings Re: Fuel Pump Return line Re: Re[2]: real time dyno? Re: Newer VATS Vehicles Re: DIY_EFI Digest V1 #248 -Reply Re: Newer VATS Vehicles Re: Re[2]: real time dyno? Re: Newer VATS Vehicles real time dyno switching between EPROMS Re: Fuel Pump Return line AND fuel line tees See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Craig Pugsley Date: Tue, 27 Aug 1996 19:57:40 +1000 (EST) Subject: Re Propane injectors > Now if anybody knows about where I can get pulsed injectors that will > work with liquid propane? A crowd over here (.au) uses stock ford (=bosch??) injectors, but fed from the bottom of the injector via a slot in the body, after the coil. The rail pressure is regulated by restricing the return line, and the un-used fuel flows "out" where gasoline USUALLY comes in. The whole system is at tank pressure (350psi??), and the injector opening times are very short. Is there such a thing as an electronically controlled diesel injector? (aka instead of the usual mechanical fuel pump distributor thing..) Cheers, Craig. go efi555 ------------------------------ From: talltom Date: Tue, 27 Aug 1996 04:02:08 -0700 (PDT) Subject: Re: Real time dyno At 09:00 AM 8/27/96 GMT, you wrote: > >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. > > > This might be a dumb question, but why do you care? As long as there is traction most power is going to directly read on accelerometer which need only establish what adjustments work best, not best as compared to XXXX. Whatever vehicle parameters are will show in best tuning for accelerometer readings. Why make it complicated? ------------------------------ From: john spears Date: Tue, 27 Aug 96 06:36 EST Subject: RE:re:newer VATS vehicles What was said about the Corvette VATS is true. I posted a more in-depth look at this a couple of months ago to this list. When working with a vette prom you must flip a different bit. In all of these that I have done, I have never needed to do anything with the code mask after after toggling from VATS to NO VATS. John Spears Speartech F.I. Systems ------------------------------ From: "Michael T. Kasimirsky" Date: Tue, 27 Aug 1996 08:15:21 -0400 (EDT) Subject: Re: Re[2]: real time dyno? On Mon, 26 Aug 1996, Michael D. Porter wrote: > 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. A dyno is typically calibrated by hanging dead weights from a moment arm built into the dyno housing. The length of the arm is known, so the torque load is known. This is used to calibrate the load cell readout. Horsepower is then mathematically calculated from the torque value. Michael T. Kasimirsky ----> mtk@xxx.edu Days: Staff Engineer or mk4u@xxx.edu ASTM Test Monitoring Center Phi Gamma Delta, Nights: 1992 Suzuki GSX-R750 Pilot NRA Life Member, AMA Member 1991 Suzuki GSF400 Bandit Mechanic DoD #1848 ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 27 Aug 1996 07:49:16 -0500 Subject: Re: Newer VATS Vehicles >More and more GM vehicles are using VATS. The newer units are still a Okay, time for me to ask the dumb question: what's VATS ? tom cloud ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 27 Aug 1996 08:05:24 -0500 Subject: Re: Real time dyno >This might be a dumb question, but why do you care? As long as there is >traction most power is going to directly read on accelerometer which need only >establish what adjustments work best, not best as compared to XXXX. Whatever >vehicle parameters are will show in best tuning for accelerometer readings. >Why make it complicated? > > I would love to have dyno ... and a place to put it ... and the time to play with it ... and the money to support all the stuff above plus everything else (including the divorce attorney). Since I don't, and my needs are tuning my EFI for optimum (in real time), the accelerometer seems the best compromise. I don't have to pull the engine, or pay someone to let me use their dyno while trying to make adjustments. Clearly, I'm not trying to compete. If I were, I'd seek out the likes of Todd and follow their lead. But, their methods are beyond me. Methinks if I could just peak acceleration and then tune for some other trifling things (like idle, cold running, etc), I'd be happy. tom ------------------------------ From: Bruce Bowling Date: Tue, 27 Aug 1996 9:52:27 EDT Subject: Re: Re[2]: real time dyno? > 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? > I always thought one could put an electrical load on the alternator, and see the RPM drop of the engine. I do not know how much power an alternator sucks up, but I can tell a RPM drop whenever I turn on the headlights at idle. I guess one would not want to put a gigantic load on an alternator for very long, but a known big load that is applied via. a PWM technique, with the duty cycle adjusted until the RPM drops a small amount, may work. With a calibrated alternator, one may get some sort of a number out which could be a mark for engine performance. - - Bruce - -- - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- Bruce A. Bowling Staff Scientist Thomas Jefferson National Accelerator Facility 12000 Jefferson Ave - Newport News, VA 23602 (804) 249-7240 bowling@xxx.gov/~bowling - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- ------------------------------ From: MSargent@xxx. Sargent) Date: Tue, 27 Aug 1996 09:58:38 -0400 Subject: Re: Re[2]: real time dyno? > how does one go about calibrating a home-made dyno? Do you really need to? For tuning, you only care about changes and maximums. You don't really care about absolutes (unless you want to brag). +--------------------------------------------------------------------------+ | Michael F. Sargent | Net: msargent@xxx.com | Phone: 1(613)721-0902 | | Gallium Software Inc.| | FAX: 1(613)721-1278 | +--------------------------------------------------------------------------+ ------------------------------ From: FRED FRANCIS Date: Tue, 27 Aug 1996 13:34:36 -0500 Subject: DIY_EFI Digest V1 #248 -Reply I've been reading the list for a while now but have never commented. I would like the list members' opinions. I want to build a fuel injected Chevy 350. It should have about 10.5:1 compression. Ported out AFR aluminum heads. TPI specialties mini-ram manifold (looks like current LT1 but made for forward cool engines) Cam with about 222deg dur at .050" and .480" lift intake and 232 deg dur at .050" and .510" lift exhaust. 1 3/4 " headers, low restriction exhaust etc.... 6" connecting rods. I'm considering buying and EFI computer and associated wiring and sensors. Talked to a guy at Mr. Gasket (they make the DFI/accel system used in many similar engines in the car mags) and he says that I would gain almost no benefit from a sequential system vs a batch fire system. I also want to look at an ECM from Motec but it is a LOT more expensive. Will there be a significant advantage to using sequential port injection vs batch fire? Does anyone have any experience with either of these aftermarket programmable systems? I want bulletproof reliability combined with stellar performance and tuneability. Will I have an advantage to having a system that is programmable vs having to get someone to burn the correct chip for my engine for use in a standard GM computer? I already have a laptop to run the software necessary to configure one of the aftermarket systems. What do you all think? ~~fred francis ------------------------------ From: "David M Parrish" Date: Tue, 27 Aug 1996 14:17:50 +0000 Subject: Re: Re[2]: real time dyno? > From: Bruce Bowling > I always thought one could put an electrical load on the alternator, and > see the RPM drop of the engine. I do not know how much power an > alternator sucks up, but I can tell a RPM drop whenever I turn > on the headlights at idle. 200HP = 149kW. On a 12 volt alternator, that's 12,417 amps! With a 120 volt alternator, it's only 1,242 amps. - --- David Parrish So. How many homes you want to light? ------------------------------ From: Todd Knighton Date: Tue, 27 Aug 1996 11:05:02 -0700 Subject: Re: Real time dyno Now, just to throw a curve at all you guys on this thread. When we calibrate engines on the engine dyno, we typically use the dyno for a load device only. We load the engine to a specific load / rpm site and calibrate the engine for the air/fuel ratio desired, not the one that makes peak power, but the one that over much pain and aggrivation has produced the best reliability / performance / economy / in other words compromise over time. Then the timing is adjusted to it's optimal value, again for no knocking nor misfire because of rotor phasing, etc. Sometimes timing is checked for optimal power, but typically fuel is not. So, the acceleration thing, is not only not practical for on the road use, but doesn't really give much results either. We usually only power test the engine once all the tuning is done. Especially if you're doing a normally aspirated engine, the differential results from changes from run to run are typically hard to tell from the errors accumulated from environmental factors. Oh, and are you guys going to factor in your correction factors for humidity, barometric pressure, and temperature to give the results from run to run more accurately? All I'm trying to say is, don't expect miracles from the readings off the accelerometer. An EGO sensor and a knock sensor from J&S with a monitor will get you calibrated 10 times faster. Don't worry about the changes till you're done then record the results and get a graph or something. The basic engine combination is more of a factor to record changes, the tuning is just set up for a specific engine combo. Todd Knighton Protomotive Engineering > Since I don't, and my needs are tuning my EFI for optimum (in real > time), the accelerometer seems the best compromise. I don't have > to pull the engine, or pay someone to let me use their dyno while > trying to make adjustments. Clearly, I'm not trying to compete. > If I were, I'd seek out the likes of Todd and follow their lead. > But, their methods are beyond me. Methinks if I could just peak > acceleration and then tune for some other trifling things (like > idle, cold running, etc), I'd be happy. > tom ------------------------------ From: Fred Miranda Date: Tue, 27 Aug 1996 11:29:29 -0700 Subject: Re: DIY_EFI Digest V1 #248 -Reply Fred, A sequential system won't provide more top end, but it might give better driveability and mpg. For a resonably priced sequential system, you might look at Autronic. (produced by an ex-Motec guy) About $1600 I've done 3 of these, Mustang SVO 4cyl turbo, my '65 Lotus Elan and an Eclipse turbo. Am about to do another Eclipse also. I have also done many TEC2 systems from rotarys to V8s. They are a good value but not as powerfull as the Autronic system. (power in terms of tunability) Fred At 01:34 PM 8/27/96 -0500, you wrote: >I've been reading the list for a while now but have never >commented. I would like the list members' opinions. I want >to build a fuel injected Chevy 350. It should have about >10.5:1 compression. Ported out AFR aluminum heads. TPI >specialties mini-ram manifold (looks like current LT1 but >made for forward cool engines) Cam with about 222deg dur >at .050" and .480" lift intake and 232 deg dur at .050" and >.510" lift exhaust. 1 3/4 " headers, low restriction exhaust >etc.... 6" connecting rods. I'm considering buying and EFI >computer and associated wiring and sensors. Talked to a >guy at Mr. Gasket (they make the DFI/accel system used in >many similar engines in the car mags) and he says that I >would gain almost no benefit from a sequential system vs a >batch fire system. I also want to look at an ECM from Motec >but it is a LOT more expensive. Will there be a significant >advantage to using sequential port injection vs batch fire? >Does anyone have any experience with either of these >aftermarket programmable systems? I want bulletproof >reliability combined with stellar performance and tuneability. >Will I have an advantage to having a system that is >programmable vs having to get someone to burn the correct >chip for my engine for use in a standard GM computer? I >already have a laptop to run the software necessary to >configure one of the aftermarket systems. What do you all >think? > >~~fred francis > > > ------------------------------ From: Bruce Bowling Date: Tue, 27 Aug 1996 15:49:09 EDT Subject: Re: Re[2]: real time dyno? > > 200HP = 149kW. On a 12 volt alternator, that's 12,417 amps! With a > 120 volt alternator, it's only 1,242 amps. > > --- > David Parrish > So. How many homes you want to light? > A few points: 1) A car alternator puts out more than 12 volts - it is regulated down to the 12 volts. If I recall, something like 60 volts open circuit. 2) You do not want to suck away 200 HP, only enough to cause an RPM drop. Yes, at higher torque, you need to suck away more torque to get a reliable RPM drop. 3) Still, the RPMs drop down at idle when I put on the lights, somewhere like 25 RPM (total guess). What is the current draw of headlights, something like 15 amps (total guess again)? So, right now, I could probably perform the following test: 1) Fix the idle to something like 700 RPM steady. Headlights off 2) Turn on headlights. See and record the RPM drop. 3) Turn off the headlights. 4) Screw up the engine somehow, like disabling a cylinder (via. spark or something). 5) Do steps 1, 2, and 3. The relative change in RPM drop between the two tests should scale, something like: scale = (number_of_cylinders - 1)/(number_of_cylinders) + Other_losses Will this work? I do not know, and I do not have the time to test this. But this test is similar to the old "eliminate-the-cylinder" test that a lot of the engine analyzers used to have, which simply shorted the coil primary when a particular plug was firing, and determined relative cylinder-to-cylinder performance by watching the amount of RPM drop. - - Bruce - -- - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- Bruce A. Bowling Mad Cow Thomas National Facility Accelerator Jefferson 12000 Jefferson Ave - Newport News, VA 23602 (804) 249-7240 bowling@xxx.gov/~bowling - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- ------------------------------ From: "John Faubion" Date: Tue, 27 Aug 1996 17:22:31 -0500 Subject: Re: Data Logging > My big problem (and why I want an accelerometer) in predicting vehicle > performance is that with the Drag car the wheel diameter is not constant > as it increases with speed and also there is no speedo for measuring > speed against a stopwatch. Also no passenger seat for the second person > to take the readings! Why not mount a pair of magnets inside the front wheel and use a hall effect sensor mounted to the brake baking plate? The rear tires may grow considerably but the fronts shouldn't. John Faubion jfaubion@xxx.net ------------------------------ From: "Simon Tippett" Date: Wed, 28 Aug 1996 08:51:08 +1000 Subject: Re: My DIY EFI Date sent: Wed, 21 Aug 1996 10:15:08 -0500 (CDT) From: Robert Van Zant To: diy_efi@xxx.edu Subject: Re: My DIY EFI Send reply to: diy_efi@xxx.edu > >Could you give me more info about your system, and the cost of it? > Ditto Me three. bob rvanzant@xxx.net That makes me Four. Simon Tippett Tippy@xxx.au ------------------------------ From: Michael Manry Date: Tue, 27 Aug 1996 15:59:08 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #248 -Reply I have used the ACCEL EFI system on a 215 Buick powered off-road car and had great success with it. ACCEL/DFI's CALMAP software lets you tune just about everything short of the color you want the car including electric fan control and Nitrous (if you're brave AND rich). They also offer an inductive pick-up option so you can connect an MSD 6A, 6AL or the new ACCEL 300+ ignition system. All of the sensors and parts are standard GM and the system is much more affordable than MOTEC, ELECTROMOTIVE, or EFI TECH. I can definitely recommend it. Hope this helps Mike Manry (ShadeTree Racing) On Tue, 27 Aug 1996, FRED FRANCIS wrote: > I've been reading the list for a while now but have never > commented. I would like the list members' opinions. I want > to build a fuel injected Chevy 350. It should have about > 10.5:1 compression. Ported out AFR aluminum heads. TPI > specialties mini-ram manifold (looks like current LT1 but > made for forward cool engines) Cam with about 222deg dur > at .050" and .480" lift intake and 232 deg dur at .050" and > .510" lift exhaust. 1 3/4 " headers, low restriction exhaust > etc.... 6" connecting rods. I'm considering buying and EFI > computer and associated wiring and sensors. Talked to a > guy at Mr. Gasket (they make the DFI/accel system used in > many similar engines in the car mags) and he says that I > would gain almost no benefit from a sequential system vs a > batch fire system. I also want to look at an ECM from Motec > but it is a LOT more expensive. Will there be a significant > advantage to using sequential port injection vs batch fire? > Does anyone have any experience with either of these > aftermarket programmable systems? I want bulletproof > reliability combined with stellar performance and tuneability. > Will I have an advantage to having a system that is > programmable vs having to get someone to burn the correct > chip for my engine for use in a standard GM computer? I > already have a laptop to run the software necessary to > configure one of the aftermarket systems. What do you all > think? > > ~~fred francis > > ------------------------------ From: Todd Knighton Date: Tue, 27 Aug 1996 16:31:02 +0000 Subject: real time dyno > For those of us without easy access to dyno, but with pretty good tools > such as LSM-11 Bosch a/f meter and a datalogger recording all engine > functions such as fuel pressure, turbo boost, egt, exhaust backpressure, > intercooler in/out, and J&S knock minitor out, do you believe you can > get decent results in the car. I saw your previous post @ such but did > not know the equiptment you were using. Obviously a dyno with readout > of bsfc and the ability to stay at a particular cell is best. On the > other hand with my logger, I can take data at 100 times per sec and > just drive the car and review data later. > Enjoyed your posts. Lotta good common sense. > Frank, Yes, you can get good results in the car, especially with a good datalogger. My point was, that acceleration is not the key element. Obviosly by your equipment list, you do not either. As well as, it's not safe to drive and try to look at gauges. A datalogger makes it very nice. Our other problem is the cars we test are extremely fast and to calibrate a 700 hp engine in a Porsche is hard to do at low speeds. We were commonly running 160 to 200 mph to get good steady state type results, otherwise you're locking up the front tires at low speed (under 100mph) to try and load the thing. Good luck with your project Todd Knighton Protomotive Engineering. P.S. I'm not trying to be a dyno snob, just trying to share some experiences with you guys, and try to keep you from killing yourselves. Almost Been there... done that. ------------------------------ From: Daniel R Burk Date: Tue, 27 Aug 1996 20:07:06 -0700 Subject: Strain gage based dyno numbers Michael: Here at Michigan Scientific where I work, the guys have calibrated their axle torque sensors by literally strapping the rear bumper of the truck to a tree. They then bring up the revs until just before the tires break, (or the tree roots give out!!) and measure the amount of linear tension on the cable. They then can assume that the bulk of the tension results from the torque of the wheels as applied to the pavement at the contact patch. Measure the wheel radius from contact patch to center of the axle, and viola! --- Rear wheel torque. If you are careful with your tansducer design, and insure there is no significant bending of your spring (aka surface to which you bond your strain gages) then you can assume that the applied force is linear until your theoretical full scale cal value. You can then measure torque much higher than that which you applied to your hapless Boxelder tree. ;) ------------------------------ From: Daniel R Burk Date: Tue, 27 Aug 1996 20:20:13 -0700 Subject: Calibration of commercial dyno load cells Michael: You can calibrate a load cell in a similar fashion: Build a rigid lever arm of known length. Mount it to the load cell such that it sticks out in a perpindicular fashion from the load cell axis, parallel to the ground. Zero out your gages to account for the added weight of the lever arm. Apply a load of known force, (20 lbs or so,) and calibrate your sensor for torque. If we assume your lever arm is three feet long, and you have placed a 20 pound weight on it, you now have 60 ft-lbs (Lbs-ft?) of torque on your cell. Again, assume that the gages are linear to account for higher amounts of torque. If 5V = 1200 ft.lbs, and zero ft-lbs equals 2.5V, you have 2mv per ft-lb, or a cal value of 2.5V plus 120mv, or 2.620mv predicted output of your load cell gaging. Cheers, Dan Burk Instrumentation Engineer for oh, about 12 months now. ------------------------------ From: Daniel R Burk Date: Tue, 27 Aug 1996 20:30:21 -0700 Subject: Re: Driveshaft slip rings Tom: Actually, a company introduced such a system this year at the 1996 SAE congress for street use. They called it an on-car dyno. I have a slip ring very similar to it that did something like 30,000 miles on Milford Proving grounds testing. It is mounted on a modified output shaft from the transmission. The very same torque passes through the output shaft as the driveshaft and you can mount the stationary part of the slip ring on the transmission. MSC slip rings have gone 100,000 miles on test cars with virtually no wear. You are right however on the fact that these devices are for testing only. Most of us could not justify the $1500 - 3500.00 cost of the slip ring. ------------------------------ From: "George M. Dailey" Date: Tue, 27 Aug 1996 20:26:22 -0500 Subject: Re: Fuel Pump Return line At 06:02 PM 8/26/96 -0600, you wrote: >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 > I agree with what the rest of the group is saying, it seems logical. However, in Frank 'Choco' Munday's book, SBC TPFI, he recommends adding the tee to the pump suction line. Based on the quality of the book, you could probably get by with it. I have complete confidence that Choco has tested it. Remember, 'It's better to burn out, than fade away....' Good luck. GMD ------------------------------ From: "George M. Dailey" Date: Tue, 27 Aug 1996 20:34:42 -0500 Subject: Re: Re[2]: real time dyno? At 08:25 PM 8/26/96 -0700, you wrote: >Will makes a good point which has plagued me over the years... how does >one go about calibrating a home-made dyno? >-- >My other Triumph doesn't run, either.... > For the in vehicle mounted dyno (strain gages on the motor mount), how about connecting a torque wrench to the motor and plotting a graph of torque vs resistance? You would probably need a 1" unit with one hell of a cheata pipe or you could use the lever equations and apply a known force. GMD ------------------------------ From: "George M. Dailey" Date: Tue, 27 Aug 1996 20:41:51 -0500 Subject: Re: Newer VATS Vehicles At 10:16 PM 8/26/96 -0700, you wrote: ... >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 Quick question for you Pete. Is the Vats error code available for the non Vetts? I could never get a vats error code on my '89 tpi (Firebird). Thanks, GMD ------------------------------ From: "George M. Dailey" Date: Tue, 27 Aug 1996 20:59:06 -0500 Subject: Re: DIY_EFI Digest V1 #248 -Reply At 01:34 PM 8/27/96 -0500, you wrote: >I would like the list members' opinions. I want >to build a fuel injected Chevy 350. It should have about >10.5:1 compression. Ported out AFR aluminum heads. TPI >specialties mini-ram manifold (looks like current LT1 but >made for forward cool engines) Cam with about 222deg dur >at .050" and .480" lift intake and 232 deg dur at .050" and >.510" lift exhaust. 1 3/4 " headers, low restriction exhaust >etc.... 6" connecting rods. I'm considering buying and EFI >computer and associated wiring and sensors. Talked to a >guy at Mr. Gasket (they make the DFI/accel system used in >many similar engines in the car mags) and he says that I >would gain almost no benefit from a sequential system vs a >batch fire system. I also want to look at an ECM from Motec >but it is a LOT more expensive. Will there be a significant >advantage to using sequential port injection vs batch fire? >Does anyone have any experience with either of these >aftermarket programmable systems? I want bulletproof >reliability combined with stellar performance and tuneability. >Will I have an advantage to having a system that is >programmable vs having to get someone to burn the correct >chip for my engine for use in a standard GM computer? I >already have a laptop to run the software necessary to >configure one of the aftermarket systems. What do you all >think? > >~~fred francis > If I were you, I would duplicate the GM LT1 engine specs (cam, CR,); install the copy cat intake to allow use of the rear mounted distributer; use a stock GM L98 ECM (MAF type). The copy cat will allow for idle control valve, right? Good look GMD ------------------------------ From: "George M. Dailey" Date: Tue, 27 Aug 1996 21:16:28 -0500 Subject: Re: Newer VATS Vehicles At 07:49 AM 8/27/96 -0500, you wrote: >>More and more GM vehicles are using VATS. The newer units are still a > >Okay, time for me to ask the dumb question: what's VATS ? > >tom cloud Vehicle Anti Theft System. Uses resister coded key and matched module to inform the ECM if the original key is used. A fail signal causes the ecm to not fire the injectors. Bottom line... this system make the car less attractive to the novice thief. Any one out there with statistics on Vette thiefts before and after Vats?? gmd ------------------------------ From: "John Faubion" Date: Tue, 27 Aug 1996 21:57:49 -0500 Subject: Re: Re[2]: real time dyno? >2) You do not want to suck away 200 HP, only enough to cause an >RPM drop. Yes, at higher torque, you need to suck away more torque >to get a reliable RPM drop. I was told a few days ago that if you applied a known load to an engine you could calculate engine torque using the know load and the amount of rpm drop. Got any ideas on what the formula would be? John Faubion jfaubion@xxx.net ------------------------------ From: peter paul fenske Date: Tue, 27 Aug 1996 19:24:05 -0700 Subject: Re: Newer VATS Vehicles At 08:41 PM 8/27/96 -0500, you wrote: >At 10:16 PM 8/26/96 -0700, you wrote: >... >>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 > > >Quick question for you Pete. Is the Vats error code available for the non >Vetts? I could never get a vats error code on my '89 tpi (Firebird). > >Thanks, >GMD Hi George The vats error code #46 is I believe pertinent to 90 and later. I think all you would have to do is disable the vats bit and not worry about it. There are four bytes in your code which have different bits to set things like shift lite,tcc, egr ect besides vats. Even if one doesn't have the code licked you could still set the bits to zero till you find the right one Took me three tries but I had narrowed it down. Error code #46 is a low level code so even if it did exist the ECM would not go into backup. And usually it is disabled by the vats set bit. But I've been told there are applications where a separate disable is necessary for the error code. Later George: peter ------------------------------ From: David Crocombe Date: Wed, 28 Aug 1996 13:47:56 +1000 Subject: real time dyno >Oh, and are you guys going to factor in your correction factors for >humidity, barometric pressure, and temperature to give the results from >run to run more accurately? >All I'm trying to say is, don't expect miracles from the readings off >the accelerometer. Ultimately I would like to measure and to factor in correction factors for humidity, barometric pressure, and temperature etc to give the results from run to run more accuracy. I thought measuring revs and acceleration could show up things like loss of traction, as well as trying to calculate power as a quantitative measure of vehicle performance. As someone mentioned, power is great for it's brag value but also to get an idea, for ones own benefit, as to how much extra power the nitrous is giving for example. >Why not mount a pair of magnets inside the front wheel and use a hall >effect sensor mounted to the brake baking plate? The rear tires may grow >considerably but the fronts shouldn't. I have been trying to work out how to mount some sort of speed sensor on the front wheel. It is difficult as it uses spoked motorcycle front wheels in an open wheel format. So there is no front brake and hence no backing plate to mount things on, just a rear hand brake and a parachute! One other thing, which we don't have a problem with at the moment but is kept in mind, is that the front wheels can be prone to lifting off the ground and hence losing the rotational information. >I would love to have dyno ... and a place to put it ... and the time >to play with it ... and the money to support all the stuff above plus >everything else (including the divorce attorney). >Since I don't, and my needs are tuning my EFI for optimum (in real >time), the accelerometer seems the best compromise. Know what you mean. Already got the divorce attorney, now just need a real time performance measuring system (dyno). I do thank people for their contributions to this DIY-EFI as I am learning a lot. Regards, David Crocombe Sydney Australia ------------------------------ From: Warren Crowther Date: Wed, 28 Aug 1996 17:23:57 +1200 Subject: switching between EPROMS Hello All, quick question: has anyone made a device that you can plugs lots of EPROMs into, plug into your car ECU, and switch between them with a switch?? I want to make one for only 2 EPROMs, and was thinking of using a simple switch to switch the chip enable between the EPROMs. Will this work?? or will the time gap when neither of the EPROMs are enabled be enough to confuse the micro, and go into some unknown state? I could use latches and some simple logic chips to get around this I guess. Any recommendations?? Warren _______________________________________________________________ Warren Crowther Software Engineer DDI +649 3610625 warren@xxx.nz Ph +649 3602834 x5625 Advantage Systems Ltd Fax +649 3764210 ------------------------------ From: john carroll Date: Tue, 27 Aug 1996 21:56:06 -0600 Subject: Re: Fuel Pump Return line AND fuel line tees It is my experience that any sort of a tee in the supply line to a pump will eventually give you problems under some condition. Certainly there are situations where the risk is minimized. If both of the supplies have plenty of head or a feed pump to supply the high head pump with several times its pumping capacity, don't stay up nights worrying about it. This is particularly true if the pumping system is not mission critical and the equipment is cheap to replace. Most fuel systems do not qualify. The problems arise when one of the lines sucks its first gasp of air. Despite the fuel available from the other line, air bubbles have been introduced into the system, and will continue to be introduced as long as it is easier to pump air from the empty line than fuel from the full one. If one insists on using a header tank, be certain to vent the header tank to the main tank, or alternativly, vent both to the atmosphere in order to equalize the pressure. At 08:26 PM 8/27/96 -0500, you wrote: >At 06:02 PM 8/26/96 -0600, you wrote: >>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 >> > >I agree with what the rest of the group is saying, it seems logical. >However, in Frank 'Choco' Munday's book, SBC TPFI, he recommends adding the >tee to the pump suction line. Based on the quality of the book, you could >probably get by with it. I have complete confidence that Choco has tested it. > >Remember, 'It's better to burn out, than fade away....' > >Good luck. > >GMD > > john carroll jac@xxx.us ------------------------------ End of DIY_EFI Digest V1 #249 ***************************** 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".