DIY_EFI Digest Friday, 12 March 1999 Volume 04 : Number 163 In this issue: Re: Chassis dynos exposed Re: VSS and Transmission Output speed Re: Bosch Fuel Pump Re: Real HP loss numbers Re: Electric water pumps (was) alt charging cont sw RE: Bosch Fuel Pump Re: Electric water pumps (was) alt charging cont sw Re: Electric water pumps (was) alt charging cont sw Re:hp loss Re: Off Panhard bar Re: Electric water pumps (was) alt charging cont sw Re: Electric water pumps (was) alt charging cont sw Re: Real HP loss numbers RE: [M] Alterpower alternator charging control switch Re: [M] Alterpower alternator charging control switch Re: VSS and Transmission Output speed Re: Electric water pumps (was) alt charging cont sw Re: Electric water pumps (was) alt charging cont sw Re: Electric water pumps (was) alt charging cont sw Re: Chassis dynos exposed Re: Chassis dynos exposed Re: Real HP loss numbers Re: Real HP loss numbers Re: Chassis dynos exposed Re: Chassis dynos exposed See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Shannen Durphey Date: Fri, 12 Mar 1999 18:34:38 -0500 Subject: Re: Chassis dynos exposed Helps me a bunch. Shannen Jason_Leone@xxx.com wrote: > > Since all this talk about chassis dyno figures and methods has erupted today, I > submit this. They're are a few distinct differences in chassis dynamometer > types. Each type has pros and cons. > > Up until a year or so ago, all the load type dynos out there had primitive > operating > systems, if at all. They worked by running the car on the dyno, loading up the > rollers (usually via a water brake system), and reading the horse power number > when the load prevented the engine from accelerating past a predetermined rpm. > > This gave you the max hp the engine could produce at that particular rpm, since > it > couldn't overcome the force being thrown at it. Take readings at several rpm > points > (usually manually recorded), and a power graph can be made, extrapolating torque > numbers mathematically. Thus, the load type dyno graphs are not "smooth" > because not every point along the curve is actually plotted, but just the > predetermined (by the operator) rpm points. The more points tested, the more > complete and smooth the curve. A primitive graph can be made with Excel, or any > spread sheet software. > > However, that is quite time consuming, and hard on the car's engine and tires. > Plus, > operator skill is essential in preventing tire slip from corrupting the data > gathered. > Loading up an engine is how a manufacturer determines and engine's power output, > by the way. > > This is all in contrast to the Dynojet inertia type testing, which simply > requires the > car to run on the rollers from standstill or low rpms, to redline or anywhere in > between (in one or several gears). The rate of acceleration is measured, and > power > is mathematically calculated using the constant of roller weight. The time it > takes to > accelerate a given mass to a particular speed can be used to calculate hp. It is > relatively painless to the car, and quickly measured. Plus, the Dynojet software > allows automatic graphing, which produces an attractive consumer product. > > However, the downside to this measuring form is that, in the real world, the > vehicle > is working harder than what is required in accelerating the rollers on a > Dynojet. > > Between the weight of the car itself, elevation changes, and surface friction, > the > actual environment the engine works in during use is quite different from its > experience on an inertia type dyno. This is an important factor to consider when > interpreting the hp gain of a particular mod/product. For example, lots of > ignition > timing can be thrown at an engine to produce big hp numbers on an inertia dyno, > but the same ignition setting can result in *less* hp when the engine is > actually > required to work on the street. Preignition or detonation can occur, tripping > the > knock sensors and causing the ECU to roll back the timing to less than stock. > Not > good for power. Same issue with fueling. Leaner fuel maps may work well when > subjected to the relatively gentle inertia rollers, but can be disastrous when > under > load on the street. > > The Dynojet is a great marketing tool, but is not an accurate, real world > measuring > device. Dynojet now has a load type device that can be added to their existing > models, but it currently is fixed, and cannot be altered. So, it suffers from > the same > drawback as the older type load dynos. > > The best of both worlds is the load type dyno with a sophisticated operating > system. For example, a Mustang MD-250 chassis dyno is rated at a maximum hp load > of 750. > However, we can load it from 0hp (simply spinning the attached flywheel and > rollers like the Dynojet) up to 750hp and anywhere in between. We can specify a > time period over which we want a load to be applied. We can simulate a series of > hills, as the car goes up and down in elevation, which obviously varies the load > on > the engine. We can set a specific rpm at which the dyno can apply a specific > load. > > In other words, the load application on a MD-250 dyno is practically infinitely > variable, > and can be as punishing or gentle on the engine as we want. All controlled by > the > Windows based software on the controller PC, with hand held operator controls. > For development use, the load ability is crucial, to produce a product that will > perform correctly in the real world. For promotional use, such for dyno days, > the > inertia mode is useful. > > Hope that clears us some confusion regarding the types of chassis dynamometers > out there. > > Jason > '93 SLC ------------------------------ From: "Peter D. Hipson" Date: Fri, 12 Mar 1999 18:45:38 -0500 Subject: Re: VSS and Transmission Output speed For equal speeds (third and fourth gear) ratio between TOSS to TISS is 1043 (TOSS) to 1194 (TISS) giving a ratio of 1.14. TOSS and TISS can get up to voltages of about 12 to 15 VAC, if open circuited. If in the TCM circuit then the values will (probably, I've not measured 'em) be lower. GM states a given voltage at a given speed, figure that the voltage while in operation will range from 4 to 12 VAC typically. At 01:40 PM 3/12/99 -0500, you wrote: >Peter D. Hipson wrote: >> >> I'm doing extensive work on the TISS/TOSS senders. No, they are not equal >> in pulses per revolution, there is a substantial difference. (I've the >> ratios, if that's important...) > >Sure, pass 'em along for posterity's sake. > >> The senders are both magnetic coil type, >> returning an A/C signal who's frequency (and voltage) varies with the RPM. >> The only reason the voltage changes is due to improved efficiency at higher >> speeds--the voltage change is not significant to the TCM, for example. Be >> aware that common mode noise can be a problem with these senders, as can >> bad connectors. As well, the sender itself fails frequently--arrggg! >> >I think I remember reading or hearing that the VSS signal voltage can >get extremely high before conditioning. What voltage levels are you >seeing on average and how high do they peak? >Shannen > Thanks, Peter Hipson (founder, NEHOG) 1995 White NA Hummer Wagon ------------------------------ From: Glen Beard Date: Fri, 12 Mar 1999 18:51:40 -0500 Subject: Re: Bosch Fuel Pump "David A. Cooley" wrote: > > Can anybody help me find out anything about this pump: > > > > Bosch: 9 580 810 020 > > 12V. 562-10 > > E7TF.9350.AA 5B10 > > Clarence, > The E7TF part number looks like a ford number... > Might call a ford dealer and ask what it fits. Doesn't Ford use allot of Bosch parts? I know they were using Bosch injectors for a while. - -- Glen Beard 95 T/A conv M6 Vortech http://home.nycap.rr.com/gbeard1/TransAm.html ------------------------------ From: David Piper Date: Fri, 12 Mar 1999 19:05:52 -0500 Subject: Re: Real HP loss numbers On my DynoJet, from coastdown measurements, we have measured from 10 to 28 HP loss in drivetrain with straight drive tranis. The 10 hp was on straight drive 280Z with smaller R180 open rear diff with new spicer UJ and synthetic lube in 4th gear (1:1). Most Z's are around 17HP at 6K RPM. A Cobra replica straight drive had 28 HP. An auto on a drag car with big Dana rear had 150HP loss at 7400RPM. The Ford 5.0L manuals are around 20 HP. Measurements are RPM dependant. Engine motoring produced around 90HP incl drivetrain loss on the Z's and 120HP on 350ci chev (Corvettes) and 150HP on big blocks. These figures are based on inertial effects as well as frictional losses. Additional load is imposed on the front wheels and by aerodynamic load which increases as the cube of speed. Hence, final tuning must be done with actual road testing, otherwise load enrichment will be insufficient. The value of the DynoJet can be fully realized with real time data acquisition measurement of engine parameters such as boost, fuel flow, fuel press, exh gas back press, intake charge temp and EGT, etc. NASCAR uses it for final shakdown b4 loading on trailer, drive train loss and vibration analysis. TurboDave At 01:02 AM 3/12/99 EST, you wrote: >Was wondering (induced by all the talk with computers recording spark signals >and computing HP) what are the actually losses in drivetrain. I've heard the >torque converter is 97% efficient at part throttle and 2 hp at U-joints (I >don't believe, that's 1500 Watts at each joint). Looking at tranny (auto and >standard) u-joints, ring and pinion, bearings, spider gears, axles.... > >Sorry, it's off the beaten path, oh well :) > >Mike > > ------------------------------ From: Clarence Wood Date: Fri, 12 Mar 1999 18:14:43 -0600 Subject: Re: Electric water pumps (was) alt charging cont sw Has anybody any experience with the *Tik-Tok* Fan/Water pump Switch made by Shogun? Advertised in Jeg's cat.#990303, pg 46-T. "It is a three position switch: pos.1 runs pump only; pos.2 it will run your water pump first, shut it off, then turn on your cooling fan-by repeating this sequence the radiator becomes a true heat exchanger instead of a temperature equalizer." It doesn't say that it is automatic, but at $80.00 it should be! Anyway, it sounds like a good idea if it were electronic. Does anybody know what the gph should be on a 6cyl engine? V8? At 01:08 PM 3/12/99 -0600, you wrote: > > >On Fri, 12 Mar 1999 ScottyCBoy@xxx.com wrote: > >> >> some guys have used things like marine bilge pumps >> they are trubine style pumps with a strait trhough flow path >> can move massive amounts of water with the larger sizes >> should be no reason no to use one of these >> >> Clive >> >> >> I have pondered the us of electric water pumps and I believe that they would >> be beneficial in many ways: >> >> First no thermostat would be needed, when the engine get's to operating temp >> the pump would turn on.. >> >Probably you would need a thermostat to regulate the varing speeds, >the hotter the engine gets that faster the pump goes. I know there >are some computers that regulate their fans this way. > >> Second the pump can run at varying speeds, while light cruising the pump speed >> would be slower than at full steam, saving fuel.. >> >> Thrid the engine could theoretically warm up quicker as there would be no leak >> past a closed thermostat and coolant wouldn't be circulating through a cold >> engine... > >Someone was told by a manufacturer of one of those pumps that it was >not wise to not run the pump when the engine was running as hot spots >can form rather quickly and damage things. > >> >> Fourth reverse flow coolant systems could be retorfitted easily just by >> reversing the current to the pump, no special reverse flow pump impellers >> would be needed... >> > >The heads/water ports are designed differently to flow the other >direction, so you cannot always just change the water direction and be >done with it, the ports are not always designed to flow both ways >correctly. The LT1 engines have an entirely differnt water port >design so they flow correctly in the other direction. My assumption >is that the normal chevy SB water ports won't flow optimally in the >reverse direction. > >> Scott > > > Roger > > ------------------------------ From: Clarence Wood Date: Fri, 12 Mar 1999 17:29:54 -0600 Subject: RE: Bosch Fuel Pump It is external and it has a threaded inlet, I am assuming that the end where the plus and neg. terminals are is the inlet, but the outlet is not threaded. Also, by threaded I assume you mean that the inlet tube can be removed. Anyway, if this is the pump you were looking for it can be found at Sherco Auto Supply, 1-800-548-6229, ask to speak to Mark. The pump is packaged as a Carter, #P74099. It is supposed to be 90psi, 38gph. Comes with a padded mounting bracket. Mark told me that it is a secondary pump for a Ford; he didn't know what model of Ford. At 02:36 PM 3/12/99 -0600, you wrote: >Well, if it is an external pump with threaded inlet and outlets, high >pressure it is probably the pump I have been looking high and low for. The 9 >in the part number refers to a domestic Bosch application. The pump I had >(leaks like a sieve now due to MTBE eating the internal O-rings) was made by >Bosch for Accel (actually, for DFI before they were bought by Accel). > >TTYL! > >Larry > >> -----Original Message----- >> From: Clarence Wood [mailto:clarencewood@xxx.net] >> Sent: Friday, March 12, 1999 1:11 PM >> To: diy_efi@xxx.edu >> Subject: Bosch Fuel Pump >> >> >> Can anybody help me find out anything about this pump: >> >> Bosch: 9 580 810 020 >> 12V. 562-10 >> E7TF.9350.AA 5B10 >> >> Thanks >> Clarence >> >> IZCC #3426 >> 1982 280ZX Turbo GL >> 1966 El Camino >> 1982 Yamaha Maxim XJ-1101J Motorcycle >> 1975 Honda CB750 SS (black engine) >> 1986 Snapper Comet lawn mower >> Clarence Wood >> Software&Such... >> clarencewood@xxx.net >> Savannah, TN. >> > > ------------------------------ From: bearbvd@xxx.net (Greg Hermann) Date: Fri, 12 Mar 1999 17:41:53 -0700 Subject: Re: Electric water pumps (was) alt charging cont sw >-----Original Message----- >From: steve ravet >To: diy_efi@xxx.edu> >Date: Friday, March 12, 1999 2:50 PM >Subject: Re: Electric water pumps (was) alt charging cont sw > >The reason water pumps are such a large HP lose is cause they need to be. >You >can slow em down some, and in some applications take em out. But, for a >street motor, >they is what they is. > For you to have an electric motor pump as much as an oem waterpump you'd, >have to have a >big a----- motor/pump to replace it. > For fast warm ups use a recirculating thermostat >Bruce Bruce is right on this, completely. (Or is it one of the little guys?) There is even a good debate possible as to whether a high pressure fuel pump should be electrically or mechanically driven, let alone a water pump, or an engine fan (if you are working an engine any kind of hard at low speeds for any length of time)! For any sizable auxiliary drive loads, a mechanical drive is way more efficient than an electrical one. Regards, Greg ------------------------------ From: "Bruce Plecan" Date: Fri, 12 Mar 1999 19:47:04 -0500 Subject: Re: Electric water pumps (was) alt charging cont sw - -----Original Message----- From: Clarence Wood To: diy_efi@xxx.edu> Date: Friday, March 12, 1999 7:28 PM Subject: Re: Electric water pumps (was) alt charging cont sw Two places might have it stewartcomponents.com, and Smokey's book on the SBC. Don't be surprised when ya see it in GPM Bruce > Does anybody know what the gph should be on a 6cyl engine? V8? ------------------------------ From: Jason_Leone@xxx.com Date: Fri, 12 Mar 1999 16:58:54 -0800 Subject: Re:hp loss <> Typically, expect a RWD front engine car to lose 20%. Expect a FWD front engine car to lose 15%. I'd guess a RWD rear engine car would be closer to 15% than 20% (ala Porsche). It depends on the individual drive train design, and the materials used. The C5 Corvette has a pretty efficient drive train, for example. Use of Aluminum and composites can greatly reduce rotating mass, and yield better response and minimise losses. You can calculate/test this by dynoing the engine on an engine dyno, then in the car on a chassis dyno. That's not too cost effective though. The best solution is using an accelerometer like the Vericom 2000. You can do coast down tests, and it can calculate vehicle specific power losses based on known algorithms and the vehicle data parameters entered. It's pretty accurate, and beats the old "Gee, Wally...how much hp does a car lose?". Jason '93 SLC (15.1% loss) ------------------------------ From: bearbvd@xxx.net (Greg Hermann) Date: Fri, 12 Mar 1999 18:09:21 -0700 Subject: Re: Off Panhard bar >Shannen, >What you discribed is a watts link. If you are serious about a 4 link, >depending on your application, consider instead a wishbone link. Current drag >racers use either a diagonal link, good only for going in a straight line, or >a wishbone setup. Contact Chassis Engineering or Art Morrison Enterprises for >technical info. Good reading would be Herb Adams, VSE fame, "Chassis >Engineering " from HPBooks, 1055. > Good Luck > Wayne Or go scrounging in a boneyard that has some old Alfas. They used an upper triangle, with two pivot points on the chassis, and a BALL joint attached just to the left side of the pumpkin, plus two lower trailing arms. Particularly if you replaced the chassis pivots of the triangle (rubber stock) with bronze on steel, also if you replaced the lower rod ends with real rod ends, they were as NICE a live rear axle setup as you could want. Another very nice set-up was the old Rover 2000 Di Dion setup--instead of a lateral link, they used half shafts with no slip joint, upper and lower arms on each side, and a slip joint in the Di Dion tube. Greg ------------------------------ From: "Bruce Plecan" Date: Fri, 12 Mar 1999 20:14:43 -0500 Subject: Re: Electric water pumps (was) alt charging cont sw - -----Original Message----- From: Greg Hermann To: diy_efi@xxx.edu> Date: Friday, March 12, 1999 7:57 PM Subject: Re: Electric water pumps (was) alt charging cont sw Actually a close vote 4-3, Sleepy napped during the vote. He also misses alot of public elections. Bruce > >Bruce is right on this, completely. (Or is it one of the little guys?) > >For any sizable auxiliary drive loads, a mechanical drive is way more >efficient than an electrical one. > >Regards, Greg ------------------------------ From: bearbvd@xxx.net (Greg Hermann) Date: Fri, 12 Mar 1999 18:14:35 -0700 Subject: Re: Electric water pumps (was) alt charging cont sw >On Fri, 12 Mar 1999, Frederic Breitwieser wrote: > >> The only flaw in this logic is that the Dodge Truck has a >> Mopar alternator which doesn't charge the battery >> effectively, hence my desire to replace it with a GM unit. >> >Why not just fix it? Or get one of the HD 100 a Mopar units (they look completely different, and are damn good!) And if that ain't good enough, do it right, and get a Leece Neville! Greg ------------------------------ From: Clint Corbin Date: Fri, 12 Mar 1999 18:34:46 -0700 Subject: Re: Real HP loss numbers At 12:52 PM 3/12/99 -0500, you wrote: >I have wondered about this myself. I have heard anywhere from 15% >to 25% in drivetrain losses. What I can't figure out is where the >energy is going. If you have a 300HP engine with 25% drivetrain >loss, then you are losing 75HP somewhere. Since it doesn't just >disappear, something has to be soaking up 75HP of energy. My >guess is that the loss would be in the form of heat which would >mean of lot of drivetrain parts would have to be getting really hot >(assuming the 300HP load on the engine). Since I have only seen >my transmission get warm, it doesn't really make much sense unless >I just haven't had the load on for a long enough period. > >I wonder sometimes if people don't estimate drivetrain losses on the >high side because they don't want to admit that their engines aren't >as powerful as they want them to be. > >Dan L Here is a couple of things to think about. One, friction is "usually" a function of velocity. The faster you spin everything, the greater the friction. If you are climbing a cliff and are actually delivering, say, 200hp to the drive train instead of the normal 35hp your drive train friction shouldn't increase much. If you have an automatic, you will probably get a bit of an increase at the torque converter under this senario. Two, There are a LOT of things on your car that get hotter than hell going down the road. When I was a kid (5 or 6), my folks had a Dodge van. On cold days during long trips I had two places I liked to take a nap: right behind the engine cowl (directly over the transmission) and right over the rearend. Why? In both places the floor was nice and toasty warm! Even when the weather was in the teen's, there was enough energy dumped by the differential to keep the floor nice and warm even with the ice cold air flowing under it! Clint ------------------------------ From: Sandy Date: Fri, 12 Mar 1999 17:43:31 -0800 Subject: RE: [M] Alterpower alternator charging control switch If you are looking for someing that is very cool in the alternator space, check out the stuff from Barnett Engineering. It's a desert topping and a floor wax...Well almost, it is a water pump with a the pulley that houses the alternator, gets rid of weight and eliminates that ugly wart that is always in the way. The only bad thing (well besides the cost) is that it only can do 32 amps. I would expect much less loss as their is one less set of bearing, and my favorite thing the weight. Sandy At 08:27 AM 3/12/99 -0500, you wrote: >Let me jump in here. Most of the performance rags 20 years ago during the >dyno tune age when the mags spent much time reporting on dyno time being >used by big teams like Mickey Thomson, Smokey Yunick, Ed Pink, Keith Black, >etc - it was quite common on motors being setup for endurance type racing >and therefore equipped with alternators to report a 5+ hp loss. Some of >this was recooped by installing bigger pulleys on the alternators. Some >did use clutches (like your air conditioner) which would dump the >alternator during peak rpm periods. Seems like Hot Rod put out a Chevy >manual sometime past which had an article on alternators and included some >discussion of this situation. > >rick > >> -----Original Message----- >> From: KD6JDJ@xxx.com] >> Sent: Thursday, March 11, 1999 9:43 PM >> To: diy_efi@xxx.edu >> Subject: Re: [M] Alterpower alternator charging control switch >> >> Mark >> I cant explain how the claim of 5 hp gain can be accomplished, can you? >> The alternator doesnt ever consume 5 hp, I dont think. That would be >> around >> 300 amps into a 12 'load'. Or , if the alternator, with its bearing and >> belt >> and electrical losses, was only 50 percent efficient, it would have to be >> putting 150 amps into a 12volt 'load'. >> Then if we are considering that the battery is charged, as stated, the >> power >> consumed by the alternator should be way under a hp. At least the power >> consumed by an alternator should be quite low when the battery doesnt need >> to >> be charged, and there are no heater motors and -or air conditioning >> clutches >> and fans running. >> >> This is the message that I read --------- >> >> Thought someone might find this interesting.... Good for 5 free hp at >> WOT. >> -Mark >> >> >> >> Return-Path: owner-merkur-owners@xxx.COM >> >> Here's a gizmo that sounds useful. It automatically switches off >> alternator >> load if you're at full throttle and you've got plenty of charge in your >> battery, >> allowing the engine to devote ALL its power to moving forward. >> >> >> Jerry ------------------------------ From: Sandy Date: Fri, 12 Mar 1999 17:44:41 -0800 Subject: Re: [M] Alterpower alternator charging control switch Oh yeah, get a magnito and cut the belt off. Sandy At 08:51 AM 3/12/99 -0500, you wrote: >Disconnecting the alternator PHYSICALLY, or gearing it down, will make >as much difference, if not more, than shutting off the field as windage >and friction losses are high. Under load at high RPM a change of pulleys >can EASILY give you 3-5 HP average.(while still maintaining adequate >output) Shutting off the field with a fully charged battery at wot? For >short term acceleration? I don't think so. ------------------------------ From: Frank F Parker Date: Fri, 12 Mar 1999 20:45:12 -0500 (EST) Subject: Re: VSS and Transmission Output speed > > > I think I remember reading or hearing that the VSS signal voltage can > get extremely high before conditioning. What voltage levels are you > seeing on average and how high do they peak? > Shannen > I have a app manual for a 4T series trans and from memory since I am out on road, I believe it goes as high as 100 volts. Can check for sure in a day or so. regards, frank parker ------------------------------ From: Sandy Date: Fri, 12 Mar 1999 17:55:11 -0800 Subject: Re: Electric water pumps (was) alt charging cont sw You can get the Barnett alternator with one of the stewart pumps, the one I have is a stewart. Not on a car yet so hard to tell how the setup will work. I was more worried about weight, as It is on a aluminum BBC so it has a little extra hp to have an alternator ;-) Sandy At 07:47 PM 3/12/99 -0500, you wrote: > >-----Original Message----- >From: Clarence Wood >To: diy_efi@xxx.edu> >Date: Friday, March 12, 1999 7:28 PM >Subject: Re: Electric water pumps (was) alt charging cont sw > >Two places might have it stewartcomponents.com, and Smokey's book on the >SBC. >Don't be surprised when ya see it in GPM >Bruce > > >> Does anybody know what the gph should be on a 6cyl engine? V8? > ------------------------------ From: bearbvd@xxx.net (Greg Hermann) Date: Fri, 12 Mar 1999 19:00:22 -0700 Subject: Re: Electric water pumps (was) alt charging cont sw >-----Original Message----- >From: Clarence Wood >To: diy_efi@xxx.edu> >Date: Friday, March 12, 1999 7:28 PM >Subject: Re: Electric water pumps (was) alt charging cont sw > >Two places might have it stewartcomponents.com, and Smokey's book on the >SBC. >Don't be surprised when ya see it in GPM >Bruce Prolly about 100 or 125 gpM for a 350! Greg > > >> Does anybody know what the gph should be on a 6cyl engine? V8? ------------------------------ From: Mark_Duewel@xxx.gov Date: Fri, 12 Mar 1999 17:57:42 -0800 Subject: Re: Electric water pumps (was) alt charging cont sw Don't leave out the electrically driven alternator! (PWM controlled too) There is even a good debate possible as to whether a high pressure fuel pump should be electrically or mechanically driven, let alone a water pump, or an engine fan (if you are working an engine any kind of hard at low speeds for any length of time)! For any sizable auxiliary drive loads, a mechanical drive is way more efficient than an electrical one. Regards, Greg ------------------------------ From: Daniel Ciobota Date: Fri, 12 Mar 1999 21:35:02 -0600 Subject: Re: Chassis dynos exposed Jason_Leone@xxx.com wrote: > Since all this talk about chassis dyno figures and methods has erupted > today, I > submit this. They're are a few distinct differences in chassis > dynamometer > types. Each type has pros and cons. > > Up until a year or so ago, all the load type dynos out there had > primitive > operating > systems, if at all. They worked by running the car on the dyno, > loading up the > rollers (usually via a water brake system), and reading the horse > power number > when the load prevented the engine from accelerating past a > predetermined rpm. > That's an engine dyno setup, I've never seen a car dyno of this type. The dynojet type systems have been around for at least three years (my earliest chassis dyno runs) [...] > This is all in contrast to the Dynojet inertia type testing, which > simply > requires the > car to run on the rollers from standstill or low rpms, to redline or > anywhere in > between (in one or several gears). The rate of acceleration is > measured, and > power > is mathematically calculated using the constant of roller weight. The > time it > takes to > accelerate a given mass to a particular speed can be used to calculate > hp. It is > relatively painless to the car, and quickly measured. Plus, the > Dynojet software > allows automatic graphing, which produces an attractive consumer > product. > > However, the downside to this measuring form is that, in the real > world, the > vehicle > is working harder than what is required in accelerating the rollers on > a > Dynojet. > Since the rollers are 1000lb a piece, a 2000lb weight is enough to stress the motor to the detonation point, if any. Detonation has less to do with load than combustion chamber temps, timing advance, octane, etc. > The Dynojet is a great marketing tool, but is not an accurate, real > world > measuring > device. Dynojet now has a load type device that can be added to their > existing > models, but it currently is fixed, and cannot be altered. So, it > suffers from > the same > drawback as the older type load dynos. Dunno about your case, but I know several race mustang owners that will disagree (one's a former NMCA champ. Lee Bender). I have seen motors set up on the ragged edge on those dynos (read, lean and advanced), without detonating on the street. No dyno can give you absolute, incontestable hp numbers, but as a tuning tool, it's a big bang for the buck. > The best of both worlds is the load type dyno with a sophisticated > operating > system. For example, a Mustang MD-250 chassis dyno is rated at a > maximum hp load > of 750. Sounds to me like you're marketing these units. I'm not saying they're bad, but don't knock down the other dynos. They're very useful tuning tools, at least for me and some other fellow racers. All dynos are good, whether chassis, engine, or, as in the case of my former vertible stang, "car mounted". Daniel ------------------------------ From: Daniel Ciobota Date: Fri, 12 Mar 1999 21:35:02 -0600 Subject: Re: Chassis dynos exposed Jason_Leone@xxx.com wrote: > Since all this talk about chassis dyno figures and methods has erupted > today, I > submit this. They're are a few distinct differences in chassis > dynamometer > types. Each type has pros and cons. > > Up until a year or so ago, all the load type dynos out there had > primitive > operating > systems, if at all. They worked by running the car on the dyno, > loading up the > rollers (usually via a water brake system), and reading the horse > power number > when the load prevented the engine from accelerating past a > predetermined rpm. > That's an engine dyno setup, I've never seen a car dyno of this type. The dynojet type systems have been around for at least three years (my earliest chassis dyno runs) [...] > This is all in contrast to the Dynojet inertia type testing, which > simply > requires the > car to run on the rollers from standstill or low rpms, to redline or > anywhere in > between (in one or several gears). The rate of acceleration is > measured, and > power > is mathematically calculated using the constant of roller weight. The > time it > takes to > accelerate a given mass to a particular speed can be used to calculate > hp. It is > relatively painless to the car, and quickly measured. Plus, the > Dynojet software > allows automatic graphing, which produces an attractive consumer > product. > > However, the downside to this measuring form is that, in the real > world, the > vehicle > is working harder than what is required in accelerating the rollers on > a > Dynojet. > Since the rollers are 1000lb a piece, a 2000lb weight is enough to stress the motor to the detonation point, if any. Detonation has less to do with load than combustion chamber temps, timing advance, octane, etc. > The Dynojet is a great marketing tool, but is not an accurate, real > world > measuring > device. Dynojet now has a load type device that can be added to their > existing > models, but it currently is fixed, and cannot be altered. So, it > suffers from > the same > drawback as the older type load dynos. Dunno about your case, but I know several race mustang owners that will disagree (one's a former NMCA champ. Lee Bender). I have seen motors set up on the ragged edge on those dynos (read, lean and advanced), without detonating on the street. No dyno can give you absolute, incontestable hp numbers, but as a tuning tool, it's a big bang for the buck. > The best of both worlds is the load type dyno with a sophisticated > operating > system. For example, a Mustang MD-250 chassis dyno is rated at a > maximum hp load > of 750. Sounds to me like you're marketing these units. I'm not saying they're bad, but don't knock down the other dynos. They're very useful tuning tools, at least for me and some other fellow racers. All dynos are good, whether chassis, engine, or, as in the case of my former vertible stang, "car mounted". Daniel ------------------------------ From: Daniel Ciobota Date: Fri, 12 Mar 1999 21:42:11 -0600 Subject: Re: Real HP loss numbers Clarence L.Snyder wrote: > > So, when someone is talking about a 75hp loss, not all that loss is > friction, > > otherwise our drivetrains would glow in the dark! However, much of > the loss due > > to momentum is taken up by the engine (more strain), which shows up > as heat in > > the coolant and oil. > > > > If my physics are wrong, please correct me. > > > > Just my $0.02. > > The indicated horsepower on an inertia dyno may indicate this as lost > power, but in fact it is not. In a sustained speed condition all the > inertia effects dissapear, and when you slow down you get the power > back. An accurate chassis dyno cannot depend on inertia alone. Technically, you're correct, hp required to bring all rotating mass up to a certain speed is actually stored, and released when you let off the gas. But, rear wheel hp is still affected by the amount of energy you store in the rotating assembly past the flywheel; thus, the larger the momentum, the more energy required to bring to a certain speed, the less energy remaining to spin the drums, thus less rear wheel hp numbers. Daniel ------------------------------ From: Daniel Ciobota Date: Fri, 12 Mar 1999 21:49:42 -0600 Subject: Re: Real HP loss numbers Shannen Durphey wrote: > Ok, I'm working to understand this. The chassis dyno has no brake, so > > they measure the change in acceleration of the drums to compute > power. This means that anything that changes the rate of acceleration > > of the wheels changes the rate of acceleration of the drums, and the > calculated horsepower. This also means that without acceleration, the > > chassis dyno cannot measure horsepower, hence no steady rpm > measurements can be taken and no tuning done at any given rpm, yes? > Correct. > This would also mean that claims like "lighter pulley adds 5 hp" are > mrginally correct based on chassis dyno measurements, but technically > should say something like "lighter pulley increases acceleration > equivalent to adding 5 more hp", since at any given rpm the hp level > is ~constant, regardless of the mass of the rotating components. > Yes? Two for two... :-) > I only ask because I can see no other way that claims for replacing > rotating components with lighter ones can add power. But I sure can > see that they'll change the rate of acceleration. Advance to the head of the class, you get an A+. Seriously, in the real world, you want to consider anything that would make a difference in your et numbers (hopefully, a positive one). Even though pullies don't add actual hp, they do help your car accelerate faster; that's what counts, right. Brake type dynos eliminate all inertia effects and give you actual engine hp (minus frictional losses); however, they totally ignore effects of lighter flywheels, different trannies, etc. There's no perfect dyno, but as tuning tools both accelerometer and brake type dynos are invaluable. Daniel ------------------------------ From: "Ferman C. Lao" Date: Sat, 13 Mar 1999 11:04:39 +0800 Subject: Re: Chassis dynos exposed Dear Jason, Would you happen to know where this type of dyno is available & where I can get more information about it? Thanks. - -----Original Message----- From: Jason_Leone@xxx.com> To: diy_efi@xxx.edu> Date: Saturday, March 13, 1999 7:19 AM Subject: Chassis dynos exposed >The best of both worlds is the load type dyno with a sophisticated operating >system. For example, a Mustang MD-250 chassis dyno is rated at a maximum hp load >of 750. >However, we can load it from 0hp (simply spinning the attached flywheel and >rollers like the Dynojet) up to 750hp and anywhere in between. We can specify a >time period over which we want a load to be applied. We can simulate a series of >hills, as the car goes up and down in elevation, which obviously varies the load >on >the engine. We can set a specific rpm at which the dyno can apply a specific >load. > >In other words, the load application on a MD-250 dyno is practically infinitely >variable, >and can be as punishing or gentle on the engine as we want. All controlled by >the >Windows based software on the controller PC, with hand held operator controls. >For development use, the load ability is crucial, to produce a product that will >perform correctly in the real world. For promotional use, such for dyno days, >the >inertia mode is useful. > >Hope that clears us some confusion regarding the types of chassis dynamometers >out there. > >Jason >'93 SLC > > ------------------------------ From: "Clarence L.Snyder" Date: Fri, 12 Mar 1999 23:58:02 -0500 Subject: Re: Chassis dynos exposed > That's an engine dyno setup, I've never seen a car dyno of this type. > The dynojet type systems have been around for at least three years (my > earliest chassis dyno runs) > > [...] The "rolling road" dynos - can't remember the brand but my memory seems to think Stewart Warner or ? from the sixties/seventies were combination load cell/inertia units. The inertia rollers could be used for brake testing as well as making the load test realistic. No fancy PC to control it, but in skilled hands you could do a full RPM range, through the gears, in about 2 minutes flat. The readings were strictly RPM and torque from which the horsepower was derived using a circular slide rule supplied with the unit. If I remember correctly there was a paper strip readout, like a printing calculator available. The one we had at the college just used a second body to write the numbers when you pushed the meter lock button. Pick your RPM, throttle up, load it down, balance load and throttle until the RPM at WOT was at spec, and read the torque. ------------------------------ End of DIY_EFI Digest V4 #163 ***************************** 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".