ND4SPD Posted January 29, 2018 Share Posted January 29, 2018 1. Engine dynamometer, engine test stand, motorna kocnica, tu se mjeri snaga/moment na zamasnjaku ili radilici, to su sluzbeni SAE (Society of Automotive Engineers) podatci svih proizvodjaca... Vise izracunima prema kojima su dobiveni SAE standardi za izmjerenu snagu/moment mozete procitati ovdje: https://wahiduddin.net/calc/cf.htm https://www.dynomitedynamometer.com/dyno-tech-talk/corrected-horsepower.htm 2. Chassis dynamometer (rolling road), tu se mjeri snaga na kotacima ili glavcini (hub dyno), gdje se izmjerena snaga uz predefinirane izracune i korekcije pretvara u snagu na radilici, gdje postoje razlike od valjaka do valjaka... O problemu konverzije, odnosno izracuna snage sa kotaca na radilicu mozete procitati dolje na linku, citirati cu najzanimljiviji dio: Dobeck got his start tuning English sports cars in a Portland, Oregon, garage in the late ’70s. He had hot-rodded the shop’s Sun infrared exhaust analyzer to improve response time and became a wiz at using exhaust-gas carbon monoxide to optimize power on the go. The trouble came later when he moved on in 1980 to open a motorcycle shop in Wisconsin. Cars were one thing, but there was no way to haul a gas analyzer as big as a TV set on a motorcycle. So Dobeck talked his inventor/fabricator father into building a stationary rolling-road that could support the rear wheel of a motorcycle on a moving drum so he could continue tuning while “driving” with the big infrared analyzer. The rolling road was designed with a hydraulic system that could be adjusted to work a bike engine harder at a given speed, something like the resistance controls on a Stairmaster machine. But because Dobeck and his dad were mechanics rather than mathematicians, they made the rolling drum heavy, and the homebuilt dyno had a surprising amount of inertia. It was accidentally pretty good at simulating a motorcycle’s ability to accelerate. Dobeck’s new bike shop opened just in time for the arrival of Japanese superbikes equipped with constant velocity (CV) carbs, which were new to motorcycling. CV carbs provided good performance, economy, and emissions, but they could not be tuned and jetted using traditional methods. Many people recommended replacing them, a $600 solution. But Dobeck understood CV carbs from the days of wrenching on English cars and modified them to allow the new motorcycles to run with performance pipes and air cleaners. Before long, bikers were traveling from all over the upper Midwest for Dobeck’s dyno-jetting service. Meanwhile, in the evenings, Dobeck read magazine stories of hot rod bikes running exhaust-system shootouts on the torque-cell dynos of famous California super tuners. Performance magazines loved dynamometers because they brought science to hot rodding. But torque-cell dynos, which load an engine by forcing it to pump water or generate electricity, are expensive, and using them has often required removing the engine from the vehicle. “I started to realize I was doing something that no one else was doing,” says Dobeck, who was using his homebuilt inertial dyno to tune bikes with the goal of improving acceleration and responsiveness. “Eventually I built a few jet kits to see what we could do with them.” Dobeck named his company Dynojet. His first big customer was K&N Filters, and it wasn’t long before he was selling lots of jet kits. His company grew at a rapid pace, and sure enough, a competitor sprang up with a similar product. “Their advertising was working,” Dobeck says. “They were taking away sales. But the product didn’t work. Not at all.” To prove it, he called several of the top engine-dyno suppliers to see if they would help him develop an affordable version of his homebuilt inertial chassis dyno that could live in the shops of Dynojet dealers to show the world what worked and exactly how well. “Every one of them laughed at me,” Dobeck remembers. One of the biggest headaches of Dynojet’s go-it-alone chassis-dyno project was figuring out how to assign meaningful power numbers in the face of unknown inertia from the moving parts of the hundreds or thousands of engine, drivetrain, and tire combinations. Wrestling to fully understand inertia and powertrain losses, Dobeck and his team quickly realized that the standard physics formula of weight, time, and distance for converting acceleration into horsepower simply didn’t work-the derived number was always lower than accepted numbers. They poured on resources and burned up time and money investigating it, but no matter what they did, the math never added up. Dynojet’s final number-fudge was arbitrarily based on a number from the most powerful road-going motorcycle of the time, the ’85 1,200cc Yamaha VMax. The VMax had 145 advertised factory horsepower, which was far above the raw 90hp number spit out by the formula. Meanwhile, existing aftermarket torque-cell engine dynamometers delivered numbers that clustered around 120. Always a pragmatist, Dobeck finally ordered his Chief Engineer to doctor the math so that the Dynojet 100 measured 120 hp for a stock VMax. And that was that: For once and forever, the power of everything else in the world would be relative to the ’85 Yamaha VMax and a fudged imaginary number. Dobeck’s engineering staff was dismayed by the decision, but the Dynojet 100 exclusively measured surplus power available to accelerate the vehicle’s mass-no more, no less-and that was true even if the modification was a low-inertia flywheel or lightweight wheels. As long as the inertial dyno’s numbers were repeatable, the critical question (did a particular modification make the engine accelerate faster or slower?) would be answered correctly. Vjerujem da su se u zadnjih 10 godina stvari po tom pitanju popravile, te da je preracunata snaga na radilici jos tocnija onoj koja bi bila izmjerena na pravoj motornoj kocnici, iako postoje razni nacini mjerenja na chassis dyno-u, te postoje odstupanja od jednog proizvodjaca valjaka do drugih, neki su poznati da prikazuju malo, drugi da prikazuju vise... Dolazimo do toga da je primarna namjena tih valjaka tuniranje ECU-a na njima, a ne prikaz snage... Ako se dobro sjecam, netko je mjerio gubitke za Lancer EVO, cini mi se englezi na lancerregisteru, ali ne da mi se sada traziti link... Dakle stavili su motor na motornu kocnicu, pa na valjke, ako me pamcenje dobro sluzi chasis dyno je bio od Dyno Dynamicsa, a izmjereni gubitci 24%... U tu brojku nisu ukljuceni gubitci u valjcima koji su predefinirani od strane proizvodjaca valjaka... Nekakav medijan koji se spominje kod Lancera EVO je 20-25% gubitaka... Lancer EVO je AWD automobil sa permanentnim AWD pogonom i tri blokade diferencijala... Postoji vise razloga tzv. parazitskih gubitaka i svi su medjusobno povezani... Dakle, gubitci mogu biti zbog frikcije, uslijed kontakta dijelova, frikcije sa uljem, te gubitka inercije zbog tezine rotirajucih dijelova, a na to se pridodaju i gubitci u mjenjacu, koji se ne mogu izmjeriti coast down metodom mjerenja na chasis dyno-u... Isto tako, ti gubitci od 24% vrijede samo za Lancer EVO i to za odredjenu generaciju Lancera EVO, te se ne mogu primijenjivati na druge modele automobila... Jedan dobar clanak o tome: Drivetrain Power Loss - The 15% "Rule" Can You Apply A Universal Power Loss Percentage To All Drivetrains? Drivetrain loss is a common topic of conversation in the tuner world because any time you strap your car to a chassis dyno, the output being measured is at the wheel, not at the crank like the published SAE net horsepower figures used by the auto industry. Strap your 298-bhp RevUp G35 Coupe to the dyno and you may be disappointed to see little more than 220-230 horses measured at the rear wheels. Where did that 60-plus horsepower go missing? It was used up in a variety of ways before it could reach the drive wheels, the primary source being what's broadly described as drivetrain loss. What's interesting about this example is that when you do the math you'll see that the percent loss is much higher than the 15 percent "rule" you'll find in any number of online threads on the subject. For whatever reason, drivetrain loss seems to be one of the most poorly understood subjects discussed on online car forums, so despite my love of the Internet and the limitless pornography it makes available to me, when it comes to a fairly technical subject like this it's hard to find good information. A few years ago, I needed to educate myself on drivetrain losses while heading a rulebook committee for a local racing series that wanted to use dyno tests to measure engine output and then convert the results to net horsepower. After fruitlessly Googling and sifting through endless car forum threads polluted with half-truths and misinformation, I turned to the same source that developed the current manufacturer horsepower standard, the Society of Automobile Engineers (SAE). On its website you can access brief summaries of technical papers published by some of the world's leading automotive engineers and download the complete documents for a relatively small fee (usually less than $10 per article). As luck would have it, in 2002 the SAE held a symposium on transmission and driveline systems, and the papers that came out of it covered drivetrain loss in great detail. One of the first things I learned from reading these papers was to completely disregard the 15 percent drivetrain loss "rule" (or any other percent value) that so often comes up during online discussions of whp versus net horsepower. The fact of the matter is every vehicle experiences different levels of drivetrain loss as determined by the design of its transmission and driveline components. Simply put, the amount of horsepower lost to the forces of inertia, drag, windage, pumping and friction are different for every engine, transmission and driveline design. So the total power lost between combustion and forward motion is specific to each vehicle and therefore no single rule, percentage or fixed number, could possibly apply to all vehicles. Even on the most superficial level, this is easy enough to understand because an all-wheel-drive Subaru obviously has a lot more driveline components to spin (front, middle and rear differentials along with front and rear driveshafts and two prop shafts) and a beefier transmission to hold all that turbocharged torque, so it's naturally going to suffer from greater drivetrain losses than a Honda Fit with its much smaller and less robust transmission, smaller and lighter driveshafts (and no prop shaft) and single differential. Breaking down the different types of losses that occur within a vehicle's drivetrain, steady-state losses occur while the vehicle is cruising at a steady or constant speed, where average angular acceleration is zero because no additional torque is being called upon to accelerate the drivetrain's rotational mass. Within the drivetrain, steady-state power losses occur from the following components: the transmission torque converter (in the case of automatic transmissions), the transmission oil pump, clutch pack drag, one-way clutch drag, seal and bearing drag, gear windage and friction, and final drive losses. Dynamic drivetrain losses, on the other hand, include the rotational inertial losses from angular acceleration occurring within the drivetrain while accelerating. In fact, during acceleration there are losses from the rotational inertia of spinning transmission and differential internals as well as driveline components like driveshafts and prop shafts, but also from the increased load and friction being generated between the gears within the transmission and differential(s). And as you already know, with increased friction comes increased heat (more on that later) It's important to understand the difference between steady-state and dynamic losses because SAE net horsepower, as reported by the auto industry, is measured in a steady-state condition. What this means is that the horsepower rating for your vehicle doesn't take into account dynamic losses that occur during acceleration. However, when you strap your car to a chassis dyno to measure its engine's output, the test is conducted at wide-open throttle and power is measured by the speed at which the dyno's rollers are accelerated. This means that drivetrain losses from rotational inertia and increasing friction, drag and windage are at work and will reduce the peak horsepower reading at the wheels. Within the drivetrain itself, the primary loss sources are the differential and final drive, with further losses stemming from within the transmission, and in the case of AWD vehicles, from the transfer case. Within the transmission, as much as 30 to 40 percent of power loss can be attributed to the pump, with the clutch contributing another 20 to 25 percent. The rest of the loss within the transmission comes from seal drag, gear meshing, bearings, bushings and windage (drag on the gears caused by the gear oil). However, when dyno testing in the direct drive (1:1) gear, power is delivered directly through the mainshaft of the transmission, so the only loss sources are windage, friction and drag, resulting in total at-the-wheel losses as low as 1.5 to 2 percent, according to the published data. Differential losses tend to be considerably larger, especially in the case of RWD and AWD vehicles where the torque path is turned 90 degrees as it enters the rear diff and exits it toward the rear wheels. In the case of hypoid-type gearsets (where the gear tooth profile is both curved and oblique) that are commonly used in RWD differentials, losses in the 6 to 10 percent range are the norm, while loss from the driveshaft(s) and prop shaft(s) tend to account for about 0.5 to 1 percent of total loss, depending on how well they're balanced and how many the vehicle is equipped with. In the case of FWD vehicles, the torque path is more direct to the front wheels and the use of efficient helical final drive gears means that drivetrain losses can be as much as 50 percent lower than on RWD and AWD vehicles. In any drivetrain component with meshing gearsets, heat generated by contact friction between the gears is a significant contributor to drivetrain loss. This is true during steady-state driving, but is far more of an issue when the throttle is mashed to the floor and the resulting thrust force and angular acceleration builds up in these drivetrain components. The heat generated by this dynamic friction is absorbed by the transmission and differential fluid as well as radiated to the atmosphere through the transmission and differential housing(s), and in some cases, via a heat exchanger or oil cooler. This absorbed and radiated heat is literally the conversion of engine torque into thermal energy because you can't technically "lose" power, but can only convert it into other things (some of our favorites being forward motion and tire smoke). It's also worth noting that the more powerful you make your engine, the greater the thrust force and angular acceleration it's able to exert on the drivetrain, generating even more friction and heat in the process. But because both steady-state and dynamic friction vary depending on engine speed, engine load and the efficiency of the engine and drivetrain's design (how well they limit friction and the associated thermal conversion of torque to heat), there's no way to apply a universal percent loss to it. Nor is it possible to apply a fixed drivetrain loss figure to your car (say 60 whp from my RevUp G35 example), because as you modify the engine and increase its output its ability to generate thrust force and angular acceleration also increases (though not in a linear fashion). In the end, there's no easy way to estimate the drivetrain loss your vehicle experiences on the road or even on the dyno. Coast-down tests are sometimes used on a dyno to attempt to measure frictional losses, but because this test is not dynamic (meaning they're not done while accelerating, but rather while coasting to a stop with the direct drive gear engaged but the clutch depressed so that the engine and transmission aren't linked) it really only captures steady-state drivetrain losses as well as rolling resistance. So rather than attempting to convert your vehicle's dyno-measured wheel horsepower to a SAE net horsepower figure using a percentage or a fixed horsepower value, you're far better off accepting the fact that these two types of horsepower measurements aren't easily correlated and forego any attempt at doing so. 1 Link to comment Share on other sites More sharing options...
Hic Posted January 30, 2018 Share Posted January 30, 2018 Opet ti protiv vjerrenjaca... 2 Link to comment Share on other sites More sharing options...
Rockatansky Posted January 30, 2018 Share Posted January 30, 2018 Aj nek čujem coastdown... Link to comment Share on other sites More sharing options...
fire Posted January 30, 2018 Share Posted January 30, 2018 Bas me zanima ako itko zna gdje se nalzi senzor u dyno-u i sto on zapravo mjeri. Link to comment Share on other sites More sharing options...
IVAN_VXR Posted February 4, 2018 Share Posted February 4, 2018 Mjeri okretni moment,a nalazi se iza kočnice tj na kraju njene osovine? Link to comment Share on other sites More sharing options...
fire Posted February 4, 2018 Share Posted February 4, 2018 19 minutes ago, IVAN_VXR said: Mjeri okretni moment,a nalazi se iza kočnice tj na kraju njene osovine? Da i zbog toga mjeri snagu na osovini valjka. Link to comment Share on other sites More sharing options...
Mitja Posted February 9, 2018 Share Posted February 9, 2018 Obicno je Torque sensor na kucistu od retardera , direkt osovini je senzor za obrtaje. Za usporedbu , na radilici motora je popularan 60-2 Bosch sistem. Kod valjka je 1000 "zuba" na obrtaj. 1 Link to comment Share on other sites More sharing options...
fire Posted February 9, 2018 Share Posted February 9, 2018 I znaci sto taj senzor mjeri? Momet(tj. snagu) gdje? Na kotacu? Ili na osovini valjka? Link to comment Share on other sites More sharing options...
Mitja Posted February 9, 2018 Share Posted February 9, 2018 Moment na razdalji od osovine do tacke gdje je senzor zasarafen u pod. 1 Link to comment Share on other sites More sharing options...
fire Posted February 9, 2018 Share Posted February 9, 2018 2 hours ago, Mitja said: Moment na razdalji od osovine do tacke gdje je senzor zasarafen u pod. Tocno, znaci ne na kotacu. Nego tu gdje rekao. 1 Link to comment Share on other sites More sharing options...
ruscic Posted February 11, 2018 Share Posted February 11, 2018 Tocno, znaci ne na kotacu. Nego tu gdje rekao.Svaki stock auto provjerin na wiki tvornicke podatke, uvik mi se slaze snaga i moment pogotovo. Jel tvornicki podatak momenta mjeren na radilici? Poslano sa mog S60 koristeći Tapatalk Link to comment Share on other sites More sharing options...
fire Posted February 11, 2018 Share Posted February 11, 2018 6 minutes ago, ruscic said: Svaki stock auto provjerin na wiki tvornicke podatke, uvik mi se slaze snaga i moment pogotovo. Jel tvornicki podatak momenta mjeren na radilici? Poslano sa mog S60 koristeći Tapatalk Kada tvoj dyno mjeri gubitke susatava da bi dobio tocnu snagu na radilici. Tako rade svi tocni dyno-i. Link to comment Share on other sites More sharing options...
ruscic Posted February 11, 2018 Share Posted February 11, 2018 Kada tvoj dyno mjeri gubitke susatava da bi dobio tocnu snagu na radilici. Tako rade svi tocni dyno-i.Sta je i normalno Poslano sa mog S60 koristeći Tapatalk Link to comment Share on other sites More sharing options...
fire Posted February 23, 2018 Share Posted February 23, 2018 (edited) Evo usporedba 3 "dyno-a" u hr. Isti auto, prodan i naplacen turbo za 420hp, a za pravo stavljen jeftin za 360hp. Uglavnom isti auto na istim postavkama. Ima jos takvih slucajeva, uvijek slicna odstupanja, doda se po 40-50hp. Edited February 23, 2018 by fire 1 Link to comment Share on other sites More sharing options...
KIMI_1.8T Posted February 23, 2018 Share Posted February 23, 2018 Jel to bivsa od Kirete? Link to comment Share on other sites More sharing options...
fire Posted February 23, 2018 Share Posted February 23, 2018 52 minutes ago, KIMI_1.8T said: Jel to bivsa od Kirete? Ne, ovo je druga. Link to comment Share on other sites More sharing options...
KIMI_1.8T Posted February 23, 2018 Share Posted February 23, 2018 A ko je to mapirao i cija je turbina? Link to comment Share on other sites More sharing options...
Dario Posted February 23, 2018 Author Share Posted February 23, 2018 1 minute ago, KIMI_1.8T said: A ko je to mapirao i cija je turbina? bog tuninga Link to comment Share on other sites More sharing options...
KIMI_1.8T Posted February 23, 2018 Share Posted February 23, 2018 Just now, Dario said: bog tuninga A turbina? Link to comment Share on other sites More sharing options...
Dario Posted February 23, 2018 Author Share Posted February 23, 2018 neam pojma, valjda neka kupovna Link to comment Share on other sites More sharing options...
KIMI_1.8T Posted February 23, 2018 Share Posted February 23, 2018 Fire, cija je turbina? Link to comment Share on other sites More sharing options...
Hic Posted February 23, 2018 Share Posted February 23, 2018 Alo....pa nisi 1ks izvukao ahahahaha Kimi, turbina je od Turbosystems iz Litve, vlasnik Mantas Pundys, iste turbine su na nasem RS6 i M3, te sada na ovom bugarskom RS6 koji je kod mene.Turbina ima billet usis, najveci koji stane, plus clipped wheel na ispuhu. Rejtana za max 400ks. Garancija 24mj. Veca nejde u to kuciste na insigniji. To mozes i sam provjeriti.Tako....ove price za malu djecu ostavite maloj djeci. Auto kad je dosao, imao je tocno 138.9kw na kotacima, i na kraju, sa turbom, wagner ic-om i auspuhom 231.9kw na kotacima. Sva 4. That is it. A pogle koje bureke se baca: Dobijes ravno kurac u dupe, a ne 20ks ahahahahahaOvo je demistifikacija onih koji mogu izvuc jedino smrklj iz nosa: Link to comment Share on other sites More sharing options...
fire Posted February 23, 2018 Share Posted February 23, 2018 Samo 45hp ti valjci vise kazu na istom autu. Nije to malo. Link to comment Share on other sites More sharing options...
Hic Posted February 23, 2018 Share Posted February 23, 2018 AhahahahahahahahahahMatematika je prokleta magija Link to comment Share on other sites More sharing options...
Zoka RS Posted February 23, 2018 Share Posted February 23, 2018 @hic kako si mogao tako covjeka zavaljati? Sjebat ga za turbo pa mu uplacivat novce na racun..? Sve ti uredno plati i ti ga izvaras.. Link to comment Share on other sites More sharing options...
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