Review of HP and Torque

1. Review of HP and Torque • Torque is a measurement of twisting force. • A 1 foot wrench with 1 pound of force pushing on the end of the wrench is said to produce 1 foot-pounds of torque. • There does not need to be motion to create torque, unlike horsepower. • Torque is a SCALAR measurement, which means it has magnitude only. • Electric motors can produce torque at zero rpm. • Engines can’t because they won’t run at low rpm.

2. Review of HP and Torque • Horsepower is a measure of work. • Horsepower can only be calculated after torque and rpm are known. • Horsepower is a VECTOR measurement, meaning that it has both magnitude and direction. • Direction in this case is rotary. • If there is no motion, no work is done. • Because of this, the engine must be rotating to create horsepower.

3. Review of HP and Torque • Can be thought of as weight lifters. • ‘A weightlifter can lift 400 lbs’ • All this tells us is that he can lift 400 lbs. • We don’t know how many times per minute he can lift this much. • We can compare this to TORQUE. • ‘A weightlifter can lift 400 lbs 5 times per minute’ • Not only does this tell us how much he can lift but how much per minute. • We can compare this to horsepower.

4. Dynamometers What is a dynamometer? On the most basic level, a dynamometer is a tool for measuring the torque output and rpm of an engine. Using the torque measurement and rpm the dynamometer will automatically calculate horsepower. Horsepower is not directly measurable. Horsepower = Torque x RPM / 5250

5. Dynamometers • Today’s dynamometers take a variety of measurements. • Air/fuel ratio (AFR). • Air/fuel ratio is measured using a device calling an air/fuel ratio analyzer. • A popular AFR analyzer is MoTeC’s PLM. • High end units are made by Horiba or Labcell. • Hobby level kits are made by various manufacturers and are available by companies such as Summit Racing.

6. Dynamometers • The air/fuel ratio analyzer has a sensor, similar to an O2 sensor, which is bolted into the exhaust using a ‘bung’. • The sensor is called a UEGO (universal exhaust gas oxygen) sensor. • Also known as a ‘Lambda’ sensor. • It is not the same as an oxygen sensor or air/fuel ratio sensor found in a normal passenger car or truck.

7. Dynamometers • The high end air/fuel ratio analyzers use a sensor which is very accurate and has a very high sampling rate. • The ‘sampling rate’ is the speed at which the measurements are updated. • Air/fuel ratio is defined as the ratio, by weight, of air to fuel. • The stoichiometric ratio, also known as ‘stoich’, is 14.7:1 for gasoline.

8. Dynamometers • The stoichiometric ratio is that ratio at which every molecule of air will chemically react with every molecule of fuel. • In practice, this never happens – there are always molecules that do not react and leave via the tailpipe. • A 14.7:1 AFR would be 14.7 lbs of air to 1 pound of fuel.

9. Dynamometers • An AFR less than 14.7:1 is considered ‘rich’. • This means that there is more fuel in the mixture than is chemically correct. • For example, 12.5:1 AFR. • An AFR more than 14.7:1 is considered ‘lean’. • This means that there is less fuel in the mixture than is chemically correct. • For example, 16:1 AFR.

10. Dynomometers • Some tuners prefer to tune in ‘Lambda’. • Also known as the ‘excess air factor’. • In Lambda, stoich is represented by ‘1’. • Anything less than 1 is rich. • For example, .85 Lambda corresponds to a 12.5:1 AFR • A 1.1 Lambda corresponds to a 16:1 AFR.

11. Dynamometers • Coolant temperature. • It is very important that the engine coolant temperature be consistent from one dyno ‘pull’ to the next or readings could be inaccurate. • Exhaust temperature (using thermocouples). • A thermocouple is a device which plugs into each individual exhaust port and measures temperature.

12. Dynamometers • By probing individual exhaust ports you can determine if there is a problem in one cylinder. Or, on a carbureted engine, you can determine if equal amounts of fuel and air is being delivery to each cylinder. • Lean cylinders will have higher temperatures that rich cylinders. • The extra fuel in a rich mixture causes combustion to be cooler due to a phenomena called ‘latent heat of vaporization’.

13. Dynamometers • Brake specific fuel consumption (BSFC). • BSFC is a measure of fuel efficiency. • BSFC is the rate of fuel consumed divided by the power produced. • BSFC is expressed in ‘pounds per horsepower hour’ or lbs per hp/hr.

14. Dynamometers • An efficient engine might be around .35 lbs per hp/hr. • An inefficient engine might be around .60 lbs per hp/hr. • It is possible that both these engine make the same amount of horsepower. • The engine with .35 lbs. per hp/hr would get considerably better fuel consumption. • Fuel efficiency very important in endurance racing (races lasting a long time – 4, 12, or 24 hours) for less pit stops.

15. Dynamometers • Intake air temperature. • The temperature of the air coming into the engine. • Air temperature has a very large effect on power output. • Colder air = more power. • Cold air is more dense and therefore contains more oxygen per unit volume.

16. Dynamometers • Ignition timing and advance curves. • Some dynamometers can track ignition timing advance. • Some dynamometers have integrated detonation detection equipment.

17. Dynamometers • Ambient conditions. • Ambient temperature. • Humidity. • Barometric pressure. • Different brands of dynamometers have different capabilities.

18. Dynamometers • First dynamometer was called a prony brake.

19. Dynamometers • Prony brake was made of wood and leather. • Wood block mechanism attached to ouput shaft of engine. • Lever arm rests on a scale (like a bathroom scale). • As engine is run, thumb screws are tightened until rpm is steady. • Force on scale is read and rpm is recorded. • Very primative.

20. Dynamometers • Different types of dynamometer mechanisms. • Type of dynamometer is determined by it absorption unit. • The absorption unit is what loads the engine. • Eddy current or electromagnet brake. • Hysteresis type is used for small engine dyno’s (<200 HP).

21. Dynamometers • Electric motor/generator type. • Has the ability to both load the engine and motor it. • This can be useful for measuring the amount of friction when the engine is motored. • Hydraulic brake • Output shaft drives gear-drive pump • Variable orifice on outside of the pump

22. Dynamometers • Water brake • Have high load capacity • Low cost • Uses something similar to a torque converter in an automatic transmission to load the engine.

23. Dynamometers • Inertial Dynamometer. • Dynojet Dyno’s, which are the most popular dynamometers, are inertial. • Do not have the ability to load the engine. • Works by spinning a large, heavy drum. • Horsepower and torque are ‘interpolated’ by how fast it takes to spin up the drum. • Readings are typically 10% higher than other dynamometers. • Many people use the term DHP (Dynojet horsepower) instead of wheel horsepower. • They are inexpensive and therefore popular.

24. Dynamometers • Different types of horsepower and torque measurements. • Brake torque and means it was measured with a dynamometer which has the ability to load the engine. • Torque is referred to as ‘Brake Torque’ • BHP = ‘Brake Horsepower’ • HP measured at the wheels on a chassis dyno is called WHP or ‘Wheel Horsepower’. • Dynojet horsepower sometimes called ‘DHP’.

25. Dynamometers • There are 2 basic types of dynamometers. • Engine dynamometer. • Chassis dynamometer. • An engine dynamometer tests the engine only. • A chassis dynamometer test the engine while it is in the car, therefore it is also testing the drivetrain.

26. Dynamometers • Engine dynamometers. • Some common manufacturers. • Superflow. • Superflow was originally ‘Go Power Dyno’s’ • First dyno was installed at Dema Elgins shop in Redwood City. • California Dynamometer was run for years out of Dema’s shop by owner Gerard Rainey. • Shop has moved to San Carlos. • Superflow offers a wide variety of engine and chassis dynamometers. • Image of Dema Ferrari 206 engine on Superflow Dyno.

27. Dynamometers • Some common manufacturers • Mustang Dynamometer. • Offers a complete line of engine and chassis dynamometers. • Eddy current type. • Taylor Dynamometer • Hydraulic and eddy current types. • I don’t have experience with there but they look to be dynamometers for large powerplants like diesel engines. • DTS (Dynamic Test Systems) • Offers complete line of engine dynamometers. • Also sells valve spring dynamometers. • Recently merged with Superflow.

28. Dynamometers • Parts of a dynamometer • Test stand • This is what the engine is bolted to. • Usually has wheels so engine can be removed from it quickly and another engine put in its place. • Engine dyno operators usually have multiple stands so engines can be swapped out quickly.

29. Dynamometers • Cooling tower • Contains coolant hose connections that connect to engine. • Used instead of a radiator. • Can be used to keep engine temperature constant • This is important for getting consistent readings. • Absorption unit • There are different types as mentioned earlier in presentation.

30. Dynamometers • Sensor box • Has leads for the different types of sensors. • May have basic gauges on it also. • Oil pressure. • Coolant temperature. • This is so if someone is in the dyno room they can keep an eye on the vital basics. • Throttle actuator • Throttle is operated remotely.

31. Dynamometers • Dyno room • Room contains dynamometer. • Has provisions for supplying fresh air into room • Has large exhaust fans for getting exhaust fumes out. • Flexible exhaust tubes mount to exhaust. • Usually there is a tool box kept in room for working on the engine.

32. Dynamometers • Observation booth: Gerard Rainey • Instruments • Torque • RPM (Tachometer) • Temeratures • Ambient conditions (weather) • Controls • Throttle • Load • Today’s dynamometers usually just have a computer instead of analog instruments. • However they still have mechanical controls for throttle and load.

33. Dynamometers • Chassis dynamometers. • Some common manufacturers. • Superflow • Mustang Dynamometers • Dynapack • Maker of hub mounted dynos • Dyno Dynamics • Dynojet • Not a true dynamometer, an inertial dynamometer.

34. Dynamometers • Roller type • Drive wheels ride on a large textured drum which is connected to the adsorption unit. • Vehicle is tethered down with tie-straps. • If tie-straps break, vehicle will launch. • Variables need to be kept constant. • Tire pressure. • Strap tension. • Sample video – Dynojet • Sample video - Mustang

35. Dynamometers • Types of absorption units • Same as with engine dynos • Depends on manufacturer • Exception is the Dynojet • Uses an inertial drum • Large, heavy steel drum. • Vehicle is accelerated when on rollers • The time it takes to accelerate the drum is ‘interpolated’ into horsepower and torque. • Can not load engine and hold rpm constant. • Readings are normally 10% higher than other dynos. • They are low cost, therefore very popular among the ‘tuner’ crowd.

36. Dynamometers • Hub type • Bolts directly to hubs • Can be used for 2 wheel drive or 4 wheel drive • Eliminates variables associated with roller types. • Are only a few manufacturers that currently make them. • Dynapack is the most popular. • Sample video – dynapack.

37. Dynamometers • A dynamometer is only a tool. • A tool for verifying power goals have been met. • A tool for confirming that a modification has made the increase in power which was anticipated. • Results from one dyno should not be compared with results from another dyno, especially of a different brand.

38. Dynamometers • Before and after test. • Vehicle or engine is tested before installing a performance part. • Vehicle is tested after performance part is installed under same conditions. • If weather is different results will be different even with corrections. • A before test on a Dynojet and an after test on a Mustang is invalid.

39. Dynamometers • Before doing the dyno run. • Temperatures must be stabilized to ensure repeatability. • Coolant temp • Engine oil temp • Transmission oil temp • Intake air temp • Doing runs one after another is a good way to get inconsistent results.

40. Dynamometers • Cooling fan for chassis dyno • Very important to have a very large fan in front of vehicle during and after runs. • Most dyno operators do not own a proper fan. • Sample photo – small fan • Dinan has a 4 foot diameter fan with shrouding that narrows down to about 1 foot by 2 feet. • Has 40 HP electric motor • Can blow air at 80 MPH. • Large fan is especially important when testing cars with intercoolers.

41. Dynamometers • Corrections • Since we can not control the weather, it is impossible to ensure consistent conditions during dyno runs. • Ambient temperature • Humidity • Barometric pressure. • Because of this, dynamometers have built in corrections which adjust results to a standard. • SAE (Society of Automotive Engineers) standard J1349 • Uncorrected • People sometimes use to make it seem their engine made more power than it did. • Do the run on a cold, dry day for maximum air density.

42. Dynamometers • Dyno videos • Cosworth 2.3 Liter • Mitsubishi Lancer • Lamborghini Gallardo • Renault F1 • Dyno FAIL videos • Mitsubishi EVO • Drag car • Unknown engine