New Zongshen RX3 (ZS250GY-3) Dual Sport

Weldangrind · 05-10-2015, 12:16 PM

Quote:

Originally Posted by katflap

I think I've got this right

Excellent! I surmised that the bell curve was torque, and it is almost the inverse of the fuel consumption rate curve, which makes perfect sense.

I am a little confused by the RPM data; do you think the chart is posting both crankshaft RPM and gear reduction RPM at the clutch?

katflap · 05-10-2015, 03:56 PM

Quote:

Originally Posted by Weldangrind

I am a little confused by the RPM data; do you think the chart is posting both crankshaft RPM and gear reduction RPM at the clutch?

Yes I think so,
From what I see the Graph is only showing the reduced Dyno RPM ,
though the crank shaft RPM and Dyno RPM is shown in the table above.

I've never seen a Dyno in action so i'm not sure what part of the set up is monitored to get the reduced RPM

oldqwerty · 05-10-2015, 05:07 PM

Well, since there is so much confusion on the dyno chart, I'll explain. My background comes from university level research testing the efficiency of bio-fuels in vehicles ranging from scooters to Class 8 trucks. Please allow me to provide a quick analysis and summary: The project was cancelled because the lab work on real vehicles could find no evidence to support the notion that bio-fuels of any sort available on a viable commercial basis in the U. S. of A. reduced the use of petroleum based fuels. Frankly, EVERY commercially available bio-fuel cost society in the U. S. of A. more petroleum than it saved. I've dyno tested hundreds of real world vehicles, so I have a little experience on the matter.

SPEED: two columns, ENGINE and DYNO. These figures give engine and dyno speeds in revolutions per minute. This information is important because if the ratio of engine RPM to dyno RPM changes the test is faulty--there is slippage somewhere in the drive train or connection between the tire and dyno, if this is a rolling dyno. Modern dynos monitor said ration and if it changes a warning goes off, because slippage is heat, and excess heat can lead to fatal events.

TORQUE: This is how much FORCE the engine is generating and is the actual measurement measured by the dyno. ENGINE is the force measured by the dyno. DYNO is the actual force applied by the dyno to counteract the force applied to the dyno by the engine. There is a mathematical relationship between the ENGINE and DYNO columns (if no slippage) too complex to include here--if you need an explanation you won't get it, but if you can understand it you paid attention in algebra in high school. REVISE: This value is torque corrected to what it would be at standard temperature, barometric pressure, and humidity. Temperature, barometric pressure, and humidity all affect actual engine output, so the only way to compare apples to apples is to correct mathematically for these variables. Measured in newtons/meter, 1 n/m = 0.737 562 147 28 pound/foot (lb/ft).

POWER: A figure calculated from the amount work divided by the time it takes to do that work (in our case, torque). Watts are the standard metric unit of power. Kilowatts = 1000 watts. Americans like to express power as horsepower. One horsepower, since it is calculated from our torque measurement, = 737.562 147 28 kilowatt. Dynos do not measure power. Power is a calculation based on the formula (torque (in lb/ft) times RPM) divided by 5252 = horsepower. All the math behind the constant 5252 and conversions for other units of measure are beyond the scope of this explanation.

FUEL CONSUMPTION: kg/h is the mass of fuel that would be required to maintain this output level for one hour. Doesn't mean much in the real world unless you have a habit of running WOT for hours at a time. On the other hand, kg/kWh is vitally important. The lower the number, the more efficiently the engine is operating. A quick glance reveals this engine is probably going to be most efficient operating under load around 7000rpm. Note that peak efficiency corresponds to peak torque. This is not at all unusual. Further evidence of a well balanced selection of engine parts is the nice, smooth bell shaped torque curve. Most engines with well balanced components that work together are this way. Mucking up this balance is why so many modified engines run so crappy. Please do not succumb to that temptation unless you know what you are doing or are building a replica engine developed by someone who does know what they are doing, which is how I learned the artisan part of engine reengineering and building.

The rest of the graph is self explanatory.

Hope this helps those who didn't have the opportunity to take advanced math and physics courses in high school.

Weldangrind · 05-11-2015, 12:46 AM

Quote:

Originally Posted by oldqwerty

Power is a calculation based on the formula (torque (in lb/ft) times RPM) divided by 5252 = horsepower.

I've read that the equation for horsepower is the reason that all four stroke engines have identical horsepower and torque values at 5252 RPM. I only presume that two strokes and diesels are the same.

oldqwerty · 05-11-2015, 10:09 AM

Quote:

Originally Posted by Weldangrind

I've read that the equation for horsepower is the reason that all four stroke engines have identical horsepower and torque values at 5252 RPM. I only presume that two strokes and diesels are the same.

That is true because of the mathematical principle of inverse operations, and is true for all engines.

05-10-2015, 05:07 PM	#3
oldqwerty Join Date: Mar 2015 Location: in a truck Posts: 116	Well, since there is so much confusion on the dyno chart, I'll explain. My background comes from university level research testing the efficiency of bio-fuels in vehicles ranging from scooters to Class 8 trucks. Please allow me to provide a quick analysis and summary: The project was cancelled because the lab work on real vehicles could find no evidence to support the notion that bio-fuels of any sort available on a viable commercial basis in the U. S. of A. reduced the use of petroleum based fuels. Frankly, EVERY commercially available bio-fuel cost society in the U. S. of A. more petroleum than it saved. I've dyno tested hundreds of real world vehicles, so I have a little experience on the matter. SPEED: two columns, ENGINE and DYNO. These figures give engine and dyno speeds in revolutions per minute. This information is important because if the ratio of engine RPM to dyno RPM changes the test is faulty--there is slippage somewhere in the drive train or connection between the tire and dyno, if this is a rolling dyno. Modern dynos monitor said ration and if it changes a warning goes off, because slippage is heat, and excess heat can lead to fatal events. TORQUE: This is how much FORCE the engine is generating and is the actual measurement measured by the dyno. ENGINE is the force measured by the dyno. DYNO is the actual force applied by the dyno to counteract the force applied to the dyno by the engine. There is a mathematical relationship between the ENGINE and DYNO columns (if no slippage) too complex to include here--if you need an explanation you won't get it, but if you can understand it you paid attention in algebra in high school. REVISE: This value is torque corrected to what it would be at standard temperature, barometric pressure, and humidity. Temperature, barometric pressure, and humidity all affect actual engine output, so the only way to compare apples to apples is to correct mathematically for these variables. Measured in newtons/meter, 1 n/m = 0.737 562 147 28 pound/foot (lb/ft). POWER: A figure calculated from the amount work divided by the time it takes to do that work (in our case, torque). Watts are the standard metric unit of power. Kilowatts = 1000 watts. Americans like to express power as horsepower. One horsepower, since it is calculated from our torque measurement, = 737.562 147 28 kilowatt. Dynos do not measure power. Power is a calculation based on the formula (torque (in lb/ft) times RPM) divided by 5252 = horsepower. All the math behind the constant 5252 and conversions for other units of measure are beyond the scope of this explanation. FUEL CONSUMPTION: kg/h is the mass of fuel that would be required to maintain this output level for one hour. Doesn't mean much in the real world unless you have a habit of running WOT for hours at a time. On the other hand, kg/kWh is vitally important. The lower the number, the more efficiently the engine is operating. A quick glance reveals this engine is probably going to be most efficient operating under load around 7000rpm. Note that peak efficiency corresponds to peak torque. This is not at all unusual. Further evidence of a well balanced selection of engine parts is the nice, smooth bell shaped torque curve. Most engines with well balanced components that work together are this way. Mucking up this balance is why so many modified engines run so crappy. Please do not succumb to that temptation unless you know what you are doing or are building a replica engine developed by someone who does know what they are doing, which is how I learned the artisan part of engine reengineering and building. The rest of the graph is self explanatory. Hope this helps those who didn't have the opportunity to take advanced math and physics courses in high school. __________________ "Thou shall not Zong" is not a commandment.
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