Anyone have rolling road results for a ZR-1?
Discussion
Here is the information from my dyno sheet. The format of the sheet looks just like the sheet posted by "b3any" in the thread "Rolling Road Dyno Sheet". It appears that they may be the same type of dyno.
Comparing his sheet to mine, I assume P-Norm is corrected crank power, P-Mot is uncorrected crank power, P-Rad is wheel output, and P-Schlepp is driveline loss.
Here is the information from the sheet:
Norm-Leistung P-Norm : 246,0 kW nach DIN 70020
Motorleistung P-Mot : 224,0 kW
Radleistung P-Rad : 184,0 kW
Schleppleistung P-Schlepp : 40,0 kW
Maximale Leistung bei 219 km/h bzw. 6090 U/min
Drehmoment M : 400 Nm
Maximales Drehmoment bei 196 km/h bzw. 5450 U/min
If we use 1 kW = 1.341 bhp, then the corrected crank power is 329.9 bhp. Using the same conversion, the uncorrected wheel power would then be 246.7 bhp. They used a correction factor of 1.09882 to correct for air temperature, etc, so the corrected wheel power would be 202 kW, or 270 bhp. The car should be 375 bhp at the crank, so I am down 45.1 bhp, or 12.0% at the crank.
The torque is also low. The engine is rated at 370 foot/pounds, and this run shows 400 Nm * .73756, or 295 foot/pounds. I do not know if this figure is corrected, or uncorrected. If it is corrected, then the motor is down 85 foot/pounds, or 22.4%. If it is uncorrected, then the corrected number would be 324.2 pound/feet. This would be down 55.8 pound/feet, or 14.7%.
I also did a run with the power key in the “normal” position. This resulted in the following numbers:
Norm-Leistung P-Norm : 139,0 kW nach DIN 70020
Motorleistung P-Mot : 127,5 kW
Radleistung P-Rad : 93,0 kW
Schleppleistung P-Schlepp : 34,5 kW
Maximale Leistung bei 221 km/h bzw. 4690 U/min
Drehmoment M : 329 Nm
Maximales Drehmoment bei 120 km/h bzw. 2540 U/min
The corrected crank power would be 186.4 bhp, and the corrected wheel power would be 135.96 bhp. According to what I read from GM, the ZR-1 in “normal” mode should produce 210 bhp at the crank, which means I am down 23.6 bhp, or 11.2% at the crank.
A friend of mine also tested his BMW 850 CSi on the same dyno six months after I did my test. Both of our cars are rated at 280 kW, and the test showed the engines were within 1 or 2 bhp of each other. The 850 registered 244.5 kW corrected. Either the dyno is off, or both of our cars are down the same percentage of power.
I would think that if the engines are indeed down from the factory rating, then the odds of our engines being down the same percentage would be quite high. Is it possible that the dyno could be off that much?
I also posted a question on the “BMW” section to see if anyone has dyno results from an 850 CSi.
If the results are correct, then the engine is off by 11.2% in “normal” mode, and 12.0% in “full” mode. Since the power loss is almost the same in “normal” as in “full”, I would guess that the problem would not be related to the full power equipment, i.e. the second set of valves, and the second set of injectors. The problem most likely is in a system used by both “normal” and “full” modes, maybe the primary injectors, spark plugs, …
Any input would be appreciated.
>> Edited by kgv on Tuesday 5th October 20:19
Comparing his sheet to mine, I assume P-Norm is corrected crank power, P-Mot is uncorrected crank power, P-Rad is wheel output, and P-Schlepp is driveline loss.
Here is the information from the sheet:
Norm-Leistung P-Norm : 246,0 kW nach DIN 70020
Motorleistung P-Mot : 224,0 kW
Radleistung P-Rad : 184,0 kW
Schleppleistung P-Schlepp : 40,0 kW
Maximale Leistung bei 219 km/h bzw. 6090 U/min
Drehmoment M : 400 Nm
Maximales Drehmoment bei 196 km/h bzw. 5450 U/min
If we use 1 kW = 1.341 bhp, then the corrected crank power is 329.9 bhp. Using the same conversion, the uncorrected wheel power would then be 246.7 bhp. They used a correction factor of 1.09882 to correct for air temperature, etc, so the corrected wheel power would be 202 kW, or 270 bhp. The car should be 375 bhp at the crank, so I am down 45.1 bhp, or 12.0% at the crank.
The torque is also low. The engine is rated at 370 foot/pounds, and this run shows 400 Nm * .73756, or 295 foot/pounds. I do not know if this figure is corrected, or uncorrected. If it is corrected, then the motor is down 85 foot/pounds, or 22.4%. If it is uncorrected, then the corrected number would be 324.2 pound/feet. This would be down 55.8 pound/feet, or 14.7%.
I also did a run with the power key in the “normal” position. This resulted in the following numbers:
Norm-Leistung P-Norm : 139,0 kW nach DIN 70020
Motorleistung P-Mot : 127,5 kW
Radleistung P-Rad : 93,0 kW
Schleppleistung P-Schlepp : 34,5 kW
Maximale Leistung bei 221 km/h bzw. 4690 U/min
Drehmoment M : 329 Nm
Maximales Drehmoment bei 120 km/h bzw. 2540 U/min
The corrected crank power would be 186.4 bhp, and the corrected wheel power would be 135.96 bhp. According to what I read from GM, the ZR-1 in “normal” mode should produce 210 bhp at the crank, which means I am down 23.6 bhp, or 11.2% at the crank.
A friend of mine also tested his BMW 850 CSi on the same dyno six months after I did my test. Both of our cars are rated at 280 kW, and the test showed the engines were within 1 or 2 bhp of each other. The 850 registered 244.5 kW corrected. Either the dyno is off, or both of our cars are down the same percentage of power.
I would think that if the engines are indeed down from the factory rating, then the odds of our engines being down the same percentage would be quite high. Is it possible that the dyno could be off that much?
I also posted a question on the “BMW” section to see if anyone has dyno results from an 850 CSi.
If the results are correct, then the engine is off by 11.2% in “normal” mode, and 12.0% in “full” mode. Since the power loss is almost the same in “normal” as in “full”, I would guess that the problem would not be related to the full power equipment, i.e. the second set of valves, and the second set of injectors. The problem most likely is in a system used by both “normal” and “full” modes, maybe the primary injectors, spark plugs, …
Any input would be appreciated.
>> Edited by kgv on Tuesday 5th October 20:19
It could be that your air inlet duct is collapsing at higher RPMs. This is quite common, as the corrugated black plastic duct softens with age.
The symptoms are a loss of around 30 BHP and a power curve that turns down quickly at peak power, instead of decreasing gently, due to the big loss of airflow. Many owners put some piano wire hoops or a coffee tin bent to the right shape to stiffen up the duct.
Another thing to check is when the dyno was last calibrated, given that your friends car was also down on power.
Might also be worth doing a compression check as a basic health check on your engine. Beyond that you're into looking at dirty injectors or maybe a port throttle problem, but I'm just guessing here.
Let me know how it goes.
The symptoms are a loss of around 30 BHP and a power curve that turns down quickly at peak power, instead of decreasing gently, due to the big loss of airflow. Many owners put some piano wire hoops or a coffee tin bent to the right shape to stiffen up the duct.
Another thing to check is when the dyno was last calibrated, given that your friends car was also down on power.
Might also be worth doing a compression check as a basic health check on your engine. Beyond that you're into looking at dirty injectors or maybe a port throttle problem, but I'm just guessing here.
Let me know how it goes.
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