After reading a lot of post where people compare dyno numbers I felt the need to make this topic for everyone.
You have to take into account the Make/Model dyno and control conditions by which the dyno tests are carried out.
Why everyones using estimated 'bhp' figures instead of measure WHP figures I dont know!
Basic template for everyone to use! ASK for some of the info from your tester and it makes it more comparable to other owners graphs on the forum. If your dyno operator doesnt know what your talking about then steer well clear. these are basic control conditions (example)
Car make & Model: Honda DC5
Mods:
XYZ
XYZ
XYZ
Dyno make/model: Dynojet 244xLC
Test mode: Inertia only
Test Standard: SAE
MEASURED run time: 9seconds (strapping tension can affect this if theres a lot of tension difference)
Amb Air Temp: 12*C
humidity: 25%
Correction factor applied: 1.01 (this is becuase of the SAE/DIN/etc standard applied
peak WHP: XXX
peak Torque: XXX
Key points for comparative dyno testing:
1.You should always have your car baseline tested on the same dyno before tuning with the vehicle up to temperature so you know what your starting with. The coolant temperature that the engine was at when the run started should be a key piece of data for when the final dyno run after all the tuning is performed. This is because you want the cooling jacket at the same temp when starting.
2.if on a roller dyno, an experienced tuner will always check tyre pressures and wheel nut torque along with doing a general safety inspection before commencing the dyno-run. These factors ARE important in maintaining consistent testing
3.When strapping a vehicle securely on a roller dyno, I had graduated marks on the straps and would note down the locations and tensions on each of the six to eight straps I used so the tension is repeatable
4.Run time matters! More-so on turbo cars. Make sure that the run time is the same as on the baseline run when final testing the vehicle. going from 6-8 seconds on a turbo car can be 20+hp difference because the turbo has more time to build pressure
5.Always have the car tested in inertia only mode if on a roller dyno and look at the WHP only... Dynojet, Mustang and Superflow have been proven to read within 1% of each other on SAE testing standard
6.Always use SAE correction standard. The correction is for weather conditions including Barometric pressure, humidity and air temperature, this makes the testing on one dyno at sea level consistent with another dyno at say 1000ft elevation above sea level.
7.HP and torque will always vary in different gears since your gearbox is a torque multiplier so make sure the tuner tests the baseline and the final measurement in the same gear
8.If you want a real-world hp/torque output measurement in a certain gear, time the car in a controlled environment from X rpm start point to redline in X gear and then at the dyno ask the tuner to also test the vehicle in said X gear with said X run-time!
9.Always look at WHP/HHP only. There is many varying methods to engine HP estimation from WHP measurement.
Roller dynos measure whp and then calculate torque from it via measured/calculated engine RPM
Hub dynos that are hydraulic based system Directly measure the torque as a pressure (force) out of the pump-head outlet then the dyno, divides this hub-torque by the overall gear ratio to give arguably the most accurate engine-torque measurements possible, they are directly measure and not affected by type slippage/flex/strapping tension etc. Then the HP is calculated from this.
Will@RDT
You have to take into account the Make/Model dyno and control conditions by which the dyno tests are carried out.
Why everyones using estimated 'bhp' figures instead of measure WHP figures I dont know!
Basic template for everyone to use! ASK for some of the info from your tester and it makes it more comparable to other owners graphs on the forum. If your dyno operator doesnt know what your talking about then steer well clear. these are basic control conditions (example)
Car make & Model: Honda DC5
Mods:
XYZ
XYZ
XYZ
Dyno make/model: Dynojet 244xLC
Test mode: Inertia only
Test Standard: SAE
MEASURED run time: 9seconds (strapping tension can affect this if theres a lot of tension difference)
Amb Air Temp: 12*C
humidity: 25%
Correction factor applied: 1.01 (this is becuase of the SAE/DIN/etc standard applied
peak WHP: XXX
peak Torque: XXX
Key points for comparative dyno testing:
1.You should always have your car baseline tested on the same dyno before tuning with the vehicle up to temperature so you know what your starting with. The coolant temperature that the engine was at when the run started should be a key piece of data for when the final dyno run after all the tuning is performed. This is because you want the cooling jacket at the same temp when starting.
2.if on a roller dyno, an experienced tuner will always check tyre pressures and wheel nut torque along with doing a general safety inspection before commencing the dyno-run. These factors ARE important in maintaining consistent testing
3.When strapping a vehicle securely on a roller dyno, I had graduated marks on the straps and would note down the locations and tensions on each of the six to eight straps I used so the tension is repeatable
4.Run time matters! More-so on turbo cars. Make sure that the run time is the same as on the baseline run when final testing the vehicle. going from 6-8 seconds on a turbo car can be 20+hp difference because the turbo has more time to build pressure
5.Always have the car tested in inertia only mode if on a roller dyno and look at the WHP only... Dynojet, Mustang and Superflow have been proven to read within 1% of each other on SAE testing standard
6.Always use SAE correction standard. The correction is for weather conditions including Barometric pressure, humidity and air temperature, this makes the testing on one dyno at sea level consistent with another dyno at say 1000ft elevation above sea level.
7.HP and torque will always vary in different gears since your gearbox is a torque multiplier so make sure the tuner tests the baseline and the final measurement in the same gear
8.If you want a real-world hp/torque output measurement in a certain gear, time the car in a controlled environment from X rpm start point to redline in X gear and then at the dyno ask the tuner to also test the vehicle in said X gear with said X run-time!
9.Always look at WHP/HHP only. There is many varying methods to engine HP estimation from WHP measurement.
Roller dynos measure whp and then calculate torque from it via measured/calculated engine RPM
Hub dynos that are hydraulic based system Directly measure the torque as a pressure (force) out of the pump-head outlet then the dyno, divides this hub-torque by the overall gear ratio to give arguably the most accurate engine-torque measurements possible, they are directly measure and not affected by type slippage/flex/strapping tension etc. Then the HP is calculated from this.
Will@RDT
