Posted: March 6th, 2005, 12:10 pm
Chassis dynos are only good for establishing a base line for all other modifications and looking for gross errors from factory specs.
It looks like the to dyno graphs were made from data from two different types of machines. If you were to put the same car on 5 different dynometer made different manufactures there could be as much as a 8 to 10 hp difference between the high and low record even if all the machines were calibrated 100% just due to difference in sensor inputs and how the software is designed to interpret them. There has been several articles written in magazine were Dyno operators do things to fool the atmosphere sensor attached to the Dyno to raise the output to what the customer is expecting. In a article in CCC (UK magazine) about 5 years ago one trick dyno operator would do is put a hot cup of tea in near the ambient air thermo sensor to make the unit think it was 24C in the Midlands in late October. In one of the American publications they took the same car to 5 shops that had the same model of Dynojet dyno on days with similar weather conditions. 3 were within 2 hp of each other which is well within Dynojets error limits, One was lower and other was way over. It was found that the sensor package had been tampered with or the car was set up on the roller incorrectly.
Other things to consider is no two production engine are going to have the exact same power output. You could have a production freak were all the tolerences are perfect and develops more power that average or you could get the the production dog which would barely pass QC. Also Mazda is well know for publishing over inflated stock power specs outside Japan. Japanese advertizing laws are different than the way we would assume it to be outside of Japan. In japan the advertized power output does not have to be the actual output just the max output for a given engine displacement for a specific class car. As a result there is the well publized litigation they lost in several countries over the output of the BP DOHC engine where the engine were actually making 10hp less that advertized specs. which Mazda had to offer compensation to people with these engines. If you noticed that Mazda also lower the output specs of the K8 in countries affected by the litigation from 130 to 128 to 125 and finally 122hp in certain markets.
It looks like the to dyno graphs were made from data from two different types of machines. If you were to put the same car on 5 different dynometer made different manufactures there could be as much as a 8 to 10 hp difference between the high and low record even if all the machines were calibrated 100% just due to difference in sensor inputs and how the software is designed to interpret them. There has been several articles written in magazine were Dyno operators do things to fool the atmosphere sensor attached to the Dyno to raise the output to what the customer is expecting. In a article in CCC (UK magazine) about 5 years ago one trick dyno operator would do is put a hot cup of tea in near the ambient air thermo sensor to make the unit think it was 24C in the Midlands in late October. In one of the American publications they took the same car to 5 shops that had the same model of Dynojet dyno on days with similar weather conditions. 3 were within 2 hp of each other which is well within Dynojets error limits, One was lower and other was way over. It was found that the sensor package had been tampered with or the car was set up on the roller incorrectly.
Other things to consider is no two production engine are going to have the exact same power output. You could have a production freak were all the tolerences are perfect and develops more power that average or you could get the the production dog which would barely pass QC. Also Mazda is well know for publishing over inflated stock power specs outside Japan. Japanese advertizing laws are different than the way we would assume it to be outside of Japan. In japan the advertized power output does not have to be the actual output just the max output for a given engine displacement for a specific class car. As a result there is the well publized litigation they lost in several countries over the output of the BP DOHC engine where the engine were actually making 10hp less that advertized specs. which Mazda had to offer compensation to people with these engines. If you noticed that Mazda also lower the output specs of the K8 in countries affected by the litigation from 130 to 128 to 125 and finally 122hp in certain markets.
meaning the horsepower found at the wheels.