Different Dyno, different results...

[Pierre]

Hi, last year we do some work on the motor of my Road King, we test it on a Dynojet model 150 Dyno, This winter we made some changes, put a D&D Fat Cat 2 into 1 and a DTT ignition, tune the bike at Laconia on the Dynojet model 250 i Dyno at Speed's Performance Plus. The bike gain a noticeable amount of torque a lot sooner but at the top it's about the same number. No problem with that but i read somewhere here that the 250 model read lower than the 150 model, is it true? and by how much lower? my number with the 150: 100 Torque, 88HP. with the 250 : 98 Torque 92HP ..... Just curious

[Mike]

Apologies for late reply, I lost track of this post. Our experiance (and others) has shown the 250i models to be approx 6% lower than 100/150/200 models. Dynojet will not confirm this. Some dynos may have software loaded into them with incorrect drum mass numbers due to upgrades or using software from other dyno's. It is critical that the correct mass is used and this is normally insured by Dynojet by sending out software matched to dyno's serial numbers and tracking upgrades. But over time tracking can get confused. Other things like the environment, temperatures, strapping methods, tire pressures, etc can also have major effects. Last, dynos can have an error of +-1hp/100. Just like flow benches, the real value is making changes and using the same dyno at the same time to compare the effect of those changes (we have a long explaination of our methodolgy on this site).
Mike

[Pierre]

thanks