Hey guys,

I've was out of town with no internet access for the weekend.... kind of a refreshing change .

I'll try to answer all of the questions here, but if I miss someone's please let me know.


The HP@50 number used by the Mustang dyno is a number specific to every model of car that represents the HP required to maintain 50mph. This number is mainly a combination of drag coefficient and frontal area for the specific car model. The Mustang dyno uses the HP@50 value along with the entered vehicle weight to calculate the load applied to the rollers through the pull. In this way, the dyno is simulating the load that the engine will see while doing a similar pull on an actual road. So basically, if the HP@50 number is higher, the car experiences more drag on the road, so the dyno applies more load to the rollers, resulting in a longer pull through the gear. While the pull is being made, the dyno software records the acceleration and then adds in the calculated load that it applied during the run in order to derive torque and hp at the wheels. So while the HP@50 and vehicle weight numbers can have an effect on spoolup and behaviour of the turbo (in the same way that going up or down a hill would), they don't really effect overall hp numbers because the software is subtracting the applied load to derive the curves. These numbers are, however, very important for results from road dyno software. Since in the case of a road dyno, the load being applied is a result of actual drag and gravity on the car, the software must estimate this load using the information given and then add it back in to derive the actual torque and hp at the wheels. This is why it is important to have correct drag and weight information as well as a very flat road to get accurate results from any road dyno software.
And FYI, the HP@50 number that was used for Jeremy's dyno is the one listed in the Mustang Dyno software for his 1998 Legacy.

As Jeremy pointed out, I did more tuning on the dyno because I was comfortable in knowing that the car was under the most extreme conditions it would see in real life, so I didn't have to worry about pushing it a bit further and then having the tune fall apart in worse conditions. When we first put the car on the dyno, it made 266whp and 235ft-lbs on the original road tune. The three of us (Jeremy, the dyno owner Paul, and myself) were very surprised at how close these numbers were to the road dyno pull that Jeremy posted previously.

As far as earlyapex's question about the lag... the VF22 is indeed a bit laggier than the vf34, but its actually not as bad as you might think. When looking at a torque curve, its important to look at the whole curve, not just where the maximum point is. Jeremy's car makes max torque at 4500RPM, but the turbo is fully spooled and making good torque by about 3600RPM on the dyno. That being said, his turbo hits full boost about 100-200RPM sooner on the road than it does on the dyno. While the Mustang does a decent job of approximating real-world load and conditions, its never perfect and thus atleast some road tuning and/or testing is required with any dyno tune IMO. The car always behaves a little differently with real world load and air-flow.

Finally, I'd like to say thanks to Paul at EIP for offering the use of his dyno for no more than meeting a fellow tuner and checking out a couple cool pieces of software. He's a very cool guy and while the shop could use a little cleaning and organization, the dyno seems to work very well.

Again, if I missed a question from anyone, please let me know and I'll answer it to the best of my ability.

Thanks