Rev-X Testing

[Power Hungry]

The nice thing about this dyno is that we can "script" a simulated environment and drive hundreds of simulated miles. The only thing we can't really account for is headwind, but grades are no problem at all.

It's our plan to eventually get a good script together and start doing some really in-depth mileage testing, just so we can quantitatively show the benefits of tuning. Combined with datalogging, it will be very useful.

[Longshot270]

Originally Posted by Power Hungry

The nice thing about this dyno is that we can "script" a simulated environment and drive hundreds of simulated miles. The only thing we can't really account for is headwind, but grades are no problem at all.

It's our plan to eventually get a good script together and start doing some really in-depth mileage testing, just so we can quantitatively show the benefits of tuning. Combined with datalogging, it will be very useful.

Couldn't you simulate a headwind by increasing pulling load? Since you can get it at a standard cruising speed that can be "scripted" in at a standard rate of parasitic loss, similar to a grade. IIRC wind resistance increases exponentially by speed, so that makes it a calculable value. Find the surface area up front, adjust for the aerodynamics (since it is not completely a flat faced cube, like the height of the windshield for example) then use the formula they use for properly gauging wind strength resistance on sky scrapers, reduce that by the ratio of frontal surface height (number you got earlier) and wheel base length for angular leverage (since the truck is longer than it is tall) to make it seem like more weight on the axle. It makes perfect sense and you could probably do the math in your head.


...yeah, I kinda made that up for the sake of humor. Don't hurt yourself on it.

That is really cool though, you'll come up with something.

[Jackpine]

About the only advantage to knowing the effect on economy due to wind, would be to adjust the fueling/timing to maximize efficiency. But, you'd really be playing with the same set of parameters as you would for anything else that creates load on the drivetrain, such as a hill, increased rolling resistance and the like. So, there's no real reason to try to simulate a wind, when it's really engine load vs fuel used that you want to improve.

And, as long as you're operating in closed loop, you'd probably have to "bias" the O2 sensor values somehow to allow much of a change, which I imagine could be done.

Bill's already said he can set the A/F ratio leaner than stoich if the load is low and it's set richer than stoich when the load is high, so using a dyno just probably allows him to refine a "theoretically derived" tune for a particular vehicle. I imagine it's time for all of us to truck on over to Georgia for a dyno tune!

- Jack