Baseline measurements

[skyl4rk]

What type of measurements could be used to determine vehicle performance without mods, then again with mods? I would like to separate technique gains from mod gains. Mainly I am thinking of aeromods, but it could be other vehicle mods such as synthetic oil, etc. The idea is to keep a record and then do the same tests for each mod to see where the performance gains are.

Assume a Scangauge is in the vehicle.

Some ideas:

Instant mpg at a steady 30mph, 40mph, 50mph, 60mph, 70mph on a flat road, no wind.

Trip average mpg between two specific points (mile markers) at a given speed.

Start coasting at a given speed at the top of a hill, measure speed at a point near or after the bottom of the hill.

Measure Cd? (I have no idea how).

[some_other_dave]

You can infer CdA from your coast-down tests, and measure A visually. (Check for other threads on those two topics on this BBS.)

Constant-state runs, both directions on the same stretch of flat road, back to back, repeated many times, in as close to windless conditions as you can manage. Average everything, look for outlying results and see if there are reasons for them. If you can keep your foot absolutely still on the gas (verify with scan-gauge), do so. If not, then use cruise control to maintain speed.

Perhaps measured accelerations, either using SG to hold a set load, or using the "accelerate" function of cruise control? I'm not sure exactly what results you'd get from that.

Sounds like you've covered the biggest ones.

Oh, try to quantify the tires' rolling resistance. I recall a thread where someone used a scale to push their car, and crunched the time/speed/force numbers to get an approximation of drag from non-aero sources. At very very low speeds, assuming aero drag is zero is a pretty decent approximation.

-soD