Quote:
Originally Posted by Madact
The torque measurement might not be perfectly precise, but if done on a very level stretch of road (ridiculous long stretches of dead flat road are kind of a speciality around here... well, within 50km of where I live, anyhow) with a warmed up car in several different gears and several throttle positions, something usefulcould probably be done with the data. Enough to do A-B testing, anyhow (still not keen on A-B-A for a header  ) |
You need to do it on the same piece of road since invisible humps and dips do affect the results a fair bit!
I put the car in 3rd gear, dropped down to 1000 rpm, floored the throttle as I passed a marked point and kept it floored to 7250 rpm. humps didn't really matter since the graph is %increase so unless there was so much extra power than the car reached the hump at a different point in the graph it would still be correct. I did attempt to remove the drag losses by subtracting a coastdown run but that can't be measured on the same piece of road as it takes a very long time to drop from 3rd gear 7250 rpm speed to 3rd gear 1000 rpm speed so I just subtracted an averaged and smoothed version.
The graph is % increase, not actual values measured in a particular unit since I had no way of calibrating it to get specific units. The graph is accurate, the only real problem with it is that it doesn't show if the peaks are due to a good new header or an average new header but a poor old header, I found it quite hard to judge that from the data, partly because the road wasn't perfectly flat even though it looked flat.
To get the torque figure you need to calculate the change in kinetic energy needed to change from one speed to the next - an amount that increases with speed, and the time taken to make that change.