Regarding your words about the Chevy Performane Division, you can do something accurate (or near) with a vacuum gauge. You drive your car, for example, at 3000 rpm on third gear and you check the vacuum in the intake of your engine.C J Murray wrote: ↑Sun Apr 21, 2019 10:37 amYes, with an eddy currant type dyno that would hold a certain amount of resistance against the engine. Even still road testing is needed to get the best result. I was told by the head of the Chevy performance division John Heinrency that even with the equipment they have that the car will not perform its best until adjustments are made based on road tests. He said the engine mapping is the most challenging and time consuming aspect of a new model.Martin Benade wrote: ↑Sun Apr 21, 2019 9:43 am This is more of a question about dyno useage- could you hold it at say 3600 rpm and 2/3 throttle steady state, and adjust the jetting for that condition? I realize if this is possible, all you would have to do is then adjust an infinite number of points to a moving target until it was good.
The reason old cars are easier is because they can't be made to be anywhere near perfect. They must be made safe at WOT and then the other settings only need to be good enough to have the car drive ok. Lean settings cause very rough running but rich settings have to be extreme to be felt.
Modern cars are mapped in the computer for every tiny difference in throttle opening, rpm, and load. Both fuel and ignition are adjusted up and down constantly. This is why modern engines perform so well and last so long.
Next step, on the dyno, you load it until you find the same vacuum in the same condition (3000 rpm / third gear in my example).
Can I bore you, one more time, with Peugeot? Every prototype engine was tested on the dyno, on the chassis dyno and on the street/test track.......... a time consumming job!
