Anybody know just /exactly/ what this is and how it works? Someone told me it was something like vtec but it sounds more like vics or something to me... either way, it has something to do with the valves right?
There is two differnt shaped runners in the intake manifold. And four butterflys that close off the round shaped runner. Below 3000 RPM the butterflys are closed makeing air travel through the smaller moon shaped runner, this keep the speed of the air faster, makes for low end tourq. than at 3000 RPM the butterflys start to open (by a electric motor) allowing larger amounts of air in to the motor.
The valves dont change in the SPI system.
This help to make a wider power band.