Discussion and questions related to the course Engine Building Fundamentals
My question is regarding the characteristics and phasing of the camshaft and how it relates (or doesn't) to turbo spool. Initially I am inclined to say that more overlap will aid in spooling the turbocharger. My theory is that the incoming air could be scavenged through the exhaust aiding in spool. In contrast, I've read that the incoming air is colder, and this colder air has less heat energy which will not aid in spool. Less overlap then in my mind would avoid this but decreases volumetric efficiency at low rpm, which results in less thermal energy routed to the turbo.
It would make sense to me that the turbo spool aspect would be much more dependent on the exhaust valve timing rather than the intake. Perhaps an early closing exhaust valve at will prevent exhaust gasses from being drawn back in?
The more aggressive camshafts you install, the later your turbo will spool. You can help it a little bit with a few things: higher compression ratio, advancing camshafts, smaller turbine AR, but each option has its own price to pay - as usually improving one thing hurts another.