fyi, direct injection gasoline thread:
http://ecomodder.com/forum/showthrea...gas-17460.html
so better to use the hot exhaust gas directly on a turbine wheel, no? a-la power recovery turbine
http://ecomodder.com/forum/showthrea...tml#post204535
as far as I know adding a heat exchanger will at most equalize the heat between the flows, vs using the exhaust directly. If hot is good, hotter is better.
re: throttle open/closed coast. I never noticed a significant deceleration difference (seat of pants) except open is a little louder.