Quote:
Originally Posted by Daox
I'd expect this. It reduces pumping losses.
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Actually it allows them to run a leaner mixture because the exhaust gasses don't 'burn'. This cools the exhaust temperature so it won't burn out the catalytic converter.
You can kinda of see it in the catalytic converter temperatures just after the ICE coolant reaches 70C. The catalytic converter peak temperature plateaus and even goes down when the car is in a sustained cruise.
Without it, they'd have to run a slightly richer mixture to moderate the exhaust temperatures especially at higher power settings.
Bob Wilson