Thread: I bought a TDI!
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Old 09-23-2021, 04:26 PM   #54 (permalink)
Isaac Zachary
High Altitude Hybrid
 
Join Date: Dec 2020
Location: Gunnison, CO
Posts: 2,075

Avalon - '13 Toyota Avalon HV
90 day: 40.45 mpg (US)

Prius - '06 Toyota Prius
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Quote:
Originally Posted by Ecky View Post
The major benefit of hybrids on the highway is that they tend to incorporate much taller gearing, and smaller engines, than would otherwise be acceptable to typical drivers.
Agreed!

On the highway a hybrid engine can be smaller and tuned for fuel mileage, which for a non-hybrid could make the car feel underpowered. But by adding a hybrid drive you can have that extra burst of power when you need/want it without having to resort to an engine built more for power than fuel mileage.

So, for an example, say you have the time and resources to convert your engine to something more efficient, say a Miller cycle or Atkinson cycle engine. Basically you'd need to increase the compression ratio and rework the cam profile so that your intake valves close much later. For the Miller cycle you may need a different turbo, or even change it for a supercharger since you'll be getting less exhaust pressure as the combustion stroke will now much longer than the compression stoke which will soak up more combustion gas pressure, leaving less for the turbo. All of this would result in a less powerful but hopefully more efficient engine. If by that point you can't stand the lack of power you can make up for it by adding a hybrid system.
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