Future lean burn engine swap into 7th generation Civic sedan? CRX HF, HX?

[19bonestock88]

Manuals are more efficient than even a CVT because there is a direct coupling between engine and drive wheel. No fluid loss, TQ converter slippage, etc...

The torque converter is just a fluid coupling between engine and transmission, so there is loss there... there is also fluid pumps in any auto, which waste power and fuel...

That being said, a lower RPM does a lot for MPG... my 07 Malibu with same engine as my 04 Ion but the 4T45 automatic got better mileage on the open freeway due to a taller overdrive ratio AND a taller final drive... however it would go down into 3rd on the bigger hills, and I can stay in 5th on even 7-8% grade without losing speed

[Ecky]

Originally Posted by mpg_numbers_guy

Good point, but you can't really store much cargo in an Insight either.

You can't move a full size 6ft bookcase in a Civic, that I'm aware of. I wouldn't ever want to own a non-hatch.

Here's 8 tires and 8 rims (separate from the tires) stuffed in the back:



But I digress.

Originally Posted by mpg_numbers_guy

If a CVT normally maintains the lowest RPMs possible, how are they less efficient than manuals? I always thought manuals were more efficient than automatics just because one could "force" them to upshift sooner.

Friction losses. In a CVT, there's a belt which rides between two cones, and the cones slide together or apart to change the gear ratio. The belt has to ride in oil because it would get very hot. Early Honda CVTs could be expected to last ~150-200k miles before wearing out.

However, CVTs can have very wide effective gearing ranges and sometimes that more than makes up for their frictional losses.




Traditional automatics use a torque converter, which transfers power between surfaces moving at different rates, much like the clutch in a manual, except they're "slipping" much more frequently. This eats at least 10% of your engine's power.