Summary of the paper.
Honda were after 18/27, 19/28 city highway for the manual and auto V-6 respectively. Reason given was fuel prices and CAFE (similar to most of the Honda economy papers, CAFE, and GHG are generally mentioned in the introduction as drivers).
First change was engine mounts and stereo system, sot that they could use their Variable Cylinder Module at higher BMEPs. (1,3,4, and 6 for 4 cylinder mode, 2,4,6 for 3 cylinder mode), the stereo used to cancel the interior harshness.
EGR increase up to 10%.
Both the above mean that the throttle openings are higher for part throttle RPM, and the engine has fewer pumping losses...The above contributed 7% of the total economy increase (note not 7% increase, 7% OF the increase).
Sliding wear of the piston assembly next target.
* two stage "plateaux" honing process gives flatter hone surface;
* "ion" plating of the oil ring to provide longer life (doesn't mention tension, but I'm surmising that the reason for chasing longer life is to do it with less tension)
* (re my surmising, another Honda paper gives about 40% drag to the piston, and 20% to each of the rings);
* Major and Minor thrusts are Mo coated, then "dots" of coating are removed, to remove surface area, and hold oil.;
The above reduced engine friction by 4% and economy by 5%. (I think this is total, as they don't have the disclaimer "OF" the total.
Changed to 0W20 oil. Reason to gain better mileage on the "city" cycle. Achieves 10% OF the improvement (relative) on the city cycle. No mention of highway...makes sense.
Next was reduction in thermal losses.
* CAI reduced air intake temps by 21C (Intereating, as if you do the thermodynamic cycle, a reduction in inlet temperatures carries all the way through compression, power and exhaust)...credited with 16% highway mileage improvement (again not sure if absolute or relative).;
* High EGR rates reduce peak combustion ptems, and thus the heat transferred (wasted) to the coolant. (no mention of water wetter, they are trying to keep energy In the engine).
Accessory losses:
* overrunning alternator bearings, so on deceleration the alternator free spins, new spring added to damp torque pulsations on re-engagement;
* looked at electric power steering, but variable volume engine driven pump won out;
Transmission
* Long Torqsion Damper spring in the converter is there to dampen the pulses in variable cylinder mode. Better spring tuning, more variable cylinder operation (50% more than previous model);
* Thinner ATF, to reduce power wasted "in the critical warmup phase";
* TCM tuning.
Aerodynamics
* Drag Co-efficient improved by 5%, lead to 12% of the highway fuel economy improvement;
Drivetrain and chassis. Target wheel bearing and other drag:
* Changes to the bearing and lip seal reduced friction on front wheel bearings by 24%, Rear bearing drag improved by 48%. Combined, were 2% of the economy improvement (relative);
* Moving the front caliper brake pivot pins (swapping the fixed and floating pins) better controlled retraction when brakes are released.
* small V spring to knock the pads back off the disk slightly to reduce drag.
* Increase in wheel diameters by an inch.
Weight (commentary on weight and EPA/CAFE requirements gradings "Touring needed separate certification);
* Engine mass reduction 5.5Kg, Intake reduction 2 Kg, Cooling system 1.4Kg;
* Revised steel sections and materials in chassis saved 18.67Kg
* Multiple weight reductions in seats and mountings...etc.
End result, and it's worth noting the "Relative" improvements, i.e. they are a percentage of the total improvement.
LX-EX, +2/+4 MPG City/Highway
EXL, +1/+2 MPG City/Highway
Touring +2/+3 MPG City/Highway
