[Mista Bone]

Originally Posted by some_other_dave

So a Fit doesn't compare to the DX?

CleanMPG Forums - View Single Post - Steady state speed vs fuel economy results

I have a question for Bone and bkuehl: Have you checked a fuel consumption gauge (MPGuino, built-in iFCD, or ScanGauge or equivalent) driving the same stretch of road at the same speed in two different gears?

-soD

None of those gizmo's were around 9-13 years ago. You had to drive a few tanks, note the mileage driven and gas used to get a true consistent AVERAGE number. Real seat of the pants driving.

Different FD + 5th ratios I have driven in my old Civic

4.250 * .702
4.250 * .750
4.250 * .771
4.250 * .878
4.058 * .702 (best mpg in my drives, stock 92-95 DX gearing)
4.058 * .771
3.722 * .878
3.250 * .702
3.250 * .771
3.250 * .878

Current combo in the CRX is DOHC ZC, 3.89 * .878 which got 49 mpg last fall. I will be switching to 4.437 * .694 in the performance build with long 5th combo. I should drop cruising rpm by 250-300.

Right now 3000 rpm = 60.34 mph using the calc. With new gearing 3000 rpm = 66.89 mph.

So 67 mph is my target speed for safe Interstate travels. Speed limit was 65 mph, now 70 mph in most places.
Current 3.89 * .878 = 3331 rpm
Planned 4.437 * .694 = 3005 rpm

Note: I don't change the tire diameter in the calc as it closely reflects the speedo reading from Honda, even though the OEM tire size is 3-5% smaller in cases. GPS or 5th wheel needed for TRUE mileage driven.

Now if I could find a state highway with a 60 mph limit that was flat and no traffic for best mpg....right at 2700 rpm cruising, at the lower edge of my preffered rpm window.