33.7 to .. 4̶6̶.̶0̶ .. 60.6 mpg!

[j12piprius]

Here's a summary of the up/down 125 mile route.

33.7 mpg --> before ultragauge / 67-8 mph
43.9 mpg (41.8 / 46.0) --> ultragauge / P&Dfco / 58.5 mph
49.6 mpg (48.3 / 51.1) --> grill blocks / P&Dfco out / P&Eoc back / 55.8 mph
52.9 mpg (55.9 / 49.9) --> wheel covers / P&Dfco all the way / 48 psi / 53-4 mph

I'm still finding P&D to be just as good as P& engine on coasting in neutral. My car coasts well in gear and there isn't much drag from the engine compared to being in neutral. Thus I usually alternate coasting in gear or neutral, depending on feel, and don't notice a significant change in the average either way. Sometimes one is slightly better, and visa versa.

Eoc would theororetically raise the average by 1.5 mpg, but that didn't work out on the previous return trip and I've decided not to do it anymore. This time I left the key on all the way both directions. The biggest difference is caused by the air resistance and the wind.

The last outward (up) trip at 55.9 mpg was quite encouraging, as the return trip had always been better. However, this time there was a headwind all the way back, the only reason I'm aware of for the 6 mpg drop. My speed has been dropping each trip, which has probably had a significant effect on the mileage. Ironically, I'm so focused on mpg now that the speed seems no different than before, when I was entirely focused on speed.

[type-S EF awd]

Those temps are getting a bit high. I would make a hole in your grill block, on the passenger side in front of the radiator, and maybe a cover you can pivot to cover or reveal the hole. I believe your cooling fans come on at 190, or they did on my CRX, and not only is that an electrical load, but that's wear on it. You could make an active air block, there's write ups on here

Another idea for your glide is to do the opposite of what some people on this forum do, and that is to make a button that Unlocks the torque converter. You would just have to find the two solenoid wires for the lock up solenoids, because if this is like my 94 civic, it uses the two for soft lockup, hard lockup and full lock up. by putting in a normally closed relay in line, and opening them during coast you will do less engine braking. Im sure you feel it unlock, when you first let off the throttle, and then re-lock and slow you down.

I have noticed in all the honda's I've owned, they don't like being shifted from neutral into gear above 3'rd gear speeds. By default if it can't make up its mind it will select 2nd gear, or begin to and then select another. So I would advise leaving the car in gear any time you are over 40mph, but you do what feels best.

[j12piprius]

The bottom grill is 60% blocked, except for the part in the middle. Previously, the temp would reach 188.6 and stay there for 95% of the trip.

My car is a 5 speed manual, and doesn't have a torque converter.

Update: the thermostat opens at 190, but the fan comes on at 185, which seems quite redundant to me.

[j12piprius]

I changed the lower grill block, and got 6 mpg less than the last time heading east, then adjusted it and got my highest west average a few days later coming back.

51.3 mpg (49.2 / 53.4) --> changed lower grill block / didn't check tires / 55.5 mph

This time I watched % engine load instead of instant mpg all the way and mostly kept it around 90%. This worked well, so I plan to keep using it from now on, but I missed the instant mpg display when gliding. Update: I've changed the display to showing 6 gauges, with % engine load above instant mpg in the lower left corner.

This is the route going east.



This is the route west.

[j12piprius]

My first mod was the upper grill block in the photo, made from a thick hdpe plastic plant pot. The lower grill block was made from a thinner plant pot, on the sides of a 7" wide opening below the license plate, which resulted in my highest mileage to this point. The coolant temp was mostly at 199, and got up to 206 on the climbs, maybe too warm as the outside temp was only low 60's, the same for the return trip a few days later. The wind was calm during both of the trips, but the mileage was 6mpg less from the second one, maybe because the fan was on more on the hills.

I changed the lower grill block to that in the photo for my next trip, made from from the very thick plastic from an old city garbage bin. This was not as good, as the mpg were less, and the temp was in the 204 to 208 range more often. Prior to the return trip, I cut off the bottom corners, an inch under the license plate, and pulled the bottom sections inward to the grill. The splits on the return trip were still not good, but improved past the peak and the mpg was my highest coming west. I think the fan was still coming on a lot the first half of the trip, as the outside temp got up to 90.

The fan coming on can explain much of the inconsistency in my mileage.

I want to keep improving the grill blocks, gain more consistency, and get the temps down so the fan won't come on. I think the upper grill block is okay, but want to improve the lower one, and add an air dam to the bottom, or else combine them together.

[j12piprius]

The wheel covers look white, but have three coats of gray.

[digital rules]

Nice job on the wheel covers!!!

[j12piprius]

previous east/west 250 mile round trips:
33.7 mpg ~ before ultragauge / 67-8 mph
43.9 (41.8 / 46.0) ~ ultragauge / P&Dfco / 58.5 mph
49.6 (48.3 / 51.1) ~ grill blocks / P&Dfco out / P&Eoc back / 55.8 mph
52.9 (55.9 / 49.9) ~ wheel covers / P&Dfco all the way / 48 psi / 53-4 mph
51.3 (49.2 / 53.4) ~ changed lower grill block / didn't check tires / 55.5 mph
54.4 mpg (48.2 / 60.6) ~ p/s delete, 52 psi tires, disc. fan, taped hood, 1/2 rounded bumper, 55.5 mph

I've been trying to figure out why my best mpg east trip was so much higher than the others. The main thing that trip was using old plant pot plastic for a 75 percent lower grill block, perpendicular to the ground, and curving around to the sides. The car was coasting awesomely during Dfco coasting, but I changed the grill block, and no other trips had come close in that regard, until the west trip today.

For this trip I had removed power steering, disconnected the fan (a mistake on the hill but otherwise fine), taped the joints in the front, and installed a rounded nose on the driver's side half of the bumper (made from gorilla tape and half of a $1 sheet of foam from the dollar tree). The latter seemed to make the most difference, as my east trip a few days ago had only a 48.2 mpg average. The mid 90's temperature probably made a big difference too.

I used P&Dfco the first 25 miles of the trip today right into a wind and managed to better my previous split by 1.2 mpg, to 50.7. Now the wind was to my left and I could feel it pushing through the slightly opened window. There were no other cars or trucks at this point, so I immediately changed to P&Eonc and noticed the difference right away. Wow, my car was coasting again like that previous trip, even better! My car has been coasting just as well with Dfco as with Eonc, I think because the aerodynamics were so terrible. Now with some improvement, the Eonc is getting much better. By 50 miles I was 6.7 mpg up my previous split, to 55.4 so far!

The next 10 miles were climbing, with 2 miles at 7%, and the average went down by 6.6, but gained 5.5 down the other side, still 6.0 ahead at 75 miles to 54.3 mpg. The remaining 50 miles were up and down, mostly down, and I managed to better my previous west average by 7.2 mpg, for a new totally unexpected record of 60.6 mpg!

[PaleMelanesian]

In my experience with this generation of Civic, the radiator fan comes on at 206F. If you're cycling between 205 (or 6) and 195, that's your fan cooling things down. Open up a bit of lower grille to keep it below that mark more of the time. I used to fully open my lower grille every summer.

[David Philips]

To reduce the transmission jerk when re-engaging after an engine on glide, note the engine on RPM on the tach of that road speed when cruising in gear and gently from idle bring the RPM up with the gas pedal and pull the transmission into gear while maintaining the the light throttle pressure. You will quickly learn to do this instinctively. Note that some automatics do not go directly to top gear when re-engaging and so it may take a second or two for the transmission to decide it needs to be in top gear. If your car behaves this way you can overspeed the engine maybe 500 RPM before engaging the transmission further easing the re-engagement jerk.