Ecomodding an automatic '04 Civic Sedan

[mpg_numbers_guy]

So I'm finally back home and man is it warm! 80s to 90s (Fahrenheit)!

Of course I immediately went back to work on my car. First step was to redo the wheel covers since they were getting a bit shabby and aren't perfectly smooth. Making them perfectly smooth will make redoing my wheel skirts easier.

So I took the first one off along with the wheel. I punched out holes for the lug nuts and air valve access, painted them black, and reattached them with the zip ties facing inward for a smoother surface:



Paint is still wet in photo so it looks glossier than it actually is. I'll try to get around to posting a picture of it on the car tomorrow.

I only got one wheel cover done before going into work. I can finally check my tire pressure now!

I was interested in seeing what kind of FE I could get on my way into work and back. Previously, my best MPG going into work was 49.2 mpg and my best driving home was 58.2 mpg.

Without actually hypermiling that much (I was using cruise control instead of P&G) I got 51.9 mpg. I noticed vibration while driving, and it turned out that I hadn't tightened the wheel all the way back on.

Drove back home that night after tightening the wheel and got 58.0 mpg despite having to drive a little less "hypermiley" due to more traffic than usual for the hour.

I slept in today due to still being exhausted from my trip, so I had limited time to work on the car. I couldn't find my template for the cutouts in the wheel covers so I had to remake it. I got around to taking the wheel cover off the passenger rear (the first cover was the passenger front), but then it started raining and I ran out of time before having to go to work.

So with three wheel covers on I drove to work. I was struggling to get good FE and got "only" 50.7. I got out of my car and realized that my trunk wasn't closed all the way, so it had been bouncing around and causing drag. Grrr lol.

BUT, on my way back home tonight (after making sure my trunk was still closed lol) I managed to score 62.6 MPG!!!

This is largely due to warmer weather, but also due to a better P&G technique: I started pulsing in 3rd gear instead of 4th gear. Pulsing is twice as quick and so my glide-to-pulse ratio is better. It seems to work!

So happy I hit my goal of a 60 MPG trip! Now for a 50 MPG tank.. I'll be filling up soon, but this one won't be above 50. It's supposedly at like 47.7 mpg right now, but this is over a period of 2 months, and I haven't averaged 50+ for that long yet. But since I'm currently averaging over 50 mpg now, so hopefully the next tank will reflect this!!

[rnjason]

Nice progress you're doin'.

[mpg_numbers_guy]

So for those of you following my O2 sensor trouble, you know I'm hopping mad about my fuel economy now, especially since Torque never showed a decrease in FE when the CEL came on.

In fact, I was so mad after filling up I almost ripped off all my ecomods right there at the gas station.

Thankfully, I didn't. Anger leads to a lot of stupid decisions.

Here is the picture of the updated wheel covers as promised:



This has now spurred me on to further ecomods while I diagnose and fix the O2 sensor issue. Hopefully when it's fixed I'll be seeing my Torque numbers become reality with those 50-60+ mpg trips!

Began my rear end mod by installing a tail extension. It measures 7.5" past the rear trunk lid and follows the curve of the trunk almost perfectly.

I first attached it to cardboard tabs that I duct taped to the inside of my trunk:



Used blue painters tape to smooth and seal the transition from trunk to tail extension:



Made 3 cardboard supports to help maintain the tail extension's shape:



Trimmed the edges of the tail extension to follow the curvature of the trunk and to provide better side visibility to the taillights to avoid any possible legal issues. Put duct tape over the painters tape for a slightly improved aesthetic appeal :



Here is the view from the rear:



And from the side:



No testing yet, as I'm very wary of driving until I get the O2 sensor fixed for MPG reasons. Since I filled up my only driving has been my 5.7 mile commute to work and back 5 days a week.

Also revised my side skirts, and they work, except that the cardboard I used has a crease in it, so I'll have to wait until I can get cardboard that is at least 30 inches wide with no crease to install them.

Also had a thought about a mirror mod. Not planning on deleting my mirrors, but what if I ran a piece of clear plastic along the underside of the mirror to mimic boattailing behind the mirror? Kind of like as follows, except with clear plastic and tapered in the longer it goes:

[California98Civic]

I like the spoiler but taper the edges a bit, starting at the point of contact with the body. I have never seen a side mirror sill like you are considering, but I would also recommend tapering it as it goes back from the mirror housing. Those hard corners are going to produce their own problems, possibly.

[mpg_numbers_guy]

The edges already taper in slightly in line with the trunk itself, like this:



How much more should it be curved?

And yes, if I were to do the mirror thing I would taper it as it went back.

Are you talking about the hard corners on the tail extension?

[California98Civic]

Originally Posted by mpg_numbers_guy

... How much more should it be curved?

Well, I don't know, of course. But I was thinking of a model like this one:

Originally Posted by mpg_numbers_guy

Are you talking about the hard corners on the tail extension?

Yes. But I have never seen anyone attempt a mod like this. But a different approach would be the "boattail" fairings another great project on this site featured: Vekke's http://ecomodder.com/forum/showthrea...tml#post251416

[mpg_numbers_guy]

That spoiler on the Prius doesn't extend very far. Probably for aesthetic reasons? My idea behind this is that airflow reattaching is connected further before detaching behind the car, thus reducing the rear area similar to a bottail but obviously far less beneficial.

After I get my O2 sensor thing fixed I'm planning on tuft testing it and experiementing with VGs. If I can get airflow to remain fully attached down the rear window, that along with the tain extension should mimic at least a partial boattail I'm thinking.

There's actually several similar examples on this site, albeit from quite a long time ago. It's more of an enlarged version of what 19bonestock88 did on his Ion, and also similar to the rear deck extension endplates that was tested on a same gen Civic coupe for a 1.2-1.4 mpg increase at 60-70 MPH.

[California98Civic]

Yes I see. But that 2013 test had a design that also featured the side panels. Those are important for the "box cavity" effect. Check out what I tried once: http://ecomodder.com/forum/showthrea...tml#post376489

[mpg_numbers_guy]

My plan is to add side panels eventually (something like this that I posted earlier, but I'm probably going to forego the side skirts) to make it more of a box cavity than a mere trunklid extension. Again I do want to test it, but that'll have to be after the whole O2 sensor thing is resolved.

My extension extends further back than yours, so that probably helps. And if I can get VGs to work (big IF there lol) the benefit should be more noticeable. It's more for air over the tip to attach and have a smaller rear area than an actual box cavity effect, yet. I haven't read anywhere of it hurting and several people have seen a benefit, so I guess we'll see.

You're making me doubt myself now lol. How am I supposed to improve aerodynamics at the rear without going for a crazy boattail since a kammback won't really help my sedan??

[California98Civic]

Originally Posted by mpg_numbers_guy

... You're making me doubt myself now lol. How am I supposed to improve aerodynamics at the rear without going for a crazy boattail since a kammback won't really help my sedan??

Didn't mean to discourage. You're doing great. And I think your trunklid plan has good thinking in it. Follow your plans and test it if you can get the time (or just track FE if you cant get the time).

It sucks when there are mechanical problems, not least because they cloud the data on the mods. But such is life. These older cars ALWAYS have somethign going wrong. For Hondas is is usually not a something that prevents operation, but we need really good mechanical operation to test these mods effectively.

Hang in there!