Ecomodding an automatic '04 Civic Sedan

[mpg_numbers_guy]

Went ahead and built my mirror boattail sill thingies two days ago (was too busy to post until tonight).

Made a template out of cardboard:






Traced and cut it out of the clear plastic and mounted with...any guesses?...painters tape and duct tape.






And as you can see, visibility out the mirrors isn't compromised at all:



Not the best looking mod, I'll agree. It would've looked better if I had used duct tape covered cardboard to more closely match the car, but I wanted to use clear plastic so visibility out the mirrors wasn't diminished.

Yesterday and today on my drives I set new best indicated day MPGs, 62.9 yesterday and 62.5 today, with trip records of 64.9 yesterday and 66.0 today. With the O2 sensor issue 66.0 MPG translates to 55.4 actual MPG.

Mirror boattailing is working for me! No actual tests yet but between that and the tail extension my coasting ability is significantly increased, and there is noticeable noise reduction around the mirrors. I would love to see some of you test it out and see what results you come up with!

Hoping to get my new O2 sensor installed tomorrow afternoon so I can test the tail extension and mirror sill boattail thingies. Guessing the tail extension and mirror sill boattail thingies (we need an official name for them ) are worth around 1 mpg each or so.

Next step: finish my second attempt at wheel skirts and wheel spats.

[teoman]

Good job!

Keep up the good work, i wish i could accomplish as much as you!

If i were you, I would download a cfd program. Autodesk has one for free and invest a bit of time in learning fusion 360, also free. Then use cfd (something like a virtual wind tunnel) to simylate many mods before you apply them.

It will look great on your CV aswell.

[19bonestock88]

Hey, I like it! Cuts drag from the mirrors without removing them or making them tiny... I wish I could follow suit

[mpg_numbers_guy]

Originally Posted by teoman

Good job!

Thanks!

Originally Posted by teoman

Keep up the good work, i wish i could accomplish as much as you!

You can, with just a little bit'a materials and a lotta bit'a time!

Originally Posted by teoman

If i were you, I would download a cfd program. Autodesk has one for free and invest a bit of time in learning fusion 360, also free. Then use cfd (something like a virtual wind tunnel) to simylate many mods before you apply them.

It will look great on your CV aswell.

Isn't that one of those programs where you have to basically try to perfectly draw your car on it or something?

Originally Posted by 19bonestock88

I wish I could follow suit

Why not?

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Replaced O2 sensor today. CEL is gone, and idle RPMs are back down to where they're supposed to be! Actual 60+ mpg trips here I come!

[teoman]

Yes, but you may be able to find the model of your car online or one that resembles it a lot.

If you draw the whole car, it will be a slight pain in the arse.

In the worst case you can use an existing model to get a feel for the mods.
https://grabcad.com/library/coupe-alfa-romeo

[mpg_numbers_guy]

Originally Posted by teoman

Yes, but you may be able to find the model of your car online or one that resembles it a lot.

If you draw the whole car, it will be a slight pain in the arse.

In the worst case you can use an existing model to get a feel for the mods.
https://grabcad.com/library/coupe-alfa-romeo

I'll have to check it out!

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What if I could swap over to lighter wheels for free.

Current setup that came with the car is 195-60-15 with the default alloys. 498mm tall.

There is someone who is wanting to trade a set of those coveted HX wheels for EX alloys and might be willing to pay a little cash too.

The HX rims are 14". The default tire is 185-65-14, which is only 476mm tall.

Someone is selling a set of new 185-70-14s for $67 OBO. With the HX rims that would be 485mm tall.

I would have a 2.61% odometer undercount.

The setup would be lighter. Not sure about the weight of the OEM alloys; weight savings would be 20-40lbs, plus be 10mm narrower per tire. Would this make up for the odometer undercount? Right now all my driving is city, but when I leave for college this fall I won't be using my car except for longer highway trips.

Would it be worth it? would HX rims fit on 185-70-14 tires?

Not necessarily serious because parental pressure doesn't want me to swap; asking more out of curiosity and for future reference than anything particular at the moment.

[19bonestock88]

Definitely swapping to a smaller, lighter wheel would help you and a slightly taller tire should help with RR... if you also fabricated a coroplast disc for the HX wheels at the same time, you’d not have any aero penalty...

The lighter wheel should help you more on those short trips, and the taller, narrower tire should help you in the highway, but you’d definitely gain something

Only downside is that with a narrower tire, your cornering speeds would have to come down a little

[mpg_numbers_guy]

Would HX rims fit on 185-70-14 tires though?

Would definitely do coroplast discs though.

The slightly narrower 185 tires are the standard width on the DX, HX, and Hybrid models. Only the LX and EX have the "wider" 195s.

The new combo would actually be shorter, not taller, by 13mm, which is why I wondered if that would offset the benefit from lighter weight + narrower width.

EDIT: OR, what about the 14" hybrid rims/wheels from the same gen Civic? Heavier than the 15" currently but same narrower tire and still lighter weight? Have 2 possible sources for these. Pros of this would be that they would be a direct swap and require no tire replacement.

[19bonestock88]

THe wheels and tires would fit fine, I missed the diameter calculation, but .5” shorter won’t hurt much, you’ll just have to remember to subtract the percentage from your odometer reading when you fill up/log your fuel... you’d still get benefit of lighter tire but not the benefit of taller tire... bumps will feel worse due to smaller rolling diameter but otherwise you’ll be fine...

[California98Civic]

Yes, those tires and wheels will fit. If you could get 185/70-r14 tires that would be even closer to the 15s. Remember too to do GPS tests of actual distance versus what you odometer says. The civics are not completely accurate to begin with. You are probably undercounting miles even at stock configuration. Get a GPS app, map a 100 mile route on GoogleMaps, and run the distance on the app and the ODO. That will give you a better sense of a reliable multiplier.