2002 Corolla - Quest for the MPG's.
 

I've been digging into ecomodder for about a year now, a d I decided it's finally time to put some of it into practice. Been driving this corolla for seven years now and it's always been reliable. It'll do 32mpg during the winter and 36 during the summer without much effort. I want to see how much it'll do.

So, first up, the easy stuff. Grill blocks! I used coroplast to block the upper grill and part of the lower. Currently experimenting with blocking it off some more.

Next, I inflated the tires to 42psi. I can definitely tell they're harder than the 30psi. We'll see what it can do. Eventually I'd like to mount the Bridgestone RE92's from the honda insight, once they're worn down.

Next, I wanted to direct my airflow through the radiator. I accomplished this with some of my old plastic truck bed liner. Just a simple rectangle piece did the trick.

Continuing on with airflow, I used a big chunk of that truck bed liner to create a front underplate. It's strong enough and also ribbed, so it doesn't flap around, but it's flexible enough to bend to where you want it. It'd definitely recommend it if you've got some laying around.

Lastly, I did a passenger mirror delete. Still experimenting with how I want to block the hole,whether coroplast or duct tape.

Mileage improments will come at the end of the week, as I don't have a scan gauge.

Moving forward, I would like to do a rear diffuser, but I'm not sure the best way to do it without creating a bigger air scoop than the one the rear bumper already makes. Any ideas are appreciated! Thanks to this forum and website for being so awesome!

Also, not sure how to imbed photos in the post, so they're in as attachments...

I think there's a minimum number of posts to be able to embed pictures. I'm surprise you can attach them, maybe things have changed.

Did the mirror delete leave a round hole? Then a plastic plug with a nice bevel could be painted body color.

The diffuser would be a lot easier without that big ol' muffler.

The mirror left a triangle with 4 holes. I'm thinking of a piece of coroplast with rtv holding it down..

I have considered a smaller muffler. My big roadblock is the big hole above and in front of the rear wheels. If I just throw a plate up, it'll just collect all the airflow under it.

Coroplast would have a corrugated edge. Sheet styrene is available at hobby shops.

The diffuser could have 'ears' that stick up into the wheelwell. Is there any room between the bumper and that red bulkhead?

I agree. Maybe delete the larger muffle and add two smaller ones along each side of the spare tire cubby. The same thing under our van. Seems FoMoCo place our muffle on its side instead of laying it flat. This could be causing some wind disturbance under the van. So it would be ideal to relocate the new muffler where the spare tire once was and then retro fit a flat skid plate from the rear axle to the rear bumper.

There is room around the back. I like the ears idea. It'll take some cardboard and a few iterations to work around all the trailing arms and stuff.

I like the smaller muffler idea, probably go with that. I can weld something up to work.

Here's some updates! I used a scrap piece of sheet metal to cover the mirror hole.

I got the torque app for my phone, and have tried it out the last 2 days.

I bought a sheet of coroplast and made a redneck two piece belly pan.

My thoughts on the torque app are that it seems to read mpg higher than it should be to me, but is quite fun to use. I'll find out tomorrow how close it is when I fuel up.

Last week's mods - 37.08 mpg at fill up. Seems to have been slightly better, since my winter full ups range from 33-35mpg.
After this fill up and driving the same 50 mile commute (round trip) route once, Torque claims I'm doing 42mpg.

Once I put on the coroplast underbelly, it says 44.5mpg over a 15mile test run.


Any recommendations on more accurate data gathering? Torque app setup and settings? Is a scan gauge more accurate than a Bluetooth obd reader + Torque? In my mind, they're getting the same data.



I've also been doing a coasting test, just under half a mile in length. Before doing all this stuff, the car would coast from 70 mph at the start to 51-52mph by the time I passed my mark. With all current mods, it is only dropping to 55-56mph. Seems to be a bit slipperier through the air!
I do know that's not scientific at all, just interesting.

' 50-mile roundtrip '
 

Not to be overly critical, but, in mechanical engineering, the car would be driven 50-miles, at 50-MPH just to achieve thermal equilibrium for all the dynamic parts, at whatever the ambient outdoor conditions were, before actual testing began.
This removes powertrain efficiency variability, after which, the actual 'source' of any observed 'change' to mpg can be properly credited with the 'attribution.'
--------------------------------------------------------------------------------------
Coolant - 203 F
Engine oil- 214 F
Transmission / Transaxle lube - 188 F
Differential - 159 F
Tires only require about 2-miles of driving to achieve equilibrium rolling-resistance conditions.
'New tires' require 4,000-miles of treadwear on them before they'll reach their advertised R-R coefficient, And as they wear out, they'll achieve their lowest R-R.

Torque app is getting data from more or less uncalibrated sensors, not that it matters. They may or may not be calibrated to the cars onboard Computer through normal useage, but you will be unaware what exactly that calibration is and it would be kinda recorded somewhere in car computer speak in car memory. I suspect it isn't a hard data point but a relationship. Only thing you can do is get many manual readings and build your own highly accurate calibration table which you are in the process of doing.

Your coasting test is giving actual good data, although is is vague. Method of scanning either by bluetooth or torque app will give you the same data it's just a different access much like hardwire telephone and cell phone will both recieve phone calls.

<rant off>

I see your point! I should call it a 25 mile one way commute, and I realize it wasn't enough to be statistically significant. I just wanted to update what I had so far with the little bit of driving I've done.


I've found a setting in the torque app to calibrate the mpg dial, I'm slowly working it down to what my tank's been saying.