Yaris mods

[spookybathtub]

I'm new to this eco-modder thing. I drive a Toyota Yaris hatchback, and I'm interested in maximizing FE without looking ugly. This is what I have planned:

heater bypass valve
belly pan
smooth hubcaps
block fog light cups
block radiator vents
kamm tail
transmission swap 5-spd to 6-spd (maybe not affordable)
rear wheel skirts

I'm going to document my progress in this thread, unless a mod suggest breaking it up into multiple threads... I don't know the etiquette here.

The car has 175K miles, and gets about 36 mpg (combined) right now. Not bad.

[spookybathtub]

Toyota recommends tires at 32 psi. One week ago I increased them to 44 psi, and also started driving more consciously, following tips from this website, and now I've moved from 37 to 43 mpg (16% increase). My car doesn't have a tach, but DashCommand is very helpful for monitoring RPMs.

[spookybathtub]

The heater core installation is complete, and it works very well. Previously, the air coming through the vents was about 15-20˚ warmer than the outside air (with AC off). This forced me to either open the windows or use the AC. This is because the Yaris uses a wimpy lever to block the heater from the air ducts.

Parts:
Four Seasons 74701 valve - $12
hose clamps - $4

This valve has a vacuum actuator, which is incompatible with the Yaris. It's very difficult to find manual valves in the right size. So I modified this with a hacksaw, leaving a manual actuator lever.

Now the vent air is almost the same temperature as outside, maybe 2-3˚ warmer. And I imagine the engine heats up faster too.

[spookybathtub]

The smooth hubcap project is much harder than I anticipated. I picked up some 16" pizza pans that fit my wheel perfectly. I thought I would fasten some tee nuts to the wheels, then fasten the pizza pans with truss head screws. (Truss heads are very low profile). I fastened the tee nuts with JB weld. But they are so far recessed, I have to use 1.5" screws, and it's extremely difficult to line up the screws with the nuts. Takes me about 15 minutes to install one hubcap, and I'm not going to deal with that every time I rotate the tires.

So plan B... I will fasten threaded rods to the tee nuts, and put hex nuts on the outside, just like lug nuts. This won't be as aerodynamic as the truss heads, but hopefully still an improvement. I'd recommend fastening hex bolts to the wheel with JB-weld, but since I already have the tee nuts permanently attached, I have to cut all-threads to length instead.

[ME_Andy]

You can buy some thin hex nuts to at least minimize how far they stick out...
McMaster-Carr

Nice work on the vent thing, that sounds interesting.

[ME_Andy]

Actually, now that I think about it, there are some intriguing options for "captive nuts" or panel nuts that wouldn't protrude at all.

McMaster-Carr

[spookybathtub]

Thanks for the link. Those captive nuts do look interesting. But I think they're designed to be fixed to the surface, and the bolt rotates with a wrench.
I think I'm going to need nylon lock nuts for safety.

[elhigh]

I don't think your 5-6 tranny swap is feasible. The 6-spd was only offered with the diesel, and I don't think the diesel was ever offered in the States. I'll research it some, though, if the bellhousings are compatible it's not outside the realm of possibility.

[JRMichler]

Look closely at the gear ratios before getting into a transmission swap. Most six speeds seem to have the same first and sixth gears ratios as the comparable five speed first and fifth gears. If so, there's no gas mileage benefit.

[Eddie25]

these are hubcaps that were fitted on my very first car. im sure blocking the holes and smoothing the lip will make a good aero wheel cover