85 Tercel 4WD Wagon - Where to start?

[Snax]

Aeropimp my ride!

Heh heh, at least it doesn't have the stock roof rack.

Honestly I think aero is the least of my concern since most of my miles are at 40 mph or less. Rolling resistance seems to be a bit high. Regardless, what would you do?

I've already blocked off the upper grille, but this was more to get the heat up faster on cooler days and doesn't really seem to do squat for FE. I've thought about wheel skirts and discs, but let's be realistic here - it's a moving trapezoid!

Almost forgot to mention that when this body shape debuted, Road & Track made a remark about it having a new aerodynamic shape. It makes me chuckle to think about it.

[red91sit]

My goodness! You've got quite a pickle there. I would imagine underbody paneling would give you the biggest first improvement. I would imagine the stock 4 wheel drive system is an aerodynamic bugger.

[Gary Palmer]

If it is at all possible, you should make it either front wheel drive, or rear wheel. Having all 4 wheels being driven really takes a toll.

Without changing the transmission, I suspect the 4 wheel drive final gearing is probably fairly high, which will cause the engine rpm to be higher, which in turn will use more fuel.

I'm not up on the mileage, but your shape is pretty similar to my 89 Honda Wagon. I am able to get high 30's out of mine, while still driving on the fast side.

One other thing you can do that may help, some, is increase the pressure on your tires, to at least as high as the max pressure, on the sidewall. I had mine up at 55 and it makes a marked difference in rolling resistance. It does affect treadwear a little, but not nearly as much as I would have expected.

Oh, welcome to GasSavers, too.

[GasSavers_DaX]

Originally Posted by Gary Palmer

Oh, welcome to GasSavers, too.

Some humor Gary? Snax has been around for a bit.

You guys are making me severely jealous with your wagons! I want an RT4 Wagovan so bad I can hardly stand it!

[Gary Palmer]

Naw, some spacing, on my part, that's part of Whoop's, in my cars name?

[omgwtfbyobbq]

What're yer trans/axle ratios? I'm betting gearing could be behind the mileage issues. 4WD doesn't seem to impact efficiency nearly as much as throttling losses do IMLE.

[ZugyNA]

I'm getting 32-33 mpg mixed in summer with the same car. 30 mixed last winter.

Compared to the Ford Escape Hybrid at 27 mixed (EPA). It's maybe 1/2 ton heavier and more power.

[Snax]

Toyota did the smart thing on gearing by installing an 'extra low' gear vs. gearing down the final drive, so it really isn't that bad with a 3.73 final and .83 OD. I doubt taller tires would do much for me around town.

Frankly, as far as aero goes, I'm thinking of just going totally the wrong way with it by fabricating two A-10 Warthog style engine nacelles to mount on the roof.

I think a large part of the rolling resistance problem is really the tires. The 155 width cheap snow tires on it right now seem to deform a fair bit radially even at 45 psi - which is their maximum rating. Likely the only way to see real improvement through the driveline however would be to remove the rear differential, but that's not really an option since I actually need the 4WD.

Regardless, I'm hoping to see considerable improvement in my FE soon, as I have a new carburetor to install. Right now the car just stinks of raw fuel if I get on it very hard.

[Snax]

Oh, and I also just realized that I do in fact have an 83. :P

[omgwtfbyobbq]

Originally Posted by Snax

Toyota did the smart thing on gearing by installing an 'extra low' gear vs. gearing down the final drive, so it really isn't that bad with a 3.73 final and .83 OD. I doubt taller tires would do much for me around town.

I think they will. For my Rabbit w/ pretty much the same sized engine (1.6l) and a slightly taller OD gear ratio (3.89/.71), and it would still benefit from larger diameter tires when cruising at or under ~40mph. The alternative being to P&G, so it yer already doing that and seeing lousy numbers then ya may want to see what's up once ya get the carb on and everything running right.