Modifying my Brick-On-Wheels

[MTUboi86]

Hey all,
I have a 1994 Ford Explorer, and I've recently been doing a lot of research on these forums and Google on aerodynamics. Considering my Explorer is essentially a "Brick-On-Wheels", I'm attempting to modify the aerodynamics with a shoe-string budget.

Yesterday I removed the roof rack bars (the tracks are still in place), and made a 'nose' for the front that essentially blocks the huge grill opening. I installed that tonight, along with a make-shift air diffuser thing on the back. I think that's the wrong term tho. It's basically a folded piece of duct tape that's taped onto the rear of the roof.

There are still openings in the bumper for air to get to the radiator (but I did tape one up to block it off).

When I get some time, I'm hoping to at least do a partial body pan to help get air around the front differential (which is huge), along with filling in all the gaps I can on the underside to help reduce drag.

I'm looking for help on all of this. I need ideas, constructive criticism, and help with figuring out angles etc. for the best nose design.
Currently, my 'nose' is made from an old poster, some wood for support, and duct tape.

Here's basically what my explorer looked like before (except I re-installed the stock air dam):



And this is what it looks like with the nose:








And this is what that "diffuser" on the rear looks like:



I took these on my phone, so they aren't that great... but they work.

[MTUboi86]

My last fill-up was 13.48mpg. That was like 95% city driving. This tank I had also drastically modified my driving style (taking it easy on the gas, going the speed limit, anticipating, etc etc). I also blocked the cold air intake portion of my air intake, so now it only sucks air in from around the exhaust (this is a stock setup, I didn't modify anything, except for blocking the cold)

My fill up before that was ~10mpg. So, an improvement for sure.

I think the 13.48mpg tank would have been better, but there were excessive detours which left me idling for a long time (it's a 2-mile drive to campus [college student], and it took me 30 minutes ... needless to say, I was about 10 mins late for class most of that time). Finally, almost all of the construction is done so no more detours (YAY!).

I mainly only do city driving ... but I'm mainly doing these mods for the 1,000 mile trips I take to go home for breaks (round trip).

My EGR valve is blocked off because it is stuck open ... but that'll cost over $200 to fix and I can't do that right now. Considering I got the best gas mileage ever (but only on a ~60 mile trip) on the "highway" (21.4mpg, 55mph) with the EGR blocked, I don't know if the EGR valve was really doing much anyways before, other than reducing emissions. Don't flame, I really want to get it fixed ... but it's $$.

Winter city driving, I average 10mpg ... lots of snow & frigid temps (20F to -20F), and I have my front hubs locked all the time so I can engage 4-wheel drive "on the fly" without stopping.

Just thought about adding some info. I write a lot, sorry about that.

[theholycow]

Slow down...by doing dozens of vehicle and driving modifications all at once, you won't know what worked and what didn't. Also, you will need to try to get a lot more data than one tank. You need a few steady tanks as a baseline before you can accurately tell the difference when you try something - and then you need a few tanks with it to be sure.

[Dr. Jerryrigger]

I very much agree with what the cow said, But i must say I like your approach to craftsmanship.
With this project it is important to think about all the variables.
The aerodynamic aspect of the grill may be making no difference and any improvements are from covering the radiator.
the speed your are driving at will make a huge difference on any gains or losses in aerodynamic performance, so to make any comparisons things have to be nearly equal.

[MTUboi86]

Originally Posted by theholycow

Slow down...by doing dozens of vehicle and driving modifications all at once, you won't know what worked and what didn't. Also, you will need to try to get a lot more data than one tank. You need a few steady tanks as a baseline before you can accurately tell the difference when you try something - and then you need a few tanks with it to be sure.

Yea, I know
The problem is, I usually only go thru a tank of gas once every 2-3 weeks because I mainly do city driving. I also don't have a garage, so I'm trying to get stuff on it before snow sticks (the snow is already flying up here...but not sticking yet).
-----

I just got back from a trip to Calumet and back. Same route as before (I posted about it on one of my other threads re: EGR valve, etc). Up here, it's a "trip". Almost nothing is more than 4 miles away before you leave the city. Round trip, it was about 27 miles. about 5 of that was city driving without the mods. I got ~17.4mpg.
If I did the math right, about 25% of the gas consumed was due to the city driving ... thus giving me approx 21.43 mpg hwy ... as a VERY rough estimate. I don't even know if I can assume that. If it can be assumed, there'd be no change in gas mileage.

I know 27 miles isn't very far for testing ... but I can't do much more than that, at least for highway. I'll be driving to Marquette this weekend, two hours each way. I'll keep track of the mileage for that and see what it says ... though, I can't duplicate it for future tests unless there's a reason for me to drive to Marquette (that's where the closest Lowe's is).

All of my highway testing is done at 55mph (the speed limit)

[MTUboi86]

Originally Posted by Dr. Jerryrigger

I very much agree with what the cow said, But i must say I like your approach to craftsmanship.
With this project it is important to think about all the variables.
The aerodynamic aspect of the grill may be making no difference and any improvements are from covering the radiator.
the speed your are driving at will make a huge difference on any gains or losses in aerodynamic performance, so to make any comparisons things have to be nearly equal.

You posted as I was still typing my post
I do the tests at 55mph, with very little of that being below 55 to get to the "highway".

For winter, I generally always block the radiator. Last year it didn't seem to do anything for my gas mileage, but I wasn't driving as light as I am now either.

[Jay2TheRescue]

In my experience trying aero mods on my GMC Sierra K1500, aero mods don't work on trucks in an urban environment. If you had more open road / highway driving then I'd say you can have at it with the body pan & everything. Sure it does something, but I think for your investment in time & materials you are better off looking somewhere else than aero.

1. Driving with the hubs locked is a big hit. I would recommend leaving them unlocked, and only lock them on days where poor road conditions are expected.

2. A grille block would be good, but not as much for aero reasons, but to help keep the engine warm. I'm not sure how the intake air is routed on that vehicle, but if it is drawing in cold air from outside, disconnect it so its drawing preheated air from the engine bay.

3. You may also want to investigate rigging up a warm air intake, and intentionally preheat the air (usually by moving the air intake near the exhaust manifold).

4. Make sure your vehicle is running in the best condition possible. This means that all fluids are checked/serviced regularly. Synthetic fluids can help boost mileage. When was the last time the transmission fluid was changed? The transfer case? Differential? Engine oil? These can make impacts on your mileage if neglected. This also means you should get the EGR fixed. Have you looked into the possibility of getting an EGR valve from a junkyard? In my area I've dealt with several U-Pull-It yards. You go in, pull the part yourself, and in the end they'd probably only charge $10 or $20 for an EGR valve.

5. Take a look at your tires. Are they the proper size, or does it have bigger tires than the factory put on it? What about your tread? Are you using a tire with a highway tread, or an off-road tread? Smoother highway tread patterns on your tires will help with mileage as compared to off-road tires. I would recommend either an A/S (All Season), or a M+S (Mud & Snow) tire. AT (All-Terrain) tires usually have an agressive enough tread that mileage will be effected. Ford usually puts M+S tires on all their trucks at the factory.

6. Most importantly, your biggest gains to be found will come from modifying your driving style.

The mileage on my K1500 may not look great, but consider that its an 11 year old full size, extended cab, 4wd V-8 pickup with 165,000 miles. My EPA combined rating is 13. (This is what the EPA expects the vehicle to do when driving 45% CITY, 55% HIGHWAY) I regularly get at least 13 MPG driving 95% short trip city. There are many 4x4 V-8 pickups out there that would struggle to get 10 with my combination of age/mileage/environment.

Good luck, and keep us posted.

-Jay

[theholycow]

Good points, Jay.

I'm not sure switching to all synthetic fluids will ever pay off in fuel economy gains, even if it's time to change them anyway. Synthetic fluids can be expensive.

My K1500 is another example for comparison. 8 year old model, 186,000 miles, 4x4, V8. My driving is not urban; it's ~40% highway and the rest is town and country roads - not as stop-and-go as urban driving but definitely not highway where my truck gets its best fuel economy. I'm beating the EPA rating by a hefty amount. My only modifications are increased tire pressure and removed FM antenna.

[Jay2TheRescue]

Which is why I said it may help mileage, but certainly if the transmission hasn't been serviced in 100,000 miles that can effect mileage and longevity of the transmission. I'm merely throwing that out there as something to look at and consider.

Another thing I forgot to mention earlier was the fuel system & filters. When was the last time the fuel or air filters were checked/replaced? Also if the vehicle is old with high mileage then a bottle of BG 44k would not be a bad idea to clean up the injectors and valves.

[trollbait]

How do you know the EGR valve is blocked?
There was a period of time when Ford had bad DFPE (I think that's the right name) sensors. It is part of the EGR system, and is responsible for monitoring exhaust gas flow. The Ranger had a bad one, and I suspect my 1996 Taurus also did. On the Ranger it was bolted to the intake manifold right up front with 2 hoses going to the exhaust. The old ones were metal, and it appeared deposits built up inside them. New ones are plastic, and run about $120 from the dealer to $60 for third party ones. Real simple to replace. The hoses are different sizes so they can't be switched.