'03 Tacoma Prerunner

[mobilerik]

This weekend I mostly spent time "finishing" or redoing previous aero projects:

• New coroplast upper grille block. Painted glossy black, it looks pretty cool, even if very imperfect. Hella better than the cellophane!
• New coroplast lower grille block. Improvement upon duck tape.
• Accessible tire valves (!)
• Plugged the tunnel under the spoiler with thin acrylic.
• Underside wheel well dam

The most important mod was obviously the tire valves. I finally pumped up my tires, which were 10% low!

The upper grille block is nice. But now that I'm no longer covering the whole front with a piece of cellophane, it's much more leaky than it was. I might try some black caulking around the edges, which could also help the looks by covering the coroplast edges. Eventually though I'd like to upgrade to something that looks nicer to begin with, like ABS.

The lower grille block is taped on with "double-duck" and folded under with zip ties. I think it may be adding drag, because I had a lot of difficulty curving it around flush with the bumper, and I ran out of anchors for the zips.

The accessible tire valves are basically the same as on Concrete's pizza wheels. To get enough protrusion to be usable, I had to stack two extenders on top of each other. I have to wonder how much turbulence is added by having those valves revolving at high speed. I might consider instead making the hole bigger but leaving them under the wheel covers.

The clear spoiler-tunnel wall seemed sturdy enough on the drive, despite being only 1/8" thick. I don't think there's a lot of air trying to scoot under the spoiler, which probably means this won't make any difference. I made it out of one 7-dollar 18x24" sheet, with a 24" center section and wings on either side.

The underside wheel well dams are an experiment - though obviously not a very scientific one - trying to prevent air from getting into the huge wheel wells from below. Because the wheel has to turn, it's not easy to make the belly screen any closer to the wheels. So with some spare coroplast, I made a front dam under the car, mostly above the lower line of the bumper. I have no idea what kind of effect to expect from this mod.

Performance: No great news to report. On my morning commute the ScanGauge told me 30.1 on a new calibration that is giving a slightly low error in miles-driven, and suggests a 30.6mpg commute. I can't yet confirm that my beginning-of-the-week readings are low, because there have been anomalies. I am sure, though, that the car is taking longer to warm up in the morning, and my getting-out-of-town marks are lower - but I haven't kept track of that well enough to know how much.

I did however expect more of a jump after the cab and bed mods, especially now that I pumped my tires. There's probably something dragging. I look forward to the day when I can finally do some science and sort out the effects of all this stuff.

[extragoode]

Do you have any sort of templates or drawings or anything? How do you arrive at the shapes for this coroplast that bends into those great compound shapes? I love your cab kammback! Do you ever haul anything? I want to do something like your rear hump, but make it easily removable for when I haul my motorcycle in the bed. I wouldn't have a truck if I never carried anything back there.

[mobilerik]

Originally Posted by extragoode

Do you have any sort of templates or drawings or anything? How do you arrive at the shapes for this coroplast that bends into those great compound shapes? I love your cab kammback! Do you ever haul anything? I want to do something like your rear hump, but make it easily removable for when I haul my motorcycle in the bed. I wouldn't have a truck if I never carried anything back there.

Yeah, I do have photos of the cutouts that you could generate ideas from. I've been figuring I'll post lots of "instructables" once I get through the next few major mods, hopefully in the next few weeks.

The way I get the shapes is to play with simple paper mockups on my desk at work, cutting and bending until the bent shape looks the way I intended it. It's not hard -- it just requires some playing around with paper and scissors.

Then once I get the general shape I'm after, I'll try it for real on the truck with some poster board, tracing out a template, taping and cutting as I need. I make and correct many mistakes along the way, but it really doesn't take very long to get a good template.

I occasionally haul. My wife often needs fill dirt for the garden and has yard waste to dump, and I need construction materials for my projects in the garage. (Building a recording studio) This weekend I'll be doing the first dump run since my installs. The "hump" is just attached to a tonneau that I remove easily. Eventually I'd like it to be self supporting to regain some space in back.

The other reason for the Prerunner is to get some good off-roading capability. One of our hobbies is rockhounding -- We like to collect fossils and geodes. Since the sites are typically far away, it's great that it's now a good highway car as well!

[mobilerik]

I just had to show this silly photo I snapped
a split second before my trip ave hit 36mpg.

I call it silly because of course it's after coasting (engine on) down a long hill. But it does demonstrate what aeromods can do for you --- I could never have coasted that hill a month ago. I couldn't even glide. Now I P&G a lot.

I was able over the New Years break to tidy up some "loose ends" from last weekend's projects.

• Caulked the edges of the grille block, and added backer rod around the headlights to seal up the front end.
• Made temporary partial front wheel "mini-skirts".
• Sealed the tunnel under the spoiler.
• Tightened the belly screen.
• Tightened the lower grille to make it more flush.
• Deleted the passenger-side mirror. Added a Wink 5-panel rearview.
• Put the tire valves back under the wheel covers.

I know everyone wants to see the partial skirts, but they're nothing special - just a crescent stuck under the fenders. I did them too quickly and in the dark, so I'm embarrassed to show them off. Besides, they're only there until the full skirts are available.

Really, the most clever fix that I'd like to report on was putting the tire valves back under the wheel covers. As I mentioned in the last update, I did the tire valves just like Concrete's, with even the same brand of valve extenders. But because of the way my valves are placed, one extender didn't give enough protrusion outside the covers to pump the tires, so I had to stack two on top of each other. This meant that the valves stuck out quite a ways. Not only did they look ridiculous sticking out of the smooth cover, but I feared that they were creating a lot of unnecessary turbulence.

My solution was to remove the second valve extender, so that I was left with the first valve extender just below the surface of the wheel cover. Now when I go to pump the tires, I screw on a second extender and pump the tires normally.


This Week's Results:

Here's a crazy irony for the week -- After this week's fillup, I am very disappointed...


... in my calibration!


My fillup was 31.5mpg. New record for a 1-week tank, by +5%!!

But the ScanGauge told me to expect to match my previous best at 30.0mpg. I thought it was going to be very accurate this week. But it was 5% off.

But what makes matters more uncertain is that I got this fillup at a different station, with the truck in a much different orientation. So really, I have no idea what I got this week. With the extra mods and obviously better coasting power, I should be beating 30mpg by a lot, and it's strange that it's not showing up on the SG. Maybe the colder mornings really are taking a toll. Or maybe my fuel system just doesn't play well with the ScanGauge. In any case, I guess I really need to stick to the same pump until i get this sorted out.

But hey... maybe it means my top score ever from the above photo is really 37.8mpg. Ha ha. That's like 210% of EPA.

[festivaWES]

nice work on all your aero mods...inspires me!

[mobilerik]

I'm fussing with the mirrors.


I now have a 5-panel Wink rearview attached to the windshield.


The passenger mirror is deleted. I covered the hole with coroplast and it looks normal. You wouldn't even notice that it's gone.

I'm hoping to fabricate something for the driver-side mirror, and I'm collecting possible reusables for parts. Plastic cups and bowls... that sort of thing. Depending on whether I can find the sizes I want, I may wind up fabbing something out of fiberglass. But I figure that route is really silly, because surely I can find plastic cups!



The photo shows a temporary solution for the highway that I've not seen posted yet. Look closely... the little convex mirror is actually extended perpendicular to the main mirror, and it nicely fits in the gap between the main mirror and the window. It's attached with a metal bracket to the inside lip. Because it's attached it this way, it's actually protected from the airstream when the main mirror is in the normal position.




I'm going to look for a flatter small mirror though, that doesn't shrink everything. I really think it's too small to use as a main driver-side rearview when it's dark. But the combination of a small flat mirror and a larger convex one inside the car could give me the width I need. OR two small flat mirrors angled differently. I don't find the Wink very helpful for seeing anything behind me on the left side, because my fat head is always in the way.

Two flat mirrors may even be "legal" for that matter. Federal guidelines call for the driver's side to have a flat "1-to-1" mirror that gives you a view roughly across the next lane, about 30 feet back.

In any case, I post this just for inspiration, until I can fab a new aerodynamic driver-side window.

[Christ]

I like the idea w/ the bubble mirror - but I have a suggestion as well for it:

Since you obviously have fiberglass experience (you talk about fabbing with it), you should be able to get another OEM d-side mirror, cut a nice oblong rectangular hole in the outboard side of it, and fit a flat "1 to 1" style mirror about 2 inches wide by 6 inches tall into it. That gives you 12 square inches, which may even be able to pass inspection in some states, and it should fit in the housing as well without protruding at all.

The only reason I make mention of the FG work is to smooth everything out so it looks like it's supposed to be there.. you could do a prelim test with duct tape though. :P

[mobilerik]

Preview:

More to come.

[mobilerik]

Front Wheel Skirts Are Operational!

Questions? Comments?

[MaxMatt]

Only one of the images from the last post works for me... :/ ??