'03 Tacoma Prerunner

[mobilerik]

Sweet! Yeah, I was looking for that, but I couldn't remember who posted it. Suppose you could post a template of the ideal curve for me to play with?

[mobilerik]

Woohoo!!! I made it !!!! The 30mpg barrier is broken.




Whew, that was close!


For the record, since last Friday's fillup of 27.7mpg, the improvement is 8.3%.

That's the effect of 5 mods completed this week:

• Smooth Wheel Covers (Sunday)
• Rear Wheel Skirts (Sunday)
• Passenger Mirror Foldback (Tuesday)
• Cab Roof Fairing (Wednesday)
• Cab Side Fairings (Thursday)

All together at the same time, they're probably worth about 10% total, or 2% each, which agrees with the findings of others who have done similar mods.


Next up -- Whatever I can get to from this list:

• Better Cab Kamm
• Tonneau Extension
• Front Wheel Well Dams
• Front Wheel Skirts
• Passenger Mirror Delete

Along with these clean-up projects to complete or improve what I already have...

• Wheel Cover Air Valve Access
• A Real Grille Block instead of this stupid cellophane wrap
• Make Wheel Skirts More Easily Removable
• Add Paint to the Belly Screen - Necessary, I don't know

and research projects...

• Sketch My Truck's Ideal Teardrop Curve
• Locate a Coastdown Hill and Cruising Test Strip

We need more emoticons on this board. I want the ones that dance around excitedly. Woohoo!!!

[aerohead]

Originally Posted by akashic

Sweet! Yeah, I was looking for that, but I couldn't remember who posted it. Suppose you could post a template of the ideal curve for me to play with?

akashic,the dark area in the template is the ideal curve.If you have a good side shot of the tacoma,scale it to just fit under the curve,where the highest point of the cab intersects the max height of the pattern.The curve dropping away and to the rear represents the ideal path,without separation,that the air will follow.-------------------------- For your shortbed,and 60-inches of bed length,I took the tangent of 10-degrees(probably a slope you wouldn't want to exceed for the short-bed),and it shows that at the tailgate,your cover shouldn't be any lower than 10-1/2 inches lower than the height of your roof.You could make up the difference with a rear spoiler laid back at a shallow angle no more than a 30-degrees which would intersect the line of the template.If you tilt it more upright,it will begin to dig back into drag.
The template will give you the better form,but at 10-degrees slope,you shouldn't get in too much trouble.P.S.,you almost have to do a rear spoiler because of the short bed!Happy fabricating!

[mobilerik]

Thanks! Here's the fit:





Wow, that's a lot of height to make up! I almost want to just stick a vertical board there to see what will happen. Or better yet, a couple of boxes. But I'm in a hurry, so I'll just make an arch-shaped spoiler.

When I make the arch, do you think I need to leave the tunnel clear, or do you think it might benefit to block it to encourage the stationary vortex, so the air knows to go above and around?

[mobilerik]

Preview of my next mod: The most visually striking yet!

It made it about 20 miles in the rain today before I watched the reinforcement fall off. It definitely needs better reinforcement all around to cope with freeway speeds. It's made of two layers of coroplast, with steel strapping. Unfortunately I only glued them on, but it doesn't matter, since it clearly needs more stability anyway. I'm going to try a layer of hardboard under it.

Because of the rain, I definitely won't be setting any records this week. My morning commute said 26 mpg, with a much more accurate calibration. So not much help for testing aero performance.

The angle is 10 degrees and is set slightly shallow of the ideal curve from the roofline. The arch passes 10 inches above the tailgate at the highest point. Rear visibility is minimally impacted, because the perspective of the rearview mirror is similar to the roofline. I'll post pix later when there is decent lighting. It does happen annoyingly that what little rear vision it does impact, it slightly obscures cars following at the proper highway following-distance. But I it doesn't completely hide them, and I can confirm by adjusting my glance a tad.

Once I get this thing stabilized, I also have the templates ready for clear "Kab-Kamm" which I hope to have ready this week, provided a few moments of dryness for the adhesives to stick.

[aerohead]

Originally Posted by akashic

Thanks! Here's the fit:





Wow, that's a lot of height to make up! I almost want to just stick a vertical board there to see what will happen. Or better yet, a couple of boxes. But I'm in a hurry, so I'll just make an arch-shaped spoiler.

When I make the arch, do you think I need to leave the tunnel clear, or do you think it might benefit to block it to encourage the stationary vortex, so the air knows to go above and around?

I would begin with a clear block at the rear.The "box" should not behave as a parachute,as it is not in the free-stream.Closed like this,it will force the surrounding air to go around,and my intuition tells me that it will behave like the Gilkison"dog-house" or my "blister",both of which added mpg to Tacoma and the T-100.

[mobilerik]

Damn, this is getting expensive, especially for a prototype. Now I need a 5'x1' sheet of plexi, just so that I can cut half of it off in a non-standard shape. Oh well...

Hey, is there any particular reason why the block would be more preferable at the rear of the spoiler tunnel than at the front? What if it was blocked in the front with some sort of curvy "ramp" to further entice the air over and around the spoiler?

[aerohead]

Originally Posted by akashic

Damn, this is getting expensive, especially for a prototype. Now I need a 5'x1' sheet of plexi, just so that I can cut half of it off in a non-standard shape. Oh well...

Hey, is there any particular reason why the block would be more preferable at the rear of the spoiler tunnel than at the front? What if it was blocked in the front with some sort of curvy "ramp" to further entice the air over and around the spoiler?

akashic,at some fabric stores,they carry a very heavy, clear sheet vinyl,which when stretched tight and stapled down, is almost as clear as glass,virtually weightless and a fraction of cost of rigid plex.It's probably tough enough to get you through testing to see if a more permanent and "expensive" mod is justified.
Just a thought.

[lunarhighway]

what if you where to raise the sides of the bed untill they are t the right height and than add a horizontal spoiler on top? shouldn't block vision to much, wouldn't really look like it was a spoiler

[Christ]

Continued banter from other thread -

Yeah, exactly like that. LOL

I was talking about the full shell though. Seems like it's just easier to make the whole thing, rather than worrying about compound air effects caused by the open area between spoilers. - To me, anyway. I could be wrong, it's happened before.

But, it seems like you've got the right idea, so I'll shut up now :P

Oh, on your wheel fairings (kilts): If your flares are ABS, You can get a spare set that will allow you to build the fairings from ABS, and you can actually "weld" them together with Acetone. (ABS melts to a putty in acetone, and will bond to other ABS as the Acetone evap's)

This might make it appear cleaner, and will leave a smoother wheel area for you to look at. Just a thought, you might not even care.

Good work so far, though, keep it up! Always nice to see someone working on a beast of burden!