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Old 11-14-2012, 02:01 PM   #31 (permalink)
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Nice- that 04 is better than the Probe on the freeway, if he's not P&G'ing.

The cap looks good. Can't wait to see the gap fillers!

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Old 11-14-2012, 03:06 PM   #32 (permalink)
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Quote:
Originally Posted by MetroMPG View Post
Congrats.

Can you give us some context for that number? What type of driving - city? Rural? Speeds?
Today I left the house, went .3 mile through the neighborhood. Turn left (stop sign) onto route 143 east, 4 lanes not divided for 4 miles (55 MPH). Hopped on I64 east, right lane 55-65 (65 limit) mostly 62 ish. 45 miles to Va beach and the pick and pull. Walked through there for 45 minutes and drove back. This time I hopped on the express lanes and went to Lunch in Poquoson, then drove home.
Total trip about 100 miles, average speed probably 50-52 MPH. Least number of lights possible. The guage read 3/4 when I had gone 93 miles first time, second time it read 101 or so at 3/4. With the cap it easily beat 125 at the same point. Coasting in this truck has dramatically improved. Going through the HRBT today eastbound I coasted for probably the longest distance yet and my speed actually increased from 55 to 65 in the tunnel, had to tap the breaks when I started to get too close to the car in front of me, even after shifting back from neutral to 5th.
This tank looks very promising, I will refill in the next couple of days at somewhere between 200 and 250 miles to see how much it takes. It's looking very very good right now, coasting opportunities all over the place, even the overpasses offer an opportunity to coast down the slope for several tenths of a mile while only loosing about 10 MPH (65-55). Let people merge in front of me and when the traffic is light I can even occasionally do some coast-drafting when the container haulers pass and pull over 50 feet in front of me.
Downhill coast-drafting can make me have to use 5th gear DFCO to stay a decent distance separation.
In the Fiesta under the same conditions I would probably be doing 46 MPG, maybe a little higher.
I guess if I can get that in the truck then I don't need the Fiesta.

regards
Mech

Last edited by Old Mechanic; 11-14-2012 at 03:21 PM..
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Old 11-14-2012, 04:14 PM   #33 (permalink)
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I've been thinking about your project as I look at it, and it is very good. I like how you kept it high to the tail lights. Also when you dive down at the end like that "sub template" I think it fills in the wake quicker and is a good thing.

If I had to wonder about something being sub optimal, it would be that it appears the sides do not taper in and the square side to top corners.

I think the sides not tapering makes the air stay at a "higher" pressure too far back, and when the side air does finally get to spill over and join the top air, there is a fair amount of pressure difference which could set the air into an energy robbing spin.

Do you plan on making something to sit on the tail gate which tapers in? If so, you may want to re-engineer the last 2 feet or so on the sides to taper in. If nothing is going to fill the gap there, you may want to consider removing the overhang so the air has a cleaner release and you reduce the potential for large pressure variations in close proximity to each other.

I know the square corners are a ease of build design compromise. I'm sure the overall reduction in them not being radiused is less than a 10% hit on what would be optimum. Keeping it high really helps that too, if you were more aggressive with your taper, then the square corners would tend be a larger concern.

Have you noticed how much more planted the truck feels at higher speeds? You've knocked the stuffing out of your lift coefficient so it should feel now like you're driving an arrow that just wants to go straight. Maybe the difference was more easily felt with my truck on icy roads, without the cap, it really skipped out on me once in a while with a cross wind, when the cap was on, it never did that.

Great Job!! Good on ya for gettin er dun!





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Last edited by ChazInMT; 11-15-2012 at 01:52 PM.. Reason: Changed Pics this time
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Old 11-14-2012, 09:08 PM   #34 (permalink)
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Chaz, the sides taper in for about the last two feet. The cap is anchored to the bed where the rectangular holes are in the bed rails from the factory. The rear holes are about 6 inches from the back of the bed and about 2.5 feet from the end of the tailgate when it is down. I would say they taper in 6-8 inches in 2.5 feet with the second half much more sharp than the first. This allowed the top panel to remain the 4X8 foot original size.

The rear has a long way to go, but most of the improvement is there already. I like to ponder the next step for a while so I won't want to redo it before I finish it. In Va anything more than 3 feet back from the bed requires a red flag, so that is about my limit. I want it to be reversible and fairly quickly removable. My thinking now is to make a "box" that attaches to the tailgate, and is located by the original latches and the cable stay locations, but could be removed in a very short time.

I would prefer to maintain the original tail lamp locations as well as the license plate and lamps. Right now I am leaning towards lexan covers from the bed sides over the tail lamps back to the meeting point a foot past the rear edge of the tailgate (down position).

On the point where the cap meets the cab. It will be more rounded and the gap filled completely as well as tapered better when I am finished. I am also going to put some wood stringers between the tubes in the cap frame to smooth out the panels. I put some curve into the top braces but it will take some more reinforcement to get the surface smooth enough.

regards
Mech
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Old 11-14-2012, 09:15 PM   #35 (permalink)
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I was watching it in the rain yesterday and a drop of rail fell from the back edge of the cap onto the tailgate at 60 MPH. It was interesting to see that the fall of that drop of water was almost identical to what it would have been if I had been sitting still instead of moving at close to 90 feet a second. A leaf stuck to the top of the cap with rainwater did not blow off in 20 miles on the Interstate.

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Mech
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Old 11-15-2012, 09:09 AM   #36 (permalink)
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Quote:
Originally Posted by ChazInMT View Post
Don't forget that when applying the "template" to a photo, you need to level the vehicle in the photo first (or rotate the template to match the vehicle pitch). The truck in that pic is sitting nose down by a couple of inches (reference the top or bottom of the wheel covers).
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Old 11-15-2012, 01:50 PM   #37 (permalink)
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Yeah, I saw the nose down nature of the beast they call Ford Ranger. I'm a believer in that we apply the template in relation to the "Ground Plane". Air don't care about the rear of a vehicle being jacked up. We move through the air parallel to the ground (99.99% of the time anyway) so if I leveled his truck it would be nose up in relation to how it really looks to the air.

I think the front tire is sitting in some deep grass too so it looks like it is angled down too because of that.

After I analyzed the thing all over I see I was off by 1 and have changed the pictures above with the new twist. I put the Template on the rims of the wheels instead this time instead of guessing at those funny looking front tires and noticed the skewage...the wheels never lie though!

Here are the 2 big pics to compare if you want, change is subtle, I moved the template a bit more forward on the second application so the top of the template was at the highest point of the truck in both images.

I felt it important to discuss this here for the benefit of anyone looking in to learn more about Template application. As always, I may be wrong and am open to discussing this, but I'm 99% sure I'm on the right track here with it all.

Original Pic

New and Improved Pic (As now shown above)
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Old 11-15-2012, 02:22 PM   #38 (permalink)
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Ha. That was kinda fun. I GIF'd the 2 images. It shows me essentially rolling the truck 1 within the template.

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Old 11-15-2012, 05:49 PM   #39 (permalink)
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Here is a picture from above (my porch) showing the taper in the sides. Also today I used my belt sander to smooth out and round off the edge where the top meets the side panels. You need to give the windshield adhesive two days to completely dry. I replaced the silver duct tape with some white tape so it would blend in with the panels better. The taper should allow me to put clear plastic covers over the tail lamps that blend in to the sides of the cap.

Tomorrow I replace the blower resistor (only works on high speed right now) and in the afternoon I will finish applying the window adhesive to the rest of the frame after I have removed some material from the wood blocks which is pushing the sides out where the taper brgins. Then I might let it sit for a day to make sure everything is completely dry.

regards
Mech
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Old 11-15-2012, 07:05 PM   #40 (permalink)
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That's great that you tapered the top panel, it should be pretty good, and if you taper in a tailgate box matching what you have shown here it'll be excellent.


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