Pickup truck aerodynamics

[aerohead]

https://ecomodder.com/forum/member-a...mendations.jpgI looked back at the 2002, Popular Science Magazine's mpg shootout, between a Ford sedan and Chevy Silverado LS 2500 Crew Cab, with 6.6-liter turbodiesel V-8, 2,667- kg curb weight, at 55-mph test speed.
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Internal GM memorandum placed this pickup at 17- mpg highway, @ 55-mph.
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GM's mpg guru, Roger Clark, recommended five aero-mods:
1) upper grille-block
2) upper fascia grille-block
3) lower fascia grille-block
4) underbody, inter-wheel, body-to-frame gap- sealing
5) and a full tonneau cover over the bed
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@ 55-mph ( 88.5km/h ) these five aero-mods increased constant-speed cruising fuel economy to 26.0-mpg ( 9.064-liters/ 100 km ), a 52.9% improvement.
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The thermal efficiency of your gasoline-powered RAM is less than a turbo-Diesel, and Diesel fuel itself has more energy density than gasoline, so your absolute mpg numbers would fall accordingly, but 12-L/100km/h is only 19.61 mpg ( at US Gallons-equivalency ), and I've seen as high as 39.9 mpg @ 65-mph ( 104 km/h ), compared to 25.14 OEM, with my gasoline-powered Toyota, so the 12-liter target seems very 'achievable.'
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And the 'faster' you drive, the more important aero becomes, as the power to overcome it is increasing with the 'cube' of the velocity, whereas, the drag is only increasing with the 'square.'
EXAMPLE:
@ 65-mph, your aero hp is associated with 65- cubed ( 65 X 65 X 65 ) =274,625.
@ 75-mph, you're at 75-cubed , or 421,875.
Performing the ratio, whatever your aero horsepower requirement was at 65-mph, at 75-mph it's now 153.61% of what it was, with just a 10-mph velocity increase ( 53.6% ), while your rolling-resistance power requirement has only risen by 15.3%.
Speed costs!

[BlackGold6.4]

In the picture section 2 the frontal area I can block off the bumper area because I have a gas engine if it were diesel than no due to the coolers down that low. Section 1 and 3 are totally doable but my plan is go further. TFL on youtube did a very good comparison on different things on and off a pick-up truck with fuel mileage differences but after all the aero vidios I've been watching it can be done way better. There are pictures from this forum that lead me to joining and a slopped back cap is one of those things I think will be very beneficial. Also the rocker area and under the truck is something I want to dig into more to. For example, instead of open skid plates I want to try thick Al. plates to smooth out the air flow.
Aerohead I really appreciate your passion on this topic thanks for all this input.

[BlackGold6.4]

Here is a sketch of my ideas for my Ram truck. We do a lot of exploring on trails in the vast bush where we live and where we go, so it's important to have these ideas removable. The approach, break-over and departure angles are important.
Because we live so far north the amount of highway miles to get to anywhere is long. For example 8 hrs non stop to Winnipeg or 9 hrs to Saskatoon or 2000 kms to Texas as the crow flies. 3 days drive to get to where my family lives in Ontario or 2 days to get to where my daughter lives in Alberta. So the goal here is to get better fuel mileage and camp where we go to save money, because a hotel cost more then a tank of fuel just for one night.
The swing out pup on the back is very similar to one we used a few years back that I think gave us better fuel mileage and held all of our camping gear, it was so convenient. It didn't come higher than the tailgate and tapered back with a smooth finish. Plus we had a tonneau cover that held all the other gear and then some. The one I have planned when swung open will give us access to the spare tire, recovery gear and other storage. Also a drop down table in conjunction with setting up camp.
The cap on the back will be some more storage and a pop-up sleeping area with canvas sides and back extended tent area to house a shower and porta-potty when required. The back area will also be easy to set up for a kitchen with access to fridge and all gear required for cooking.
Looking forward to some input from you guys and also refining these ideas, please feel free to give me your thoughts or ask any questions to help understand more.

BlackGold6.4

[Piotrsko]

Don't forget to seal the gaps between the cab and the bed. I prefer pool noodles.

[BlackGold6.4]

Originally Posted by Piotrsko

Don't forget to seal the gaps between the cab and the bed. I prefer pool noodles.

Yes good point, have been thinking about that. My thought was to use some of the stock rubber that goes between the cab and bed. That means drilling small holes that the factory clips can pop into but also means having the gap exactly the same. My truck didn't come with a rubber seal between the cab and bed so maybe some noodles will work there too.

[j-c-c]

Originally Posted by aerohead

https://ecomodder.com/forum/member-a...mendations.jpgI looked back at the 2002, Popular Science Magazine's mpg shootout, between a Ford sedan and Chevy Silverado LS 2500 Crew Cab, with 6.6-liter turbodiesel V-8, 2,667- kg curb weight, at 55-mph test speed.
--------------------------------------------------------------------------------------
Internal GM memorandum placed this pickup at 17- mpg highway, @ 55-mph.
--------------------------------------------------------------------------------------
GM's mpg guru, Roger Clark, recommended five aero-mods:
1) upper grille-block
2) upper fascia grille-block
3) lower fascia grille-block
4) underbody, inter-wheel, body-to-frame gap- sealing
5) and a full tonneau cover over the bed
--------------------------------------------------------------------------------------
@ 55-mph ( 88.5km/h ) these five aero-mods increased constant-speed cruising fuel economy to 26.0-mpg ( 9.064-liters/ 100 km ), a 52.9% improvement.
--------------------------------------------------------------------------------------
The thermal efficiency of your gasoline-powered RAM is less than a turbo-Diesel, and Diesel fuel itself has more energy density than gasoline, so your absolute mpg numbers would fall accordingly, but 12-L/100km/h is only 19.61 mpg ( at US Gallons-equivalency ), and I've seen as high as 39.9 mpg @ 65-mph ( 104 km/h ), compared to 25.14 OEM, with my gasoline-powered Toyota, so the 12-liter target seems very 'achievable.'
--------------------------------------------------------------------------------------
And the 'faster' you drive, the more important aero becomes, as the power to overcome it is increasing with the 'cube' of the velocity, whereas, the drag is only increasing with the 'square.'
EXAMPLE:
@ 65-mph, your aero hp is associated with 65- cubed ( 65 X 65 X 65 ) =274,625.
@ 75-mph, you're at 75-cubed , or 421,875.
Performing the ratio, whatever your aero horsepower requirement was at 65-mph, at 75-mph it's now 153.61% of what it was, with just a 10-mph velocity increase ( 53.6% ), while your rolling-resistance power requirement has only risen by 15.3%.
Speed costs!

Where the above 5 aero mods in any particular order?

[COcyclist]

Looks good. I hope you will start a build thread when you start on the cap/topper.

[BlackGold6.4]

Originally Posted by COcyclist

Looks good. I hope you will start a build thread when you start on the cap/topper.

Thanks and yes I will start a build thread but still have a lot of research to do.

[freebeard]

What are the open questions?

[BlackGold6.4]

Open questions? Well I think you mean something like this.

1. Safe reliable easy on and off attachments for the front air dams and side curtains
2. Shape of front air dam after front off road bummer is built

I'm looking at materials to use even though I know how I'm going to build the moulds but may need to change that according to choose of material. Already have seen some options on this forum.

The pup on the rear is just going to be a shell over an inverted tire/gear carrier to act as not only storage but a tail that is shaped to the rear of the truck to help break the wind turbulence known with flat backs. With that it will be fibreglass, keep it simple type thing.