Improving mpg with a RTT

So my rack is almost level with the roofline of the truck and my Tepui Tent sits up real high. Has anyone experimented with a large fearing or spoiler type thing?

Thinking about building one that mounts to the rear factory roof rack mounting holes.

I also thought about getting a roof rack like the Prinsu Cab rack and seeing if that would help.

Any ideas?

 

@HomerTaco has a real nice setup.

 

I'm guessing the best thing you could do is to lower the rack to get the RTT down to cab height. But I'm not sure that lowering the rack or installing an air dam will give you much improvement. I suspect that the bigger, turbulent, low pressure area behind the truck caused by mounting the RTT anywhere (just like filling the bed to cab height or higher with anything) has the biggest effect.

Im not a aerodynamic engineer, and I didn't stay in a Holiday Inn either, but years ago I studied up on the effect of installing tailgates made of netting on pickup trucks. Turns out that the net tailgates actually decreased fuel economy. The reason is that a fairly stable "cushion" of air forms in the area between the top of the cab and the top of a solid tailgate. As the truck drives down the road air smoothly flows over the cab and tailgate. Removing the tailgate or installing a net tailgate disrupts the airflow around the truck by creating a whole lot of turbulence (drag?) behind the cab and the truck. I dunno if what I think I know is actually right. But there it is.

 

Older pic but you get the idea:



Makes a HUGE difference driving at highway speeds.

 

@HomerTaco do you have any moar pictars of how you attached that. I tried going through your build but I got lost in the 100 plus pages lol

 

I've changed it around a bit since I have the full PrInSu Rack setup. The full build is in my build thread here. (way back on page 27)

It now mounts on the cross rails of the PrInSu not the OEM roof rack:



I would not do a trip of any length without it. The fairing serves as a deflector for branches on the trail too.

 

Awesome thank you

 

Sorry to raise this back up but having the same issue here... Where can I get one of those fairings :O

 

That was a just DIY build out of pieces I got from Home Depot... I could not find a commercially made one that fit my application so I just "Macguyvered" one on my own.

 

I am le sad I am making that trip to gulches in a few weeks and trying to maximize this MPG again.

 

I'll be there & will have it on. You can check it out in person.

 

Initially I ran the RTT over my shell and lost about 2-3 MPG when at highway speeds. It was frustrating as most of the camping locales around here require an hour drive on the highway. I decided to center the tent on my truck to improve the COG and lower it to reduce aerodynamic drag. I sold my basket-style BajaRack and purchased BR's flat, utility rack. I moved the RTT onto the utility rack (over my cab) and now I would say the MPG loss is barely noticeable, maybe less than a MPG. I would guess a large spoiler, like what's pictured above, would improve my numbers even more - I knocked around the idea of making a Maxtrax mount that utilized the Maxtrax's as a faring. Maybe I'll have some time to fab one up this summer. My wife and I just finished a 5k mile road trip out West and averaged 17MPG in our heavily laden Tacoma. When running the RTT I stay below 65MPH (55 MPH is ideal) and that seems to help a lot with handling and fuel economy.

 

Just saying if you want to make another for a Prinsu roof rack I am okay with that! Lol, I will have to check it out though for sure. Thanks Craig!

 

It was very simple to build - here are some better pics from my build thread:

https://www.tacomaworld.com/threads...homertaco’s-build.131392/page-27#post-7560163

 

Realistically anything over the roof is going to drag and make noise. A fairing would help you, how bout a lower bed rack? I forget it's there, quiet and no less mpg than usual road trips. I don't use my RTT annex and this works for me the best

 

Very good setup if you do not have a Cap on the bed!

 

Thanks! At times I still want a cap but I like this set up more.

 

I think i will be in the same boat. I am having a RTT Rack built by Red Beard Fab here in Hell Paso. His name is Adam Cox. I'm sure you can find him on F Book. We discussed a wind deflector mounted to my roof at the back where the roof rack would mount. I'm dropping it this weekend so he can get it measured up. I'll post pics of course.

 

I just yesterday picked up an adjustable over shell ladder rack to use for a RTT rack. It just unbolts for normal use and I still get the use of the dry(ish) storage under the shell. This is a must for camping with the kiddo. Mom and kid in the RTT, and I will be out in the Tent-cot.

Brandon

 

What kind of mpg do you get?