Gobi Stealth Rack
- Thread starter MeBe4running
- Start date
Antman
Elite Member
That is the most ridiculous thing I've heard. The rack weighs 70 lbs- my groceries weigh more than that each week. Maybe a loss in mpg from the wind drag, but the weight, gimme a freakin break...
kingpin748
New member
1engineer
Moderator
Remove Excess Weight
"Avoid keeping unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your MPG by up to 2 percent. The reduction is based on the percentage of extra weight relative to the vehicle's weight and affects smaller vehicles more than larger ones."
Fuel Economy Benefit: 1–2%/100 lbs
Equivalent Gasoline Savings: $0.04–$0.08/gallon
The above quote came directly from fueleconomy.gov and is a very simple answer.
The key thing is to differentiate the effect of weight on stop-and-go driving vs. steady-state cruising.
"In steady-state cruising on level roads and with everything else being equal (e.g., a car made of aluminum vs. an indentical car made of steel), weight doesn't have much effect on mileage. Weight slightly increases the rolling resistance of the tires and slightly increases the drag of the bearings in the wheels, but at anything but very low speeds, these are minor contributors to overall vehicle drag - the big factor is aero resistance which is not affected by weight at all.
But in stop-and-go driving, weight has a big effect on mileage because you're constantly accelerating the weight up to speed, and then wasting this energy as heat when you apply the brakes."
This is a good explanation also from a different source and I did not include any with mathmatical formulas as there is not one little "super gas milage formula of if you add X weight you will decrease your gas milage by y" and also the math, while not difficult, is very complex and cumbersome.
The best rule of thumb for weight is this: Every 100 pounds added to your vehicle will drop your gas milage 1-2%. So you can see there is a drop in efficiency for adding the rack. It is slight but these things add up quick.
Now, I don't know what I said that would have caused you to post your comment. I did not say how much efficiency will be lost, just some will be lost. Most people seem to forget about weight and efficiency but remember the aerodynamic losses. I was just reminding them is all. If you think my posts are "the most ridiculous thing I've heard" or "gimme a freakin break" then you are entitled to your opinion but I usually don't post something unless I know a little about the subject.
One more thing: In the case of the gobi rack being discussed the loss due to weight will be greater than the aerodynamic losses. Why? I'll let you do the math and figure it out as your response to my result will be much more emotional than factual.
sp8ball
New member
Don't trust the government!
Can't wait to see the pics of the ladder. Antman's rack is supposed to arrive today, and we'll be having an install gathering at his place this weekend.
1engineer
Moderator
I usually don't trust them either. In this case though it is common knowledge for most. All things being what they are, If I needed a heavy duty rack this would be the one I would buy. They are very functional and look good too.
SeattleMike
New member
My rack weighs 90 pounds and I lost 1 mpg in city driving as soon as I put it on. I lost another 1 mpg when I added the tent. City driving is affected most because that extra weight affects every acceleration, most of which is done in the city. My cargo kit cost me another mpg and it can't possibly be from drag because it is in the cabin.
Not even Antman can change the laws of physics.
I think it was called parasitic drag from my undergrad days:
http://en.wikipedia.org/wiki/Drag_(physics)
MeBe4running
New member
True.....
Thank you for your long detailed response. I don't disagree, whatsoever. I just suggested that they may be a decrease in fuel economy due to wind drag without mentioning weight at all. I still have a tent to put on, axe and shovel, 60'' Inch High Lift Jack, Lights and the list goes on. I ready for a decrease in fuel economy. I'm not worried about that; (yet) till gas is $10/gallon. If I was I would drive a Prius. This is not my city cruiser, i live 4 mile up a dirt road.:snacker:
Thank you for your long detailed response. I don't disagree, whatsoever. I just suggested that they may be a decrease in fuel economy due to wind drag without mentioning weight at all. I still have a tent to put on, axe and shovel, 60'' Inch High Lift Jack, Lights and the list goes on. I ready for a decrease in fuel economy. I'm not worried about that; (yet) till gas is $10/gallon. If I was I would drive a Prius. This is not my city cruiser, i live 4 mile up a dirt road.:snacker:
1engineer
Moderator
No worries here! My original response was posted because you did not mention weight and I know most people forget about it and then complain about the gas milage after the mod. I was just tryin' to help.
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1engineer
Moderator
Here's my "emotional response": Gimme a freaking break.
That's what I thought. Enjoy your new rack.
1engineer
Moderator
Absolutely! Too bad you don't live closer or I would buy you a beer and we could talk about the cool mods you did, the gravitational effects of rotating vs. static mass, women and life in general. Just reel me in if I go too far out on the proverbial ledge! :cheers:
MeBe4running
New member
No worries here! My original response was posted because you did not mention weight and I know most people forget about it and then complain about the gas milage after the mod. I was just tryin' to help.
I must laugh at this. You see people with strong options (whether right or wrong) on youtube and similar sites, starting literally a World War. Because of different interpretation's and politics involved.
The more I experience today's society the more i want to get in my 4runner and get off the beaten track!
I thought your response was detailed and well thought through, so thank you.:thanks:
MeBe4running
New member
That's going to be one sweet set up! Please post pic's once installed. How are you going to wire it through? I thinking of getting a buddy whose a dealer to do mine, as well its a lot harder than the FJ. (previous truck) Any thoughts or ideas please share. :thanks:
Theresa619
New member
Yes, the wiring is already installed for the lights.
Ray Dunakin
Senior Member
According to the trailduty.com website, Gobi's "Stealth version provides a flat surface structure front to rear along roof rack’s highest surface level."
Yet in all the photos I've seen, the top bar at the front end sticks up higher than the rest of the structure. In fact I can't see any difference between the Stealth and Ranger versions. What's the story??
I would really like to have a rack that is level from front to rear, so that any items longer than the rack itself can be strapped down without sticking up at the front.
Yet in all the photos I've seen, the top bar at the front end sticks up higher than the rest of the structure. In fact I can't see any difference between the Stealth and Ranger versions. What's the story??
I would really like to have a rack that is level from front to rear, so that any items longer than the rack itself can be strapped down without sticking up at the front.
Last edited:
Mistaken
New member
You can order yours that way from Gobi. The Ranger is taller.
