Can anyone articulate why Ford rates the 2.7 ecoboost with payload package as a GVWR of 6900 (for screw, 4x4, 147 wb) yet for both the 5.0V8 and 3.5 Ecoboost, the same truck gets 7000 GVWR?

Edit, discussion should be limited to 2018 trucks for the moment.

 

A guess on my part but the engine weighs about a 100 lbs less so the actual weight the truck can carry is about the same as the 7000 lb GVWR trucks.

 

...and (also guessing) Ford probably doesn't want to have a higher max payload on the 2.7 than on the 3.5EB.

 

Correct! Remember that GVWR is the vehicle weight+payload capacity. Therefore, if 2 trucks are identical but have different engines, then the different weights of the engines will result in different GVWR.

 

But the original poster's point was that payload capacity should actually be 100 pounds higher if the engine is 100 pounds lighter, assuming the lighter engine is capable of providing the power needed at GVWR. The chassis, brakes and suspension should all be capable of the same GVWR as the heavier engine, thus switching to a lighter engine should buy you more payload, just as reducing heavy options would.

 

The shortest answer possible?

Because Ford says so. Engineering, Legal, Marketing, Sales and I'm sure many other departments have a say in the ratings on the vehicles for sale.

The bottom line is the ratings and Mfg cert (White GVWR sticker on driver's door frame) are what they are and can't be changed without significant expense.

 

I would assume payload is largely calculated with the rear GAWR in mind, whereas the engine puts most weight on the front axle. I can only assume basing on memory, but taking two identical trucks with different engines will have a bigger difference in the fGAWR compared to the rGAWR.

Now the fGAWR should theoretically stay the same, which means an engine weighing 100lbs less means you can load an extra 100 lbs. But weight ratings which take payload into account, are calculated not only by the strength of the frame and suspension components, but also the vehicle's ability to pull, handle, and brake safely. So from a truck frame's perspective, hauling a load above the frame in the bed, or sticking out the back attached to a hitch, is still the same regardless of if the engine up front is 100lbs lighter or not. So that 100lbs being taken away from the front just reduces the GVWR but can still have the same payload.

Hope that makes sense. I tried to find some documentation I've read on it before that's much more specific and clear with no luck, so hopefully what I dug out of the back of my mind makes sense lol

 

Ah, that's a good point.

I'd also expect that the lighter engine may get a lower fGAWR and softer front springs, given—as you noted—the owner is more likely to add significant weight to the rear of the truck, and the front axle load won't change as much from the factory weight.

 

2018? 2.7L may get the LD frame. 3.5 & 5.0 gets the HD frame.

 

Manufacturers have to follow many safety standards to set GVWR. Braking, vehicle stability, and manufacturer internal standards for durability, dynamic stability and handling to name a few. This why many vehicles total AWR is much higher than GVWR.