Too heavy for highway speeds?

Hey guys first post here! been searching obsessively since I bought my already modded truck a few weeks ago.

My problem is: she will not stay in 4th (D) at highway speeds AT ALL. If I want to go 70 I have to be in 3rd (at 3200 rpms)

Would a gear change give me power in fourth?
Will reversing the lift and getting smaller wheels be in vain because of the extra weight?

 

Your profile says 4 cyl automatic transmission. That’s a limitation.

 

Since you have a 6" lift, do you have oversize tires?

 

Yes they're 33s (275 70 18) 18s being required for this procomp lift.

 

Nothing wrong with 3200 RPMs, smaller, high compression engines create power at higher revs.

 

Thanks for the reply. So staying in 3rd at all times isn't an issue? Could a regear let me be use 4th at lower rpms?

 

Your mileage will suffer, the engine will basically handle it, this is the trade off with the more efficient smaller engine, but I'm sure you already knew that. I am less familiar with the GenIIs so I'll let others comment on optimal gearing for highway, I tend to think of re-gearing for low end.

 

Taller tires = effectively higher rear gear. That will make any engine work harder.

 

Extra weight, lift, assuming oversized tires, the 2.7 in combo with and automatic is going to be a nightmare on the highway under those conditions.

 

Welcome to TW!!

 

Assuming you already have factory 4.10 gears, then regearing is not necessary. You are asking a 4cyl to do too much and unfortunately dropping down in lift and tire size is likely not an easy or cheap option either if you have a 6" drop bracket lift. I don't think you will be pleased with a smaller tire size with a 6" lift. Going with a 6" DB lift is the main problem I have with your build. It was unnecessary and difficult to reverse in order to fix your current issue. A 3" lift with a CMC would've worked for your build.

 

The auto trans is your biggest limitation. That being said I have a 4 cyl 5 speed on 33” mud tires that weights about 5600 pounds. I switched to 4.88’s and run down the highway at 75 in 5th gear all day long sitting right at 2900-3000 rpm. I gained 2 mpg over the identical setup with stock gears and constantly rowing back and forth between 4th and 5th. My truck bone stock was at 2700 rpm at 75mph btw

 

The engine is currently lugging in 4th (that's why the transmission is shifting down to 3rd) and will use more fuel in 4th than it will in 3rd.

Gear swaps are nothing more than fine tuning the setup, if it's a dog before the gear swap it'll be a slightly peppier dog after the gear swap.

 

Has your speedometer been adjusted for the taller tires? If not, you might be going 75+ with it reading 70. These trucks with the 4 cyl really don't like going 70+ mph, especially with the automatic, lift and taller tires.

 

I bought the truck like this and I'm new to 4x4 in general I just liked the armored bumpers... that being said I have a guy that says he can reverse the lift with some fabrication. I screwed myself I see

So I put some smaller tires on the 18s to mimic a closer to stock wheel, and she's able to do what I need on the highway. Can i assume then a gear change will give me this acceptable performance with 33s?

 

Guys at ECGS told me with the auto tranny and stock 4.10 gears that I would be at 2700rpms at 70mph with 5.29 ....

 

6in DB lift, bigger tires and armor on a lil 2.7L auto.... yeah its gonna be a dog especially with stock gears.

 

Regear and be happy

 

It'll be close to the same as stock after the gear swap.

 

That’s basically correct. Your overdrive ratio is .71. Mine with the 5 speed is .81 so yes even with 5.29 you would still be lower rpm than me with 4.88. According to the calculator on grimmjeeper you would be at 2664rpm at 70mph with that size tire and 5.29 gears