4.8 to 5.3 stuff..

I have a 1999 extended cab shortbed 4x4 with 4.8 and 3.73 gears, I just got back from my first trip with this truck, it did great except for the long rolling hills on the interstate, It was really hard to maintain my 70-75 mph speeds without it downshifting on these hills which i dont like, it was really bad since i had my 700 pound motorcycle in the bed of the truck. My old 1989 silverado with 5.7 TBI never had to downshift going up hills on the interstate and i want to make my 1999 more like that. Would dropping in a 5.3 help much with this? Yes, i already know a 6.0 would but i already have access to a 5.3, so thats why im asking about it. I would like it to not have to work so hard on the next long trip on the interstate hills so was thinking of dropping the 5.3 in if it will actually do better with this...?

Swap the pistons from the 4.8 to the 5.3 and get a tune and some bolt ons and you got just watch ya want :)

well, i really dont want to tear into the engine, just swap it out..

You will gain a little bit maybe 20-30hp, but if you only want a ill bump get some boltons and a tune.

But with just the swap to 5.3, would that get me up those hills on the interstate without it having to downshift being the bigger engine having more torque?

It might, but the time and money invested will be far more than simple upgrades.

yes but i dont think any upgrades would give this small motor much more lower end torque besides a turbo. Not trying to build a race truck or anything, just want to be able to do 75 up the interstate with my motorcycle in the bed without it struggling on the hills so bad..

A tune will net you 15-20ish gains across the rpm range. A P&Ped throttlebody will get you gains down low and same for a CAI. Maybe $500 to get all that and see easy 35 gains.

playing around with shift points in the tune can be a benefit to you.

I hate to pour gas on the fire but when my rcsb 4.8 silvy was stock with only exhaust and cai it really struggled pulling my 21 ft boat. The 4.8 was always searching for a different gear. Bought a 00 Yukon with 5.3 the other day and I thought for sure this big heavy vehicle is going to struggle with this big heavy boat but...... I was very impressed ! My Yukon gets up to 70 and stays there, and isn't constantly down shifting.