Jigidy

Hey guys, Extremely new member here requesting your help.

I had a 2000 Silverado with the 5.3L V8 and traded it in for an 08 with the 4.8 Liter V8 thinking I would save some money both on purchase price and on gas.

I have not been pleased with the 4.8L (truck is a 4 X 4, z71, with 4 speed Automatic.) The little engine is fine cruising around town 55mph and under, but on long road trips with gear trying to due 75 or 80 mph the engine constantly kicks down a gear and I go from 17 MPG to 14 just to go the speed limit. If I have my bikes or canoe on top and there is a head wind it's really a joke.

I love the truck other than the engine and was wondering if there were any "mods" I could do to help increase performance, and which ones would be the best bang for the buck....dual exaust, turbot system, new computer chip. I haven't ever done anything like that but would seriously consider it to help this truck out.

Any suggestions would be greatly appreciated.

Thanks

Jigidy

Hunt4X4

air intake and exhaust systems would only help you out minutely if any at all, but headers could help out a little but they cost a fortune to install. i also dont have much faith in gas engine chips or tuners. i would look toward either getting a 5.3 back or larger, but i understand you probably wouldnt be a big fan of that. the thing is that you not only need more horsepower, you need more torque which comes with the larger engines. But new headers would be a start as well as some throttle body spacers. And an exhaust system would make it sound stronger and may help a little

Jigidy

Thanks for the advice, I may just keep my eye out for a used silverado with the 5.3 and trade my old one in one day.

zm1040

I feel like you should not be going that fast and be expecting your engine not to have trouble, especially with a 4x4. I would lower your speed to 70 and see how that goes and yeah go for a 5.3. Going 70 you should probably get 17 or 18 on the highway... suppose it depends on the gear ratio in the back though.

Hunt4X4

also while you have the 4.8 chech the gear ratio and make sure that its all correct. if the gear ratio is off it can cause problems with acceleration and cause you to have to play more with your foot pedal to keep a certain speed. do this especially if you have tires smaller or larger than stock. but eventually you will need the 5.3 or 5.7

Jigidy

Hunt4x4, Thanks thats excellent advice about the gear ratio, I hadn't thought of that. My 5.3 had no problem cruising on the interstate at 75...but like I said the 4.8 is always kicking down a gear (makes me wonder if the newer 6 speed transmission would be better suited for the 4.8) I don't know anything about gear ratios but I will ask my local mechanic what he thinks. I have not modified the tire size from original.

Thanks again.

Hunt4X4

no problem, i hope that that will narrow it down for you. The six speed is always nice to have just make sure if you do get one that its a trustable brand, like jasper or one from GM even. i hope this all helps. Let us know if it works out or not.

CoffeyLover

I am in the middle of having my 4.8 swapped for a 6.0... might be something to look into, but it is big $$$. My 4.8 blew, so I was forced to change it.

Jigidy

CoffeyLover....did you look into replacing the transmission with the 6 speed instead of replacing the engine? Has anyone done this? I think the 4.8 would perform a lot better with a 6 speed transmission rather than the 4 speed I currently have.

Thanks for your help.

CoffeyLover

I did not look into that as my engine blew so I had no choice but to replace it. I really wanted more power though. I would much rather achieve higher horsepower using a bigger motor with less mods, than a smaller motor with more mods. I will be looking into a six speed swap soon, although money is becoming a factor for me