5.7 vortec towing

Hi guys. This is my first post and have been a member for about a month. I have a '99 burb 4x4 with 5.7 and have been doing alot more towing lately. I haven't had any major issues with loads up to 7000# with the exception of certain hills, but I am looking to gain some mpg. and maybe some power cheap. It has a K&N filter and I have gotten rid of the central sequential junk under the intake with a plug and play conversion kit and that made quite a diff. Thought about exhaust but would never get it past my wife and have heard mixed results with exhaust. programmers???? I don't know anything about them and have heard mixed on those with stock components. Any advice is appreciated.:biggrin:

Hi guys. This is my first post and have been a member for about a month. I have a '99 burb 4x4 with 5.7 and have been doing alot more towing lately. I haven't had any major issues with loads up to 7000# with the exception of certain hills, but I am looking to gain some mpg. and maybe some power cheap. It has a K&N filter and I have gotten rid of the central sequential junk under the intake with a plug and play conversion kit and that made quite a diff. Thought about exhaust but would never get it past my wife and have heard mixed results with exhaust. programmers???? I don't know anything about them and have heard mixed on those with stock components. Any advice is appreciated.:biggrin:

It is hard to get power and MPH togeter.
And with a big sub and 4W and low gears and trailor towing good MPG is
going to be hard to get.

Give it a good AC delco tune up.

Pitch the K&N And leave the rest of it alone.

Your OEM exhaust is the best exhaust system you can get.

Most programers and chips are set up for more power but with more power and big foot your gas mileage goes away.

Also seting up a programer or chip on it is a illegal operation.
As in tappering with emmisions.

I'll second MT. If you want the towing capability, you're gonna sacrifice MPGs.

Keep 'er tuned up, clean the IAC, PCV, and EGR valves and check for vacuum leaks that could cause you to run rich.

If you know you've been running rich (if you tow that much weight alot then my guess is you're hammer down much of the time), check the cat for obstruction due to it partially melting (they get super hot when catalyzing the excess fuel into CO2 and water). If it needs replacing, you can consider a higher-flow cat and a cat-back exhaust system. The performance gain is minimal, but they cost little more than an OEM replacement. I will suggest that if you tow long distances to consider a quieter system to reduce interior noise.

Also, replace the O2 sensors if you're over 100k. These can contribute to poor efficiency as they age.

Finally, when you're not towing, take it easy on the throttle. All the standard driving tips apply...no jack-rabbit starts, coast to the next light in traffic, smooth acceleration to get to the highest gear and TC lockup quickly. You're most efficient when your at the speed just above TC lockup...45-55 mph. You have no slippage in the tranny and wind resistance is still fairly low. Go above 60-65 and you start battling drag.

Hope this helps!

Hi guys. This is my first post and have been a member for about a month. I have a '99 burb 4x4 with 5.7 and have been doing alot more towing lately. I haven't had any major issues with loads up to 7000# with the exception of certain hills, but I am looking to gain some mpg. and maybe some power cheap. It has a K&N filter and I have gotten rid of the central sequential junk under the intake with a plug and play conversion kit and that made quite a diff. Thought about exhaust but would never get it past my wife and have heard mixed results with exhaust. programmers???? I don't know anything about them and have heard mixed on those with stock components. Any advice is appreciated.:biggrin:


programmers do create better customized performance. however more power will mean lower gas MPG...

since towing heavy loads are frequent , I would use only synthetic transmission fluids and engine oil synthetic.

I gained alittle over 1 MPG when I got rid of the non synthetic.

the rear diff oil with these loads requires frequent changing. the diff gets hot. do this when the fluid gets dark. probably every 20 - 30,000mi with your towing use.

the O2 sensors get worked hard with this towing , make sure they [upstream] get replaced if they are past 100,ooomi.

I use a F.A.S.T. programmer for my '96. Lets you adjust engine and trans programs separately. Not something you want to change often, unless you like reprogramming the radio each time (several fuses must be removed to flash the ECU).

There is no way to get good mpg, even with the 5.7, especially when towing. A Banks system (CAI, headers/full exhaust system) would prob give good gains in power and mpg if they're still available, but they're pricey.
I'm lucky to get 11.5-12mpg hwy, and 9-ish towing an 8000-8500lb boat.