03 Lb7 Boost Issue Please Help!!!!!!!

[SSDIESEL]

Alright here is the setup I have a 2003 lb7 I have the edge juice/attitude, airaid intake, banks exhaust, and banks waste gate actuator. I have owened this truck since new and the truck has always had great power. at the first of this month i installed a 6" lift with 35" tires and 20" rims i sell this stuff for a living and was prepaired for a small lose of power but to my dismay i have no power i can't even break the tires free. so i sent my edge back and they reflashed it and tested it and said everything was fine. i reinstalled the chip today and the power feels a little better but still feels week ( the night before i installed the lift i smoked an srt8 charger so i know the power was there) but i noticed today my peak boost is only reaching 19.6lbs and i still cant break the tires free even while power braking. my question is where did all the power go. please help my truck, its not fun to drive anymore what can i do to fix it. p.s. my cadillac cts is now way faster then my truck and thats not right.

[WyTTraven]

are you still running the stock gear ratio? If so that would explain some of the loss in power. If you search around on the net you can find an online calculator that with put you in the ballpark has to what gear ratio you should be running with the new tire size. I have an older suburban with a 4" lift. I went from the stock 235/15 to 33x12's.. HUGE loss in power because of the stock gear ratio...still fun to drive though.
What were your boost pressures before the lift? Is there a chance that any of the clamps were loosened during the install that didn't get tightened up completely?

[Mark Rinker]

Well you got the look, but no guts now. Which would you rather have?

Lower the gears - or lower the truck!

[jeep hauler]

Thats alot of power and traction on the tranmission.. Have you upgraded the the trans?

[DmaxMaverick]

Several conditions come into play with your situation. The larger (much larger) tires change your final drive ratio. They also change the rolling resistance and mass of your rotating hardware. All this takes more power, too. As far as getting the rear tires to break loose, several things you've changed are going to make this more difficult. The larger and more massive tires/wheels are pretty obvious. You also drastically changed your center of gravity. With the center of gravity raised well above stock, the weight transfer to the rear wheels during acceleration is increased, as well. That means greater friction where the rubber meets the road, and more power required to break that friction.

Install OEM tires/wheels and try again. You will still have the weight transfer effect, but your acceleration should be the same (or similar) as before. It will take more power to get the rear wheels to break loose, but your acceleration should be similar, to a point. The faster you go, the greater your aerodynamic resistance will be increased, due to the lift.

[SSDIESEL]

i was able to get 24-28 pounds of boost before and i dont think even changing to the much bigger tires would have affected that. i was thinking that my banks big head waste gate actuator may be going bad but im not sure. also my sister has an almost the same truck and setup i have ( 02 gmc same lift,chip, and intake) and her truck seems way more powerfull

[DmaxMaverick]

None of what you did should change the boost. Could be the Banks Big Head is failing. I haven't heard of one failing, but there has to be a first. If your boost has dropped, that would certainly explain a power loss. It's difficult to tell someone on a BB forum how much power they should have, or understand what they mean by "less power", not having driven the vehicle. If you "lost" more power than you should have, all we can do is try to tell you where it went. Boost, on the other hand, is a hard number we can deal with. If you say you had 24 PSI of boost, and now have 18, that's something we can use. All you need to do now is find out what caused your boost to drop. I'd start by looking at the actuator (Big Head). You need to see it when you hit max boost. If it pulls off, then it's the actuator. If it doesn't, then it's turbo performance, air or fueling related. A dirty air or fuel filter can reduce performance, including reduced boost.