Hello Everyone, just got a new toy a few months back, and need some help. Bought a 2012 silverado crew cab with a 4.8, with a 6 inch lift and 33 inch tall tires with 13,000 miles. Found truck was really SLOW!!! So...... Ended up boosting the motor, but here is the problem we dynoed the truck on 12 lb and it only made 385hp, went to 16 lbs and no increase in power, tring to understand what is going on.

 

Need more info on the mods done

 

A little info on the setup, it's the stock 4.8. Turbo is 70 trim compressor with .81 back housing , Intercooler is 33x16x4, piping is 3 inches on the cold side and then converts to 4 inch from mass air to throttle body. Hks blow off valve, tail 44 mm waste-gate. Injectors are 60 lbs, and the truck has a 4 inch down pipe all the way back!!! AFR is 10.7 WOT, any ideals why it's make so little power on 12 lbs , and ..... No additional power on 16 lbs... any ideals will be greatly appreciated!!!!!!!!

 

.81 housing probably given you a good amount of back psi at that level.
What cam is in it?

What did it Dyno pre turbo?

 

It is the stock cam, although I did notice this motor comes with 243 ls6 heads from factory. I was thinking maybe camshaft was maxing out...

 

Here are some pics of the build

 

Pics.

 

Finish stage

 

More pic

 

Fab stage