I currently own a 1998 Chevy extended cab C1500 with the 5.7-liter V8. Aftermarket add-ons include a K&N Filtercharger and a Gibson Performance Exhaust system.
Chevrolet claims 255 horsepower and 300 pound/feet of torque to start. I noticed a large difference after these easy add-ons. How would my current setup compare with a new '99 with the 5.3-liter Vortec engine as far as horsepower and torque?
Some quick and easy intake and exhaust modifications can make a noticeable improvement to a truck's performance. K&N is advertising an increase of up to 10 horsepower with the addition of the Filtercharger, while Gibson Performance Exhaust claims a maximum gain of 30 HP with the use of their latest "cat-back" system.
We have to keep in mind that when the manufacturer says "up to", this indicates the best they've done on one particular vehicle. Without pulling your truck up on a dynamometer we really can't be accurate on torque or horsepower. So, for now, we'll simply split the difference and say you're getting an extra 5 HP from the intake assembly and 15 HP from the new exhaust. This will presumably give you a grand total of 275 horsepower out of your old faithful 5.7-liter V8, or like we used to say, a small block Chevy.
The new Vortec 4800, 5300 and 6000 engines are entirely different animals than their predecessors. It was a new concept that GM unveiled to power the Corvette. Chevy and GMC trucks then used the Vette's LS1 engine platform in a cast iron version as opposed to aluminum for added durability.
The 5.3-liter is pushing 270 horsepower at 5000 rpm and 315 lb.-ft. of torque at 4000 rpm. The horsepower is up and the peak torque down from your 1998 5.7-liter, but Chevy claims the broader torque range designed into the new small blocks make up the difference in overall performance.
The simple add-ons to your '98 Chevy C-truck may have gotten you up a hair in horsepower as compared to the '99, but keep in mind that the aftermarket manufacturers produce performance stuff for them also.