Speed Secrets: It’s Time to Juice the LS

It’s time to add some Zex power to an LS engine in this episode of Speed Secrets with Richard Holdener. 

Typically, nitrous comes in two different configurations. For EFI applications there is the wet fogger system, where you combine nitrous and fuel in a single fogger nozzle and install it somewhere in the air intake system. Although, if you were looking for nitrous for a carbureted application, a perimeter plate type system would be the way to go. While both systems have their benefits, a perimeter plate system can take some of the guess work out of where to install the nozzle and ease installation. For this reason, the nitrous guys at Zex have created a perimeter plate nitrous kit for LS EFI applications. To see what this kit can do, Richard Holdener with Speed Secrets grabbed a test engine and headed to the dyno.

To give the kit a good start, he started with a 5.3L LS that had been bored and stroked to 383ci. With forged internals, the engine offers a strong base that can hold up to the nitrous. To give the LS stroker a little head start on power, Richard added a healthy Comp 54-457-11 cam with .610/.617 lift, 223/231 duration, and a 112 LSA. Upgrading the valve springs with Comp dual valve springs, he then installed CNC ported high flow cylinder heads and finished it off with a Fast LSX-RT intake and a matching 102mm throttle body. A combination that proved itself with 544 HP @ 5,900 RPM and 514 Lb-Ft of torque @ 4,800 RPM of naturally aspirated power. 

The Zex perimeter plate for LS EFi applications is designed to be sandwiched between the throttle body and intake manifold, making installation easier and optimizing the spray pattern. With a little juice, the LS stroker made 694 HP @ 5,900 RPM and 704 Ft-Lb of torque @ 4,800 RPM. Proving that good things happen, with serious gains of 150 HP and 190 Lb-Ft of torque, when nitrous and a healthy stroker are paired together.