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Squeezing 723 hp and 727 lb-ft With Nitrous Express

A couple of months ago, we outfitted our GM Performance Parts LS1 crate engine with the complete Patriot Performance package ("Patriot Games," Dec. '04), consisting of CNC-ported LQ9 aluminum cylinder heads, a 1.7:1 shaft-mount rocker assembly, a healthy roller cam, along with the factory LS6 manifold, which produced 506 hp and 459 lb-ft. To further take advantage of the increased airflow, we then swapped the potent factory LS6 manifold for the F.A.S.T LSX unit, netting us an additional 16 hp and 7 lb-ft, bringing the total to 522 hp and 466 lb-ft. As impressive as it was, we wondered how much power we could extrapolate from a stock bottom-end LS1. Although our time on the dyno was finished for the day, we had plenty of opportunity to put our warped minds together and concoct various options on taking the LS series to the next level.

For this round, we opted for the Nitrous Express Twin EFI MAF nitrous system, specifically designed for LS1 and LT1 engines. Its method of delivering fuel and nitrous is unique. Unlike other systems that employ a single nozzle, the MAF billet aluminum housing replaces the factory piece and allows the mixture to flow directly into the manifold. The new MAF housing has four inlets, two for nitrous and two for fuel, and can be arranged in a number of configurations. A single-stage system is good up to 250 hp. Using the second pair of inlets creates a two-stage system that'll produce as much as 500, assuming you have an engine with forged components and a fuel system that can handle it.

Since our LS1 features a completely stock bottom end and has already produced pretty stout figures on grunt alone, the object was to see just how much more there was to be gained with the power adder. We'll admit that we initially wanted to limit the testing with a small shot, but our dark side convinced us to try the 200 pills. If you were impressed with the Patriot-equipped all-motor numbers, then you have to check out what a little bit of gas can create.


Our Patriot Performance LS6 Stage II cylinder heads are worked over factory LQ9 6.0L truck pieces with their complete line of valvetrain, a newly formed 59cc combustion chamber, along with 2.05/1.60 valves. When matched with a Patriot billet-steel camshaft, 1.7:1 shaft mount rockers, F.A.S.T. LSX manifold, and LSX 78 mm, the formidable combination generated 522 hp and 466 lb-ft on grunt alone!

The NX Mass Airflow (MAF) nitrous system, with its dual AN -3 inlets, can create a two-stage nitrous system. Nitrous and fuel is supplied to each side, where they merge through the billet aluminum housing and exit directly into the manifold.

Start by disassembling the stock MAF housing. Remove the four Torx screws on each corner and gently separate the plastic sensor housing. Be sure to avoid contact with the MAF's hot wire and to retain the O-rings from the factory housing.

Install the O-rings on the new housing, replace the Torx screws, and your final assembly should look similar to this. Last, double-check that the arrow on the plastic sensor housing is pointing toward the inlet side.

Nitrous Express scribes the inlet, outlet, and purge ports on all of its nitrous solenoids. Like most other systems, the inlet is on the side; however, the outlet port is underneath the solenoid. If you don't plan on utilizing it at the time of install, the port opposite of the inlet is the purge and must be capped with the enclosed 1/8" NPT plug.

Before installing the outlet fitting, we installed the mounting brackets with the supplied hardware.

Contingent on the application, there are a number of places to mount the nitrous and fuel solenoids. For our purposes, we found it extremely convenient to piggyback them on the factory coil-pack bolt.

Every kit includes an AN -3 fuel line that allows you to tap directly into the fuel system using the stock fuel test port. Since we're utilizing aftermarket fuel rails, we simply added a T-fitting at the back of the rail.

An SHO AN -4 stainless braided line feeds the nitrous and extends from a solenoid featuring an AN -4 inlet fitting and leads into the MAF housing with an AN -3 fitting.

Should you desire a two-stage system, the secondary inlets can be used for additional big horsepower gains or to help soften the hit with two smaller shots. For example: a 75 hit out of the hole, followed by a 100 shot once you've obtained maximum traction.

Here's a quick tech tip: If your nitrous system is completely wired and the solenoids still won't activate, check the ground. We originally grounded ours to the rocker covers, only to discover that it wouldn't work.

With our timing at 28 degrees total, the 150hp jetting in place, our mule blasted out 672 hp and 677 lb-ft, with the plugs looking perfect! In anticipation of the 175 and 200 jetting, we swapped out the factory plugs for colder Densos, and dumped in a few gallons of 100-octane Rocket Brand fuel to avoid any chance of detonation.

The 175 hit rewarded us with 686 hp and 687 lb-ft, but it was the results of the 200 shot that made a serious impression with a mind-numbing 723 hp and 727 lb-ft.


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