Nitrous Installation - A Big Shot Of Power

Adding an Extra Punch to One High-Revving 377

Jessie Coulter Jul 31, 2006 0 Comment(s)

In a world where bigger is better, engines with less than 400 inches are sometimes overshadowed. But in today's world of techno performance, a big dose of nitrous to a smaller motor can garner huge results. To learn just howmuch power we could gain with a medium-sized powerplant, we took a Dart block that was punched out and finish-honed at Smith Performance and Machine and packed it full of high-quality components including a completely balanced Lunati 377ci stroker kit, Brodix Track 1 M2 CNC heads, a Lunati solid-roller camshaft, a Brodix intake, and a Holley 950-cfm Ultra HP carburetor.

With this setup, the 377 easily spun to 7,500 rpm, producing 485 lb-ft at 5,800 rpm, but more importantly we achieved a neck-snapping 597 horses at 7,000 rpm. Of course we couldn't leave well enough alone and subjected the motor to a bit of juice. Utilizing a complete Nitrous Oxide Systems Big Shot kit, we installed the 175-horse jets to demonstrate how nitrous can affect the power curve. As expected, the torque jumped immediately to a massive 753 lb-ft of torque at 4,700 rpm and 830 hp at 7,200 rpm. Of course, this amount of torque is far more than most small tires can glue to the pavement. So in order to help control the ludicrous amount of power, we took it a step further by adding a progressive controller to the mix. This allows the end user to ramp up the nitrous at a slower rate. While these controllers have been proven, it's important to perform periodic maintenance on the solenoids to prevent failure--and nobody wants that. Read on to see how to add juice the right way.


Feeding the hot 377 powerplant is a 950-cfm Holley Ultra HP, which features a smooth venturi, screw-in air bleeds, and notched floats.

We removed the 1-inch spacer to install the 5/8-inch Big Shot nitrous plate. The Big Shot kit includes longer studs if needed and is adjustable from 150- to 400hp settings.

A little application of Teflon paste and the nitrous fitting is ready to install. The inlet screen catches potential material that could plug the nitrous or even hang the solenoid open.

To install the solenoid fittings we first clamped the nitrous solenoid in a vise. A shop rag helps prevent the clamps from damaging the stainless base. Be careful to clamp only the base and not the upper shell. Pressure on the upper shell may damage the magnet and ruin the solenoid.

We used these trick billet brackets (PN 16515NOS) to mount the nitrous and fuel solenoids.

We chose this billet micro-switch bracket (PN 16512NOS). This attaches to the side of the main body and is activated with the secondary linkage at WOT. The bracket comes with a new micro-switch and two 8-32 stainless screws. On some carbs, including the Ultra HP, you will need to tap the holes in the main body for installation.

You'll need the correct amount of fuel pressure during setup, typically 5-6 psi. You'll also need a jet adapter fitting that will accept the fuel jet and screw into the line coming out of the solenoid.

Using the fuel jet that was in the fuel side of the nitrous plate we can now set flowing fuel pressure. We armed the system with the nitrous bottle off and set the fuel pressure to 5 psi.

Reading spark plugs is the best way to see what changes are necessary. The plug on the right has been lean or ran with too much timing. The light tan color on the left plug is a good-burning plug with proper tuning. Generally, bluing of the plug with nitrous is a sign the tune-up is on the edge.

Here's what comes in a typical solenoid rebuild kit. The NOS kit even comes with a handy wrench to remove the solenoid stem.

We removed the solenoid cap with a 3/4-inch wrench. This nut should only be snug, as overtightening can crack the magnet inside the cap.

This handy tool comes in the rebuild kit and allows you to remove the solenoid stem. Never use pliers on this stem, as they would crush the hollow shell and ruin the solenoid.

The plunger and spring are shown here being removed from the solenoid base. When inspecting the solenoids, look for indentions or raised areas in the puck.


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