Michael Galimi
April 1, 2008

Just By flicking a switch, output increased by nearly 100 rwhp in the '84 Mustang that was used for this article. That wonderful increase in power came thanks to a plate nitrous system from Edelbrock. Nitrous has long been known to be a cheap and effective horsepower meter. The Performer RPM kit (adjustable to 250 hp) was set at 100 hp, and we repeatedly made 98 more rear-wheel horsepower than our baseline runs in naturally aspirated trim. That equates to approximately a 112hp increase at the flywheel.

The action of flipping the switch refers to us arming the nitrous system, which at wide-open throttle (WOT), adds the nitrous and fuel mixture. Simply stated, nitrous-oxide injection is a way to add additional air and burn more fuel without relying on Mother Nature. Nitrous (N20) is composed of two atoms of nitrogen and one atom of oxygen. The atom of oxygen is what our engines crave, since an internal-combustion engine harnesses the power created when we burn air and fuel. The two parts of nitrogen help to deliver the concentrated oxygen part to the combustion chamber. Once inside the cylinders, the combustion process (and subsequent heat) breaks down the nitrogen and frees the oxygen. Due to the greater oxygen content, additional fuel is required to maintain the correct air/fuel ratio for proper burn inside the cylinders.

A plate nitrous system in carbureted applications requires a simple carb spacer with spray bars running through it. One side feeds nitrous while the other feeds fuel. Nitrous oxide is stored under pressure, inside a bottle, and is delivered to the plate in liquid form. Once it's introduced into the atmosphere, nitrous turns from a liquid state to a gaseous one. It's mixed with fuel and sprayed into the intake runners, through the heads, and into the combustion chambers. The process is simple, effective, and most importantly-cost effective.

Like everything in life, moderate dosages can be healthy, and too much is harmful. We have seen nitrous work great on stock engines, though the owner must exercise restraint and not put too much in at one time or manipulate the tune to push the engine too hard. It's far too easy to load up the big nitrous pills and let it rip.

Edelbrock supplied us with a plate nitrous system designed to work on traditional 4150-style intake flange openings. The system is adjustable from a 100hp shot to a whopping 250hp increase. The kit comes complete with nitrous bottle, lines, wiring, a WOT activation switch, and other stuff to successfully add this system to virtually any carbureted vehicle. Additional equipment installed includes a purge kit, a bottle heater, and quick-release bottle brackets-all sourced from the Edelbrock catalog.

The test vehicle belongs to Justin Burcham of JPC Racing, and this '84 Mustang GT is his former daily driver. The car has been sitting for a few years, and he decided it was time to get it back on the road. The engine is fairly basic-a long-rod 306ci. The crank is stock, and it swings Chevy steel connecting rods and 10.5:1-compression pistons. A mild flat-tappet camshaft features 0.540-inch lift on both intake and exhaust. The heads are a set of Patriot Freedom aluminum castings (180cc intake ports), and the intake is a rather inexpensive Professional Products single-plane piece. Burcham bought the intake from some guy for peanuts, and he now knows why it was so cheap-one runner was cracked. We used JB weld to close it up for the test. Shortly after our photo shoot, an Edelbrock Victor Jr. was bolted to the engine.

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Backing the budget-minded engine combination is a rare Doug Nash five-speed transmission. Hanlon Motorsports recently repaired it due to a grinding Third gear. The rest of the car consists of a six-point rollbar; HPM rear suspension; and UPR K-member, A-arms, and coilovers. Burcham employs two fuel systems: one to supply the engine and one dedicated setup for the nitrous. The engine inhales 93-octane gasoline thanks to a Mallory fuel pump and ½-inch fuel line. The nitrous system is fed pump gas via a Holley Blue pump and ½-inch fuel line. A stock tank received a sump at the bottom.

Since this was a stock block utilizing a lightweight set of pistons, we elected to control our urges and run only a 100hp hit of nitrous. Fuel pressure on the engine side was set at 7 psi, and we ran the nitrous system's fuel pressure at 8 psi. Timing for the horsepower baseline runs registered 34 degrees. In that trim, the '84 Stang kicked out 345 rwhp, and it lost 10 hp when we backed down the timing to 30 degrees-335 rwhp for those who aren't math nerds. A few degrees of timing must be removed when adding nitrous. The amount of timing dropped is dependent on the amount of nitrous injected. All kits are different, and we suggest following the instruction's sugges-tions. The jetting charts are also listed in the instruction manual; our Edelbrock plate uses a 55 jet on the nitrous side and a 61 fuel jet for the 100hp increase. With the nitrous and fuel flowing, power shot up to 443 rwhp. It was a consistent output reading, too-three more pulls were made and produced near identical results.

We resisted the desire to add more nitrous. After all, the 100 load provided us with an impressive 98hp gain at the rear wheels. That equates to about a 112hp increase at the crankshaft. Adding more nitrous most likely would have added greater power, but Burcham didn't want to puke the insides all over the floor in search of it.

The flick of a switch will put a smile on your face and a frown on your competitor's. The installation was quick, and the results were well worth the cost. The Performer RPM is listed in Summit Racing's catalog for $480. That works out to about $4.89 per rear-wheel horsepower-quite a bargain indeed.

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Ten Tips from Edelbrock's tuning guru, Steve Johnson
Our good friend Steve Johnson, Motorsports Director at Edelbrock and head dude at the specialty nitrous shop, Induction Solutions (www.induction-solutions.com) shared a few nitrous tips with us.

1. Never inject nitrous into an engine that is not running.

2. Always check to make sure your fuel system is capable of providing enough fuel for the nitrous system. If you're running one fuel pump for both, then make sure the pump is capable of doing so.

3. Follow the instructions closely, and pay attention to the manufacturer's tune-up information. Understanding how much timing to pull out for the nitrous system's horsepower level is key.

4. Mount the nitrous bottle with the tag up and at about a 15-degree angle facing toward the front of the car. Most standard nitrous bottles have the siphon positioned properly when the bottle tag is up. If you want to mount a bottle straight up, you can turn the outlet to the rear of the car.

5. Run colder spark plugs. The instructions should have a recommendation on the heat range.

6. After a pass, check your spark plugs (all of them) to verify whether the engine is running rich or lean. A lightly tanned porcelain, with little to no bluing on the tip of the ground strap, is usually a safe place to start.

7. Always run bottle pressure in between 900 and 1,000 psi, or as stated in your instructions.

8. Get a purge kit, bottle heater, and an inline nitrous pressure gauge; it will be money well spent. The purge will ensure you put fresh nitrous in the engine and eliminate a delay at the crack of the solenoid. The bottle heater keeps the bottle pressure up. The pressure gauge helps you keep track of the pressure, aiding in consistent and effective nitrous usage.

9. Medical-grade nitrous is not better than non-medical grade. It is also illegal to possess medical stuff, so don't even bother trying to get some for your Mustang.

10. Start with the smallest jets and work your way up from there. Resist the urge to go directly to the biggest horsepower ratings.

Bonus Tip: Never run nitrous through your engine below 2,500 rpm and always when at wide-open throttle.