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When it comes to power adders, these days it seems that nitrous has taken a back seat to forced induction -- both by turbos and superchargers. But if you are a fan of bottled horsepower, rejoice! Modern engine management systems are actually making big power combos with nitrous easier than ever before.
We recently had the chance to spend some time at the shops of Prestige Motorsports in Concord, NC, while they were working on a 427 cubic inch Ford Windsor build that Holley just gave away to one lucky fan (Click Here to read the story). The idea of the build is to put together a very healthy Windsor-based Ford that can be used as a daily driver, has enough power on its own to spin the tires in any gear AND be able to bust off a grand in horsepower any time you want with a healthy dose of nitrous.
Prestige is no stranger to building high horsepower street engines with incredible durability, so they knew exactly what they wanted as a baseline for the package when it came to building this Ford. Being able to reliably handle extended 1,000-horsepower blasts is a lot easier said than done, so the parts chosen have to be able to take the heat. For the block, Prestige went with a Man O’War cast iron block from World Products. While it will accept standard Ford Windsor components, the new Man O’War has recently been redesigned to be one of the stoutest Ford blocks on the market. The blocks are now cast from 40,000 psi iron with thicker main webbing and larger galleries for the priority main oiling.
Internally, the rotating assembly is made up of a set of forged Eagle crank and rods, with pistons from DSS Racing. Meanwhile, the cylinder heads are from Air Flow Research. These are AFR’s Renegade 20 Degree Competition cylinder heads with 58cc combustion chambers and 220 cc intake runners. They are also fully CNC ported and should flow an absolute ton of air. And helping make sure the cylinder heads receive all the air they can use, they will be fed with a Holley Hi-Ram intake and not one, but two, Holley 1,000 cfm throttle bodies mounted up top.
Valve timing will be handled by a Comp Cams solid roller camshaft. It is a pretty big boy, as it’s ground with 260 degrees of duration at 0.050 tappet lift for the intakes and 274 for the exhaust. Lobe lift is 0.431in/0.430in and there’s a 114 lobe separation. They activate a set of 1.6:1 ratio Scorpion rocker arms, so gross valve lift will be 0.690in for the intake valves and 0.688in for the exhausts.
But what’s really cool here is the nitrous system. We aren’t using any exotic or race-only components. In fact, everything is right out of the NOS catalog. And we aren’t even using a few components most old-school gearheads would consider mandatory. We’re actually leaving out the fuel solenoids and all the associated plumbing, which simplifies the installation and tuning chores significantly. The extra fuel to mate with the nitrous will come directly from the fuel injectors.
This engine will be fuel injected, with a Holley Terminator X ECU controlling everything. No separate nitrous controller is necessary. Because the Terminator X operates as an all-in-one package, you can do things with a nitrous setup that just a few years ago were impossible for the average guy.
Previously, when most hot-rodders were running carburetors, adding nitrous required plumbing along with solenoids for the nitrous, a separate set of plumbing with solenoids for extra fuel and a box of jets for tuning. And if you don’t add enough fuel when the nitrous kicks in (which will cause the engine to go way too lean) you have severe detonation and expensive engine damage in your future.
That all goes away with the setup Prestige is using. Instead of a separate set of plumbing just to add extra fuel to keep up with the nitrous hit, Prestige is allowing the Terminator X ECU to read the sensors and add the correct amount of fuel through the injectors. This means you need to use a set of appropriately large injectors to handle the nitrous hit (We are using a set of 80 pound injectors here.), but the benefit is you never have to worry about tuning fuel jets, only nitrous jets, to dial in the air fuel ratio.
Another benefit is the ease of tuning, including progressive activation. The software that comes with the Terminator X doesn’t require some arcane knowledge of computer coding to tune your engine. In fact, there are even dedicated tables for nitrous that allow you to specify exactly how much you want depending on engine rpm’s or time after activation. You can even ramp up the amount of nitrous you want depending on rpm or time, and the computer manages the fuel mixtures throughout at the air/fuel ratio you request. So for our run on the dyno what worked best for us was to have the NOS nitrous system activate at 5,000 rpm at 25 percent, then ramp up to 75 percent at 6,000 rpm where it remains throughout the rest of the pull.
With most carbureted systems, you have to tune with physical jets, and once the solenoid kicks on it is all or nothing. In our case we simply threw in two large #73 nitrous jets (one for each plate) because we knew it would be more than our needs would require, and allowed the Terminator X to control the amount of nitrous the engine would actually see.
Previously, when you wanted to make big power numbers using nitrous without blowing the tires off with one giant hit, you had to set up multiple stages, or circuits, to ramp up the power -- which gets complicated pretty quickly. With the Terminator X it was surprisingly simple. We just used the “Progressive Control” table on the Terminator X software, adjusted the line graph on the laptop and sent the update back to the ECU. It really was that easy.
So if you are at the track and don’t want a really hard nitrous hit to blow the rear tires off you just make the nitrous progression a little more gentle.
Not every block can handle continuous 1,000 horsepower blasts without giving up the ghost and splitting down the middle. That’s why Prestige Motorsports spec’ed out one of World Products’ newly revised Man O’War blocks. They are extra beefy with high tensile strength iron in the casting to handle tons of power with ease. This particular block has a 9.5-inch deck height, and it’s been bored and honed to 4.125 inches
One trick that allows the Man O’War blocks to handle extra power is, along with the thicker main webbing, World Products switched from the OEM 1/2-inch main bolt size to high-strength ARP studs that are slightly smaller at 7/16 of an inch. The smaller stud diameter allows for extra iron on the main webs. The crank is a stroker forging from Eagle which extends the stroke an extra half inch over stock to 4.00 inches. That brings total displacement to 427 cubic inches.
The reverse-dome pistons are from DSS Racing. These are high-strength 2618 forgings with a 22cc dish and a 1.280 compression height to go with a 6.250 connecting rod. Notice the unique “X” etched into the piston skirts. This is a DSS proprietary design that they say helps retain oil and protects against damage from fuel wash. The rings will be 1.2 mm, 1.5 mm and 3.0 mm.
Assembler Larry Broeker installs the solid roller from Comp Cams. It is ground with 260/274 degrees of duration at 0.050 tappet lift with 114 degrees of lobe separation. Gross valve lift will be 0.690 for the intake valves and 0.688 for the exhausts.
In order to handle the extra heat from combustion created while the nitrous is flowing, Prestige swapped in Inconel exhaust valves (also from AFR) in the ported AFR cylinder heads. The valves are sized at 2.100 for the intakes and 1.600 for the exhausts and the chambers are 58 cc’s.
From this angle you can see the ported 80 cc exhaust runners. The valve springs are upgraded to keep from going into coil bind with the high valve lift and have approximately 220 pounds of pressure on the seat. The locks are retainers are both steel.
The rocker arms are a set of Scorpion’s Endurance Series aluminum rockers. They are in the stock 1.6:1 ratio
The intake manifold is a Holley Hi-Ram. Here, you can see the lower half and the tunnel-ram runners which are capable of incredible flow. Holley offers different tops depending on your requirements. Prestige chose to go with a dual quad 4150-size flange, which you will see in a moment.
Before final assembly, Prestige port matched the Holley Hi-Ram’s runners to the AFR cylinder heads. It is impossible to match an intake to every head out there, so even though the Hi-Ram has incredible performance right out of the box, they also have thick enough walls in the lower runners so that they can easily be ported to match the specific heads you are using for best performance.
Now the lower half of the Hi-Ram can be bolted up. Notice how straight the runner path is from the plenum to the cylinder head.
Instead of a separate fuel circuit complete with fuel solenoids, we’re depending on the Terminator X to monitor the air/fuel ratio and increase the fuel appropriately when nitrous is added. This is really cool because the Terminator X is fast enough to add fuel incredibly quickly and keep the engine from melting down. But it also requires larger fuel injectors that can provide a consistent, quality spray pattern at both low and high load. We are using a set of 80 pound per hour injectors from Accel and feeding them through a pair of Holley fuel rails.
One issue you often see with tunnel ram intakes is you have to pull the intake to remove the distributor. But in this case Broeker was able to drop in the Holley Dual-Sync distributor no problem. He just pulled the cap, installed the distributor and reinstalled the cap.
The plug wires are a set of Accel’s relatively new Extreme 9000 wires with the super heat resistant ceramic boots.
Here’s a look with the dual quad plenum top bolted up. An O-ring seals the upper and lower plenums, so there are no gaskets or silicone to deal with.
For the nitrous system, we’re using a NOS nitrous plate system that includes practically everything we need for this unique setup.
The nitrous plates bolt right up to the 4150 style flange, and the throttle bodies will go on top. Notice that the plates have color-coated fittings for both nitrous and fuel. We are only using these for nitrous, so we’ll just plug the fuel inlets.
Broeker sets the throttle bodies in place. These are Holley’s universal square bore throttle bodies rated at an 1,000 cfm each.
The solenoid is basically the gate controlling the flow of nitrous into the engine. When we hit the targeted rpm (5,000 in this case), the Terminator X ECU will send a signal to the nitrous solenoid, it will kick on and open flow from the nitrous bottle to the dual nitrous plates.
Prestige’s Doug Aitken hooks up the 427 Windsor up on the dyno. Here, he’s plumbing up the purge valve. This isn’t the most elegant setup for the purge system, but we just need something simple to work on the dyno.
Since we are using port fuel injection, we don’t need a complicated throttle linkage that opens one set of venturis more quickly than the other like you normally see with carburetors. Instead, both throttle bodies open equally at the same time.
At the start of the dyno session we installed #73 nitrous jets in both of the plates. They were bigger than we needed, but that was fine because the plan was to progressively pulse the solenoids with the Terminator X ECU.
Here’s the table we used in the Terminator X software to control the nitrous progression. As you can see, we have the nitrous kicking on at 5,000 rpm at 25 percent and ramping up to 75 percent at 6,000 rpm. That was enough to break 1,000 horsepower, so we had the Terminator X keep the nitrous flow at 75 percent through the rest of the run. Adjustments, however, are as simple as a few clicks on the laptop.
Look closely inside the rear throttle body and you can see the nitrous spray from the plate.
Overall, the results of this build on the dyno were fantastic. Without nitrous, this 427 Ford Windsor produced 631.7 horsepower. But then add the nitrous and you’ve got an absolute beast. We stopped at 1001.2 horsepower when we hit our thousand horsepower target, but we were still at only 75 percent of a pair of #73 jets, so there is obviously more left if you wanted even more power.