In the first installment of our 6.0-liter Power Stroke Engine Build series, we performed a complete rebuild on the Ford powerplant. We took you step by step through the teardown, machining, and assembly of the engine. In addition, we gave you all the details on the aftermarket performance products that were used, and why each part was chosen for this build. Now, we’re adding nitrous.
In that first article, we also shared our dyno results. The newly rebuilt Power Stroke cranked out a very healthy 528 horsepower and 1,364 lb-ft of torque. Not bad for fuel-only performance. However, like you, we are never truly satisfied, and more power is always a good thing. So for the second chapter, we decided to give it a nitrous oxide kick.
For that nitrous upgrade, we turned to a well-established company with a good reputation for a variety of nitrous oxide injection systems, Nitrous Express of Wichita Falls, Texas. After speaking with Ryan Lewis at Nitrous Express about what we were planning to do with our 6.0-liter Power Stroke Engine Build project, he recommended its NX SX2D (P.N. NXD4000) nitrous system that includes two Pro Power Lightning solenoids (.120 orifice), two dry nozzles (dry nozzles mean that the Nitrous is sprayed without fuel), -6 AN feed line, a 15-pound bottle, and a boost reference progressive controller. The Nitrous Express Maximizer 4 Progressive Controller (P.N. 15957) is a part of this kit.
Let’s begin with the brains of the NX SX2D system. The Maximizer 4 is a two-stage controller, and can be programmed to operate in time, RPM, MPH, throttle percentage, or boost-pressure mode. Our 6.0-line Power Stroke as with all modern diesels is forced induction, but this system is designed to work with naturally aspirated trucks as well.
Having 100-percent flow initially will almost completely eliminate turbo lag. – Ryan Lewis, Nitrous Express
Time-based progression is a good choice for drag racing applications. The RPM mode is said to work well on rigs that have enough traction to deal with full nitrous power at the top end of first gear. The Maximizer 4’s miles-per-hour progression is nice for racers who go back and forth between starting from a dead stop to rolling starts.
When the programmer is in throttle percentage mode, it allows the driver to “pedal” the vehicle in the event of wheel spin — the flow of nitrous goes up and down as the throttle is “worked” — which is appropriate for bracket racers who are looking for consistent ETs.
However, according to Lewis, the ideal mode for the Maximizer 4 progressive controller when used on diesel engines (such as our Power Stroke) is the boost-based mode. “The boost function is best for diesels because it helps build boost fast. It allows you to bring on the nitrous to a high percentage as early as possible.”
Lewis continued, “The system gets up to 100 percent nitrous right away, drops down to say 30 percent, and then ramps back up to 100 percent flow, and that all happens in just over a second. Having 100 percent flow initially will almost completely eliminate turbo lag.”
As far as where to mount the controller, we took Nitrous Express’ suggestions literally and found a location away from heat sources so the wires would not get cooked and damaged (on top of the AC evaporator box). We also made sure it was in a spot that would never get water, mud, snow, or ice that might be on our boots anywhere near it when we were getting into the vehicle. This will help make sure none of the controller’s connections come into contact with corrosive elements.
Installation was fairly straightforward and ended up going pretty quickly because we only needed to reference the boost on the Maximizer 4. If we had wired up all of the sensors, it probably would have taken a fair amount of time. The installation instructions are detailed and easy to follow, but tracing wires takes time. Lewis told us, ‘This system is more labor intensive than the others Nitrous Express offers because you have a controller to wire in rather than just a WOT switch to hook up, but you have more control.”
At first glance, when it came to programming the Maximizer 4 controller, it seemed a little overwhelming. There were lots of things to calibrate and adjust. Ultimately it was really just a matter of taking our time and carefully following the instructions, step by step. Lewis said, “Overall, the programmer is really easy to use on the software side, and it’s just a matter of answering questions to get it all set up.”
“There are three or four really important points to programming the Maximizer 4 unit. However, the most important thing is to get it to 100 percent flow as soon as possible in your ramp, as soon as traction allows.” Lewis explained,” It makes it a lot easier on the solenoids and the overall system, because until the system is at 100 percent flow, the solenoids are opening and closing at a rapid rate. However, at 100 percent they are open all the time, so there’s less wear and tear on the solenoids. If you want to program it to say, 50 percent flow, that will work, but it’s just harder on the solenoids in the long term.”
The system was set to be controlled on boost only. We decided that boost was the best indicator of engine load and demand. Both stages were used during the dyno pulls, but initially, we tuned the system with only one stage. We did this by watching our smoke levels out the tailpipe.
We brought the nitrous in very slowly and then as our boost levels increased, we ramped up the delivery until we were wide open with an 0.136 jet. Then we brought in the second stage to clear up the remaining excessive fuel. The second stage didn’t require any fancy tuning. We simply allowed the delivery to be linear (the default). The second stage was also running one of the 0.136 jets.
We found that an extremely important thing to remember when adjusting boost levels is that the controller is reading absolute pressure. So zero pounds of boost is actually around 14.7 psi (varies by temperature and altitude) at sea level. This means if you want the boost to come in at 20 psi of boost, the controller needs to be programmed to come in at 34.7 psi.
When you’re getting your Nitrous Express system set up, don’t be afraid to slowly progress to larger and larger jets and tuning. For us, it was all a matter of trial and error. Most people would agree that it’s better to start on the safe side than trying to go too aggressive.
When we started to lay the system out, we sat down and made an Excel spread sheet with the voltage and pressure range from 0 to 5 volts. Then we added another column for boost pressure (we subtracted 14.7 from the pressure column to get these numbers). This meant we could find the boost range we wanted, and cross reference that to the controller pressure. This really came in handy, and you may want to do the same.
This is the Excel spreadsheet we used when setting up our Nitrous Express system. It allowed us to make adjustments to get the system right where we wanted it to be.This methodology allowed us to have a maximum amount of pressure the MAP sensor was able to read, and consequently, the progressive controller. For our 2004 6.0-liter Power Stroke, the maximum pressure the controller could read was roughly 48 absolute psi or 34 psi of boost. We made sure that our two stages were at their total output before this level, otherwise, we would be out of range and the stages would not be at 100-percent.
When it came time to dyno the truck after the installation of the system, we were happily surprised by the numbers. We expected it to be very close to 700 horsepower with the 190 cc injectors we used. The progressive controller allowed us to bring on the power smoothly and as a result, the engine never bogged down when it was loaded by the dyno.
We honestly believe that this is one of the reasons the numbers are so high. With nitrous coming in at 100 percent, the 6.0-liter Power Stroke was making 777 horsepower and 1,792 lb-ft of torque. As a matter of fact, if you check out the dyno chart below, the power was still coming on rather aggressively. You will see that during run Number 3, we pulled to 3,700 rpm, but during dyno run Number four, we pulled it to just 3,200 rpm before backing off on the throttle. We’re sure that the engine’s horsepower output could have easily topped 800 if we had not begun to experience some driveline (we’re not sure if it was the trans or the torque converter) slippage issues.
Even more unfortunately, we were not able to record peak torque values during our runs because of how the dyno was loading. We had it loaded at 100 percent. As a result of this high load, when we dropped engine speed down to 1,500 rpm, the exhaust gas temperature (EGT) went extremely high (1,600 degrees F or higher) during the pull. We made the decision to play it safe, and made the pulls starting at 2,000 rpm to ensure that our EGT would stay in a reasonable and safe range. (This is a freshly rebuilt engine with cast aluminum pistons.)
Aside from all of those complications, we did see a maximum gain of 293 hp at 2,700 rpm, and a total gain of peak torque of 571 lb-ft at 2,650 rpm. We think that is a darn good result, and were quite happy with the overall performance of our Nitrous Express NX 4000 system installation. Lewis told us, “In the end, the power gained really depends on the size of the jets and how much fuel you can get into it. Diesels are all about the amount of fuel you can feed them.”
Although the installation was fairly straightforward, with no complications, you may want to have a pro shop do the job, if you are not an experienced mechanic. When we have the chance, we’ll get it back on the dyno (thanks to the guys at Diesel Dynamics for the install and dyno work) and see if we can’t show you all of the power we believe this engine can make.
In the meantime, as mentioned already and seen in the dyno video below, we are very satisfied with the gains made from the installation of the Nitrous Express NX 4000 kit. What do you think we should do next? Let us know in the Comments section below.