The Holy Grail of street car performance is massive power—think four digits on the dyno—coupled with stock-type drivability, all wrapped up into a package that can pull up to any gas station and push the 93 octane button on the pump. Well, that’s precisely what I’m going to tell you about today, with a twist. This particular car owned by Brian Warcup is his second go-round with this type of build, which features a Hellion Power Systems Sleeper twin-turbo system installed on Warcup’s 2018 Mustang GT.

The first build of Warcup’s 2015 Mustang seen above was completed last spring. The engine assembly was handled by Dwayne James, then the car was put together by Chris Groves and Matt Sturgeon at The Dyno Edge in Albuquerque, NM, tested on the dyno and delivered to the NMRA’s Route 66 race. After a quick session of NMRA True Street, tragedy struck: Warcup had enlisted fellow NMRA devotee Vinny Palazzolo to bring the car home from Route 66 to the East Coast. Just a short distance out from the track, Palazzolo had a steer tire blow out on his tow rig, which jackknifed the trailer, wrecking his car along with Warcup’s fresh build in the process. Palazzolo managed to rebuild his race car in record time and win the NMRA Street Outlaw championship in 2019, but Warcup had to wait for the insurance adjuster to send him a check for his battered machine—and save up enough money to replace all of the parts and pieces for yet another build.

Fast-forward several months to the winter of 2020, just before the coronavirus took over the world, and I found myself at Palazzolo’s shop, R&S Automotive Specialists, in Spring City, PA, watching as he and his team put together another Mustang for Warcup. This time around, Warcup chose a mildly-used 2018 Mustang complete with 10-speed automatic transmission and gasoline direct injection (GDI), neither of which were available in 2015 and made for substantial upgrades to the car’s performance when compared to the first car. There are several touches on this car that didn’t exist on his first build, and make this car one of two on the planet with these modifications. The first is owned by Albuquerque native and Hellion customer Keith Slight; that car has also made over 1,000 horsepower to the tires and was used for the initial development of these direct injection products.

Warcup is one of the B Team crewmembers who work on Haley James’ NMRA Renegade car, which is part of Team Hellion’s assault on NMRA competition. As such, he’s had a front seat while Hellion founder John Urist has incorporated GDI into his Street Outlaw machine. The GDI system on Urist’s Street Outlaw car is similar to that used in the current Mustang generation, so Warcup’s proximity to Urist’s tuner and GDI wizard, Uwe (pronounced OO-veh) Ostmann, of Xtreme-DI factored heavily into his decision to use Xtreme DI’s equipment on this machine.

Basics Of The Build

Hellion Power Systems has been at the forefront of top-shelf aftermarket turbo system construction since 2004 when Urist and partner Dwayne James founded the company with an eye on proving the viability of powerful bolt-on turbo systems as a solid choice for late-model vehicles. Today they manufacture systems for Ford, Chevrolet, and Mopar; the Sleeper Hidden Twin Turbo System found in this article is one of the company’s most popular—and for a good reason.

“The turbo system can be fully adjustable from five pounds to over 35 pounds of boost, and the owner won’t need to change anything. There are no belts to change. This turbo kit is the most advanced turbo kit on the market. And then the fueling for these cars is the most advanced fuel system on the market. The bottom line is that Ford gave us this great technology, and we decided to push it to its limits. It’s the most power you can make with a stock simple Mustang, and fuel economy will increase with a turbo system. It’s 8-second horsepower on pump gas—go to the track and then drive it 500 miles home,” says Hellion Power Systems CEO John Urist.

The flexibility of this turbo system is what makes it so attractive, as the kit can grow with the owner’s needs as time passes.

“Brian’s car was a good candidate to test these new 62mm turbos from Forced Inductions to make sure they fit our kit properly. The Hellion Power Systems kit is so flexible that we have our base Sleeper 62 mm turbos, we can use Precision 62 mm turbos, Precision 64s, Garretts, we can put anything in it. Hellion even has options for twin 78 mm turbos to use with this kit, which will make 2,000 horsepower pretty easily with proper fueling,” says Urist.

To prepare for the massive performance increase expected from the pair of turbos, Warcup decided to upgrade the car’s suspension and driveline using a variety of components that are documented to be necessities on the S550 platform.

UPR Products set him up with a set of its IRS bushing lockouts and rear swing arm spherical bushings, along with Pro Series toe links, vertical links, and adjustable camber arms. A REV Series carbon fiber driveshaft from QA1 sits inside one of Stifflers’ driveshaft safety loops.

BMR Suspension’s rear drag springs and minimum-drop front performance springs combine with Viking Crusader double-adjustable rear shocks and factory front dampers to provide stable ride quality with the performance required under power. R&S also installed a pair of BMR’s IRS subframe support braces to stiffen the rear of the car. This assortment of suspension parts is a tried-and-true combination that has worked well on many S550 Mustangs in the last five years.

We even found an unexpected mouse nest under the intake. Thankfully there were no chewed-up wires.

Although the parts are small, the MMR billet oil pump gears and crankshaft sprocket correct a significant potential factory deficiency. Urist stresses that they are not necessary for a turbocharged application. Still, the timing cover was off anyway, and although the 2018-up Gen 3 Coyote powerplant has proven to be quite robust in factory form, with pushing the limits on tap for this project, the gears and sprocket were deemed to be cheap insurance. The details of removing and installing the oil pump gears and sprocket—along with timing the four-cam engine—are more detailed than we can fit into this article. There are several solid videos on YouTube detailing the process. I’ll get to the reason that the timing cover was off in a moment, along with the XDI angle of why this car is significant to the development of future high-horsepower street-style Mustangs.

“With a supercharger, the common recommendation is to change the gears, since the front of the crank is yanked on by the blower belt, which creates harmonics. That doesn’t happen with a turbo car in a typical application. We did them here because the timing cover was off already,” says Urist.

The base installation of the kit itself is relatively simple: remove the stock exhaust, bolt in the new headers from Hellion, and mount the turbos to their mounts under the car. Then, run the cold-side tubing forward to the intercooler, connect the downpipes to the exhaust—in Brian’s case, a brand-new Borla S-type cat-back was installed—and plumb in fluid lines to supply the turbos.

Blowoff valves and wastegates in every Hellion kit are from our site sponsor Turbosmart; in this case, a pair of Comp Gate 40s and Vee Port Pros were used.

I’m boiling it down to the basics here because there are many steps in the process, but none of them appeared daunting to me, just time-consuming. I’d even feel comfortable attacking this install in my garage. Hellion provides an excellent installation guide with every kit that thoroughly explains each step, and the HPS tech team is available by phone should there be any hiccups. Vinny and Jason from R&S kicked the install out over a couple of days with ease.

A significant advantage of this system is the mechanical scavenge pump, which feeds and scavenges the oil to the turbochargers. Urist says that it’s critically important to have this in place to ensure a long-lasting turbo kit regardless of turbo type.

“We return the oil to the engine properly and reliably. The pump system is easily mounted to the front of the engine and driven by a pulley bolted to the crankshaft,” Urist explains.

One area where I was impressed by the kit was the installation of the Sleeper tube into the factory airbox. It was certainly helpful to have an air saw to open up the required areas of the factory airbox, and the completed appearance was simply impressive. If you didn’t know there was a turbo kit on this car, you’d never know by looking at the finished product without really digging into the car. The tube simply looks like it’s part of a cold-air intake system that uses the stock airbox.

It truly is a bolt-on system that doesn’t require any cutting of the car’s chassis; I was surprised by that and impressed at the same time.

“You can make 800 horsepower on pump gas with direct injection with no problem. If you want to make 1,000 horsepower on real pump gas with direct injection, you have to do the fuel system,” says Urist.

This concept brings us to the next portion of the article, which applies to the crazy owners like Brian, who want four-digit horsepower at the wheels without the hassle of dealing with searching for E85 or race gas.

“We wanted to add the fuel system to take the car to the next level. People don’t have to have this to put the kit on. This is the most advanced direct injection upgrade available in the world for the Mustang. These two together are the pinnacle of efficiency, and with that efficiency comes horsepower,” says Urist.

The coolant tank cover from JLT Performance really helps to finalize the stealthy underhood appearance of this package.

The Peak Of Pump Gas Performance

The gasoline direct injection system, as produced by Ford, combines with a traditional port fuel injection system to provide fueling to this Mustang. This particular car has seen a host of upgrades and ensures fueling will not be an issue, especially with the pump gas plan.

Enter Uwe (pronounced OO-veh) Ostmann from Xtreme-DI. His credentials are distinguished; after 13 years working on the front lines of high-tech racing efforts such as Audi’s Le Mans LMP1 program, the Corvette C7.R, and Ford’s Daytona Prototype 3.5 EcoBoost programs for Bosch Motorsport, Ostmann broke away from the mothership to found Xtreme-DI and become the only Bosch Motorsports dealer in the world with a focus on high-pressure GDI race projects. My conversation with Uwe detailed not only the specific parts and pieces delivered by XDI for this Mustang, but also broader theory discussion about direct injection that I’ve decided to save for a future upcoming article here on Front Street.

It’s important to note that the fueling strategy for this car includes several components: a brand-new high-output Xtreme-DI high-pressure fuel pump, a set of eight Xtreme-DI direct-injection injectors, and a new XDI in-tank 400 lph fuel pump. The car also received a set of 56 lb-hr Ford Performance port fuel injectors and a plug-and-play PowerMAX fuel pump booster from JMS as part of the Hellion kit.

Let’s talk about why the direct-injection system on this car makes it possible to develop four-digit horsepower with ease, on regular old 93 octane pump fuel.

“The way you quantify the capacity of the direct injection high-pressure fuel pump [HPFP] is to realize that it works very similarly to a one-cylinder combustion engine. You have a round piston that goes up and down, and then you have your stroke that is defined by the crankshaft. When you want to increase displacement without touching the piston, you take a crank with more stroke. With a high-pressure pump, it’s the same thing. The component of the engine that defines the stroke on the high-pressure pump is the lobe on the camshaft that drives it,” explains Ostmann.

And now you know why we took the front of the engine apart—to install what Uwe calls his “fuel cam”: a stock Coyote exhaust camshaft which has been modified using a proprietary process to install a new drive lobe for the high-pressure fuel pump. By increasing the stroke of the drive lobe, the distance that the piston inside the pump travels gives it more displacement. The drive lobe is the large triangular lobe in the center of the photo above.

“The camshaft uses a proprietary XDI lobe that is designed to optimize the dynamic behavior of the high-pressure pump; it’s the combination between the high-pressure pump, the spring of the high-pressure pump, and the profile of the cam lobe,” shares Ostmann.

In this case, the HPFP itself—with its bigger piston—moves 45 percent more fuel than the high-pressure stock pump, and with the fuel cam installed, the system is capable of 60 percent more flow. Ostmann also says that the pump can be run without the camshaft, but the desire to show off all of the technology was paramount to the installation, so it was included. This is how the car can make so much power on 93 octane pump fuel. Most of the increase is realized with the pump installation, and that last 15 percent is from the camshaft change.

We also must consider the Xtreme-DI high-pressure fuel injectors used in this application, which are brand new. The standard measurement for rating a high-pressure direct injector is to measure it at 100 bar, which is 1,450 psi of pressure. These injectors are rated at 1,750 cc at 100 bar (65 percent more than factory) and are run in the car at 200 bar (2,900 psi). At that pressure, they become a 2,500 cc injector. According to the laws of physics, as you double the pressure, they gain 41 percent more flow.

“The devil is in all of the little details. With the higher pressure, the challenge is that you keep the injector linear, and it behaves the same at all pressure levels. Every injector gets tested statically and dynamically. The dynamic test includes an idle point to ensure that the spread at idle [between the set] is good; they get matched at that point as well. We always take the actual injector core from the engine family; we do not mix and match from other engines. The solenoid internals stay identical so that the ECU driver characteristics can stay identical, and that’s the whole dynamic behavior thing because they are peak-and-hold injectors. The one big difference from port injectors to DI injectors, because they have to open and operate at so much higher pressure, they’ve changed the whole valve group, the electrical part of the injector. It runs up to 15 amps peak-and-hold signal, where a port injector runs at 1 amp or so. The power stage of the ECU is matched to the injector. If you don’t stay in that envelope, it behaves differently. And the further you are from the happy combination, the more sensitive [the engine] gets. The areas where you see it first are at idle and high pressure,” says Ostmann.

He also explains that the spray pattern is extremely critical, but we’ll save that for the next article along with some of the other significant tidbits he shared with us about direct injection. Rest assured that you’re going to want to keep an eye out for that piece as well. Check out the video above from Bosch on the basics of GDI theory and operation.

The Tuning Specifics

It’s important to note that this car is one of only two in the world with this configuration of direct injection parts that have actually been completed and on the dyno, so you could say Warcup was comfortable being a guinea pig of sorts.

To make 1,047 horsepower at the wheels on 93 octane pump gas is a monumental feat. In the not-too-distant past, this achievement would require alllllllllllll of the E85 fuel at a minimum, and more likely some form of race fuel.

Not so with the advanced technology offered by the direct injection system.

“If, every injection, it injects the exact perfect quantity [of fuel] at 3,000 psi, it vaporizes perfectly every time, and the spray goes into the right spot every time, you have a perfect mixture every time. That means you do not spray on the walls, you do not wash the oil film [off the walls of the cylinder], you do not puddle on the piston, you do not spray on the back of the valves, so your mixture is always 5-micron droplet size vaporized, and that avoids detonation. When you do port injection and spray with 70, 80 psi into the port, you have a big film on the wall, and you have a mixture going through the intake valves with bigger droplets, it sticks somewhere. The problem with that is since it doesn’t burn as clean, you’re going to have detonation. With high-pressure direct injection, where the piston and ports have the right shape, and it all works together, the engine does not detonate on pump gas,” says Ostmann.

None of this comes together without precise ECU tuning, and that’s where Rob Shoemaker of Palm Beach Dyno comes into the picture. The Palm Beach team is the exclusive provider of custom tunes for several Hellion applications, 2018+ Mustangs among them.

To make nearly 3.5 horsepower per cubic inch on pump fuel is no easy feat. It is always challenging to get a tuner to give away secrets for fear of tipping off the competition, but I managed to corner Rob for a quick discussion about what he’s looking for when he tunes an all-out application like this one.

“With the included data that Uwe gave to me, it was easy to dial in and didn’t vary too much from my regular Hellion tune. There was a little bit of tricky stuff that I did with some of the fuel injection pressures and changing the windows a little bit for the injectors. They are much bigger so you can play with the window and you don’t need as much fuel here and there. We were able to make some great horsepower out of it. It was very surprising,” says Shoemaker.

Even with all of this fueling capability, Shoemaker says he was still conservative with the timing advance to ensure the engine would be safe on pump fuel. The ignition timing was reduced by approximately five degrees across the board to reduce the chances of an unwanted engine issue.

In Conclusion

What more is there to say? We’ve shared the details from the experts on what it takes to build four-digit horsepower on pump fuel in a car that appears as docile as a stocker until the loud pedal is pressed.

“This tiny little motor with all stock parts and a bolt-on turbo kit makes 1,000 horsepower—it just goes to show you how far we’ve come with technology and how well everything works together,” says Shoemaker.

Warcup sums up the entire build simply: “The process started for me back with the ’15 when it went to Dwayne. The difference from the finished version of that one to this car is incredible. I can’t say I was 100 percent convinced going in that we’d get to the target number, but trusted the guys behind the design that everything would go as planned. The car cruises like it’s stock while daily driving, but once it’s time to go, the power in it just doesn’t quit. I can’t thank Vinny enough for the work he put into getting the car ready. I definitely didn’t plan to be building another Mustang so soon, but the work he put in to turn it around quickly once we got all of the parts was awesome. John, Uwe, and the rest of the companies involved with this car have all been great on tech support and guidance as well. Can we just get back to racing already?”

And now, for the grand finale: the Mustang spinning the R&S Automotive Specialists Dynojet to four-digit horsepower on pump gas. Check it out above!