Mike Galimi
June 1, 2015

The more things change, the more they stay the same. The 2015 Mustang GT features a similar Coyote 5.0L engine as the previous-generation Pony car, but it has been wrapped in a completely new body and chassis. With any new Mustang release there is a transition period when companies ramp up R&D, figuring out solutions to go quicker, faster, and then bring their latest products to the market. For this round, JDM Engineering tackled one of the first aftermarket installations of a Roush Performance Phase 1 supercharger system. The results were spectacular.

For Roush Performance, adding a supercharger to the 2015 Mustang GT wasn’t as complicated from the hardware side of the equation. Perhaps the biggest change to the high-tech Coyote 5.0L platform has been in the cylinder head department with tricks and features learned from the 2013-2014 Boss 302 program. This has helped pushed the base power up to a 435hp rating, but because the cylinder heads are the same style casting, the supercharger’s manifold bolts right onto the engine.

The bump in factory-supplied horsepower comes courtesy of larger intake and exhaust valves, better valvesprings, revised intake and exhaust camshafts, and revised ports for improved flow. Even the bottom end has been beefed up with better crank and rods with an updated piston design—all good news for those who are into forced induction. The front-engine accessory drive (FEAD) is largely a carryover from the previous-generation Mustang. It might sound like the setups are strikingly familiar, and while Roush Performance did have an easy time with most of the kit, some of the underhood accessories (like the air-to-water intercooler reservoir and coolant overflow tank placement, heat exchanger, various lines, and intake tract) are all-new for 2015. Couple that with an entirely new PCM calibration strategy, and the Mustang required a bit of re-engineering to be applicable to the S550 models.

At the time we covered this installation the Roush PCM calibration, dubbed Roush Diagnostic Tool (or RDT), was the only tuning available for the kit due to the use of a Shelby GT500 throttle-body. Had the kit included a factory throttle body, then Jim D’Amore of JDM Engineering could have designed his own calibration using his SCT tuning software. The RDT requires an IDS or similar scan tool to reflash the factory PCM. If you do not have the recalibration tool, you can send your PCM and a small nominal fee to Roush for reprogramming. Pretty soon D’Amore will be capable of tuning the larger throttle body and many other aspects of the PCM thanks to a revision to the SCT program.

With the PCM concerns out of the way, the system itself is the same setup we’ve sampled many times on the pages of MM&FF. The R2300 is a supercharger unit that includes the TVS 2300 rotor pack. It is a Roots-style supercharger, meaning the two rotors mesh together, pushing the air towards the discharge area of the unit. The TVS 2300 version measures 2.3L, and the Eaton Corporation (manufacturer of the supercharger rotor pack) has created a highly efficient rotor package called the Twin Vortices Series, aka TVS. The improved efficiency is seen with a greater volume of air pumping through the rotors, as well as decreased inlet air temperatures. This means more power from the same 2.3L supercharger displacement compared to the earlier designs.

The Roush engineers took the opportunity to redesign the packaging around the TVS rotors for even more airflow thanks to a revised intake tract and inlet elbow compared to previous Roush superchargers. The lower manifold has a self-contained air-to-water intercooler core to help chill the incoming air being discharged from the supercharger, while the front-mounted heat exchanger keeps the water/antifreeze mixture cool during street driving. The R2300 supercharger we sampled on Carl Mehaffey’s brand-new 2015 Mustang GT was equipped with the standard 85mm upper supercharger that generated 12.79 psi in our test.

The boost-tickled Coyote motor jumped output to an impressive 578 rwhp, and the torque peaked at a rather impressive 474 lb-ft, at the wheels. The 12.79 psi manifold pressure reading was due to the stock exhaust. According to D’Amore, this tends to choke the engine’s ability to breathe and results in a higher manifold pressure. He said typical Roush superchargers kits with the 85mm blower pulley and mild exhaust mods should see 10-11 psi on Coyote engines.

The out-of-the-box performance and excellent street manners reveal the engineering and planning that Roush put into the system. After all, the company has been working with the Coyote platform since its inception. The question that begs to be asked: What would this car do with more boost, better exhaust, and some sticky rear tires? We’ll find out shortly.

01. The Phase 1 kit comes complete and retails for $6,795, plus the cost of installation and dyno time.

02. The virgin 5.0L engine had a scant 120 miles on the odometer when it was dropped off at JDM Engineering.

03. The intake manifold is removed and in its place is a new lower manifold by Roush Performance.

04. Perhaps the biggest step in the entire installation is grinding down the bosses on the front cover. The intake ports and water pump opening are taped up for protection. The grinding isn’t a surprise step, as the previous supercharger kits from Roush and also Ford Racing require this modification.

05. Here is a close up of one of the bosses that have to be trimmed down. JDM Engineering uses a special set of cutters that makes this part of the job quick and easy.

06. After the engine is taped up, the technician also wraps the engine compartment in plastic to minimize the mess and ensure that no aluminum chips get into any unwanted areas.

07. Here, two bosses have been trimmed down to the base of the front cover. This is done because a new pulley and belt wrap are used with the Roush blower.

08. The third boss isn’t removed; it is simply modified with an air-operated cutter. It has to be cut in half as shown.

09. The instructions are very specific and detailed on how to modify this aluminum boss and here is the finished product.

10. Once all the cutting and cleaning is completed, the engine is unwrapped and the technician bolted on the lower intake manifold, which includes an air-to-water intercooler.

11. The R2300 supercharger is then bolted to the manifold

12. One of the upgrades Roush made to the newer model R2300 is the more efficient intake tract into the rotors. The elbow on the backside of the supercharger is significantly larger than the previous model.

13. On the left is the intake elbow for the 2015 Mustang while the right is the previous generation elbow. Note the significantly larger and oval shape of the latest elbow.

14. A twin-bore 60mm throttle body comes standard in the kit, a much larger improvement over the factory 80mm single-bore throttle body. It is the same throttle body used on the GT500 engine.

15. The reason for the three bosses that were either removed or modified is the heavy-duty FEAD that is bolted on to the front cover.

16. A standard 85mm pulley has been used in the kit and boost peaked at 12.79 psi, largely due to the stock exhaust system, according to Jim D’Amore of JDM Engineering. A larger exhaust system would have dropped the peak boost in the upper rpm range.

17. The factory overflow tank is then moved over to make room for the Roush-supplied intercooler reservoir. A massive heat exchanger is mounted in front of the radiator to help keep the intercooler’s liquid chilled during street and track use.

18. The Roush R2300 supercharger kit is 50-state legal, meaning the air filter is contained in a box. The air filter is a high-flow unit, and with 578 rwhp the enclosed system isn’t hurting performance too much.

19. Here is the voucher for the Roush calibration download; only one per kit is issued. If you do not have an approved recalibration device, Roush charges a small fee to update your PCM, which requires you send in the box and wait for it to be returned.

20. Producing 578 rwhp, a Roush-supercharged 2015 Mustang GT will be no joke on the street and track. Unfortunately the cold weather prevented us from flogging the car at Raceway Park or Atco Raceway (in Englishtown and Atco, New Jersey, respectively), but we’ll be back.