The Pursuit of Power & Perfection

The automotive rabbit hole is one that truly not even the most devoted enthusiasts know the depth of. Jimmy was faced with the choice of going down one, or just simply walking away after his Audi S5 was left crumpled from a winter weather fuelled collision. Circumstances at hand during the time of his accident were good and bad for Jimmy. The motorist that hit him was uninsured and with covid in full swing there was no way he was getting any of the cars monetary value back through legal action. The virus did give him plenty of free time to fix the car if he wanted to though. Weighing the fate of the car's future in his hands Jimmy decided to go in headfirst and bring back his car. Luckily he wasn't going in blind or unprepared. He had people willing to teach him how to take care of the car's body, and paint needs. Going into the car this deep meant he was really gonna be married to it. So he was gonna make sure the car went back together the way he wanted.

Initially this proved to be somewhat frugal of a decision. For instance, a replacement shock absorber was over a grand. With one of them being bent, there was only one way around the active strut tax. Which was to completely ditch them in favor of air ride. Making his own custom setup with the help of a repurposed compressor he wasn't into the bags much more than he would've been into the struts. He also replaced the front bumper with an RS-style cover. The remaining parts needed were sourced with OE equivalents. With everything fitted and the car straight he finished up with a fresh coat of paint for the whole car.

To celebrate Christmas and the car's return he embarked on a voyage from NH to Florida. During which it snowed on his way there and way back. Luckily he and the car were spared from Murphy's law during the weather. The work he did pleased him, he was glad to have his car back. There was still one thing he needed to attend to, and that was the engine. The B8 S5 he had was an earlier example that came with the direct-injected 4.2 V8. It wasn't powerful enough for him or his friends, who ragged on him for having a slow V8. His options forward with this motor were expensive and frankly fruitless. A supercharger kit was available for this car but it was selling for five figures and offered less than 500 horsepower. So he began looking into alternative means of power. Audi's four liter twin turbo V8 caught his eye. This particular swap is gaining popularity today, but when he took it on the helpline for this swap was slim. Luckily he had found a Russian car forum where one of the members did this swap. This helped him lay a framework for what he would have to do. Though before he did the swap he'd need a motor. Knowing this he bought a whole car. The donor was an S8+ that got into a rollover. Being an S8+ meant it came with the RS spec engine, and plenty of good parts to help him recoup some costs. 

B8’s never came with a 4.0tt, but his original engine was somewhat related to the 4.0. With a similar general footprint it should bolt right in. Which it kind of did, a combination of both engine mounts had to be created to clear the starter, and the radiator had to be moved forward with custom lower mounts. With that minimal fabrication, the engine went right in. Despite the exhaust ports on the 4.0tt being flipped to make the hot v configuration the downpipes still bolted right up to the S5’s stock catback. The 4.0 was finding itself at home in the engine bay. Just because it looked like it fit, didn't mean it was meant to go there. If he ever intended on it running in the car long enough to get him anywhere a cooling system was in order. Luckily the S5 had plenty of radiators he could use/repurpose. He ended up being able to plumb the water to air intercoolers into the cooling circuit by using a t-fitting off of the side mount radiators. Making the coolant for the charge air coolers basically at the end of the closed circuit cooling loop. 

The most grueling work began when it came time to get the 4.0 running. Of course, the ECM was going to have to be recoded to communicate with the rest of the vehicle. The coding would be almost useless though if the newly acquainted messages wouldn't be able to go to the right place. So Jimmy spent many late nights repinning the harness to create a plug-and-play harness in preparation for a properly tuned ECM. An endeavor that proved insane in the very sense of the word. He went through numerous ECM’s and almost just as many tuners. It was like Groundhog Day. Luckily he eventually met someone who worked with him to create a basemap the car could run on. Key word could, because his troubles were not over just yet. Fueling was the last hurdle he had to get over before the car would do more than just crank. After some digging, he realized the B8’s fuel pump wasn't working because the ECM wasn't designed to work with a PWM pump. So he fitted a B8.5 S5 pump that operated with a three-phase pump and control module. 

Having the car finally running with its new heart made him ecstatic, especially because the condition of the engine was unknown. He happily drove it on the base map with all of its early tuning quirks. Things like the throttle mapping and the lack of boost made for an interesting driving experience. Even with the turbos effectively turned off the car's performance was comparable with its stock form. The driveability wasn’t though. You could hit the gas and count for a few seconds before you got your requested power. The widowmaker tendencies were caused by the ECM's throttle mapping. Coming from an automatic car and now being in a manual meant the ECM was reluctant to give you what you wanted without a TCM to help it decide. After a few seconds though it would give in and let you have all the power. He was able to minimize this when he began working on the stage 2 ECM with Andrew from Ghost Tuning. This was a good thing because a stage 2 4.0 with a 4-second throttle lag would have been a legitimate widowmaker.

Of course the cars a driver, and of course he’s proud of the work he’s put into it. But he didn’t go down the rabbit hole to just settle. He wants to polish his driving experience, I just caught him in the midst of it. He’s down for anything, pulling the transmission in favor of better gearing? Sure. He's ready to dive deeper into the ECM tuning to eliminate throttle lag too. He doesn't shy away of possibilities for improvement. Jimmy and his story with this S5 may be one of the better ways to represent the incomprehensible dedication that is possessed by the automotive enthusiast.