The new S55 engine on the F80 and F82 BMW has a lot of potential. Everyone is jumping on the bandwagon to deliver more power with a ECU flash and other bolt-on products. To tune the M3 M4 car, you have to have special flashing equipment that does not come cheap. But once your able to read and write to the ECU, you have to create the calibration data. Our tuning brand, VR Tuned, has new a ECU Flash for the S55 engine and it does really well! We have tested this both on a US car using a Mustang Dyno, running 93 octane and our tuning partner in Europe with a Maha dyno on 98 octane. One test car being a M3 and the other being a M4. Previously having worked on a M4 exhaust system and VR Tuned Tuning Box kit, we were familiar with where our baseline numbers should be and what tuning would do. But as we looked around at other dyno sheets, we became slightly confused.
First and foremost, our opinion on dyno tests… A dyno should be used to measure power. It should be used to measure the delta in your before and after tests. The top end number does not matter if it made 450, 411, 390 to the wheels. We look for the gains and the overall driveability improvement. We use a Mustang all wheel drive dyno here in Arizona. This dyno gives you the most real world results. Typical AWD drivetain loss is 20%. So this would be calculated as Factory Crank HP x .75 = AWHP. Other dynos such as a DynoJet can be compared to a circus bear spinning a rolling drum. Even looking at their dyno graphs is not helpful. Yes the BMW is rear wheel drive, but when you drive, you dont just drive with rear wheels do you? We chose to run the car in AWD to not incur any drivetrain faults or issues with the highly sificsticated BMW traction control computers. When we run cars, we also chose to do 7speed or less cars in 3rd gear and calibrate RPM at 3000. 4th gear might be more 1 to 1 with more engine load, but you would just see the curve shift to the right. The speeds on the dyno can get a little unsafe and if a strap breaks, game over!
So when running the BMW M4 on the dyno, you see the top end taper off significantly. Whether running in Sport or Comfort Mode, the car just does not want to pull on the top end. When we did our baseline test as seen here, we even had to put about 500lbs in the trunk because the car wanted to spin the wheels on the dyno. So the car was making great stock power. Looking at others dyno, this was not the first time this happened. What we realized is it is all about airflow. The S55 engine needs a lot of air to make those strong top end runs. So unless you have a true wind tunnel, its going to be hard to replicate 100mph driving conditions. We adjusted our 3 large dyno fans to be directly on the intercooler and blow through the kidney grills.
Our baseline line test gave us 377 all wheel horsepower and 385 ft/lbs of torque. The torque was pretty flat from 3000 rpm to 5300 rpm. It immediately started dropping at 3900 rpm and then really fell on its face at 5800 rpm. A 3rd gear pull had us doing about 90mph at 7300rpm. So in real world driving, the 0-60 definitely suffers. With the ECU flash, our torque rolled in similar to stock but at 3300rpm it rocketed up to 440 ft/lbs at the wheels. This peak at 3940rpm was about 60 ft/lbs gain. The torque continued to increase over stock until about 6300rpm where it met the stock numbers. Even through the higher rpm of 5380 to 6000, we are still gaining about 10-20 ft/lbs over stock. For horsepower, the gains are instantly realized at about 3100rpm. The 2 graphs show us Sport Mode (closer dotted line) and Comfort Mode (further apart dotted line). Like most new turbocharged vehicles, sport mode gives us faster throttle response and a increase in boost where the top end will taper off. With Sport Mode, we gained about 50 wheel horsepower at 4400rpm and kept a nice 20-30hp through the beginning and end of the curve compared to stock. The airflow factor came into play at around 6500rpm. In addition to the ECU Flash, we also tested our new Agency Power catless downpipes compared to the high flow cat we did on the other BMW M4 here. This will show us if the drop in power is caused by airflow or exhaust restriction.
The Agency Power downpipes are all stainless steel, TIG welded and feature a CNC machined flange all made here at our Arizona facility. Since these downpipes are catless, we did a stage 2 ECU flash to account for a cat delete to not throw a CEL. Typically on turbocharged cars, you see downpipes add 20hp by reducing the restriction caused by factory downpipes. The turbos like to breathe and these help that. Similar to what we have done on other N54 BMW cars, the N55 F82 downpipes feature smooth bends and larger diameter piping. With less restriction comes a louder more rasping tone similar to the previous E90 V8 as heard here. So will they make a impact to the M4 on the dyno? The downpipes made the torque increase right away. Having the torque jump from a stock 385 to a tuned and downpipe added 452 ft/lbs to the wheels. That is a 70ft/lb gain. The downpipes on their own added about a 20 peak torque gain and averaged about 10 ft/lbs from 4000rpm to the end of the test at about 7300rpm. Horsepower had nearly the same curve as just the VR Tuned upgrade did. It gained a consistant 10 wheel horsepower to about 5000 rpm where the downpipes helped out on the top. The top so an increase of about 15-20 awhp all the way to the end of the test.
So what did we learn from our tests? The BMW M4 M3 F80- F82 needs good airflow to dyno properly. An ECU tune will give you huge midrange power. Like other turbo cars, doing a catback exhaust and catless downpipes will help the mid to top end power. All of these upgrades are of course available from our BMW M4 M3 Performance Parts Store here.
- Buy the VR Tuned ECU Flash for the BMW M3 M4 F8x
- Compare the VR Tuned ECU Flash to the VR Tuned Tuning Box
- View ECU Removal Instructions for the BMW M4 F82
The Video
The Car
The Dyno Tests
The Downpipes
The ECU Removal and Flash