Having Updated The Chassis And Bodywork On Project M3, It Was Time To Add An Afe Intake And Exhaust To the 4.0 V8.
Since this is part 5 in our tuning series on our 2011 BMW M3 with Competition Package, you can assume we've come a long way since the beginning. To date, we fitted carbon fiber pieces from BMW Performance and Turner Motorsport (TMS). Mechanically, there's been a six-piston Brembo brake conversion as well as some wheel spacers and H&R springs from TMS, plus 19" Forgestar wheels with Continental ContiSportContact3 tires.
This month, we're embarking on the first of our explorations into the 4.0 V8. This engine has become legendary both for its 414hp output as well as its 8400rpm redline. Yet despite exceeding 100hp/liter, this naturally-aspirated motor is also gaining a reputation for some remarkable dyno numbers.
We're regularly seeing many tuners proclaiming surprising numbers from conventional tuning parts, so we thought it was time to get elbow-deep in the discussion.
To kick-off our engine tuning program, we visited Advanced Flow Engineering (aFe) in Corona, CA. Specializing in domestic truck intake systems, aFe has broadened its reach with a range of BMW tuning parts for everything from the E36, E46 and E9x 3-Series through the 5-, 6- and 7-Series to the X5, Z4 and the latest 335i.
Company president, Nick Niakan has a particular affinity for BMWs, and is the driving force behind the new range of replacement filters, throttle body spacers, cold-air intakes and now cat-back exhaust systems.
With some impressive horsepower numbers quoted in the company's marketing literature, we were interested to see if we could replicate the numbers on our Project car.
With the aFe exhaust reported to give 13hp and 16 lb-ft of torque, we wanted to try it for ourselves. Never mind, 18hp and 15 lb-ft from a cold-air intake. So we headed out to the company's manufacturing and development center to have the parts fitted and dynoed.
aFe has two cold-air intake systems for the E9x M3. One replaces the stock air box with a 6" cone filter. Supplied with a heatshield and air scoops, it's quoted to give 15hp and 13 lb-ft.
A more stealthy approach is with the CAI we chose. It has a large oval filter and plastic intake tube but retains the stock air box to reduce noise and avoid underhood heat. A molded recess in the aFe intake tube seals the air box to ensure a cold air supply.
Surprisingly, aFe claims this system produces up to 18hp and 15 lb-ft thanks to an increase in airflow of 41% over the factory intake.
There's a choice of an oil-free Pro Dry S synthetic fabric filter or the oiled washable/reusable Pro 5R five-layer filter with progressive media to provide high-flow with best protection. We started out with the dry filter but switched to the oiled one searching for more power, with no measurable difference.
Fitting the intake is straightforward and definitely a DIY proposition. There is a slight increase in induction noise, but it's not as distinctive as the conical intake would be.
We were first drawn to aFe's shiny Mach ForceXP cat-back exhaust system by its intriguing 3" resonance chambers. They sit alongside the mufflers and are designed to give a broad power curve while canceling high frequency sound waves. We're told this would produce an aggressive note on full-throttle but make it smoother at cruising speeds.
The 3" exhaust system is made from TIG-welded, mandrel-bent, polished 304 stainless steel with quad 3.5" tips. It certainly looks very good and is claimed to weigh 49 lb, saving 20 lb over the factory exhaust but uses the stock mounting points.
The company claims 13hp and 16 lb-ft for the system, which is again simple to fit but requires two people and a lift ideally.
Before the aFe parts were fitted, two of the company's technicians, Jonathan Perez and Carlos Villegas expertly strapped Project M3 to their Mustang dyno.
Because it sits in traffic most days, it took a few runs to get the ECU thinking properly, and on the fourth of five runs we recorded peak output of 287whp and 216 lb-ft of torque.
Ordinarily, we'd fit and test the parts individually, but aFe wanted to do everything at once so we returned to the dyno with the exhaust and intake installed. It was a relatively cool day, so the temperature and humidity hadn't changed much during the hour or two between the runs.
Unfortunately, after five or six runs, we weren't seeing any gains from the new parts. In fact, we were struggling to find the stock output. It was decided that a few miles on the ECU would help it recalibrate to the improved airflow.
We returned to aFe's dyno several weeks later and, as the graph shows, we still couldn't find the promised horsepower increase. The aFe personnel were clearly disappointed and suggested a problem with the dyno was a possible cause.
The 'seat of the pants' dyno suggests the V8 has lost a little tractability pulling from low revs in a high gear, but does seem to rev more cleanly through to redline.
Having lived with the aFe parts for several weeks, we can report the exhaust has a very distinctive sound. Unfortunately, it drones little at low speed, which is a shame if your commute involves lots of traffic like ours. But once you get above 2600rpm, those resonance chambers start working and make it much quieter. It would be great for track days or for anybody who wants extra attention around town; it certainly gets you noticed!
Overall, the quality of the aFe parts is what surprised us most. The welds, the plastic molding, the fit; it's all first rate. And since the system is significantly lighter than stock, it again makes sense for track use.
So while we didn't make any power, there are lots of reasons to use the aFe components, which would probably see more benefits from a car with software.
With so much manufacturing now done overseas, we were pleasantly surprised to discover all aFe's products are produced right here in California, and most of them in the Corona facility.
Employing a large staff of designers and engineers, the company develops all its own products, buying new cars whenever necessary to ensure a perfect fit and good results.
With a 3D modeling machine connected to the designer's computers, prototype systems are created and revised rapidly as they search for the desired numbers.
Once satisfied with the product, the in-house machine shop fabricates the tooling to produce plastic intakes and rubber end-pieces for the cotton gauze or oiled filter media.
Workers then build the filters and send them to the packaging department still hot from the molds. The system is flexible enough to fulfill one-off orders or large batches, depending on the orders in the system.
In part six of our M3 makeover, we hope to swap the aFe parts for some Gruppe M or even BMW Performance components to compare results.