ET Tech In et 8/09, we saw an 8hp peak gain by upgrading the driveline fluid with products from Bavarian Autosport. This month, we crank things up to see what BimmerWorld's Sunbelt OBD2 cam kit is about.
"Many of our customers have performance parts on their cars, so we offer this kit in multiple combinations," said BimmerWorld's James Clay. And having a 3.5" intake and air mass sensor, 24 lb/hr injectors plus an M50 manifold conversion (et 12/07), all we needed were the new cams and software.
We ordered the cams, but before we sent out our ECU for a reflash, BimmerWorld convinced us to first test an Active Autowerke track pipe that replaces the factory cats and bolts between the exhaust manifold and rear muffler.
Track pipe The BW/Sunbelt cam kit software is offered in three stages for cars with factory headers or aftermarket, and a third optimized for AA's track pipe. Before testing the cams and pipe together, we wanted to see what the track pipe would do on our car without additional software. So we trekked over to our installation and dyno facility, Modified by KC, where a new 237whp baseline was established on its 424x Dynojet.
We were sent an OBD1 pipe with only one provision for an 02 sensor (as opposed to four on OBD2), but BimmerWorld would take care of it with the software later to ensure no check engine lights would appear, saving us from needing 02 simulators. Following a trouble-free installation by to MKC's Ryan Charlton, we were pleased to see no CELs anyway.
At idle and light load, the car didn't seem much louder, but at wide-open throttle it was a different story. Frankly, Project M3 had become one the loudest cars we've ever driven. And although aggressively sweet, the noise brings unwanted attention on the street.
We can't blame the track pipe completely since the UUC RSC36 is also one of the best flowing E36 exhaust systems as well as one of the loudest. With stock cats, the RSC36 is livable. Without them, this combo is a little too much for my ears.
However, power immediately rose to 244whp and 231 lb-ft, with gains throughout the curve. Peak gains were a healthy 9hp at 6000rpm and 10 lb-ft of at 4400rpm - more than we'd ever seen from a cat-back system. We also found a 12 lb weight savings over the stock cats, but please note the track pipe is illegal for road use and only meant for racing.
Camshafts The BW/Sunbelt 276/272°Sport cam kit was designed for street M3s. We were apprehensive about installing them given the labor cost, mileage (147k) and that they're a little more aggressive than the popular Schrick cams. But Clay put us at ease, "Sunbelt cams are a modern design that rev high safely while reducing valvetrain stress for longevity," he explained. Despite this, we ordered new valve springs, hardened retainers and valve keepers (collets) from the dealer per BW's recommendation. If you're thinking about lifters, now's a good time also. But at $32 each online (x24) for OE ones, it adds up.
The E36 M3's Vanos system is a complex variable cam-timing unit with chains and gears. The factory specs call for 8.5mm of travel with stock cams. BW recommended moving the Vanos sprocket one tooth over to reduce travel to no more than 8mm. But given our mileage, we took the more expensive route of contacting Dr Vanos, who sent us a rebuilt Vanos unit.
Specializing in single- and dual-Vanos units, Dr Vanos is popular among BMW racers. The stage 1 unit sells for $250 (plus a refundable core fee) with modified internals to remove the rattle you hear at idle.
We opted for stage 2 for $375 with its coated cam gears and thrust washers, further reducing noise and friction at higher revs.
Instead of moving the Vanos over one tooth, Dr Vanos shimmed our unit to limit the Vanos sweep to the 8mm limit, removing the guesswork and allowing Ryan to install it easily.
With everything fitted the car fired cleanly and without CELs. But there was a rumbling song at idle, akin to a musclecar. When you install Sunbelt cams, don't be surprised if the idle hunts and stalls for 15min as the ECU adapts to find the right fuel mixtures. After a few easy miles, the idle settled at a steady 800rpm.
Climbing up the revs, the engine was as smooth as ever. While there's a loss in low-end torque, similar to what we saw with the M50 manifold conversion, it isn't noticeable when cruising or under load in lower gears.
By 3500rpm, there's a huge ramp in power, similar to a 3psi jump in boost. It's addictive. In first gear, roll into the throttle at 5mph and by 15mph the tires are howling through redline. A fast shift into second and the tires don't find grip until mid-gear. In third, floor it past 70mph and the top end starts to feels like a supercharger, and you think it could rev forever. After a couple of rips, it's obvious this installation was well worth it.
Back on MKC's dyno, we were pleased 258whp (261whp in fourth gear): impressive, considering the high mileage, stock head and headers.
How do our latest upgrades affect real-world acceleration? Prior to our AA track pipe and flywheel upgrade, we'd made two passes using our GPS-based PerformanceBox from VBox, registering 0-60mph in 5.4sec and a quarter-mile time of 14.1 at 101.4mph. With BW's flywheel (et 07/09), AA track pipe and Sunbelt cams, 0-60mph improved to 5.2sec with 13.9 at 104.3mph.
When looking at the dyno graph, it's easy to be distracted by the loss in low-end torque and ignore the gains over 4000rpm, which peak over 18hp and 13 lb-ft of torque at 6900rpm - twice the improvement we've seen from the milder Schrick cams.
With only the addition of BW's mildest Sunbelt cams, Project M3 is now significantly quicker. To prove this, we performed a third/fourth gear acceleration test and extrapolated 60-120mph times. From a 14.2sec base run, the car improved to 12.8sec with the cams alone. That's knocking on the door of E46 M3s, which dyno only 15-20hp more.
Will we achieve S54 power with a 7000rpm limit and no boost? Stay tuned.
For more pics on our cam install, visit www.eurotuner.com
|BimmerWorld||AA track pipe||$699|
|BimmerWorld||M50 manifold adapter||$169.99|
|BimmerWorld||intake boot elbow||$99.99|
|Dr Vanos||stage 2 Vanos||$375|
|Bavarian Autosport||gaskets, washers||$68|