Project BMW M3 Part 13: A fresh motor--the components

I haven't opened up the 3-liter motor that croaked on me back in late January, but I'm guessing by the compression ratio and leak-down tests that it was the head gasket, specifically the part in between cylinders 5 and 6. It wasn't an emergency, because I had already made plans for a new, low-compression motor with forged internals months before.

Bavarian Engine Exchange is a well-established business dedicated to the re-manufacturing of BMW engines in the U.S. and offering them at affordable prices. The company backs up its products with a two-year, unlimited mileage warranty.

My initial plan was to keep the stock 3-liter displacement. That way, I would only be pushed up one class at time-trial events for having the turbo. But after realizing much of my fun would be experienced off the track, I opted for the torque-rich 3.2-liter found in OBD-II M3s. I don't care what time-trial group I have to compete in anymore--Project M3's too much fun to drive to worry about that kind of stuff.

Another reason I opted to go with a 3.2-liter was Karl Hugh of Active Autowerke, the brains behind Project M3's turbo system. He'd already programmed chips specifically for these "built-up" 3.2-liter turbocharged motors, and I didn't feel a need to reinvent the wheel, especially with AA being clear across the country. With so many AA-turbocharged, built 3.2-liter M3s running around in Miami with hardly any issues, I wanted the same for Project M3. These low-compression motors have already been proven, and Karl discussed the companies he'd had success with in building up these 400+hp motors--JE Pistons and Pauter Machine Company.

Pistons and Piston Rings
JE Pistons, probably the most well-known forged piston manufacturer in America, supplies top engine builders for such racing series as NASCAR, NHRA, IHRA and IRL. If these guys can build pistons for 6000-hp dragsters, I reasoned that JE's forged pistons should easily handle Project M3's comparatively wimpy power.

The company uses CNC machines for manufacturing and purpose-designed forgings, enabling it to maintain exact specifications and close tolerances. Finite Element Analysis (FEA), Ultra Crown and Digital Three Dimension Piston Crown Machining processes are used in designing and testing of the pistons. The company reports it's the only high-performance piston manufacturer to earn the QS-9000 quality standard.

I decided to use JE pistons over the stock BMW units because BMW's stock pistons are cast, leaving them more vulnerable to failure under extreme, high-horsepower conditions compared to forged pistons. How else do you think those juiced-up Skylines, Supras, Porsches and other turbocharged cars are making so much power on stock bottom ends? A major factor is forged pistons. Forged pistons can withstand the higher pressures and heat in high-performance motors more effectively and drastically reduce the possible catastrophic consequences of detonation and excessive heat in the combustion chambers. Forged pistons are for engine longevity, peace of mind when pushing your internals to the limit.

Project M3 received a set of custom low-compression pistons from JE to lower the compression to about 8.5:1 (stock is 10.5:1). The stock compression limits turbo boost to about 9 psi on good gas. But even on Project M3 I wanted to go the safer route, even if I were to run at only 9 psi (I know this probably won't be the case).

AA supplies a thicker copper head gasket to lower compression (as seen in Part 8), but achieving that CR with low-compression pistons is the better way to proceed. This allowed me to revert back to a stock 1.8mm head gasket, which was supplied by BMP Design. The JE pistons are 330 grams apiece compared to 440 grams for the stock cast pistons.

When having a motor beefed up, it's important to eliminate the weak links with quality products. It's also critical that the cylinder and combustion chamber pressures are maintained--and this is why JE Pistons uses Total Seal piston rings. Also used in road racing, drag racing and high-performance street engines, Total Seal piston rings are a result of extensive R&D and manufacturing machining and technology. The company focuses solely on developing piston rings for any and all applications. (Personally I have a lot of faith in companies that specialize and dedicate all their efforts to one specific function.)

Connecting Rods
After hearing AA's praise for Pauter Machine's billet rods, I gave the firm a call. Pauter has been around since the mid '60s, manufacturing high-quality racing products. Since the mid-1980s the company has been using CNC and Computer Aided Design (CAD) technology in its R&D.

Pauter Machine's billet rods are forged from E-4340 chrome-moly and are custom made to order for import and domestic street and race cars as well as motorcycles. Pauter doesn't store many off-the-shelf products; its experience has taught the company that even in two identical situations there's always a slight variation to the optimum rod specification by engine builders. There are also plenty of different race classes with different engine regulations to deal with, so company sees the only way to totally satisfy the customer is through custom work.

Pauter 4340 rods for BMWs are unique. They have a simple beam design, which completely eliminates thin and non-uniform cross sections over the total length of the beam. That improves the resistance to cracking and metal fatigue. The non-tapered beam profile helps spread harmful stress over a larger area in order to disperse destructive loads from one particular area. Pauter also designs its rods to incorporate needed material in critical transitional areas for maximum support where it exactly needs it, such as under the wrist pin.

Pauter Machine offers three different weight categories for any one specification, enabling the company to make the proper rod for a particular horsepower and rpm requirement. Visually they're pretty much identical, and the only way to tell is by a gram scale. The AA-specified Pauter rods I got for Project M3 weigh around 500 grams each, which is about 70 grams lighter than the stock, forged steel ones. Pauter now also offers rods for other European model cars including Porsche and VW, as well as titanium rods for those with the money and intention of building an even lighter and stronger motor.

Cylinder Head
For the cylinder head I relied on the company that's been able to supply Project M3 with a variety of parts I've needed, including O.E. items--BMP Design. The company sent the much-needed 1.8mm head gasket with removable rings, valve guides, titanium retainers and high-performance valve springs. The rest was supplied by Bavarian Engine Exchange.

Instead of regular O.E. steel retainers, I ordered the titanium replacements from BMP. The company reports its retainers are manufactured from the highest quality aircraft-grade titanium. This added strength, along with the reduced weight, gives Project M3 an added margin of safety. The valve springs BMP sent are slightly stiffer to handle the extra power of the motor--another safety measure.

At the same time these parts were being shipped, Bavarian Engine Exchange was already at work on the cylinder head I ordered through them. The company CNC-ported and hand-polished the cylinder head for increased flow, an option you can have done to any of the motors you purchase from them (Bavarian Engine Exchange reports a 15% gain from this option).

Although Project M3 now has a bigger and stronger motor, I figured why stop there? In the quest for more stupid power, I sent Active Autowerke back the Stage 2 TD06 20G Mitsubishi turbocharger that came with the Stage 2 kit in order for to have it rebuilt to a Stage 3 configuration. On the Stage 3 turbo, AA uses a Garrett/Mitsubishi hybrid, using the same exhaust housing and wheel of the Stage 2 but mating it to the compressor side of a Garrett T60-1 (good for 500+hp). Using the Mitsubishi exhaust side of the turbo maintains the responsiveness of the turbo and minimizes any increased lag from the larger compressor wheel--the turbo still kicks in at around 3500 rpm. However, using the 25% larger Garrett wheel allows more boost to be run in the end and gives a cleaner, smoother pull.

The fun doesn't stop there. To maximize the mid- and upper-range torque, I got a set of turbo-specific camshafts from Active Autowerke, reground factory BMW cams that have about the same duration as stock but 10.9mm of lift, improving the low-end torque of the motor and reducing the effects of turbo lag. In order to cope with these AA Stage 3 components, I picked up a set of 11mm head studs (stock studs are 10mm) and a larger fuel pump from AA. The only thing left to have fully converted to an AA Stage 3 system is the switch to a Stage 3 intercooler offering twice the flow of my Stage 2 unit. But the custom work involved in order to fit that sucker is a little too costly for me at the moment, and I think I'm happy at a maximum boost of around 12 to 14 psi anyway. People who want over 450 rhp will most definitely need that stage 3 intercooler.

I sent all the parts to Kevin Silva of Bavarian Engine Exchange, the man behind Project M3's new motor. Since the only non-factory parts were direct replacements for the original motor components, Kevin didn't have any installation problems. The only modification needed was drilling and tapping the block and head to fit AA's 11mm studs. The new threads were reinforced with TIME-SERTS(R). Because of the thickness of the new AA studs, the cams have to be removed in order to torque down the cylinder head.

This motor is a complete replacement, and the only actual engine upgrades that will be used from my last motor are the evosport pulleys featured in Part 6 (01/02). Speaking of evosport, my faith in the company so far with Project M3 (it has installed practically everything) has led to my hiring the guys for Project M3's motor swap. evosport technician Frank Lopez had completed another motor swap involving a supercharged M3 engine just a couple of days prior to mine, so I knew he'd be warmed up. Taking out the motor took him about three quarters of the day, and he expects about another full day, maybe slightly longer, to install the new one. Stay tuned.

Bavarian Engine Exchange
Bavarian's commitment is to service excellence. The Northern California-based company dedicates its resources to building quality motor and driveline components with a fast turnaround time so the customer gets the desired parts quickly. Through its Website and answering service, the company has made the task of ordering and receiving products from it a real turn-key operation for its customers, which include BMW dealerships, BMW repair shops, automotive body shops as well as private individuals.

Although the company specializes in rebuilt BMW engines, its inventory includes a number of other components, including cylinder heads, camshafts, transmissions, clutches, differentials and steering racks. All core deposits are 100% refundable regardless of the condition. Every part has a two-year, unlimited mileage warranty and, in the event of a defect, the company pays labor charges up to $500 to have the replacement motor reinstalled, plus $200 towards rental expenses--the people there really want you to have a risk-free experience with them. And for an extra 30% of the cost, you can get a lifetime warranty on the motor.

With its huge inventory of motor cores, Bavarian Engine Exchange has the luxury of being very selective in choosing only the best cores to rebuild--and the rest get tossed out. Each selected core then undergoes a careful inspection, and after passing it's disassembled, cleaned, stripped and precision measured for specifications. All of the machine work is done to exact tolerances, and all measurements are triple-checked before re-assembly.

The re-assembly process is done entirely by hand and in a climate-controlled clean room by certified engine technicians. During assembly all machined surfaces are measured once again for accuracy, followed by a quality control inspection after assembly. The engines are dynamically tested for compression, leakdown, oil pressure and oil leaks using an ultra-violet dye process. Once completed and thoroughly checked out, the motor is packaged in a wooden crate for protection against shipping damage, and the package is insured at full value in the unlikely case of a transit mishap. Shipping to anywhere in the U.S. in included in the price.

Should you choose the Performance Upgrade option, Bavarian Engine Exchange will include flow-tested CNC machine porting and hand polishing to the cylinder head, as well as Bavarian Engine performance camshafts. I got my own turbo-specific camshafts elsewhere, but I went ahead and had Bavarian Engine Exchange port and polish the cylinder head for Project M3.