Running a considerable amount of boost (more than 9 psi with this turbo) required lowered compression. In order to do this, evosport had to install AA's thicker head gasket to further lengthen the distance between the piston and the valves, thus increasing the volume in the combustion chamber and reducing compression.
When the heads were pulled off, evosport technicians found evidence of recent piston contact with the valves. The contact wasn't hard enough to bend a valve and make the car run terribly--my last and best 262-hp dyno pull had been done at our tech center just the day before. But, it was enough to disrupt the valve guides, requiring a rebuilt head.
Because of his experience with Schrick cams in S50 motors, I contacted Al Hafner, owner of BMP Design, to see if he had any idea how this could have happened, and if the higher lift Schrick cams had anything to do with it. Al was sure that was not the case. "That would be quite odd," said Al. "I know lots of guys using those cams on the street and racetrack without any problems. You might want to see if the head gasket on there was at least 1.74mm." We checked the gasket, and it was close to 2mm--plenty of thickness.
Finally, further examination revealed a very possible milling of the head from what was probably the result of an engine overheat while the car was in the hands of the previous owner. What this would have done is bring the pistons closer to the valves than stock during combustion, raising the compression. This would explain why the car made so much power stock, and why the compression tests revealed about 220 psi across the board instead of the expected 205 to 210 psi.
With stock cams, this didn't pose a problem. But with the Schrick cams lifting 1mm higher than stock, this finally brought the pistons in slight contact with the valves. There was no way of knowing this would happen, because in the Schrick camshaft installation the cylinder head did not have to come off. There was no way of seeing the mill job without pulling the head completely off like evosport had to for the AA turbo installation, and thank goodness for that. Running around with 400 bhp and shot valve guides is not my cup of tea! For this reason, before you install more aggressive cams like the Schricks, make sure the entire engine is to O.E. specs.
Thankfully, I had tuners such as evosport and BMP Design that were quick to rescue Project M3 from any fatal mistakes. BMP's massive warehouse in Tyler, Texas, carries just about any product you need for your BMW M3, including racing components. The company quickly sent out new factory M3 intake and exhaust valves, valve guides and a valve cover gasket set. When I received the guides, evosport did an excellent job in having the cylinder head rebuilt, resurfaced and reinstalled. The fresh cylinder head went back on the car, and I was ready for the rest of the turbo kit.
The components of the turbo kit were a really tight fit--there's not a lot of room to work with in the M3. AA had done well utilizing the limited amount of space, but the install isn't easy.
There were some fitment problems on the exhaust side. The center muffler and connector came up about 2 in. short of reaching the rear AA muffler, and the instructions didn't prepare us for an additional welding job, bringing the center muffler together with the external wastegate bypass pipe.
In any case, the evosport technicians showed tremendous patience. Although AA offered to send the correct length pieces, the technicians welded a 2-in. piece of 3-in. piping to connect the rear muffler and welded the turbo downpipe to the external wastegate bypass pipe. This saved a few days in having to wait for the correct pipes to get here from Miami. Special thanks to evosport for the turbo install and to BMP for the cylinder head components.