Quote:
Originally Posted by TheAxiom
Cams, head work, Headers?
Like why you went 288* vs 272*?
Suspension?
I'm just curious (seriously) on what made you pursue those options?
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Headers: I've had the headers for awhile (like 3 years) - bought them because cheap power - and had been planning to install them with the rest of the bits since they were around and I had to tune the ECU anyway with the Evolve airbox install (a good time to code out the front O2 sensors). Bought the Evolve because 20+ horsepower and
oh my god that noise 
Suspension: I wanted to fit the the widest front tires I could under the fenders and have a fat square wheel setup (because being able to rotate front-to-back and keep only one width of spare wheel around seemed very convenient, and I really wanted to dial out the understeer as much as possible), and built a very nerdy spreadsheet to calculate what combination of offset, wheel / tire width, spacers, and camber would be required to make it happen. Ended up with the APEX setup (EC-7 18x9.5" ET35 w/12mm spacers in the rear; stud conversion). Converted to studs because changing wheels trackside without studs sucks. Math said I needed around -2.5 degrees of camber to tuck the fronts under the fenders, so I knew I needed camber plates. Didn't want to just put camber plates on the stock suspension, knew I wanted coilovers to properly corner-balance the car and set ride height, found the Ground Control setup, researched it, found a bunch of folks tracking cars with them and very happy, called GC and talked about my goals for the car and they recommended the 550 / 700 setup with rear sway delete to keep the car neutral while cornering but to provide more rear grip coming out of corners. We talked for awhile, it's clear they know their BMWs, I bought them for half the price of the KW v3s, and they've been amazing for the car on the track. At this time, bear in mind, the car was intended to be dual-use and also a mild / relatively inexpensive build. I've been ridiculously happy with the GC suspension.
Cams: picked the 280s because they're the most aggressive N/A cams recommended for street use, and the combination of the CSL-style airbox and big duration cams (1) sounds f___ing amazing, and (2) makes very good power over a broader range, with a good mid-range torque bump. Still meant to be a relatively mild street / track day car at this time.
Headwork: talked about this a bit in the first post, but generally, once I had to take the head off, it didn't make sense to re-install it with 81k km on it. I almost always follow the "upgrade rather than replace" policy - especially with this car, where hop-up parts are
way cheaper than OEM, so I looked into what would be necessary to bump the redline a bit, and what were generally the best-regarded top-end internals by endurance racing folks. I ended up on the phone with the folks at Achilles for awhile, chatting about options (including considering +1mm valves / VANOS delete - Minos' suggestion was "keep VANOS. Delete it when you really hate your wallet"), and settling on the SuperTech setup with steel retainers, since Ti retainers crack much more easily. He, again, clearly knew his stuff, and shared a lot of learnings from racing / customers who race without even a hint of hesitation. So I looked around for a machine shop / engine builder nearby, found the shop that builds Spec E46 and race S54 engines, and brought everything in to them. They recommended the headwork based on significant experience building motors for racing BMWs, I checked with Achilles and they agreed with the recommendations, so that's what I did. This is when the conversation about rod bearing clearance / rod big end roundness / etc. happened and I decided to have experts deal with the bottom end. Molnar rods were recommended by several endurance racing folks as excellent for RPM and durability (I'm staying N/A so don't need turbo internals), and if I'm replacing the rods, doesn't make any sense to leave the pistons. And this is pretty much where the wheels came off and it turned into a "damn the torpedoes" track build.