Thanks for the update. I like how well this one is thought out.

That flair teaser at the end has me stoked. This is going to be a badass BMW. Thanks for the update, Terry.

Bad to the bone.

I ran EPAS for only a few thousand miles and wore out two woodward steering joints fairly quickly. The usual Borgeson joints are a little bigger and might last longer, but for anyone putting in epas up at the column, keep this in mind and I recommend trending towards larger joints/shafts and as always minimizing your angles. I'm not worried about Vorschlag doing the right thing so much as us hobbyists who incorporate these things.

For the record I used a Saturn Vue motor (pullout) and it actually worked very well, although I never got it on track with big stickies up front.

Another place where home brew gets into trouble is when people separate the box from the column for packaging reasons - it can be done but the sensor wires between the controller and motor are very "sensitive", and if they fail, so does power steering or even worse it can command left or right ! I heard about one crash that happened because of this.

I'm doing a Ron Sutton style front end now, so I've moved back to hydraulic (Sweet rack as he uses) but otherwise I would have happily stuck with the epas.

Project Update for August 15th, 2017: I started writing this in July and got buried with other projects and work. We have accomplished a lot on this car since the last update and I will try to show as much as possible here. I will go over the custom fuel cell + fuel filler neck and oil tank, along with the mounting structure and fire proof enclosures for all of that.

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We also will cover the aftermarket front bumper cover install as well as the structures built to hold that and twin oil coolers. There were Lexan rear side windows and back window added. And we built some really big ass flares to cover the big ass tires. Lets touch on those first!

WIDE BODY FENDER FLARES

This section could be huge, but go read the flare section in my June 9th post in our E46 330 build thread, and we can all save some time. In that post I cover the flaring options and installation techniques, and even reference this car's flare job.

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As I showed last time, we are building this E46 M3 around what I call "GOD'S TIRE SET" - a 335mm wide front and 345mm rear Hoosier A7 DOT tire setup. I've run these tires successfully on our TT3 Mustang (above left) and even briefly on our 92 Corvette (above right), and I'm building my new C6 Z06 project around the same set of tires too. I say if something works, stick with it!

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It took me decades of dabbling in "wide tires" before I managed to work my way up to this mega-sized set. We progressed the wide wheel/tire thing on our STU classed BMW E36 M3 in 2006 (running 18x10" wheels under stock fenders), then went to 315mm tires on the Alpha E36 LS1 (above right). Our GRM Challenge winning E30 V8 got 18x11" wheels and mega-sized box flares after that.

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We were already stuffing 18x10" wheels and 285/30/18 tires under BMW E46 cars ten years ago

The most tire you can fit under stock E46 M3 fenders is roughly a 285mm front and 315mm rear. I've run 285mm square on many E46 M3s and have installed M3 fenders on non-M E46 models to be able run that tire size. But that's just not wide enough for a powerful road course car. I always ALWAYS want to run the widest tire that "a driver can afford", and this car has the power and the potential of very few, so it deserves THE BIGGEST.

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Last time we had fitted the 18x13" wheels and 335F/345R tires, and they obviously had a lot of poke past the M3 rear and non-M front fenders we had stuck on the car (this chassis was purchased without front fenders). Instead of buying then just cutting up valuable OEM E46 M3 fenders we kept the ~$35 front fenders from my old 330 on there to cut and build upon. Before we started cutting metal it was time to break out the craft paper and scissors...

FLARE DESIGN MOCK-UPS

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The front mock-up flare (above left) was designed and shaped first. We were looking for some specific aero improvements that help reduce drag (covering the front of the tire) and help create downforce (evacuating the wheel well from behind). We went over several vent shapes and decided on an extended width fender face that is open at the leading edge of the door. The rear flares would follow the same mantra but it was later revised a bit. And while aero takes precedence, the style is important for Optima D&E judging, too. Nobody wants an ugly race car.

MAKING ROOM FOR THE TIRES - REAR

Anyone can slap on a set of pre-made "flares" fairly quickly, and the Stance Crowd often does this without doing the necessary cutting and fabrication work underneath. The real work is in the chassis clearancing - making room for the tires to travel in the "bump" direction (up) as well as allowing the front tires to "swing" while steering. This is often why I recommend a fabricator do the initial work on any custom flare installation, and not a painter. Sometimes paint and body shops don't understand the dynamics of how a suspension works on a street or race car. They also tend to use a bit more body filler. To keep weight to a minimum and allow for maximum tire clearance we tackled the custom steel flares in-house on the E46 M3 here. We will do a complete track test before the flares ever see any bodywork/paint, too.

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Left: Making room for tire clearance before the flares go on is key. Right: As is thorough testing before paint!

Cutting and welding to make room for mega wide tires is difficult to do correctly and retain a waterproof and strong unibody once you are done. I've seen some janky cutting done under some flares and they leak water inside, smoke, fuel, fire, etc. These sections that are modified really need to have an air tight seal to be FIREPROOF when complete, and this isn't something you can afford to half-ass.

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Normally on a unibody car cutting the rear fenders and merging them back together is the hardest part - and this car wasn't any easier than normal. What we do is take the wider tire & wheel, remove the rear spring, and compress the rear suspension into the bump stops (ie: "full bump travel"). If the car's inner structure allows it we cut the outer fender sheet metal (sometimes 2 layers) all the way above up to clear the top of the tire at full bump.

This 345/35/18 Hoosier is a really tall tire (26.8" tall) but it was still possible to get full tire clearance and not cut into the rear inner fender beyond the centerline of the tire. We were prepared to do that, if necessary. This car needs about 3" of bump travel with the MCS RR2s and it now has it. Due to aero loading it will have some rather firm springs on track, so we might never see 3" of bump in actual driving.

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MAKING ROOM FOR THE TIRES - FRONT

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I've flared a lot of BMWs and normally the front fender clearance is a breeze. You mark the highest part of the tire at full bump and trim the sheet metal fender. Done. Takes 30 minutes per side, tops. But I've never added 335mm front tires on a BMW...

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Just like we had to do on our BMW E30 V8 with 18x11" fronts, this E46 M3 needed EXTENSIVE mods to the frame horn above and the chassis behind the tire to clear the 13" wide tire swinging at full lock. Large chunks of the inner fender structure were removed.

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The part of the upper frame horn that was removed was replaced with some formed 18 ga steel sheet metal, shown above left. The same template and shape was used on both sides, just inverted for the right/left fenders.

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The surrounding metal was cleared of paint with the pneumatic wire wheel called the Krud Buster. Awesome tool. Then this panel was stitch welded in place to tie the structure back together.

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And just like how I did the same reinforcement work on the E30 (above left), Ryan added square tubing to replace some of the missing sheet metal structure on the E46 M3 (above right). All of this was TIG welded in place (way better than my E30 welding!) and the raw steel was all coated with more zinc primer. Now we are ready to add the actual flares.

BUILDING CUSTOM STEEL FLARES - FRONT

We are building these flares out of 18 gauge steel with the hopes of being able to pull molds off the final set. And while we could have made them out of foam and fiberglass, we are not a composites shop. This is the best way to make a one-off set of wheel flares in-house. They will be strong and can also be used to pull molds off of afterwards.

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Ryan started by adding some "landing" zones for the front flares by adding some flat sheet in the horizontal plane at the front and back of the front wheel front wheel arch opening. We will add a front "canard" portion that attaches to the front bumper cover and this landing pad will be the seam.

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The wheel arch had a rolled upper edge added in the bead roller (above left). With this "skeleton" added on the outer edge of the flare the gap to the fender could be bridged.

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The upper curved section of the flare was cut from steel made from transfers from the cardboard templates. These sections were then rolled and reformed in the English Wheel (above left) and the edges that meet the wheel arch were rolled in the bead roller (above right) and formed further in the shrinker stretcher (not shown).

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These horizontal flare sections were fitted to the framework of the flare and fender but went back into the English Wheel a few times to be fitted.

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Initially these horizontal sections were made from one piece of sheet - which was a very long, multi-curved panel. These were later were re-made in 3 pieces, to get a better curved fit. The rear section was templated with blue tape (see above left) and you can see the seams in the top/middle and at the rear third (see above right).

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To create a gap at the door opening there was a "flat" section that was welded to the middle of the curve on the front flare. Finally a vertical panel tied that "flat" upper section section into the rear landing pad. This vertical panel has a curve that mimics the stock fender shape, just moved outward five inches. The total flare width at the curve is 8.25" - its pretty massive.

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You can see the large vent opening at the rear of this panel which will be used to evacuate the wheel well. There are all sorts of curved and formed edges on this panel to give it strength, cleaner airflow and better looks.
The look we were going for was sort of a modified/curvier DTM flare. The entire structure shown above is attached to the fender, which can be removed as a unit.

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The 3 layers of now cut-apart steel for the rear fender structure were hammered into place, cleared of paint and undercoating, then carefully stitch welded together via a MIG. There's no way to get to all of the factory coating on the inside sections of the sheet metal but a MIG can power through this stuff better than a TIG. Once both rear fenders were cut and welded, the areas were primed with self etching primer (needs to have "zinc" somewhere in the name) and the car was reset at ride height. It looks ugly but THAT is what needs to be done under any unibody car BEFORE you start a proper rear flare job.

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BUILDING CUSTOM STEEL FLARES - REAR

The rear flare fabrication follows the same process as the front, starting with the front and rear "landing pads" then the formed outer arch framework.

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The curved horizontal flare sections were made from multiple pieces this time to keep the curves following the bodylines better.

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Ryan finished up the rear flare and they looked great - from the side (see above right). But from the rear there was something odd about the rear vent opening. There was an attempt to widen the rear fender to follow the rear taillight shape. It just... didn't look right.

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Several of us stood around the rear flare one afternoon and we drew some lines in sharpie as well as blue tape. We all weighed in and together came up with a new shape.

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Above shows version 2 of the rear flare. The boxy rear section was scrapped in favor of a tear drop shape to the added vertical section, which blends into the fender at the tail light. Some curved air deflectors were also mocked up in cardboard.

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Once again everything shown attaches to the rear fender. There will be additional portions that tie the rear bumper cover into this flare on the back side as well as a skirt that ties into the lower front section of the rear flare - as well as the trailing lower edge of the front flare.

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Everyone was happier with the look of this version so the other side was begun. With a final design locked down the second side was slightly easier to duplicate in a mirror image, pulling templates from the right side pieces to make the left side flares.

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I'm happy with the look, Jason likes the airflow shapes, and Ryan likes the tire clearance - and the customer likes it all. Again, we obviously have some missing sections to tie into the flares sections at the front, middle and back, but the "wheel flares" are complete and ready for final welding then track testing before bodywork and paint.

CUSTOM FUEL CELL + OIL TANK + ENCLOSURES

The images below may look pretty mundane but there was a lot of thought, planning, and custom fabrication that went into these items and enclosures.

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Let's break it down into sub-sections, starting with the fuel cell decision.

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WHY USE A FUEL CELL?

The stock fuel tank in the BMW E46 has both good and bad properties. Good: it is strong, compact, mounted very low in the chassis, just aft of the front seats. Under the rear seats, under sheet metal, completely sealed away from the cabin. It crashes well being in the rear middle of the car, too.

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On the bad side the saddle shape makes for nasty fuel slosh in lateral loading and the "tunnel" between the two sides is too tight to fit dual 3" exhaust pipes and still keep good ground clearance. It is also plastic which means in a fire it can melt, rupture, etc. That isn't super common in crashes, but it is a possibility. Also, one side of the E46 saddle tank is much smaller than the other, as you can see above left. It is cheap and easy to just re-use this tank - which is what I did on my personal E46 330 race car.

In use a fuel cell provides a minimal anti-slosh effect due to the foam that is inside the bladder but can be designed to always pick up fuel. A fuel cell bladder is VERY tough and made to hold up very well in a motorsports crash. The bladder is mounted inside of a can that is made of steel or aluminum, with one end (usually the top) that can be unbolted, to extract the bladder for service. The bladder has to be replaced every 5 years to maintain FIA certification, so keep that in mind. The fuel cell foam can also degrade, especially when exposed to (and soaked /stored with) ethanol.

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For many decades an FIA approved fuel cell was required for many road racing and hill climb (like the Pikes Peak Subaru STi above) classes, but safety improvements in modern OEM plastic fuel tanks - and their common, optimized placement under the car behind the front seats - has allowed these to be permitted in many Wheel-2-Wheel racing classes. We are building this E46 M3 for NASA Time Trial and Optima competition, so a fuel cell was not required, but it is never a bad idea. They do tend to be safer than almost any OEM fuel tank.

We talked about a custom fuel cell early on. Trunk mounting is the easiest and probably smartest move. There are many rectangular shaped fuel cells with an aluminum enclosure and kevlar bladder, like the ATL below in the 69 Camaro track build. This is mounted behind the axle just forward of the rear bumper.

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I usually forego this in my own cars because I don't do wheel-to-wheel racing, but for serious builds a fuel cell is pretty standard. If packaging had permitted, we would have used an off-the-shelf fuel cell / shape and stuck it in the trunk. If possible, try to use an off-the-shelf cell. You will save mountains of packaging hassles and costs by sticking with common fuel cell shapes.

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This car, being built for Optima competition, needed to be more optimized. Visible "race car" things (like a trunk mounted fuel cell) can sometimes spook the D&E judges. Besides, having a big chunk of weight in the form of 16-20 gallons of fuel mounted way out back makes for some weird polar moment issues.

MAKING A CUSTOM FUEL CELL CAN

Pretty early in this project we decided to make a custom fuel cell, to gain the exhaust clearance room in the tunnel, add safety, and keep the fuel load as low and centrally/rear located as possible. Putting it in/under the back seat would also leave the trunk floor area open for a diffuser - another really useful addition to get additional downforce in an Optima car (rear wings are severely limited in that series).

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This custom cell was modeled somewhat around the lower shape of the right/passenger side of the OEM saddle tank, just made significantly taller. It actually holds 16 gallons all on the one side, which equals the OEM dual saddle tank's volume. We figured it would be easier to do a couple of sessions in a row on track feeding a hungry 800 hp engine if we had a full 16 gallons on board. Ryan made the "can" out of aluminum plate that was TIG welded together, with a flange on the top to be able to access the bladder inside.

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The shape of the can is funky - not rectangular - and this will cost us later when we have a custom bladder is built, but the alternative is a compromise of one sort or another. Of course there is a hole in the rear seat floor to let the taller portion poke through - to get the fuel volume we needed. This hole will need to be sealed up from the cabin, and an enclosure around the fuel cell can will be needed as a firewall. That work is shown below in another sub-section.

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The fuel cell can is 15" tall and sits about 5" above the rear seat floorpan, but sits no lower under the car than the OEM saddle tank. The fuel cell can is mounted inside of a mounting structure or "cage" made of 1" square steel tubing. The upper portion can be unbolted to remove the can.

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The entire "cage" bolts into the rear seat area - and also holds the dry sump settling tank, which I will talk about below.

DRY SUMP TANK MOUNTING

Running a dry sump oiling system is a really REALLY good idea on a car like this that has massive race tires (13.8" wide), lots of downforce, and a built race engine. And any dry sump oiling system needs an oil settling tank / reservoir.

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There are two schools of thought on oil tank placement with a dry oiling system: the engine builder wants it up front RIGHT next to the engine, with minimal plumbing runs. Mounting it under the hood at the firewall is common. The chassis engineer wants this 10-14 quart oil tank at the opposite end of the chassis than the motor, to keep improve rearward weight bias. This "trunk mounting" option is somewhat less common, but it is done.

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On this car we split the difference, mounting the oil tank opposite of the fuel cell, sitting behind the driver. It also pokes down through the rear seat floor, to keep the weight as low in the chassis as possible.

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The shape of a dry sump tank is also important. The taller the tank the more distance the settling oil has to travel and hopefully the more baffles it can pass through to remove entrapped air. The oil that hits spinning engine parts can get whipped up like a milk shake and turn into foam. Foam doesn't "pump" well and lubricates even worse. The longer the oil has to travel inside the settling tank, the more air gets removed and the more "liquid" it becomes. So a tall/skinny tank is more advantageous than a short/fat tank. But all sorts of sizes are available to help builders package the oil tank in their application.

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The tank that fed the 7.0L LS7 engine in the the factory equipped dry sump C6 Z06 was tall and skinny. One major change happened from 2007 through 2013 model run of this car was - to make the tank larger in volume, going from 6 quarts up to 9 quarts (bringing total oil capacity of engine + tank + cooler from 8 to 11 quarts). There are even larger capacity oil tank units for this OEM LS7 application from the aftermarket.

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We chose an ARE tank (p/n 7025A) which has a 25.5" height and 6" diameter. This holds 2.5 gallons of oil (10 quarts) and is the "Tall and Skinny" option. These are more of a chore to package inside of a race car. We also ordered the ARE tank mount (p/n 7000) to hold the tank, which was mounted to the 1" tubular structure mounted in the back seat.

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As you can see it sits pretty high in the chassis but its 25.5" tall. It sticks down under the rear seat floor (through a hole) as far down as we could comfortably put it, too.

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This hole of course has to be covered, but a fire proof aluminum enclosure will handle that.

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