Oil Catch Tank

As car engines run pressure is created in the sump, through the movement of pistons  and also combustion gas passing by the pistons. This has to be vented somewhere, and traditionally this is connected to the rocker cover. This of course does not get rid of the pressure, just moves it elsewhere where pressure is also created. The rocker cover is then vented, via a valve, to the intake system which means these gases are burnt in the engine. This is done to prevent this air, which contains oil mist and combustion residue, from being dropped on the road. This is fine for road use, but tuned and/or highly abused engines do not like this mist on the inlet as it effectively decreases the octane of the fuel being burnt. There are many variations on how the above is achieved, and all cars have nuances, but the theory is the same.
The answer for competition use is to vent the crankcase and rocker cover to a vented catch tank. This then catches all the oil, and any other nasties, and can be drained after the event. For track use there are rules about how big they have to be (At least in the UK there are) but not for rallying. I went for the largest I could buy ready made anyway.

 Fuel Tank

The standard fuel tank is under the floor. This keeps it out of the way and makes best use of space, but susceptable to damage on inevitable off road excursions. We decided to move it to the boot, quite common. Shaped tanks for Escorts are readily available, but not for E36 M3s. I vaguelly hoped that an escort tank might fit, but it didn’t. I made a wooden mock-up, pictures are elsewhere, with the intention of giving it to the local allot fabricator, but that didn’t work out. Rather than drive around the country showing it to various fabricators I draughted it using a 3D CAD package.
Here is the tank drawing, and a photo of the actual tank placed in position, added in mid December 09.
The finished tank is baffled, to stop fuel sloshing about wildly, and has a mechanism to keep the pump fed with fuel even when cornering.

Pipe Line Fittings

First things first, I hate buying fittings. You seem to inevitably need to adapt from a 3/25″ Smeldon, to a 4.65mm Left Handed Whatsit, which is only available on the 5th Sunday in February.

Anyway, enough of that rant. On a road car the brake lines are run under the car in solid pipe, and then in areas where suspension moves are run in a flexible pipe. The difference in a competition car is that brake lines are generally run inside the car, again to keep them out of harms way, and also the flexible pipe is steel braid covered for protection. When you put your foot on the brakes a piston is pushed forward generating pressure, this pressure is transmitted along the brake lines to the wheel cylinders, which then move out under this pressure, causing the brake pads to grip the brake disc. Very little fluid actually flows along the pipe, but the pressure is transmitted instantaneously. The pressures generated are very high, as much as 2000psi, or 138 Bar. This can cause the standard hoses to bulge, giving the brake pedal a soft feel. Steel braided line does not do this and the brake pedal in a competition car should feel much more solid under heavy braking. Under normal braking you would struggle to notice the difference.

Getting all the lines made up with the right fittings is a complete nightmare of a job, so I went to see a supplier complete with all the bits we needed to join, and a sketch of all the fittings we would need and after a couple of hours we got the fittings assembled.  The ends of these hoses are re-usable so you just buy a few meters of braided hose, cut to suit and then install the ends. Fitting the ends can be painfull, the steel braid tend to fray slightly, and always gets in your finger.