Stainless Exhaust Tubing

Which diameter to choose

The diameter follows how much air goes through the engine, not how you want it to sound. A practical guide: 60 and 63 mm on naturally aspirated engines up to 2.0 litres and on small turbos, 76 mm on turbos of 250 to 400 hp, 89 mm above 400 hp. On a small engine, a pipe that is too wide slows the gases and you lose torque in the middle of the range, which is exactly where you pick up after a slow corner.

On a turbo, the sum is different. The turbine breaks up the pulses anyway, so after it you run the thickest pipe that fits under the car. The long explanation, with what happens at the weld and how much the system grows when hot, is in the pipe selection guide.

Specification

• AISI 304 stainless, it does not stain after a winter of salted roads
• 1.5 mm wall, the thickness at which you do not blow through the pipe when welding
• 100 cm pieces, the price is per metre; you order as many as you need
• outside diameter 60, 63, 76 and 89 mm

Stainless or mild steel

Ordinary steel blows through after a few seasons, at the welds and on the low sections, where condensate sits after every stop with a hot engine. 304 stainless does not have that problem. You pay once more and you skip the second rebuild.

What else goes into the system

Changes of direction are made with bends and link pipes, the mounting and sealing with accessories and mounts, and the noise is settled with a silencer. The rest of the system is in exhaust systems.

Before you cut

Measure with the suspension loaded, not with the wheels in the air on a ramp. The axle hangs when you lift the car, and a pipe that clears by a millimetre on the ramp grinds on the floor at the first kerb. Leave room for expansion at the joints and do not mount the pipe rigidly to the body: stainless grows noticeably when hot. Where it passes near a loom or the tank, add heat insulation.