Spark Exhaust Conic Adapter Tube Ø 60 to Ø 40 mm 110 mm Universal SGMA14

A hundred and ten millimetres of stainless cone that takes sixty millimetres down to forty. Seventeen euro instead of a fabricated transition.

Key Features

• Conic adapter tube, stainless steel.
• Ø 60 mm at one end, Ø 40 mm at the other.
• 110 mm long.
• Joins Spark's most common silencer inlet diameter to its most common link-pipe diameter.
• Spark part number SGMA14, made in Mantova, Italy.

The Two Numbers It Bridges

Sixty is the inlet of Spark's universal Force Evo, Konix Evo, Grid-O and Megaphone silencers. Forty is the diameter most link pipes and mid-sections are built at.

Between those two sits this cone. It is the single most likely transition a Spark-based custom build will need, which is why Spark makes it as a part rather than leaving it to the fabricator.

Why a Cone and Not a Step

A sudden change of diameter is a pressure step: gas that has been travelling at one velocity meets a different section and part of the energy reflects back up the pipe. A gradual taper does the same job without the reflection.

A hundred and ten millimetres over a twenty millimetre change is a shallow taper by any standard. That is the point.

Making the Transition Yourself

The alternative is a rolled cone, which means a flat pattern, a set of rolls, a lengthwise weld and a great deal of fettling to make both ends round. It is a genuine sheet-metal job and it takes longer than the rest of the system.

At seventeen euro, this article is not a compromise.

Welding It In

Both ends are plain tube ends, so both can be butt-welded or sleeved. Tack in four places, check the alignment down the bore before running a bead, and remember that the cone will pull the assembly out of line if the tacks are uneven.

Length Matters Here

A hundred and ten millimetres is not a lot of space to lose in a tight build, and the cone cannot be shortened without changing the diameters at its ends. Measure the run before ordering: if there is no room for a full-length transition, a stepped joint made from two tube sizes is the fallback.

Direction

It works either way round as a piece of metal, but gas flows better through a diffusing cone than through a contracting one. On a normal build the 40 mm end faces the engine and the 60 faces the silencer.