Spark Exhaust Bent Tube 45° Ø 48 × 1.0 mm Stainless Steel Universal G9148

Forty-eight millimetres at forty-five degrees. The section that carries four cylinders at once, in the angle that turns it toward the silencer.

Key Features

• Mandrel-formed 45° bend, AISI 304 stainless steel.
• Ø 48 mm outside, 1.0 mm wall thickness.
• Straight tangents at both ends.
• Matches Spark's 48 mm straight tube, article G9012.
• Spark part number G9148, made in Mantova, Italy.

The Angle Off the Collector

A four-into-one collector leaves the engine pointing wherever the header geometry dictates, which is almost never where the silencer wants to be. The first bend after it does the largest single change of direction in the system.

Forty-five is usually enough. Where it is not, a forty-five followed by a thirty covers a further sweep with less flow loss than a single right angle at the same total angle.

Flow Through Two Bends

Splitting a turn into two shallower ones and letting the gas settle between them costs less than taking it in one bite — provided there is a straight in the middle. Butt two bends directly together and the benefit disappears; the flow never recovers before the second disturbance arrives.

Two tube diameters of straight is a reasonable minimum. Three is better.

Where the Diameter Belongs

Downstream of the collector on a middleweight four, or as the entire run from the header junction back on a large twin. Forty-five to sixty millimetres is the usual band for that section, and forty-eight sits in the middle of it.

Why a Bought Bend at This Size

Forty-eight millimetres of one millimetre wall is at the limit of what a workshop bender will form without folding the inner heel. Diameter is large, wall is thin, and that ratio is exactly what makes a tube collapse rather than bend.

Thirty-five euro against two ruined lengths and an afternoon is not a close decision.

Trimming Without Losing the Tangent

The straight ends are what you clamp, align and weld against. Cutting a bend shorter is normal, but take the length out of the curve rather than off the tangent — a bend with no straight left is difficult to hold square and harder to weld.

Ordering

One bend per article. Spark builds 30°, 45° and 90° at this diameter. There is no 180° at 48 mm.