Exhaust Header Mockup Kit 1.75" Tube (44.45mm OD) – 136pc BUILDER

Exhaust header and manifold mockup blocks for 1.75" mandrel bent tube

Our standard shop kit for builders working in tube. 136 magnetic mockup blocks sized to 1.75" outside diameter (44.45mm), enough to model a four or six cylinder header with blocks spare to trial a second routing before you settle on it. The extra volume over the STARTER kit is what lets you build two versions side by side and pick the better one, rather than dismantling a good design to test an idea.

What it does

• Model four and six cylinder headers and manifolds in full, with blocks spare for alternatives
• Trial competing primary routes without breaking down the first attempt
• Balance equal length primaries by block count
• Model the merge collector and confirm the collector angle before you cut
• Confirm turbo, wastegate and downpipe clearance before any tube is cut
• Generate an accurate cut list and material order

Kit contents (136 pcs)

• 12 × 30° 1D
• 12 × 30° 1.5D
• 12 × 45° 1D
• 12 × 45° 1.5D
• 12 × 90° 1D
• 12 × 90° 1.5D
• 25 × 15 mm straight
• 12 × 25 mm straight
• 6 × 50 mm straight
• 4 × 75 mm straight
• 4 × 100 mm straight
• 6 × Flexible Flange Adapters
• 5 × Flat Pipe Measuring Gauges
• 1 × Pipe Guide
• 1 × Heavy Duty Plastic Carry Case

Tube compatibility

Matched to 1.75" outside diameter mandrel bent exhaust tube, 44.45mm OD. This is a tube kit, not a pipe kit. Tube is sized by its actual outside diameter, while NPS pipe is sized by nominal bore, so 1.75" tube is not interchangeable with our 1.25" or 1.5" NPS SCH10S kits. If you are building in schedule 10 pipe, choose one of those instead.

Bend radii on tube

On tube, D refers to the actual outside diameter. 1D is therefore a 44.45mm centreline radius and 1.5D is 66.7mm. This differs from our NPS pipe kits, where D follows the nominal size rather than the OD, so blocks will not match across the two systems.

This kit ships with 1D and 1.5D bends. A wider 2D radius (88.9mm CLR) is available separately in our 1.75" tube bend add-on packs, for long sweeping primaries where flow matters more than packaging.

Header mockup, step by step

1. Mount the flange adapters to your head flange or turbo flange
2. Snap bends and straights together, rotating each joint to clear obstructions
3. Adjust until every primary is routed and the lengths are balanced
4. Count your blocks for the cut list, then cut, tack and TIG weld to match

Specification

Made to order in Britain

Every kit is produced to order in our own workshop rather than pulled off a shelf. That is why we can supply centreline radii and tube sizes the imported kits do not offer. Need a size that is not listed? Get in touch and we will quote it.

FAQs

BUILDER or STARTER?
STARTER covers a single four cylinder header. BUILDER gives you enough blocks for six cylinder work, or for trying two routings on a four cylinder without dismantling the first.

BUILDER or WORKSHOP?
BUILDER suits most one man shops. WORKSHOP adds enough volume for V8 header work and for keeping several projects mocked up at once.

Can I get 2D bends for this kit?
Yes. Our 1.75" tube add-on packs cover 30°, 45° and 90° in 1D, 1.5D and 2D, so you can add the wider 88.9mm CLR radius to the 1D and 1.5D blocks supplied here.

Will these blocks work with my 1.25" or 1.5" NPS kit?
No. Tube and pipe are different diameters and each size is a separate system. Blocks will not connect across sizes.

Can I mix 1D and 1.5D bends in one header?
Yes, and most builds do. Tight 1D bends get you round obstructions, 1.5D bends flow better on the open sections. Both radii are included in equal quantity.