Exhaust Header Mockup Kit 1.75" Tube (44.45mm OD) – 73pc STARTER

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

The entry point into the Bendlabs system for builders working in tube rather than schedule pipe. 73 magnetic mockup blocks sized to 1.75" outside diameter (44.45mm), the most widely stocked header primary size in the UK. Route all four primaries into a collector, check them against the block, chassis rail and steering shaft, and settle the design before you cut a single mandrel bend.

What it does

• Route a complete four cylinder header or manifold in plastic before cutting tube
• Balance primary lengths by counting blocks instead of estimating
• Design equal length headers where primary length actually matters to the powerband
• Model the merge collector and confirm the collector angle before you cut
• Find clearance problems on the bench rather than halfway through a weld
• Produce an exact cut list so you order the right mandrel bends first time

Kit contents (73 pcs)

• 6 × 30° 1D
• 6 × 30° 1.5D
• 6 × 45° 1D
• 6 × 45° 1.5D
• 6 × 90° 1D
• 6 × 90° 1.5D
• 12 × 15 mm straight
• 8 × 25 mm straight
• 4 × 50 mm straight
• 2 × 75 mm straight
• 2 × 100 mm straight
• 2 × 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

Is this the same as your 1.5" NPS SCH10S kit?
No. That kit is 48.3mm OD schedule 10 pipe. This one is 44.45mm OD mandrel bent tube. The blocks are a different size and will not connect to each other.

Tube or pipe, which should I be building in?
Mandrel bent tube in 1.75" OD is the standard for naturally aspirated headers and plenty of turbo work, and it is what most UK suppliers stock. Schedule 10 pipe has a thicker wall and is favoured for high temperature turbo manifolds. Order the kit that matches the material you buy.

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.

Is 73 pieces enough for a four cylinder header?
Yes, for a straightforward four cylinder layout. Tight engine bays needing heavily convoluted primaries may use more, in which case add a bend pack or step up to the 136pc BUILDER kit.

Why 1.75"?
It is the most common header primary size in the UK and the one every mandrel bend supplier carries. If you need another tube diameter, get in touch and we will quote it.