Ford Barra Head Studs (Australian XR6 Turbo, FG, FG-X)

TorqBolt Barra head studs (TB-BARRA-MP35N) ship as 14 M12 x 1.5 studs in MP35N (260 ksi) or Custom 465 H1025 (220 ksi). The Barra is the Australian equivalent of the 2JZ in tuner culture, and the bolt-on stud upgrade is one of the first modifications on any high-boost Barra build alongside the famous Plazmaman intake and Garrett G-series turbo.

Barra head stud installation

1. Remove factory bolts in reverse pattern.
2. Chase all 14 M12 x 1.5 holes in the iron block deck.
3. Install studs hand-tight, back off 1/2 turn.
4. Set head with new Cometic or HKS MLS head gasket.
5. Lubricate threads + under-nut face with moly lube.
6. Tighten in 3 stages, criss-cross from center outward: stage 1 at 30 N-m, stage 2 at 60 N-m, stage 3 at 100 N-m final.
7. For 1000+ hp builds (modified turbo, race fuel): torque-angle stage 4, turn each nut 90 degrees from stage 2.
8. Re-torque after first heat cycle.

Barra family fitment

All Barra turbo variants (240T BA / BF, 270T FG, F6 270T, 310T FG-X, Sprint 325T) share the head-bolt pattern, and the TB-BARRA-MP35N kit fits all. The naturally-aspirated Barra 195 / 220 (XR6 NA) shares the same pattern but typically does not need stud upgrade since boost is not in play.

Installation best practice

Achieving the design preload is as much about the install method as the bolt: lubricant matters (published torque values assume 0.13 to 0.16 friction coefficient; anti-seize or moly-disulfide reduces friction 20 to 30 percent and over-stretches the bolt at the published torque). Direct bolt-stretch measurement with an ultrasonic gauge or stretch gauge over the bolt centerline cuts preload variation to under 5 percent vs torque-only at 25 percent. Race builders measure stretch.

Re-torque after first heat cycle (run engine to operating temperature, allow to cool overnight, re-check torque) recovers preload lost to embedment at the faying surfaces. Conventional alloy-steel and MP35N bolts benefit from re-torque; torque-to-yield (TTY) bolts are NOT re-torqued and are typically replaced rather than reused after disassembly.

Alloy choice vs build budget

For street + occasional drag (target 500 to 700 hp): heat-treated AISI 8740 chromoly at 200 ksi is sufficient. For sustained 700 to 1000 hp street/strip: Custom 465 H1025 at 220 ksi or L19 race-grade at 270 ksi. For 1000+ hp drag racing or roll-racing: MP35N at 260 ksi. The bottom-end limits (rod tensile, main-cap stretch, deck flatness) become the bottleneck above this level, not the bolt.

Frequently asked questions

What is a 12-point bolt?

A 12-point bolt has 12 splines arranged every 30 degrees on the OUTSIDE of the bolt head, also called a bi-hex or double-hex bolt. The 12 external splines provide twice the wrench-engagement angles of a standard hex head, allowing higher applied torque before cam-off, which is why aerospace and motorsport applications adopt the geometry.

Are 12-point bolts the same as ISO 14579?

No. ISO 14579 specifies an INTERNAL hexalobular socket head (similar to Torx) recessed inside a cap screw. External 12-point bolts under MS21250 / NAS1351 / AS3216 use an EXTERNAL bi-hex head driven by a 12-point socket wrench. Both involve 12 features but on different sides of the bolt head and require different drivers.

Which alloys does TorqBolt manufacture 12-point bolts in?

TorqBolt produces 12-point bolts in A286 (UNS S66286), Inconel 718 (UNS N07718), Ti-6Al-4V Grade 5, MP35N (UNS R30035), Custom 465 H1025, AISI 8740 chromoly heat-treated, AISI 4340, 17-4 PH, H-11 tool steel, and L19 race-grade alloy steel. Choice depends on tensile target, service temperature, and corrosion environment.

Is TorqBolt AS9100D certified?

Yes. TorqBolt operates under AS9100D Rev D and ISO 9001:2015 quality management systems, audited annually by the registrar. NORSOK M-630 and NACE MR0175 / ISO 15156 qualifications cover offshore and sour-service applications. Mill test reports MTC 3.1 standard and MTC 3.2 critical-service witness are issued with every lot.

What lead time should I expect?

Stock alloys (A286, AISI 8740, AISI 4340, 17-4 PH, 316 stainless) ship in 4 to 6 weeks. Specialty alloys (Inconel 718, MP35N, Custom 465, Ti-6Al-4V, L19) ship in 8 to 12 weeks depending on raw-bar lead time at the alloy producer. Critical-service orders requiring third-party witness inspection (MTC 3.2) add 1 to 2 weeks for witness scheduling.

Request a Quote

Send a build sheet (engine variant, target boost, fuel, gasket choice) and we will return a firm quote within 24 working hours. Email info@torqbolt.com, call +91-22-66157017, or WhatsApp wa.me/912266157017.