Trackspeed Engineering

Trackspeed Engineering - Inconel Stud Kit (m8x1.25)

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  • Regular price $169.00
  • Will be in stock after

Don't allow the failure of an inadequate $2 stud to ruin your next track day. Eliminate turbocharger fastener failure with Trackspeed Engineering's Inconel stud kit. 

M8x1.25 application available for Trackspeed EFR turbo kit, and other Borg Warner turbochargers. 

Stud kit includes: 

  • Four Inconel studs with rolled threads 
  • Four Stage 8 stainless fastener sets  
  • ~2cc bottle of Resbond 907TS threadlocker


For years, the fastest turbocharged Mazda Miatas in the country have struggled with the issue of fastener failure. The stresses and strains of extreme thermal cycling, high-RPM vibration and high g-force cornering combine to exceed the high-temperature yield strength of standard mild steel or normal 304/316 Stainless steel studs. As the yield strength of the fastener is exceeded, it begins to expand, or creep, causing an immediate reduction in preload on the nuts, akin to literally loosening them with a wrench. Once the fastener has worked its way loose, vibration will continue to spin the fastener off. If a high quality locking nut is used, the entire stud will spin out of the manifold. Safety-wiring all four nuts and studs together is only a temporary fix - after only a few sessions a steel stud will creep and cause exhaust leaks regardless. 

A material-based problem requires a material-based solution. Enter Inconel, a nickel-based superalloy that sees duty in environments such as jet engines and nuclear reactors. Inconel is available in a wide variety of alloys, allowing Trackspeed to select an alloy that had a similar coefficient of thermal expansion to steel, but far higher high-temperature yield strength. Inconel studs do not exhibit the same creep when exposed to high-temperature stresses, allowing the fastener to maintain preload and work as intended. 

"Trackspeed Engineering's Inconel studs are machined in the United States of America specifically for use in turbocharged Miatas. Because these are not off-the-shelf items, we are able to specify exact dimensions to ensure adequate thread engagement in the manifold as well as ease of installation with the manifold in the car. In addition, we were able to specify rolled threads which cause less stress concentration during production and result in a superior fastener. The end result is an exceptionally high-quality stud designed specifically for cast manifolds tapped to M8x1.50. 

In order to complement our high-quality studs, we have chosen two products of similar quality. Stage 8 Fasteners provides the nuts, retainers, and clips for our kit. These nuts are significantly easier and faster to install than standard locking nuts or copper split-locking nuts. Once the nuts are all installed and tightened, retainers and clips are installed. If one of the nuts attempts to back its way off of the stud, the retainer interferes with its surroundings and prevents the nut from loosening any further. In order to fasten the stud into the manifold, Resbond 907TS thread locker is used. 907TS does not exhibit the temperature deactivation that other chemical thread lockers do, but is still mild enough to be removed with hand tools should the need ever arise. It is the ideal thread locker to complement our studs."

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