I've got a greddy manifold, the bolts keep coming loose,I've tried fancy nordlock washers and spring washers but its still happening. It seems now the threads are going in the manifold as well, I will be drilling them and fitting a helicoil, is there anything else I can do?

 

I drilled mine through and tapped them for the stock manifold studs, this plus nordlocks holds everything together very well. I did, of course need to drill the turbo holes larger and find nuts that fit.

 

I did the TSE 10mm Inconel studs on mine. Had to drill the turbo holes larger as well.

 

Trackspeed Engineering Inconel Stud Kit

If you want to fix it once and be done, our kit is the answer.

 

have you tried re tightening them when the car is hot?

 

I have tried tightening hot and cold, although the TSE kit looks great I need the car back on the road ASAP, so will probably try tapping the holes for standard manifold studs

thanks for the replys

 

Research "Thermal Creep." That is what is happening to your bolts. That will also eventually happen to ordinary steel studs used in this application (remember that the exhaust studs on the head get water cooled -- not so for the turbo studs). This is a materials science problem.

10mm mild steel exhaust studs will last longer than your 8mm bolts, but are not a permanent solution.