Quote:
Originally Posted by Rawknees'Turbo
The entire run of air cooled, turbo 911s used all dilivar studs (exhaust and intake sides), and they are just as susceptible to breakage as any other (plenty of broken examples can be found on this forum) - except for the type of dilivar stud used on 993TT (and maybe 964TT - not sure about those), which have a great record of non-breakage.
With non-turbo engines, steel were used on the intake sides and dilivar on the exhaust sides in an attempt to balance out the differing expansion rates of the intake-v-exhaust side of the cylinders & heads and maintain consistent clamping forces, but the dilivars have proven to be very failure prone.
No one that has posted in this thread suggested cheaping out and not replacing the all of the dilivars.
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My 964NA came with dilivar studs on both intake and exhaust side. None were broken when I tore the engine down, but all are being replaced nonetheless.