I am trying to summarise in one thread information regarding the studs, nuts and bolts that connect the head > manifold, manifold > turbo, turbo > elbow, and elbow > downpipe on S14 and S14a cars. Currently any information is scattered around the board (and is sometimes inconsistent), so to have correct information in one place would be very useful.
Please let me know if I have made a mistake and I'll correct this entry accordingly.
Head to manifold:
Eight M10 x 1.25 (fine thread) studs, 44mm long (11mm-11mm-22mm, thread-shank-thread).
[The standard thread for M10 nuts/bolts is 1.5mm pitch; 1.25mm pitch is referred to as 'fine' pitch. You'll also need M10 fine thread nuts if you have to buy any new ones.] (See later post for photos.)
Manifold to turbo:
Four M8 x 1.25 studs, 40mm long (14mm-10mm-16mm, thread-shank-thread). The manifold is secured to the turbo studs using nuts and locking tabs.
Turbo to elbow:
Two M8 x 1.25 studs, 45mm long and three M8 x 1.25 bolts, 45mm(??) long. The elbow is secured to the turbo studs and bolts using nuts and locking tabs. (See later post for photos.)
Question:
- What length are the bolts that secure the turbo to the elbow?
Elbow to downpipe:
Three M10 x 1.25, length ??mm studs.
Questions:
- What length should the elbow to downpipe studs be?
- Do these studs need to be shouldered?
- Are they the same as the head to manifold studs?
- Should locking nuts or locking tabs be used on these studs?
Notes for people installing a new manifold, turbo or elbow:
From reading this forum, it seems that it is not uncommon for the studs, nuts or bolts securing the turbo to the manifold and/or the elbow to work themselves loose, or shear off altogether. Thus many folks replace some or all of their studs when they have their turbo off.
When removing their manifold, people often find their head to manifold studs to be broken or in need of replacement.
Studs are generally regarded as being superior to bolts. Thus some people replace the three bolts holding the turbo to the elbow with studs when they have their turbo out. Apex sells both turbo studs and head to manifold studs [Nissan part #: 14065-75F00].
Instead of using locking tabs in conjunction with standard nuts, many people buy locking nuts, such as “K nuts” or “Aeronuts”, to ensure the studs on the turbo don’t work themselves loose over time. Locking nuts for the turbo studs are sold by Apex , Driftworks and Merlin as well as other suppliers and engineering shops.
Again, please let me know if I have made a mistake and I'll correct this entry accordingly. Thanks to Digglett, Mark , AlexTheGreat and Jam00 for their input so far.Originally Posted by Jam00
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- I've actually already been through that + the follow up comments with a fine-toothed comb. But feel free to point out anything I've missed 
. Incidentally, the reason I have put this guide together is in order to get everything I need in order to carry out Aitch's turbo gasket guide.
Despite much searching on the board, I had not come across that thread. Thanks! :thumbs
