CNHSS1 wrote:The 1800Ti manifold was originally made by Beans Engineering for Reliant. as you know, Beans Engineering went on to buy Reliant at some point in its grim history.
back to the manifold, its design is a mirror image replica of the Nissan Silvia one that was originally fitted to the engines but wouldnt fit due to it fouling the chassis. the theroy behind the 'split' arrangement is quite common on japanese turbo motors, the theory being that the separate gas flow paths keep the gas speed up, reducing lag. The idea is pointless on the SS1/Silvia engine due to the undersize T2 turbo, wheer lag is near non-existant anyway. the split gas setup can be found on Nissans Skyline range where the bigger turbos used do affect drivability and spool up times.
the problem with the T2 turbo is that when the boost is cranked up to 10psi and above (still low pressure for a turbo engine) the extra restriction of the convaluted flow path actually causes more trouble than its worth. its common practice on the split design of manifolds, to trim away the centre part to allow better gas flow on boost at higher revs (4.5k and above). in theory it would affect the low rev response, but this is only true with bigger turbos than the T2s used on SS1s/Sabres.
the effects of the restriction to the gas flow, further heats the already super heated exhaust gases to the point wheer the casting is close to glowing when you give it much welly. I dare say the nissan original casting material was of a higher grade than the 'floor sweepings' that Beans used for the SS1 bespoke item.
Craig, a sticky post like this?CNHSS1 wrote:the silvias suffer the same problems as the SS1s with the exh, turbo etc studs coming loose. main reasons are extreme heat (like most turbo setups) and the offset design of the exh manifold, albeit mirror images of each other.
there are various ways to improve the situation, but none are perfect as its really a design issue.
i use 'tri-lobe' nuts on the studs where possible. these are a copper colour when new (coating, nut pure copper nuts) and have a flange washer built in, along with a three point 'crimping' that pinches the stud. they act like a nyloc, but withstand the heat and do away with the need for the washer. i use them on all the head to exh manifold studs EXCEPT for the b*&%$*d one underneath nearest the distributor. Any Ti owner thats had to remove the manifold will know which one i mean. i use a std nut, albeit S/Steel, so i cnj spin it on and off with my fingers. you can use the trilobes there but due to access you cant spin them on and its a very long laborious process turning the nut 20deg at a time
the trilobe nuts can also be used on some of the turbo to elbow and indeed turbo to exh manifold too, but the washer flange has to be ground off.
Second issues are head studs. the nissan head to exh manifold studs arent very long when screwed into the alloy head and its very common for the weight of the turbo assembly and manifolds to strip the threads. if any are stripped, Heli-coiling is the best answer, simple and effcetive.
if they arent, and you can get the studs out, replace with a 50/50 offset stud (same amount fo longer thread either side of centre shank) as theres more tapped depth to the head holes than the std studs use. gives a bit more purchase and stops the blighters stripping as easily.
next is replacement gaskets. only use genuine nissan gaskets, everything else are just sh*te and will have you repeating the horrible process very soon.
my methods for torquing up the gaskets is to fit the gaskets and tighten them up to FT (er, VERY tight ) then leave them for at least 6-8hrs. tighten them again. you will be amazed that they actually torque up 1/4 to 1/2 a turn again!! if time is avaialable, leave overnight and try again. turbo gaskets are multilayer S/S pressings and do compress, hence the 'loosening' issues. i do the manifold to turbo and pref elbow too, on the bench and then offer up to the engine to re-fit water and oil feed ppes. again same method is used to head and exh manifold gaskets.
run the car gently for a few miles, avoiding lots of boost, and return to the garage. CAREFULLY spanner check any nuts that you can easily get at whilst hot (PLEASE BE VERY CAREFUL!!!! ).
allow to cool and then check as many of the nuts as you can get at with std and 'bent' spanners.
that method has worked for me for years now, on hi mileage road Tis and my racers.
another tip the nissan guys use, is once all the torquing up and first test run has been done, allow to cool and then smear exh paste on each of the protruding stud threads (after the nuts). this hardens to a rock-like substance, stopping the nut un-winding. its easy enough to chip off with a screwdriver and wire brush should you need to rebuild at a later date. Not Hi-tech, but works.
next is making up bracketry from the engine block (loads of tapped spare holes on the head and crankcase) or gearbox to the down pipe or turbo elbow to help and support the weight of the turbo assembly. again its common practice on the later nissans but must allow some movement for heat expansion. its really there only to dampen out the flexing when red hot.
finally Jim, regarding the inner walls of the split manifold design, just trim away the thinnest parts, these are the most likely to burn up and fly thru the turbo and engine and destroy them. the main thickness parts can stay.
apologies for the long post, but ive told so many guys the same thing over the years, now its down on a thread itll save me repeating it each time.
You just post your lines to this thread and I will remove this 'me quoting you' post.