Much debated - Exhaust manifold studs and nuts

Hi all Yes I know a subject done to death and I know that Ti studs are the ultimate answer. And that stainless steel studs have they're own potential issues with the ali heads. But what I've not seen discussed is the used of brass nuts on stainless or Ti studs to lessen the issue of removing the nuts from the stud of your choice? Thoughts?

Mainly after some research on here I took the view that SS bolts would be OK provided you keep an eye on them. I applied high temp alu anti seize and intend to check them, and re-apply alu anti seize, every few years. My car is not a daily but I cover about 8K per year in all weathers but more in the summer. I already had the TI studs but went the SS bolts and sold the studs.

Thanks for the response. Mine were drilled/replaced before I bought the car but with plain steel bolts. Anything threaded into aluminium is a weak spot, so I'm going to replace with SS studs fitted with aluminium grease. I'm just surprised I haven't see people using brass nuts as a further method to ease removal.

I wnt down thr Ti route when I did mine. I bought off Ebay. https://www.ebay.co.uk/itm/203697578476 Ti will not corrode in Aluminium and in anycase by going the Ti stud route you're going to be indoing a Ti nut on A Ti stud so won't be an issue. The studs above have a multi buy discount so were approx £70 all in. After the hassle of drilling out the snapped studs £70 odd wasn't a big deal. I acknowledge that SS studs and nuts would be just as good.

I did mine a few years ago on my old c4. Thread is somewhere on here! I used mild steel studs with copper nuts. I've done countless motorcycles over the years all with Ali blocks/heads and this is the tried and tested method and has been used for years for various vehicles. Only my opinion but different metals can cause galvanic corrosion and various other issue plus drilling a ti stud out will be even less displeasurable than drilling the steel bolts out!

I was told off a mate of mine in the aerospace industry never to use Titanium with Aluminium as they're at the opposite end of the galvanic scale and fuse together - it's a big no no in his industry. I had quite a discussion on here about it a few years ago. Titanium has excellent knitting properties into other materials too. I should know, it's holding my front teeth in to my skull. I replaced my rotted steel bolts with Stainless Steel ones 8 years ago and even now they just wind in and out no problem. Edit: Post here: http://911uk.com/viewtopic.php?t=147385

Re titanium: galvanic risk also varies a lot depending on the alloy. I am no metallurgist but I would guess that aluminium used in planes (eg 6061 grade) is different to engine blocks.

I recently drilled our the bolts and replaced with studs and nuts. I used steel studs and copper flashed nuts (ebay). The reason i did this was that should you need to remove the manifold again the nuts will wind off. Should the worst happen you can still drill the mild steel studs out while the engine is in situ. You cannot drill titanium (easily). The cost o fmy solution was peanuts. The next time i do this, maybe on my 997, I will use brass nuts simply because i have restored a number of classic cars and always used brass nuts. I can also say that drilling out the broken siezed bolts on a 996/7 is a lot easier with the engine out!!!!

I'm half way through drilling mine out at the moment but still undecided on what to replace them with. Started with the OS, 5 snapped heads and one that had to be drilled off as there was nothing left to grip. Pretty crappy job but a decent guide to centre the pilot hole makes life a bit easier. This was a test fit on the eBay stainless manifolds and the quality is very good. [img]https://thumbsnap.com/s/c8NLiexg.jpg[/img]|https://thumbsnap.com/c8NLiexg

I'll be doing this on my C4 cab soon. Not looking forward to it. MC

Stainless is better than titanium as far as galvanic corrosion goes but not a huge amount. Neither are ideal though so I'd just go Ti for its other advantages. A compound such as Tef-gel should be used. The idea is to use studs and nuts though, not bolts. If you use Ti studs you should never have to remove them again, so no issues. :thumb: Edited to add - OP. You are correct in that you must use copper nuts on the Ti studs. Then if they ever seize and strip during removal, the stud being far tougher than the nut means the nut will strip, not the stud. You then just clean the threads up on the stud and fit a new copper nut. Using bolts is asking for bother, especially stainless ones, as you're still going to get galvanic corrosion plus you're wearing the threads in your heads every time you remove them. :hand: I've just fitted these to my GT3 as Poppopbangbang doesn't make his anymore. These took ages to arrive though. https://www.stringtheorygarage.com/...haust-manifold-stud-kit-911-996-turbo-gt3-gt2

I forgot to add that you will need to buy the STORMSKI jig. And an extra long drill bit to be able to get at the bolt under the engine number casting plinth. Expensive but nescessary.

I used A4 stainless bolts with aluminium antiseize. Seems to work fine to me.

...and a fraction of the cost.

...stainless bolts in mine and like Alex said they are very easy to remove :thumbs: