Re: Volvo AQ 171c Exhaust manifold
They are very rare. The AQ171 is not common in the states and it carries a different manifold bolt pattern than the 8-valve heads.
I've searched for these engines in the past as they are much sought after in the RWD Volvo enthusiast community. I race Volvos and have a completely built 400+hp 16v engine. When I searched for AQ171 engines I found they were too rare and not worth my time to source their parts as I could have custom parts made faster for a similar price.
There used to be a place I know you can get AQ171 manifolds from but I've since searched for it and can't find it. They were $1000+ dollars for a new one. They are no longer available from Volvo.
I don't know how bad yours is but the scarcity of the part makes other options like trying to refurbish the one you have worth exploring.
Also as a last resort you could consider this adapter I came up with. I made an adapter to use a Volvo 8-valve turbo manifold on a 16v cylinder head. It worked very well and a guy I know is now making them from steel. If you were to bolt one of these adapters us racers came up with to your AQ171, you could then use any 8-valve Volvo marine exhaust manifold on it. If you did that you may have to get a different riser and pipe setup but that could work and be done rather cheaply.
The last option and it's not cheap, is that there's a company in Australia making direct replacement AQ171 manifolds from stainless steel. They would increase power and have a 5-year warranty. That's the ONLY new source for one of these manifolds I know of.
Volvo Penta AQ171 AQ251A 855434 Exhaust Manifold 5 YR Warranty Stainless | eBay
They also show up from time to time on Ebay used for $500 or more.
Feel free to PM me with any questions.
