Orientation of head to exhaust manifold gaskets
 

Just purchased 2 exhaust manifold to head gaskets to install new headers.

These are p/n A0411A04A and superced 44616AA290.

The issue is that unlike the old gaskets these new ones have a 1mm raised lip on the two ports of each gasket and they’re only on ONE side of the gasket.

Wondering if anyone knows which way the gaskets are meant to be orientated.

Does it actually matter? Would seem to if they’ve gone to the effort..

It would seem to me that the gasket should be placed such that the exhaust gasses would flow over the lip on the gasket. From your second picture, the top side of the gasket (in the picture) would be up against the head.


Best get another opinion, ol humfrz is heavy on the pain meds … :sigh:

Thanks for the reply.

My thinking as well but would be nice to have it confirmed by someone who’s actually used them. It’s a job that’s not hard to do but one you want to do only when absolutely necessary and then correctly.

A simple ‘place this way up’, stamped on them would have made things easy.

Ya, I hear ya.

I'll ring up ol @ermax for some insight, since he has had his engine apart - :thumbsup:


humfrz

Think I’ve found the answer, and got it from a motorcyle forum of all places.

Basically; “Bevel to engine is best. Header flange crushes into flat side of gasket, while beveled/raised ports of gasket flattens against machined surface of head exhaust outlet.”

Pretty much as I expected.

Having said that the gasket apparently works either way just not as efficiently or reliably..

Feel free to get confirmation though..

I've heard it doesn't matter but I'd be reluctant to squish that ring against aluminum.

My thoughts exactly. I've had 4 sets of the gaskets on my car and none of them looked like that. There are other gaskets like that in the rest of the exhaust and they aren't directional but they also aren't between aluminium and steel. If I was going to pick a direction I would go with the smooth side against the fragile aluminium surface.

Raised bevels are very soft, due to thickness, stainless steel. These are a replacement for the older gaskets for whatever reason. Probably for standardisation across the platform.

Pretty sure these are and were used on the WRX before being OK'd for the FT86 so given they use a similar if not same head and manufacture process you'd expect them to be suitable for either.

My headers come with a recessed edge that may not fully compress the gaskets bevel when torqued up.. I'll assess when i have all the parts off and can trial either way.

Sorry for digging this up. I have the same question about these gaskets. Did you figure out which orientation was the correct one?

As humfrz says, top of the gaskets per second photo against exhaust heads!