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Stock Exhaust Manifold? When To Change?

Badgaz

By Badgaz,
in Engines & Forced Induction

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

Of course, there is absolutely no expansion, and washers have 100% holding capability. Fark engineers are hard to deal with sometimes. :P

As Badgaz said, the holes are slotted for a reason.

Badgaz Experienced

Badgaz

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Posted

i noticed they don't slot them very nicely...just two round holes next to each other...so i die grinded the hump between the two holes as this was catching some of the thread when i was trying to put the manifold back on...pissed me off that did.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

If it did expand as you are saying scotty the nuts would work loose instantly.

Anyway, some things dont matter to making power!

I can guarantee you it does expand, nothing would stop it doing so. Having the washers there isolates some of the force on the nuts, keeping them in place most of the time. If you tried to use just the nuts you might have problems...

GTSBoy Grand Master

GTSBoy

Posted
Posted

I cannot see that the nuts would slide across the washers or that the washers would slide across the manifold flange. If they did then the torque on the nuts would have to be really low and there would be no tension in the studs and the conical washers would have no compression and everything would just fall apart. If there is real thermal expansion* along the length of the manifold (turning up as real dimensional change, not just as compressive stress) and this results in the manifold flange surface moving in relation to the head face, then the only way that it is being allowed to happen is through sideways deflection (cantilever loading) of the studs near the front and rear end of the manifold. Seeing as these are the ones that tend to break......

*I don't dispute that there is some dimensional change - it is hard to believe that there wouldn't be some. What I dispute is the idea that the fastener surfaces that are clamped together (nut, washer, flange) move relative to each other. Bendy studs I can believe.

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