I have a 2011 Ram 1500 in NW Iowa (rust belt) and no issues with broken exhaust bolts.
My son's 06 Jeep Commander 5.7 did break some exhaust bolts, but we got them fixed a couple of years ago and no problem since
My other son has an 06 Chrysler 300C with no broken bolts or issues

JS

I have seen the issue more with 2013 and later 5.7's, so I am under the impression it was a change in materials...

Mmm, not really. There are many grades of stainless that can be hardened, example: most or all the trim pieces in your car.

I don't know as though the solution is just because there is a washer there, I think it helps if the bolt is longer... think about bending a coathanger back and forth to break it, if you grab a long section and bend it back and forth a given amount like say 1 foot and bend it back and forth 1 inch it will take forever to break it, now if you grab it 1 inch apart and bend it back and forth about 1 inch it will break pretty quickly, that is what is happening on these hemis, they are short bolts being bent back and forth a certain amount that is much more than an iron manifold on an iron head would be bent, that iron manifold, iron head and long bolts because of the spacers is not really taxing the bolts enough to break them, they are not experiencing as much stress and not on such a short distance. I think a longer bolt and a spacer would reduce the stress and save the bolt even if it was the same material.

My 2006 5.7 never broke any bolts. The manifolds did warp though.

I would think that unless the washers were the cone shaped kind or made to absorb the expansion of the different metals the bolts would be just as likely to break but have a longer area to break in.

They just give a longer bolt that can take the bending stress better, those washers cone type or not don't slide around or anything, if they did they would wear out and loosen up.

Sorry, I should have used more words and written more clearly in that sentence.

It should have read:

Not having the end manifold bolt fasteners thread into bolt holes in the aluminum cylinder head at 90 degree square would be an improvement.

If the end of exhaust manifold bolt holes
and their mating threaded holes in the aluminum metal of the cylinder head
were drilled and tapped at some degree of angle outward,
and the hole in the manifold made oval shaped
(or simply bigger diameter)
the thermal expansion of the exhaust manifold would not result so quickly in
the cast iron of the manifold eventually contacting the bolt threads in a “shearing” type collision
similar to how sheets of metal are ripped in two by metal shop “Shearing Machines”.

“Avoid exceeding maximum allowable shear stress levels to avoid metal failure”

is the modern advice from
3 dimensional principal stress fracture mechanics.

100 years ago engineers thought you could
pull on a bolt too much (tensile stress)
or
push on a bolt too much (compressive stress)

Today it is realized that either
“pure tensile stress“
or
“pure compressive stress”
inherently also creates SHEAR STRESSES inside materials
and importantly these internally created shear stresses
are inclined at various angles
that look “cone shaped” in 3 dimensional view.

When one of these “cones of shear stress distribution”
reaches a certain level
cracks begin growing in size
and the material eventually splits in two.

Too high a “principal” shear stress in one small region
is the “true” enemy.

Three dimensional matrix principal stress analysis
....is the scientific “slang” for this

Works for rocks as well as metals

This is what I have been tryna right here.

Pretty sure it's just the cheapest crap fasteners they could find. Been working with alloy heads and iron manifolds for close to 40 years now and most of the Honda and Toyota cars don't do it

Gus

On the new dt body style ram, 19+ they added tie bars for the manifold bolts, now the manifolds are all cracking. I've replaced a ton of them, both sides

Yup. I never could sell a stock manifold till recently, now they are going like hotcakes, down to my last pair of eagle truck manifolds.

I don't recall the Neon's 2.0 or the K car 2.2 busting off studs, iron manifold, alloy heads

I have a theory that it is low octane fuel , high loading like towing , steep grades or heavy throttle , causes the timing to retard and you get real hot exhaust manifolds. I would run midgrade or higher quality fuel and this problen could be mitigated .

What he said!

If you’ve ever had the manifold off of a Nissan V8 it’s very similar to a Hemi head. Difference being they used a larger fastener in the head. Those manifolds have been cracking for years…..and the cat is integral to it $$$.

as WV said, now the Hemi manifolds are cracking. Easier than extracting broken bolts.

I’ve actually used a step drill bit and widen the end holes on the manifold side hoping that maybe it’ll prevent “shear” and perhaps the bolt will have room to bend some. I’ve also been putting a bead of copper RTV on both sides of the gasket on those end ports. I’ve seen where bolts can be broken, but no leak using that method.

I hear about chronic lifter failures on the Gen III Hemi. And now exhaust manifolds. Does Chrysler have any engineers left in Engineering?

The cone washers do something or they'd never have bothered using them in the past. It's not a bending stress it's more a sort of tensile stress on the bolts from the manifold heating up.

Either way something isn't right with the design. I forget what make or engine it is but for one make their solution was putting in bigger softer bolts because while they were easier to break they were more forgiving to the pressures going on in the application they were being used for.

Install headers instead?

In the early smog years the higher exhaust temps were causing bolts/studs to break. Our fix was to remove them all install new studs (with very light touch of anti sieze into the heads and then the cupped washers and bronze nuts. Check torque after a few heat cyclings and generally the carboning up and re-torque would seal them and the studs would not break.

You are talking about a completely different type of failure here and your reasoning does not apply to this subject, sorry.