Ceramics?

So, a discussion I had the other day led me to look at some ceramics for a project of mine. Got me thinking, is there any reason something like an intake manifold, distributor housing, or maybe even an exhaust manifold couldn't be construction of ceramics?

Some of the stuff I was looking at had pretty high compression strength up to 1900*F prior to any heat treating (2700*F with) which puts its solid performance higher than AL and around stainless steel performance. I mean, something like an intake manifold doesn't really see any stress other than thermal in the tensile direction, and even then most ceramics have the ability to withstand 4000-6000 psi in tensile stress before any reinforcement such as fiberglass is introduced.

With low relative thermal conductivity compared to AL and SS, it would seem that it would keep an intake charge cooler.

Now, I'm not sure about costing issues (actually looking into it out of curiosity), so maybe that's a bigger factor than I'm accounting for. Both are easily castable and many ceramics can be machined in final form.

With the intake and dizzy, you're probably safest. There was a string a while ago I believe somone was discussing using high temp plastics for intake, and unless you're boosting it should be safe. The vibration and tortioning on the exhaust would be too much for ceramics I would think. Perhaps if there was a lower mount point from the exhaust to the block, the tortioning should be minimized, with a flex section between the manifold and the pipe.

About the same cost for a mold for casting ceramic intakes would pay for a mold to make plastic intakes. Just about all of the modern EFI engines have plastic intakes. Ceramics do have good compressive strength, also need is good tensile stregth and a certain amount of flexibility for torsional loads. There are still some other good applications for cermics in engine. Find a way for piston to cylinder seal and it would be fantastic for cylinder liners.

Finally got some cost data. materials are significantly more. Machinable ceramics are about 20 times more than comparable sized AL stock. I may look at the machinability of castable ceramics. They have a slightly lower heat resistance, but still good to above 1100*F. The casting process may make it more feasible, since casting AL will not be allowed by my wife, despite the homemade forge plans I have.

CobraSix":2ymv22dv said:

The casting process may make it more feasible, since casting AL will not be allowed by my wife, despite the homemade forge plans I have.

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Too bad, I myself have a bum alloy rim we're planning on melting down in a forge once we settle on a plan and build it. Word is working with molten AL is unhealthier than cast iron, on an outgas level. We'll worry about that after the forge is complete.

Well, my mistake was telling her about it prior to just doing it. I mean, my forge was going to be behind my garage, which is detached about like 50 feet from my house.

I thought about moulding my own intake manifolds with two 32/36 progressives split between 1-2-3 and 4-5-6 on the CI head, but I think on a prototype level, I'm going to have to fab the pieces up with stock and weld them. Then I can decide if I want to have them machined from solid stock by my shop or have mounlds made and have them finish the product. *If* it looks like there's any money in it that is...

For casting alum, would the 'lost wax' process work?

Lost wax should work fine, though the inside diameter might be an issue. I haven't taken any casting classes yet (so i don't know for sure), but there's a good arts school in Berkeley that teaches several. I took beginning blacksmithing there and it was a good course.

Ford 460 engines, including the one in my pickup, but especially those installed in poor airflow engine compartments in RVs, are notorious for having the exhaust manifold expand and break the boss in the head that holds the forward mounting stud for the manifold. Now this is an iron head and an iron manifold, so the expansion rates are sort of similar even though the head is cooled. Now, I wonder (and I sure don't know) if you'd have a lot more problems with different rates of thermal expansion/contraction if you try a ceramic exhaust mainfold (which would hardly expand at all, right??) on an iron head, or worse, an aluminum head.

(FWIW, if anybody has a 460 with an exhaust chirping on startup, listen around the forward exhaust ports with your stethescope or piece of hose. If you find the noise, pull the manifold and you'll likely see the stud broken loose in the head. After you get a head repair shop or other welder to cast-iron weld your head, and after you re-drill and tap the hole for the stud, the fix for this problem is to drill out all of the holes in the mounting flange of the manifold . . . except for the center holes; they will do the side-to-side locating of the manifold. Drill the holes nearer the center maybe 1/64" over what the factory did, and the outer holes 1/32" oversize, giving the manifold more room to "grow" without breaking anything.)

Depends on what you are calling "ceramic". Any type of traditional straight clay product from an art supplier will not survive the vibration and if exposed to exhaust, most likely won't survive the initial thermal expansion rate much less repeating it thousands of times. I have a flame ware receipe here that'll take the heat and not crack but it can't be confined, bolted down or restricted in any way. Casting ceramics is easy, given you have made a proper mold, however; it has a large percentage of shrinkage and warping depending on material used (10-12%.) Of course you could hand build it from clay slabs but the above applies even more so and then you need to let is dry VERY slowly...and it'll still warp and break when hot or loaded in any fashion.... "Ceramics" also hold heat once hot and for a good while too.

I've done a fair bit of aluminum casting too and as long as you are in a well ventilated area you don't have anything to worry about health-wise. You will have shrinkage problems as above. Welding up a manifold is far less complicated on a science and production level.

"Ceramics" is a very broad term for a LOT of completely different materials with substantially different characteristics. Most everything that will survive you can't afford. Believe me when i tell you; you can't make motor parts out of mud....trust me....

Ceramic is common in cars today. Most of our fire pumps are a carbon infused ceramic seals. Some of the newer turbo parts are ceramic. But like most have said ceramic is fragile. Yes you can add glass or carbon ect. But to make it anti fragile it would be self defeating as the weight alone would be prohibitive.
This is why al, SS, and CI are far more common.
Though I think a set of glass ceramic headers would be freaking awesome as over time the heat and exhaust gases would impregnate the material. Creating nothing let than artwork. They are far to sensitive to shocks, “think potholes, accidents”

Also when forging anything. Go buy a good face mask. 3m sells a half face with filters that indicates replacement for less than 80$ usd. As someone who works in the fire service. Heat + man made materials = greater risks of cancers or other issues.