[DylanBerg]

I just finished my final project in SolidWorks were I designed a half cylinder valve. I previously started this thread on the topic.

http://www.e90post.com/forums/showth...f+cylinder+cam

Theoreticaly a half cylinder valve will increase airflow and improve engine efficiency. I also made the valve stem elliptical to prevent rotation like someone suggested.

Here are some pictures of my project:

The FEA stress analysis shows deformation under pressure.

[michaelthepsycho]

Hmmm... I had this idea too. Never knew why they didn't make it this way.

[DylanBerg]

I think they don't do it because the valve deforms and it does causes irregular airflow. But it would be interesting if there was a prototype

[Efthreeoh]

The production costs for such a design would be enormus.

[michaelthepsycho]

Originally Posted by dillbob3124

I think they don't do it because the valve deforms and it does causes irregular airflow. But it would be interesting if there was a prototype

Is it because it would be structurally weaker at the "wings?" What about a different type of stem that supports the load more evenly?

Originally Posted by Efthreeoh

The production costs for such a design would be enormus.

I think it's the logistics of getting a whole industry to adopt it that would be costly. Production is just production; they can always find a way to make it cheap. It would be just the heads and valve-train that are different, wouldn't it?

[DylanBerg]

I believe the 'wings' of the valve causes the unnatural airflow into the chamber. The wings would also make it so there would be less strength to the valve. I tried a new design for the valve, the change is how the stem curves into the base. I would run flow dynamics on the different type of valves, to see the airflow across each, but my computer is to slow. I'm sure some engineer could figure out a way to make the design work though.

[Silver-Bolt]

The points of the "wings" would never withstand the heat from combustion. From a manufacturing standpoint the cost to produce the vavle and seat would be astronomical. Getting the od shape to seat and seal would be a serious challenge. Air & fuel flow would be irregular at best. Keep thinking outside the box but there are serious flaws still.

[Robin_NL]

Very interesting and kudos to the OP for the idea/pictures/info.

Originally Posted by Silver-Bolt

The points of the "wings" would never withstand the heat from combustion. From a manufacturing standpoint the cost to produce the vavle and seat would be astronomical. Getting the od shape to seat and seal would be a serious challenge. Air & fuel flow would be irregular at best. Keep thinking outside the box but there are serious flaws still.

This and the air and fuel flow as well....

[Efthreeoh]

Originally Posted by michaelthepsycho

I think it's the logistics of getting a whole industry to adopt it that would be costly. Production is just production; they can always find a way to make it cheap. It would be just the heads and valve-train that are different, wouldn't it?

Valves for high rate production engines are usually forged to ensure longevity (durability) of the part at the lowest production cost. Forging makes a rough part shape that needs to be then precisely shaped, straightened, and machined. It is far less expensive to shape symmetric parts (i.e. square or round) than non-symmetric parts such as oval-shaped valve stems, and half-round valve heads. To make that valve, you are adding a 3rd dimension (axis) to the straightening and machining tolerances. The oval-shaped valve stem needs to be precisely aligned with the half-round shape valve head. This is not to mention the additional machining tolerance needed for the head; a precisely cut oval valve stem hole align on axis with the half round valve seat. Then you have to consider the stem seals, keeper mechanisms, and other ancillary parts affected by the non-symmetrical design.

Even if the industry were to adopt this design and develop rapid production machine tools to make the valves, because of the machining and tolerance requirements it will take probably twice as much time to produce the valve, which design probably does not provide that much more engine efficiency.

[DylanBerg]

Originally Posted by Efthreeoh

To make that valve, you are adding a 3rd dimension (axis) to the straightening and machining tolerances

Are you a mechanical engineer because you are very knowledgeable with the geometric tolerances and machining process?

[Efthreeoh]

Originally Posted by dillbob3124

Are you a mechanical engineer because you are very knowledgeable with the geometric tolerances and machining process?

No. My background is in manufacturing.