[DylanBerg]

Hey I am doing a project for school and was wondering if any cars have ever had a Single over head cam where the intake cam takes up half the cylinder and where the exhaust cam takes up the other half of the cylinder. So it would be like a half moon for a cam.
I was also wondering would there be any benifits to this configuration compared to a DOHC.

[RobertRO]

I am not sure I understand correctly what you mean.
I guess you're asking about a SOHC which actuates 4 valves / cylinder, out of two cams per cylinder - one actuating both intake valves and the other both exhaust valves.
For example, something like this:
http://upload.wikimedia.org/wikipedi..._Cylinders.JPG
but with one single intake cam replacing a cluster of two cams.
Or you meant something else?

Later edit:
Many years ago I visited the Deutches Museum in Munchen, Germany. I remember that I was bemused by the Daimler Benz DB 601/605 engine, which was used on some German WWII aircrafts. It had an odd valvetrain setup, with a single camshaft actuating 2 intake and 2 exhaust vales per cylinder, out of just 2 cams. I guess this engine may be closer to what you're looking for.
Here are some links:
www.aviation-history.com/engines/db605.htm
upload.wikimedia.org/wikipedia/commons/6/6c/Daimler_DB_605_cutaway.jpg
Maybe you can find somewhere else on the Web larger pictures of this engine.

[DylanBerg]

If the first picture were the large single over head cam covering the entire surface of the valve and the other drawing were a DOHC.

[RobertRO]

First, I don't think that you'll find a production car that used an engine with the valve setup you indicated in the first picture (two "half-moons" covering almost the entire surface of the cylinder head).

Hey I am doing a project for school [...] Single over head cam where the intake cam takes up half the cylinder and where the exhaust cam takes up the other half of the cylinder. So it would be like a half moon for a cam.

Second, I think there may be an issue with the terms you're using.
Based on the pictures you posted, I conclude that you meant 2 valves, and not 2 cams. In other words, your subject is not the device actuating the valves (which is a camshaft with the cams cut on it, and rockers / fingers where applicable), but the devices which open and close the intake and exhaust to/from the cylinders, which are the valves.

There's a lot of literature on-line on the subject of valves, including why 4 smaller valves are usually better than 2 large ones.

Keep in mind that during the 100+ years of internal combustion engine, more or less everything has been tried and tested. For example, there were attempts to use concentric valves, such as this one: http://ip.com/patent/US2988071

[DylanBerg]

Yeah my terminology is definitely wrong but if anyone else wants to elaborate on the concept it would be much appreciated.

[MisterSkiMask]

the problem with valves that are not round would be proper seating, adequate strength, and additional weight.

I would also suspect strange/irregular flow characteristics, and hot spots leading to uncontrolled detonation.

[Silver-Bolt]

Originally Posted by MisterSkiMask

the problem with valves that are not round would be proper seating, adequate strength, and additional weight.

I would also suspect strange/irregular flow characteristics, and hot spots leading to uncontrolled detonation.

I addition to these issue heat would focus on the points and cause detonation and likely burn the valves.

[DavidJS]

Valves tend to rotate, which would not be good for that design.

[Silver-Bolt]

Go for a 2-Stroke design with no valves.

[DylanBerg]

Thanks for the help guys. The project is we have to take an existing item and improve it and then create the design in solidworks. I'll probably still do a huge valve I just hope my teacher doesn't know its not an improvement.

[Silver-Bolt]

Originally Posted by dillbob3124

Thanks for the help guys. The project is we have to take an existing item and improve it and then create the design in solidworks. I'll probably still do a huge valve I just hope my teacher doesn't know its not an improvement.

The theory may indeed be an improvement. However as stated above there are several flaws to the design. If the valve stem was not round the roation problem can be solved. You also need to factor for the intake to exhaust ratio. There is a reason intake and exhaust valves are not the same size.