The middle cylinders must have two into one exhaust port of some kind.

Interesting picture that I never noticed.

http://forums.pelicanparts.com/uploa...1321670050.jpg

The center two share the same exhaust port. A little reversion does get into the 2nd port in the firing order. Some guys make a flipper that goes into the port but it does kill power. Full tilt drag flat heads get a 4th port added but it doesn't work for street cars. I would say due to heat.

Strange flat head tech. Both banks coolant are stand alone in the blocks and heads. they have their own water pumps. they do share the same radiator and coolant but there isn't a passage from side to side of the block

<iframe width="420" height="315" src="http://www.youtube.com/embed/o_QyUD6V5_I" frameborder="0" allowfullscreen></iframe>

Pratt & Whitney R-4360

The largest, most complicated piston engine mass produced in the US. 28 cylinders, 71.5L (4,360CI), air cooled, 3,000hp at 2,700rpm.

http://farm7.staticflickr.com/6220/6...73e6b3ee_z.jpg
Pratt &amp; Whitney R-4360 by cjcam, on Flickr

http://farm7.staticflickr.com/6035/6...e80b6509_z.jpg
Porsche 962 engine by cjcam, on Flickr

http://farm7.staticflickr.com/6110/6...24c290bb_z.jpg
4-cylinder &quot;911&quot; engine by cjcam, on Flickr

Lycoming? Continental?