Hi Bernie,

 

I am not aware of any chronicle of “Plugs Up”.  There are a few words at this URL about that type of installation and why it was done.

 

http://www.flyrotary.com/whypu.htm

 

There is also my website hosted on this URL

 

http://www.dmack.net/mazda/index.html

 

which you may find some useful information.

 

As you surmised, the principal reason I had for doing plugs up at the time, was it lowered all the high profile items such as alternator, mechanical distributor (really tall), oil filter, water pump inlet, etc below the stock cowl line of my Rv-6A. 

 

Here is what I have found to be the benefits.

 

1. No need to machine or remove any high profile items – may not matter depending on your aircraft type
2. Simplified exhaust in that it went straight down from the block and made one 90 deg turn to the rear
3. Gave lots more room on the side for induction system rather that bring it across the top of the engine were there is not much room.
4. Essentially eliminated the problem of  flooding of the engine as the excess fuel simply drops out the bottom exhaust port and because the plugs are vertical (on top), no fuel can accumulate in the spark plug ports which is what really necessitates removing the plugs in many cases of flooding with the regular on the side plug position.
5. Prevents my fuel system (rails, injectors, etc) from being above (gravity wise) the hot exhaust manifold – so any fuel leakage is more likely to blow out the rear of the cowl than drop on a very hot exhaust manifold
6. Made making a motor mount fairly easy in that the large air condition compressor bracket holes in the front iron housing provides a strong mount, you will then need to also brace the front (flywheel end) against flexing.

 

Here are what I see as the disadvantages

1. All the vendor items are designed for the normal automobile orientation.  For many things it doesn’t matter, but for instance, you can’t use the same motor mount design as the normal orientation.  So vendor produced products such as intakes and exhaust system will likely not work.
2. You do have to make a special oil sump to keep the oil level in the block from blocking the flow back channel in the center housing
3. Folks think you are weird {:>).

 

Despite having “plugs up” and it working fine, I am not an unreasoning advocate of it – mainly because just about all vendors are building their products for the normal orientation and there is the task of making your oil sump as well.   But, there is no technical reason (despite what some may claim) not to run the rotary “Plugs Up” – just may be some practical reasons not to.    So you have to assess its benefits versus disadvantage in your particular situation.

 

Ed

 

 

Ed, I am certainly interested in anything you have that concerns the "Plugs Up" design. I only signed on with your bunch the other day, and the  "Plugs Up" idea has already made it extremely worthwhile for me to join you.

Do you have an archive of all the  "Plugs Up" messages/photos? That would be very valuable, kind of like a  "Plugs Up" training manual. I have not seen this idea elsewhere, but it makes so much sense and solves all kinds of problems. Besides taking care of the space problems, it's ideal for routing the exhaust down and out, and getting the intake and fuel stuff away from the exhaust area. Thank you, Bernie.