My Kis Cruiser - Custom 4 into 1 Exhaust

N247BR

Firewall Forward - Custom Exhaust Fabrication

After looking for an off the shelf exhaust system that would fit my requirements and not finding a good match I decided to give Aircraft Exhaust Inc. a call about their design your own Custom Exhaust System.

The process starts with obtaining a collector based on your requirements and the exhaust port connectors from the custom exhaust manufacturer. You supply the necessary PVC pipe and joints to custom design a system to your exact requirements. The following show the completed mockup to be sent for fabrication.

While I was working on the fabrication of the system a couple of other pilots who have planes on the field where I have my hangar stopped by to see what I was doing. One of them was familiar with the process and started discussing it with me. The other had absolutely no idea of what I was doing...only that I was building my exhaust out of plastic. Finally after about 10-15 minutes he couldn't take it any longer and asked "Aren't you afraid that your exhaust will melt?". I thought his friend was going to laugh himself sick. We finally explained that this was just a mockup and it would be used to build a stainless steel version.

A trip to Home Depot resulted in a good supply of 90, 60, 45, and 22.5 Degree PVC connectors and several 2 foot lengths of PVC pipe. Get more than you will need, you can always take some back. Start by mounting the collector where you want it to be positioned when complete. It must be placed and held firmly in position while working on the assembly. The process will take lots of fitting and refitting.

The above is the completed mockup before gluing all the componets together. The length of the individual exhaust pipes are all within 1 inch of each other.

The number 4 pipe takes several turns that don't appear to be needed but are there to equalize the length. I had to assemble, disassemble, and rework several times to
equalize the lengths. Time consuming and frustrating.

Once all the pieces were cut to the proper length and dry fit into the collector they had to be marked to identify how they went to gether and which pipe was which. The entire system would then have to be disassembled yet again. Each piple would then be reassembled using PVC Cement and screws to lock all the pieces into their proper position for shipment. Once everything was glued into place it was fully assembled again to make sure everything fit as designed.

The heat muff for cabin heat will go where shown. If needed, carb heat could be place on the other side.

The underside of the fuselage along the Center will have a
stainless steel panel with fiberfax backing installed. The fuselage panel will protect the fuselage from any exhaust heat.

Care must be taken to ensure clearance between exhaust
components and anything that might damage them. Or any components which might be damaged by the hot exhaust pipes.

The above show the routing of the system between the engine and the underside of the plane.

The view from the side shows how closely the cowling fits and how far back the full system will go. Some adjustments will be needed to the cowling to provide more space from the exhaust pipes.

The completed mockup is glued together and ready to be
disassembled at the collector for shipment. When removed from the engine, the mockup retains its shape exactly as formed.

I was concerned having a large portion of the HOT exhaust
system under the fuselage and what effect that head might
have on the Fiberglass structure. My solution was to fabricate a protective belly pan from the same stainless steel material used for the firewall. I also lined it with the fiberfax used on the firewall. The tape just holds it in place.

The installed belly pan is shown in place on the underside of
the fuselage. It extends back beyond the tail pipe extensioin and far enough that I could include a short muffler beyond the 4-into-1 collector. This should provide complete protection for the underside of the fuselage. The pan is currently being held in place with pop rivits. I will probably add some glass and filler to dress up the edges and provide additional holding power.

These photos show the mockup on the fabrication table as they began construction of the system. The remainder of the photos show the trial fitting of the complete system. It really looks good and fits exactly as designed.

One big issue I encountered with the exhaust system was how to lock the four-into-one section on to the four individual exhaust pipes. The section slides onto the four pipes but didn't seem to go all the way on and nothing I could do would slide it on farther. Each pipe goes in about an inch but I thought it could go on farther.

Another problem was how to support the weight of the pipes and still allow movement with the engine. My final solution to both problems was a rather odd bracket and strap system that connects to the fuselage at two points with thick rubber straps to a bracket attached to the rear of the pipe. The idea is to both support the pipe and keep it from sliding backwards.

Note: Some of the dates (2007 and 1/1/2009) are wrong, the camera kept resetting the dates.

After looking for an off the shelf exhaust system that would fit my requirements and not finding a good match I decided to give Aircraft Exhaust Inc. a call about their design your own Custom Exhaust System. The process starts with obtaining a collector based on your requirements and the exhaust port connectors from the custom exhaust manufacturer. You supply the necessary PVC pipe and joints to custom design a system to your exact requirements. The following show the completed mockup to be sent for fabrication. While I was working on the fabrication of the system a couple of other pilots who have planes on the field where I have my hangar stopped by to see what I was doing. One of them was familiar with the process and started discussing it with me. The other had absolutely no idea of what I was doing...only that I was building my exhaust out of plastic. Finally after about 10-15 minutes he couldn't take it any longer and asked "Aren't you afraid that your exhaust will melt?". I thought his friend was going to laugh himself sick. We finally explained that this was just a mockup and it would be used to build a stainless steel version.


A trip to Home Depot resulted in a good supply of 90, 60, 45, and 22.5 Degree PVC connectors and several 2 foot lengths of PVC pipe. Get more than you will need, you can always take some back.	Start by mounting the collector where you want it to be positioned when complete. It must be placed and held firmly in position while working on the assembly. The process will take lots of fitting and refitting.


The above is the completed mockup before gluing all the componets together.	The length of the individual exhaust pipes are all within 1 inch of each other.

The number 4 pipe takes several turns that don't appear to be needed but are there to equalize the length.	I had to assemble, disassemble, and rework several times to equalize the lengths. Time consuming and frustrating.

Once all the pieces were cut to the proper length and dry fit into the collector they had to be marked to identify how they went to gether and which pipe was which. The entire system would then have to be disassembled yet again. Each piple would then be reassembled using PVC Cement and screws to lock all the pieces into their proper position for shipment. Once everything was glued into place it was fully assembled again to make sure everything fit as designed.

The heat muff for cabin heat will go where shown.	If needed, carb heat could be place on the other side.



The underside of the fuselage along the Center will have a stainless steel panel with fiberfax backing installed.	The fuselage panel will protect the fuselage from any exhaust heat.

Care must be taken to ensure clearance between exhaust components and anything that might damage them.	Or any components which might be damaged by the hot exhaust pipes.


The above show the routing of the system between the engine and the underside of the plane.

The view from the side shows how closely the cowling fits and how far back the full system will go.	Some adjustments will be needed to the cowling to provide more space from the exhaust pipes.

The completed mockup is glued together and ready to be disassembled at the collector for shipment.	When removed from the engine, the mockup retains its shape exactly as formed.

I was concerned having a large portion of the HOT exhaust system under the fuselage and what effect that head might have on the Fiberglass structure.	My solution was to fabricate a protective belly pan from the same stainless steel material used for the firewall. I also lined it with the fiberfax used on the firewall. The tape just holds it in place.
	The installed belly pan is shown in place on the underside of the fuselage. It extends back beyond the tail pipe extensioin and far enough that I could include a short muffler beyond the 4-into-1 collector. This should provide complete protection for the underside of the fuselage. The pan is currently being held in place with pop rivits. I will probably add some glass and filler to dress up the edges and provide additional holding power.

These photos show the mockup on the fabrication table as they began construction of the system. The remainder of the photos show the trial fitting of the complete system. It really looks good and fits exactly as designed.

	One big issue I encountered with the exhaust system was how to lock the four-into-one section on to the four individual exhaust pipes. The section slides onto the four pipes but didn't seem to go all the way on and nothing I could do would slide it on farther. Each pipe goes in about an inch but I thought it could go on farther. Another problem was how to support the weight of the pipes and still allow movement with the engine. My final solution to both problems was a rather odd bracket and strap system that connects to the fuselage at two points with thick rubber straps to a bracket attached to the rear of the pipe. The idea is to both support the pipe and keep it from sliding backwards.