This exhaust manifold and silencer was designed to optimize each performance criteria:

The Exhaust :

- The original gas recuperation system has been replaced with a 4 branch manifold.

- By taking into account the engine’s characteristics (bore, stroke, opening and closing of valves…) and the available place inside the engine compartment, an optimal theoretical length was calculated for each primary pipe. To insure the same optimal output for each cylinder, each pipe has the same volumic length, and neutral fiber.

- An identical length of primary pipes ensures an equivalent output for each cylinder. This in turn reduces fuel consumption, diminishes engine vibrations, by as much as 60%,, which leads to a higher level of comfort inside the cockpit.

- Cylinder head flanges are made from 316 L stainless steel. Primary pipes and collectors are made from inconel 625 sheets. With a high thermal resistance, this alloy insures an excellent reliability for the exhaust system.

The Silencer

1- In order to keep the aero dynamical envelope as « clean » as possible, the silencer is integrated inside the engine compartment, in regards of the environment and the spatial availability.

2- The silencer works by diffraction, with a chamber made out of a drilled sheet of metal. The absorption is done through padding around the relaxation chamber, made from layers of metal sheeting. The acoustic gain, approx. 15%, is mainly due to the loss of high frequencies, which significantly improves the acoustics’ onboard.

3- This exhaust system includes a cabin heater, which is as efficient as two original cabin heaters, thanks to a higher thermal exchange surface.

4- Finally the manifolds and silencer are attached to the engine itself. This prevents having problems with the engine movement compared to the cockpit, which can sometimes induce abnormal wear and even breakage of the linking tubes, in spite of their mobility. Our exhaust system was designed and made thinking in terms of complimentarity, in order to have a homogeneous operating envelope. This is crucial in obtaining good reliability.

1. Dismantle upper and lower engine cowling.
2. Keep the 4 cylinder head gaskets.
3. Install on the left side of the engine (as seen from the cabin) the support bracket with the supporting washer (11).
4. Install, on the right side of the engine (as seen from the cabin), the support bracket (10) w/o the supporting washer and taking in sandwich the gas control bracket.
5. Set up the cabin heating box (4) on left rear primary pipe n°3 (1) with the straight part d50 mm facing the firewall, and w/o tightening the M4 screw (29).
6. Pre assemble the carburetor heating box (14) onto the 4 branch manifold outlet pipe (5) w/o tightening the M4 screws, by positioning the bent pipe d50 mm towards the air box entrance.
7. Install the 4 primary pipes (1) onto the engine. Set up the braking washers between the cylinder head flanges and the aircraft tightening nuts (31).
8. Fit the 4 branch manifold (2) onto the primary pipes, by the matching numbers engraved on the mounting lugs (3) of the primary pipes. Put the M5 screws (24) and the Simmonds bolts (26).
9. Attach the first half of the silencer support clamps (8) onto the support bracket (10) using the M8 screw (21).
10. Fit the silencer (6) to the end of the 4 branch manifold outlet pipe (5) w/o tightening.
11. Install second half silencer support clamp, which has a lug (9) onto the left silencer support clamp (11). Use M6 screw (21) and the Nylstop nut (27) .
12. Install second half silencer support clamp, w/o lug (10) onto the right silencer support clamp (11). Use M6 screw (21) and the Nylstop nut (27)
13. Fit the silencer outlet support clamp (33) onto the silencer outlet (7).
14. Install the silencer outlet pipe clamp (33) onto the silencer support clamp with a lug (9). Use M5 screw (24) and Simmonds M5 nut (28).
15. Tighten all screws.
16. Check that all the fuel pipes or electrical cables are far away from the exhaust manifold. If not isolate with thermal protection every part that might be deteriorated or divert with a clamp.
17. Move the fuel filter 70 mm higher and 270 mm to the right of the plane. Adapt fuel tubing to this new configuration.
18. On certain aircraft types, the cabin heating inlet box can be in contact with the silencer. In that case, move the box 10 mm higher.
19. Bring in the lower engine cowling and cut out parts in contact with the silencer.
20. Cut out part of the engine cowling in contact with front right primary pipe. Assemble the cowling deflector (32) following the d11910 plan.
21. Install lower cowling.
22. Install upper cowling.

Download files Annexes            Report test         Structure