1-Output Improvement

This exhaust was designed in order to increase the engine output:

Photo Primary pipe, 4 branch manifold

Every cylinder outlet tube - primary tube - is 880 mm long. This is the optimal length considering the data from the manufacturer (length, bore, valve opening, etc.), and the available space inside the engine compartment.

Each pipe has the same volumic length, and neutral fiber. Identical lengths of primary pipes ensures an equivalent output for each cylinder, reduces fuel consumption, diminishes engine vibrations by approx. 60%, which leads to a higher level of comfort.

The 4 branch manifold – 4 primary pipes linked to a collector and to an outlet – enables a good mix of the gases, increases available torque and power.

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 to the exhaust.

Photo Cylinder head flange.

2-Silencer

The silencer works along two principles :

A chamber made out of a drilled sheet of metal ensures the diffraction.

Padding around the relaxation chamber, made from layers of insulating material, enable the absorption.

The acoustic gain, of approx. 15%, due mainly to the loss of high frequencies, significantly improves the acoustics’ onboard.

3-Silencer mounting

The available space inside the engine compartment is not sufficient to receive the silencer: it is fastened under the cockpit.

The cylinder head flanges insure the rigidity of the collector’s fastening on the engine.

The engine mounted on silent blocks has a certain mobility compared to the cockpit, during cruising for instance.

All the conditions put together imply a specific stud, and the right build between the collector and the silencer.

Photo Screw and fastening bolt of the silencer Vertical tie rods Silencer clamp.

A twin ball joint pipe between the outlet pipe and the silencer compensate vertical and lateral movements.

During manufacturing great care is taken for the sealing of the twin ball joint, without reducing the mobility

Small vertical tie rods link the silencer clamps with the cockpit. They compensate lengthwise movements of the silencer.

Structural elements which support the silencers are made out of 15CDV6T, which is used in aeronautics for mechanic-welded components. Surface treatment prevents them from corroding.

Paulstra type supple ball joints enable a vibration free link up between the tie rods and the under cockpit supports.This combination of mechanical elements enables mobility between the collector and the silencer, limits mechanical constraints, and improves global reliability.

The Exhaust Manifold

Remove lower cowling
Remove original gas recuperation box.
Install primary pipes onto the cylinder heads, on the exhaust exit, without forgetting the original joints.
v Fit the 4 branch manifold, by matching the numbers on the flanges (n°2 in the following exampl) –
Fix the screws, and tighten.
Fit the support for the outlet pipe clamp, onto the engine sump tightening screws.

2) Plug in the carburetor heating boa pipe onto the hot air box 12 which is attached to one of the primary pipes.
Install the boa pipe clamp 21 then tighten.
Plug in the other extremity of the carburetor heating pipe 12 into the carburettor admission box.
Install the boa pipe clamp 21 then tighten.
Check the caruretor sensor wires are as far as possible from the exhaust pipes.
Install the 4 branh manifold clamp 7 onto the outlet pipe 4.

3) Install the 4 branch manifold support 6 into the engine.
Fix the 4 branch manifold support on the silent block side onto the 4 branch clamp, with a CHC 1=25 screw (25) and a Simmonds nut 15. Tighten.
Attach the cabin heating box 8 into the outlet pipe 4.
Screw the 12 flat headed screws M4 9 and the auto lock washers d4 23.
Turn le cabin heating box as shown on the picture and tighten all the screws. Fit the the cabin heating bend (19) into the original cabin heating boa pipe (cf image 2).
Fit one extremity of the cabin heating boa (1=500) onto the cabin heating box.
Install the d70 clamp 20 and tighten.
Fit the other extremity of the cabin heating boa onto the cabin heating bend 19.Fit d70 clamp.
Install a (/)44 tightening clamp into the cabin heating bend’s slot 19 then around the front right primary pipe.
Check that the two half boas are not in contact with the ewhaust pipes.Tighten the clamps.

4) Reattach the tightening clamp of the spark plug wire onto the intake pipe, with a 5 cm value.Check the spark plug wires are not in contact with the primary pipe.

Detach right hand side pilot seat.
Unfasten sound proofing foam on the floor.

The silencer

Drill fixing holes for the silencer under the cockpit, following the the information on the attached plans (ref : Monet 2 et Monet 4)
The positions of the fixing holes match the original rivet holes.
Attach the support and silencer assembly under the cockpit.
Fit the supple ball joint pipe 13 onto the outlet pipe 4, after having slid the silencer 28 to the back in its clamps.
Be careful that both parts are properly pushed in.
Tighten the fitting screw.
Slide the silencer to the front, and fit it into the supple ball joint pipe.
Tighten the fitting screw.
Tighten the silencer clamps 10 and 11, after having checked the tie rods 12 are vertical.

Put the sound proofing foam back on,
Reinstall the RHS pilot seat,Reassemble the lower engine cowling.