Following graphs show very well the engine power versus backpressure of the exhaust system. Please read: Back Pressure
Graphs are from Mr. Chance, custom 720 cubic engine destined to the 5.000,00 Kilometres Rally in Tunisian Sahara.
Graphs with the friendly approbation of Mr. Chance.
Type : Citroen 2CV
Gearbox : 2CV long ratio, tyre 135mm
Engine : 720 cubic, 8:1 compression ratio, 7,5 mm/288° camshaft, manifold with Weber carb and air filter coming from Visa engine. Custom flywheel with high inertia and low weight. No indication about connected sand filter.
Engine kilometres : ca. 1.000,00 miles
Exhaust system :
Date of Dyno run : 15-09-2003
Black curve is the final power curve with the expansion chamber.
Red curve show the power curve with emptied standard Walker crossbox.
Power curve in comparison
Torque curve in comparison
With standard exhaust system the engine will not rev up 5.000 RPM, acceleration was very lazy, engine hesitating during acceleration with floored accelerator in second gear!
Mr. Chance comments to engine combo :
The exhaust is only a little noisier than the standard and has a metallic ring to it. With the Visa filter and this exhaust the car is quite comfortable.
Clear message :
Been in 4th gear, you must no longer gear down for accelerating ...