Marinediesel 5L V8, Руководство пользователя, Страница: 197 / 248

Owners Manual 195 Section 6 - Engine
Exhaust Back Pressure
General Information
All exhaust systems have some restriction to flow, or what is called “exhaust back
pressure”, but this must remain at a minimum. The power output of an engine is directly
related to the amount of exhaust that can flow out of the exhaust system. For example,
engines will generally suffer approximately a 10 horsepower loss for the first 1 psi (7
kPa) of exhaust back pressure.
A higher output engine will cause a greater backpressure using the same size exhaust
system as an engine with less output. On boats with through the hull or through the
transom exhaust, it is recommended that the boat’s exhaust system be designed and
tested for the highest horsepower engine to be offered in that boat.
Marinediesel specifies the following maximum backpressure, which can be measured
using the test outlined following.
Exhaust Back Pressure Specification
Model / Application Measurement
All Engines Maximum 1 psi (7 kPa)
Ensure that both cylinder banks of any engine are tested. Record the highest back
pressure readings. If pressure is excessive, changes must be made to the system to
reduce the pressure; including but are not limited to the following:
x Reduce exhaust system length.
x Increase exhaust system diameter.
x Reduce muffler restriction if equipped.
x Ensure that through the transom or through the hull fittings are above water.