Effects of Aftermarket MagnaFlow Exhaust on 2014 Grand Cherokee 5.7L V8 Power Output

Question:

Hi. Ive read a lot on forums about loss of low end torque when mufflers/resonators sre d/replaced with aftermarket units. Yet I read that a Magnaflow system will give an increase of aboyt 8hp/10 ft. Lb. Im confused! Can uou please set me straight?

asked by: Scott H

Expert Reply:

It is easiest (for me!) to think of engine intakes, exhausts, resonators, etc. as parts of the vehicle "respiratory" system. After all, in a way an engine is simply an air pump; it "inhales" air and "exhales" exhaust. Changing any part of this system will tend to either increase or reduce the engine's ability to mix air and fuel.

Power and torque are a result of air/fuel combustion and a new exhaust for instance that allows the engine to more freely release exhaust can allow better combustion and hence more power. In the same way a dirty air filter will restrict air intake and limit the engine's ability to burn fuel.

Combustion in modern computer-controlled vehicles means making a change to one part of the system can sometimes require changes elsewhere. A more freely-flowing exhaust like the MagnaFlow # MF16929 that fits your Grand Cherokee with V8 hemi will pass more exhaust since it has no baffles that restrict air flow.

This exhaust certainly has the potential to deliver power/torque gains but since it does not operate in isolation, but instead as part of the overall system, its actual gains can depend on the other components. This is why no specific gains can be predicted for any given vehicle. Often makers like MagnaFlow will say "up to" when quoting possible performance gains from their stainless exhaust systems like # MF16929.

expert reply by: Adam R