glovemoney

Can someone explain to me why a secondary cat delete subbed with a straight pipe might reduce hp (that's what I have seen on threads)? Can that be true.

Also why would a more aggressive muffler system like eisenhaus Improve hp?

Sorry for the dummy questions. Thanks

Scat01

I have heard the reduction of back pressure by making such changes can reduce low end torque, but never heard of a reduction in HP??? Somebody will chime in to explain....

glovemoney

Ok, maybe that is what I have read. Why would it reduce low end torque?

Peabody

Your basic dilemma in designing an exhaust system is that you want a strong pressure wave from the exhaust to reduce fuel/air losses from the cylinder but this effect works against flow volume. I'm not sure how this dramatically effect has carried over to modern Mercedes engines, but when your running at lower RPMs, you tend to escape fuel mixture out the exhaust port if there isn't sufficient pressure wave to hold it in. The escaping fuel/air mixture at low RPMs results in a lowered torque curve in this range. At higher RPMs, this effect can reduce flow volume and limit how much fuel/air can fill your cylinders.

The ideal system will generate sufficient pressure waves to limit fuel escape but not limit cylinder fill at high RPMs by using baffles to reflect the pressure waves so that as RPMs increase, more waves arrive after the exhaust port is already closed. By reducing the strength of these pressure waves, they increase flow volume, which increases horsepower.

krnxalex123

aftermarket exhausts tend to b lighter a lot lighter

Richie999

Engines are air pumps, to oversimplify. The basic trick is more air in with more air out, and the engine is more efficient and can make more hp.

Keep in mind that the weak link syndrome applies here. If you dramatically increase the "more air out" side w/o increasing the "more air in" side of the equation, you may not see the desired result.

My guess is that the exhaust on these cars is not the weak link and thus adding exhaust is really more for fun and not real results.