This is a question I get routeinly, week in and week out. Weather its from phone calls, email, private messages on forums or dm's. We get this question a lot... And it's a good question to get. Why would a high horsepower Mercedes need a set of headers? If you have a supercharged or naturally aspirated 55 AMG Kompressor in the E / CLS / SL / CL / S / G variety or am 63
AMG equipped with the M156 engine to the older M113 C55 and CLK55. There is no doubt that your car would benefit in a multitude of ways from a set of MBH headers.
The witty remark to this question (one I have used before) would be "have yo seen the factory exhaust manifolds?" Implying that they are the horrible thing on Earth. In a lot of ways this is completely true. The factory exhaust manifolds are an abomination, but more on that later.
The real answer as to why your Mercedes needs a set of headers has to do with a few aspects. Those are..
Restriction
Back Pressure
Boost Pressure
Fuel Mileage
Air Fuel Ratio
Horsepower
A good set of long tube header will treat all of these aspects.
Restriction
Let's start with what everyone knows. Restrictions. An engine is a giant air pump. It's all about air in and air out. If the air coming in can not get out as fast as it comes in then there is a restriction. There are lots of ways to reduce the restriction of an engine. You can do extrement costly internally mods like valve work and CNC ported heads, and or a larger cam to to keep those valves open a bit longer. Those are all good.. However the easiest way to free up one of the biggest restrictions in a modern engine is to look at the factory exhaust.
OEM exhaust manifold on a Mercedes AMG is in the style of a log. Meaning they have one master tube/pipe with 4 ports that attach to the engine head. If you look at a standard E55 or another Kompressor AMG's exhaust manifolds you will see doesn't look like an overly small manifold. However looks can be very deceiving. The outer shell of the factory manifold is just that, its a shell or a molded in heat shield if you will. It is when you actually dissect the exhaust manifold to expose the tubing that the exhaust gassed actually travel in that you see the problem. This tubing that makes up the internal part of your M113 55 AMG engine looks more like pipe you would use run water to your shower at home with.
Think about this,In each side of your big horsepower E55, CLS55, SL55 CL55, S55, C55, CLK55 AMG
has to push all its exhaust gasses out of a 1.62 inch hole! Its the equivalent of trying to breath through a straw. Each primary tube coming of MBH 55 headers is 1.75 inches alone! Then exiting out in to a 3" merge collector. It's no wonder our headers make about 50 wheel horsepower alone over the stock manifolds. By freeing the restriction you are freeing up a lot off thing and the end result of our headers on a 55 AMG equates to picking up 50 wheel horsepower. Its amazing and that kind of power difference transforms the way your car feels… In a good way.
Back Pressure
What goes hand and hand with restrictions in exhaust components, like exhaust manifold on your Mercedes AMG, is back pressure. We should think of back pressure as an invisible force. As it builds up it impedes the flow of new air trying to get in and and new exhaust gasses trying to get out. Back pressure from built up exhaust gasses makes the engine have to work a bit harder to do its job. The result is the engine has to use more energy (fuel) to overcome it. In compassion it would be like running with weights on. You can do it but you will have to work harder.
At MBH, our headers are designed to help remove that pressure build up inside the engine so the exhaust gasses can exit at a much easier rate. In turn this allows air coming into your engine to gasses coming out of it to be more free flowing. As a result, freeing up the restriction reduces the back pressure..
Boost Pressure
For any of the people who monitor their supercharger knows there is safe PSI and not safe PSI. Too much boost pressure and you will pop your engine or destroy your supercharger. In the world of the 55 Kompressor AMG where people are running 180mm crank pulleys or 77mm snout pulleys to make more boost. It’s not uncommon for them to be at a outer limits of what is considered a safe PSI or boost pressure for the M113 without fueling mods and time spend on the dyno for custom tuning.
Adding a set of our long tube headers to your car, no matter if you run the stock pulley of any variation of performance supercharger pulleys. You will see about a 1 psi drop in boost pressure without any adverse effects. In fact your supercharger will love you for it. It just means that you reduced the stress on your supercharger as it is now able to make the same power, but with the reduction of some internal stress and restriction.
Reducing your PSI in turn can have a positive effect on how your supercharged engine cools. Less boost pressure mean less heat and that mean your intercooler works a little less hard and in turn your heat exchanger doesn't have as hot of fluid in it to be cooled off.
Fuel Mileage
Now if you can control your lead foot, you should also benefit from a small bump in fuel economy. Since the engine has less stress or forces working against it in the form of pack pressure. The engine becomes a little bit more efficient, since the air getting out is now free flowing and not allowing for the build up of back pressure. This reduces fuel consumption mean better gas mileage.
Air Fuel Ratio
From the factory, lots of Mercedes AMG cars come with very rich fuel mixtures or air fuel ratios. Also known as AFR. Cars like the Mercedes E55 AMG can come with an AFR some place around 10:1. That is way more fuel than there is air. Some would call this a very safe range, As your risk of detonation is very low at this AFR. However your risk of having gas come out your tailpipe becomes closer to reality when you hang out in the low numbers of what is considered optimal air fuel ratios.
Adding a set of our long tube headers, as you know will reduce back pressure, boost pressure and fuel consumption . As the domino effect we talked about earlier keeps going, the reduction in fuel consumption along with our free flowing long tube headers means that the air fuel ratio is allowed to lean out a little bit. The result is your AFR creeps up to something like 11:1. Still a very safe range, but better in every aspect than a 10:1 AFR.
Horsepower
Take everything that was discussed and put it all together You have reduced the restriction, removes a bunch of back pressure, made the supercharger work a little bit more efficient and leaned out your AFR. All this equals horsepower and lots of it for your Mercedes 55 AMG and 63 AMG models. With Naturally aspirated M113 AMG’s like the CLK55 and C55 picking up about 30 wheel horsepower. E55,CLS55, S55 SL55 CL55 and G55 all making about 50 wheel horsepower. C63, CLK63, E63,CLS63, S63 and CL63 all make about 40+ wheel horsepower. Add some other supporting mods and MBH headers will make even more power.
This is why your Mercedes need a set of good long tube headers. You are literally choking your car by leaving the factory manifolds on. I hope this helped some people see the true benefits of a MBH header equipt Mercedes AMG.