If you drive a diesel-powered vehicle that has a diesel particulate filter (DPF), you may be considering upgrading your exhaust system. You may also be wondering, "Is a DPF back exhaust even worth it?" given that the DPF must stay where it is.
Here at Manta Performance, we are happy to answer your DPF exhaust questions! We pride ourselves on designing and producing the highest quality exhaust systems, including those for vehicles that come with a DPF.
It all comes down to your vehicle and what you are doing with it
A diesel particulate filter, or DPF, is a device that removes the soot from diesel exhaust. The technical term for soot is diesel particulate matter, from which the DPF gets its name. Soot is actually very small carbon particles produced by diesel engines, due to the makeup of the fuel and the incomplete combustion that results when it is burned in an internal combustion engine.
These tiny particles of soot have been identified as a health hazard when they are inhaled by people, contributing to lung cancer and other major respiratory diseases. As a result, governments around the world have enacted regulations which have led to the widespread use of DPFs on diesel vehicles to minimize the effects of diesel particulates on peoples’ health. By catching and destroying harmful diesel particulates before they can escape your vehicle and be breathed in, DPFs keep our air cleaner and healthier. These regulations also prohibit you from removing the DPF if your vehicle came from the factory with one.
Turbocharged engines on 4WDs need bigger pipes
Generally speaking, a turbocharged engine benefits from larger pipes – up to a point. Most Manta systems made for turbodiesels use 3-inch pipes. This provides several benefits:
- Faster spool-up of the turbos
- Improved gas flow
- More power
- Larger drop in exhaust gas temperatures
But there is a limit, and that has to do with the size of the turbo outlet pipe. In a vehicle like the 70 Series 4.5L V8, the turbo outlet is only about 2 inches across. This means that there are no extra gains from going up to a 4-inch pipe over a 3-incher. Another good reason to use 3-inch pipe is that in the event of any pipe damage that happens off-road, you should be able to find 3-inch pipe at most repair shops.
There is an exception to this rule, and it applies to twin-turbo engines like the one found on the 200 Series, as well as big displacement engines such as the 7.3L V8 on the Ford F250. A 4-inch system works well with these types of engines, giving you improved flow as well as a better sound!
Normally aspirated engines on 4WDs need smaller pipes
While a turbo acts as a compressor to pack more fuel and air into the cylinders, a normally aspirated (NA) engine must do without this upstream boost. These NA engines rely on a principle called exhaust scavenging to efficiently suck the exhaust gases out of the cylinders when the valves open.
What is exhaust scavenging?
Exhaust scavenging is a process that starts when your NA engine’s exhaust gases exit each cylinder and travel through the exhaust system as quickly as possible. The high speed of the departing exhaust gases then creates a negative-pressure area inside the cylinder, which works to pull more fuel-air mixture into the cylinder for the next combustion cycle. When the scavenging process is optimized, it’s like having a mini-supercharger on your engine.
Pipe size is critical here – pipes that are too large will reduce the scavenging effect, decreasing torque, slowing down the exhaust flow, and impairing the engine’s performance. Manta Performance exhaust systems are engineered to maximize this scavenging effect, boosting your car’s performance significantly.
Years of experience have led us here at Manta Performance to use 2.5-inch pipes on our NA exhaust systems. By maintaining the right amount of exhaust scavenging, the 2.5-inch pipe produces improved performance and preserves low-end torque, especially when extractors are added.
The same principles apply to street vehicles
For street exhaust systems, our guidance is the same as that for off-road vehicles. For turbocharged and supercharged vehicles, a Manta system with 3-inch twin pipes will flow over 800+kw, which is perfect for a blown powertrain or a vehicle with an upgraded cam. It also gives you a deeper, louder note.
For NA street vehicles, our 2.5-inch twin systems will flow up to 500+kw, which is ideal for a naturally aspirated engine. This is also a quieter option that provides less interior resonance.
What about header pipe sizes?
We are often asked, “What is the ideal header primary pipe size?” The right answer depends on the modifications made to your vehicle and how you plan to use it:
- For a daily driver, a 1 3/4-inch primary pipe provides great mid-range torque, while slightly reducing your top end power potential.
- For blown engines and racing use, a 1 7/8-inch primary pipe gives you the best top-end performance, but you will lose some mid-range torque.
Bottom line, whatever mods you have made or planned, Manta Performance has the right exhaust system for you and your vehicle, wherever and however you plan to drive it!
