The benefits of the sport exhaust is:
- improve the power of the vehicle
- reduce the weight compared with stock exhaust system
- improve the sound and volume
- reduce the maintenance costs because the quality of new materials is much better
- provide sporty looks and individuality of the car
Normally when designing a sport exhaust we are looking for a change in the exhaust sound, but of course this is with consideration of the customer's requirements. We can add more sport resonators/mufflers in order to reduce the noise levels.
When installing an exhaust manifold and a bigger turbocharger like Garett GTB2260VK, the flow of the exhaust gasses increases. This necessitates designing a sport exhaust system with bigger diameter. According to the modification, for VAG 1.9 TDI we install sport exhaust with pipe diameter in the 63mm-76mm range.
Although strictly individual the catalytic converter is one of the major bottlenecks when creating a sport exhaust system. We can replace the cat with a resonator or a straight pipe with a sleeve. The oxygen sensor is pushed away from the direct exhaust gasses flow on the new exhaust system. This way we can keep the factory readings of the sensor. In some cases, a change in the software might be required.
"Twin-loop" mufflers force the exhaust pulses to travel through the muffler body twice. This way they reduce the noise without sacrificing the engine performance. This type of muffler is much better option for controlling the noise compared to the regular muffler silencer which creates a bottleneck by reducing the diameter of the exhaust pipe.
When having an engine with forced induction, it is necessary to replace the turbocharger in order to achieve more power. The new turbocharger usually have different connecting flanges and different overall dimensions. Also, the location of the turbocharger presumably requires a better tuned exhaust manifold. To achieve a maximum effect, the exhaust gasses driving the turbo have to arrive for a shortest possible period of time with a minimal loss of energy. The stock cast-iron manifold is made after these guidelines but it also have drawbacks like: limited flow (due to the diameter of the runners) and uneven pulsation (in other words, the exhaust gasses are trying to get out in one pass and hence they are "pushing" each other). Tuned exhaust manifold should supply the gasses to the turbocharger with optimal flow and minimal windage. We recommend that you use a tuned exhaust manifold in all cases when the target power increase is greater than 40%.
What is "reversion"? During valve overlap, when both the intake and the exhaust valves are open, part of the exhaust gasses travel back through the pipes and enters the combustion chamber. This happens when the piston moves downward in the cylinder thus creating vacuum. The exhaust gasses which return back contaminate the combustion chamber by displacing the fresh air/fuel mixture. This process effectively decrease the power and the efficiency of the engine.
The anti-reversion chambers help decreasing the contamination of the air/fuel mixture by exhaust gasses which returned during the overlap. The result is cleaner mixture, lower temperatures and of course, more power.
The main function of the rollcage is to preserve the pilot and the passengers in a case of an accident. All cages must discharge its duties, regardless of the material used. These are made from seamless pipes, according to customer’s requirements, the purpose of the tuned car, and the FIA regulations.
We will make a short summary of the materials used for making rollcages and we will also explain their advantages and disadvantages.
The advantages of the T45 and chrome-molybdenum pipes is that they are stronger, which allows for a pipe diameter reduction, still attaining the needed strength. This leads to decreasing the rollcage weight with 10-15 kg. Maybe the only considerable disadvantage of these tubes (except the higher price) is that they are harder for processing and welding.
The CDS tubes are easier for processing and welding, and also they absorb the kinetic energy more smoothly, yet they are heavier.
Extreme Tuning strongly recommends that you only entrust to a certified expert welder who has an experience in the installation of protection cages. Non-compliance with the welding technology especially when using T45 and chrome-molybdenum can result in micro cracks and can compromise the integrity of the rollcage.
A sport exhaust manifold after the catalytic converter usually decreases the fuel consumption just a little bit, but it produces a better sound.
When changing the catalytic converters with free flowing resonators and sport exhaust system, the consumption can decrease with up to 2-3 liters depending on the engine's displacement. The factory tuning settings remain the same, but the resistance in the mufflers is decreasing.
On the other hand, adding a sport exhaust manifold and an exhaust system is often related to more power, new tuning settings, and more engine improvements. People who do that are aware that the actual fuel consumption will increase in order to get the best result from the tuning.
When determining the dimensions of the manifolds and the exhaust system we take some facts into consideration including the current modifications and the desired effect.
The information published above is a product of the observations of the Extreme Tuning team.
Random diameters and badly designed manifolds can actually make the things worse.
Wrapping of tubular manifolds with heat wrap is extremely useful because of number of factors.
The most important thing is to keep the temperature of the exhaust gasses and their velocity. With tubular manifolds, the walls of the runners exchange heat very fast and if they are not thermically isolated, micro vortices will appear around and the exhaust gasses will decrease the velocity (their kinetic energy) when overcoming these vortices.
The faster heat exchange leads to greater fluctuations in the walls temperature for short periods which causes the material to shrink and expand multiple times. In the time, bending causes mechanical stress and very small cracks that can result in a visible crack in the manifold. Expand/shrink frequency decreases thanks to the thermal isolation. This leads to smooth transition between the temperature amplitudes.
Another important effect of using the heat wrap is keeping the heat in the engine bay under control. For tuned cars and especially these having a turbocharger, the manifold is often exposed to temperatures of approximately 700 degrees Celsium which makes it potentially dangerous for the surrounding components. The heat wrap will also prevent melting of tubes and cables.
Extreme Tuning team suggests that you always use a heat wrap for a tubular manifold.
