Since September 2018 GPF has applied to all new GDI/Petrol (Gasoline Direct Injection) cars with a specific conformity factor. Its purpose and introduction are to restrict the level of emissions exiting from the exhaust in a similar way that DPF works on diesel models.
Why are manufacturers equipping their vehicles with particulate filters?
Legislation, Governments, pressure to tackle climate change and reduce pollutant emissions are the driving force behind the changes. Depending on the country you are in when reading this, different regulations apply but in short, lowering emissions globally requires a significant and strategic process.
“A dramatic increase of vehicle production and critical rise of environmental pollutions, global warming, climate, greenhouse and transportation growth make countries around the world unite to find effective solutions. Thus, they agree the situation requires very strict, urgent actions in law and regulations to reduce passenger vehicle pollutions.”
Pshtiwan M. Sharif et al 2019 IOP Conf. Ser.: Mater. Sci. Eng. 469 0120701
Worldwide emissions standards and regulations have also stepped up to ensure manufacturers are not complacent.
“(WLTP) is the new protocol regulation and requirement process to measure exhaust emissions in the real world with the real driving emissions (RDE) Test. EU is the first to introduce the (WLTP) as a legally binding procedure to achieve uniform test protocol throughout the world. The (WLTP) is taking in to consideration optional equipment of the vehicle for everything that increases the vehicles fuel consumption and its emissions, the type approval will become a lot more complex. In fact, every vehicle gets its own CO2 rating based on its equipment, body type, aerodynamic properties and mass.”
Pshtiwan M. Sharif et al 2019 IOP Conf. Ser.: Mater. Sci. Eng. 469 012070
If you consider that companies openly advertise DPF removal on diesel vehicles (which is illegal), it is likely that the advice will be similar for the GPF; to remove the system altogether, or to remove the internals and weld it closed. If companies do not offer legal products, then customers are only left with one choice; Revo believe that choice should, at least, be legal.
The latest generation 2.0TSI engine (Gen3) is equipped with a GPF and has formed part of an extensive and in-depth research and development program. This focussed on the implications of this filter in regards to ECU calibration changes. There have been some substantial changes in factory form to keep in line with the latest Euro 6.2 emissions laws, which we will most likely see across more vehicles in time. Most notable is the introduction of the GPF and the change to the single port injection system.
Increased restriction from Governments globally on emissions means that GPF (Gasoline Particulate Filter) is here to stay. Revo stand firm on creating products that are legal. We don’t want our products to incriminate our customers, which is why we don’t create products that are illegal or ‘for track use only’.
Throughout the development of Revo’s performance ECU software for the 2.0 gen3 engine, close monitoring of the GPF system has been an essential step in finding the limitations and tuning potential of the newer DNU engines.
So, what exactly is GPF?
Referred to as GPF, PPF or OPF it applies to petrol engines only. Gasoline Particulate Filters (GPF) are derived from Diesel Particulate Filters (DPF) found in all-new diesel engine powered vehicles.
Gasoline particulate filters (GPF) are used to remove particulate matter from the exhaust gas from a gasoline direct injection (GDI) engine.
GDI vehicles are becoming more popular due to the regulations to reduce CO2 emissions, at the forefront is legislation like Euro 6.2.
However, a GDI engine has a higher emission of particulate matter than a port fuel injection gasoline engine. GPF controls the particulate emission by trapping the particulate matter, ultimately making the cars we drive cleaner to the environment.
It comprises of a honeycomb-like filter structure made from synthetic ceramic material. The filter captures soot particles as the exhaust gasses pass through.
This soot is then burnt and the filter regenerated when the exhaust temperature is high. In most cases the filter is operated under a constant trap and regenerate cycle in a passive manner. Whereas a DPF traps soot and then needs a special engine mode to regenerate.
GPF filters are highly efficient, capturing in excess of 90% of airborne particulates which would otherwise be released into the atmosphere.
While the GPF and DPF technologies are closely related, there are a number of differences in the filter configuration, operation and control strategy, which are due to the differences in the operating conditions, and the particulate emission rates and composition between gasoline and diesel engines.
Could you remove GPF altogether?
Sure, a few tools and a bit of time will see to that. Or you can purchase a delete pipe for ‘off-road use only’. Removing any DPF/GPF will allow exhaust gasses to flow more freely, potentially improving performance.
However, removing the GPF will more than likely deem your car illegal for road use. As the car will no longer meet the emissions standards intended set by certain countries. Removal can also trigger an EML/ECU warning.
“Removing the GPF will deem your car illegal and will most likely trigger an EML/ECU warning.”
It’s always an easy option for many aftermarket tuners to suggest removing emissions-based components, especially as it is significantly cheaper to remove than it is to design products that work with the GPF.
However, if it’s a road car that’s a completely different consideration and if you intend on using it as a daily though you could be in for problems.
If Governments are coming down hard on manufacturers, they will be looking out for people removing them after purchase. Revo’s mission is to develop products that are road-legal, and don’t require you to break the law to enjoy.
You also need to consider that if you do remove, or ever need to replace the GPF it’s likely to be an expensive exercise based on the known costs of DPF replacement. Our extensive software development takes protecting the GPF into account.
Two types of GPF.
Drivetrain layout means two types of GPF found in VAG 2.0T vehicles. The 4WD vehicles have two smaller GPF’s, whereas the 2WD vehicles have a single larger one. This is largely due to the space restrictions with the propshaft on 4WD models.
“Revo does not support the Removal of GPF!”
What’s the ‘real’ tuning impact?
GPF causes additional restrictions inflow – that is THE key limiting factor they bring. Essentially the car isn’t getting the same amount of air through the cylinders (compared to a non-GPF at the same boost level) and airflow is critical to making power of course.
However, this is a non-removable restriction that we must work with to get the best from the car and the software. And, following our extensive testing it actually isn’t as restrictive (in terms of producing increased performance) as we had first anticipated it might be.
At the time of writing this there isn’t much real-world information available about the GPF as it’s such a new introduction.
GPF also mutes the car’s exhaust tone. As aftermarket car tuners we’re all about those addictive exhaust notes; fortunately, Milltek produce a ‘GPF/OPF-back exhaust system’ so you can do something about improving the noise with an aftermarket solution that still allows you to retain the GPF and abide by the necessary laws.
The BIG question.
“What impact does GPF actually have on performance?” Well, our extensive software development has surpassed our own expectations. We answer that question in much more depth, here.