Westcoast

From the dyno postings, JCR OAP delete and Race pipe is good for about 25 HP, throw on the Race headers and get another 30 HP... it's a new world, or should I say engine!

Josh_357

I wasn't sure where to share this data collection, but seems most relevant in this thread. Keep in mind I am not a lawyer and I do not pretend to be one, I am only reading publicly available information and sharing my personal interpretations. I assume no liability for any action taken by any individual based on my interpretations.

I think I've found data that supports what we all think we knew about the GPFs and US emissions requirements for these 4.0l 718. I wanted to know what I/we are doing by modifying these OAP pipes and what the potential implications are regarding Federal and CARB emissions equipment requirements.

I've pulled the Certificate Summary Information for PORSCHE AG 2021 model year test group MPRXV04.0S82 evaporative family MPRXR0150R82 from the EPA. This Cert covers both Federal and CARB vehicle certifications for MY2021 718 4.0l cars. In this document it lists the emissions equipment certified, specifically 2TWC/MAP/DFI/2WR-HO2S/2HO2S (718 6-cylinder Series), this matches the CA emissions label on my MY21 GT4. This decodes to the following:

2TWC - 2 of Three Way Catalyst - Primary Cats
MAP - Manifold Absolute Pressure
DFI - Direct Fuel Injection
2WR-HO2S - 2 of Wide Range Heated Oxygen Sensor - Fuel Ratio O2 sensors
2HO2S - 2 of Heated Oxygen Sensor - Primary Cat efficiency O2 sensors

What device that is missing from this list is GPF: PM filter for spark-ignited engine. So therefore my interpretation is that GPFs are indeed not active emissions devices and are not official emissions devices. So I can personally feel comfortable removing or modify them without emissions implications.

elevensheep

Has anyone done this mod on a European delivery GT4, and can comment whether this triggers a CEL warning?

thanks

JCR-Porsche

Yes it will throw an OPF error almost immediately

JC

elevensheep

thanks, is there an easy way to get rid of that without remapping the ECU?

DC021

Don’t think it’s possible without some sort of ECU tune to block out that set of codes…

Just throw a JCR / BC FAB / 9M rear section on there and call it a day… maybe a set of headers as well down the road!

JCR-Porsche

There will be.. We have a plug in CAN module which works 99.9% of the time but still requires further development to make sure it's 100% reliable in all conditions

JC

DC021

Oh that’s gonna be awesome for the Euro owners JC!

TTFLT6

What does this mean? "I drone in any gear, RPM or seed." I suspect a typo?

ace37

seed—>speed is my guess

thomas_gt4

This would be absolutely fantastic for us with Euro cars. Thank you JC! A CAN module and a JCR Superlight Race Pipe for me please :-)

JCR-Porsche

Expecting to have this completed by the end of Feb '22

JC

toy4speed

Thank you for the info and your work! May not have much benefit for the average GT4 enthusiast, but for autocrossers in SCCA it could help fortify the argument that the OAP is not an emissions related part, thus replacing exhaust components behind the cats are legal for SCCA stock class competition. Not aware if the rules committees of SCCA have officially ruled on this particular issue but have heard there are possible efforts to do so.

Josh_357

I had not considered that. I am an SCCA member, and have submitted it now.

DC021

I’m not a SCCA Solo/Prosolo auto crosser am a regular on Road Racing side of things. Happy to write to the CRB if needed!