Moving Cats downs stream, o2 extension harness
 

Hey Forum,

I'm setting up some resonated TP's with helmholtz resonators and moving the cats more down stream. (supercharger set up keeps blowing these into pieces).

This is actually for my 07 HR nismo, but I believe the downstream o2 are the same on the 370's. Found this place on the forum, but having trouble determining the type.

HR/VHR Oxygen Sensor Extension harness AFR Sensor

I thought of cutting, splicing, and extending the o2 wires themselves, but i usually prefer a more cleaner setup if possible.

Appreciated the help!

I believe it's different for the 370z years as well though, I know when I ordered my headers 09-13 was different than 14+

Yeah, the upstream and downstream sensors have different connectors. When doing long tube headers, those are upstream... before the cats. The post-cat (downstream) are the one's in question.

I'm going to take a gamble on these to source the connectors. I'll use my own wires

https://www.ebay.com/itm/33428050199...cAAOSwc~xhwD5D

Looks like those worked. I purchased a spare motordyne Y section and replaced the flex sections with a clamp on high flow cat cells. Idea is that if I move the cats more down stream, they will stop blowing into pieces. If they do, then easy replacement. I put on resonated Fast Intention TP's with Hemholtz resonators like the Motordyne ART's. I am hoping that I can bring down IAT's in WOT (because of back pressure on stock cats) but at the same time keep the exhaust drone/rasp/loudness down so I don't go deaf.

Harness I created was 24".

Tracker - Thanks for this thread. I’m in MA, too. I currently have Fast Intentions RHFC and 18” Resonated CBE and will be going supercharged later this year. Current plan is to keep the RHFC’s until they die (estimated ~15k miles on them), then would pursue something with cats further back - I just hope I can get a year or two (summers only) out of them without damaging anything. I’d be interested in your (or anyones) experience on volume of RHFC vs ART pipes or similar. I have a Roadster so am already near my, and my quiet neighborhoods, tolerance for volume.

On my 07 Nismo, I went through a set of FI HFC's in a single year with the OE Stillen supercharger set up. I use Sebastian @SpecialtyZ on tuning. The OE Stillen setup is so just problematic and I had to stay on the richer side because of the MAFs being before the blower. Being rich is basically how my first set of FI HFC's went. Lol.. a WOT pull one day, a pop.. then massive hole in those. I put the stock cats on and wasn't long afterwards that those went.

I'm now on my 2nd year with Topgunz A-A upgrade after 15+ sessions with Seb and have not had any issues with Cats. I'm running stock cats with a Motordyne TDX, down sized pulley and Zspeed clutch set up. I love the gains on TopGunz kit and my A/F is more predictable. I went from 338wHP to 450wHP with the new set up. Problem is that my IAT's get high and I see knock and it pulls timing. (probably because the stock cats are a restriction now).

HFC's on the Motordyne was very loud. I actually enjoyed the sound with stock cats, but IATs. ART pipes seem to be the go to with the supercharger. Sebastian gave me a tip to move the cats further down if TP's were too loud, So.. thus this the changes. Won't be able to run it until the spring though.... my Nismo's are hibernating

Are you cutting up OEM-fitment cats/HFCs and welding them in downstream? Or are you going for an universal fitment performance cat like something from G sport?

https://gsportbygesi.com/


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The original topgunz kit? The intercooler in that kit is unfortunately trash, I was seeing IATs at 142+ degrees from a single pull when ambient was around 80. I swapped over to soho's intercooler and it helped significantly.

Edit: Here's a video of a pull with sohos intercooler, IAT's still obviously climb decently well but it's still no where near as bad as before with near same ambient: https://www.youtube.com/watch?v=EJHfLymEaLw