Hey
I'm installing a Pettitracing HF Cat with a nipple for the air, but I'm not sure if it's safe to plug the oem rubber hose (photo below) or if it will melt with the catalyser heat...
Can you recommend me a high temperature hose to plug the air inlet from a High Flow Cat ? I'd like to avoid soldering it, if possible.
thanks

 

Doesn’t a check valve attach to the cat air pipe first, then the hose? Otherwise hot exhaust can backfeed. That would also move the hose back 2-3 inches, out of the direct heat exposure zone.

 

Yes it does. On the photo it's the check valve along the rubber hose (it's out of frame and in the wrong direction, just to test fit)
I actually plan to cut the oem inlet from the stock cat and then connect it with a hose to the HF cat... So I may solder it if I can't find a high heat hose..

 

I would use a piece of silicone hose, you can find it in larger diameters. It can take like 400 degrees or so, that would work fine.

Dale

 

I’ve been toying with the idea of adding a vibrant hfc back on my FD and am even of thinking of adding the air pump back on. Could I just weld a nipple in front of the cat or is that all just waisted effort?

 

^I'm not sure about the airpump fitting if you're wedded to Vibrant. But Bonez and I believe, the rx7store HFC both have the pipe. And if you decide you don't need it it's easy to plug with a bolt and clamp. I've been running mine that way for 10 yrs/50k miles.

 

Thank you Dale,
I'll try with a silicon hose then !

 

You can try silicone hose which is rated to around 350 deg F. Better would be to weld a proper metal tube and flange for the check valve such as below

 

Yep I'll do that if the silicon hose fails . It will be a good excuse to buy my first welding machine

I also found some exhaust cat specific hoses on amazon US : Unfortunately they don't ship to Europe so I'll try with a mishimoto hose that I have.

 

I have the rx7store midpipe with the large Magnaflow muffler in it that I’d like to keep so I’m going to weld a cat either into my exhaust or in my down pipe. I believe the dp location may be too hot. Still in the planning phases.

 

Apologies for the bump, after my shift this morning tried to get my Bonez HFC + new exhaust installed and noticed since I had a midpipe anyways, i didn't have any hose going to my Airpump (which I believe is still intact) and the HFC didn't come with any hose to run to the Air pump. I was trying to locate the airpump underneath the car but couldn't find it and just went to sleep to do this another day.

Reading some posts on this thread, correct me if I'm wrong, are basically saying you can seal off the metal relay that is supposed to be hosed to the air pump? Basically for people who don't have an airpump? I'm not too sure about the mechanics of the airpump, and know a lot of people say it's counterintuitive to the design, and was put on just so it can pass emissions. If I am running a straight pipe, but my airpump hardware is still mounted on the engine (and in working condition), does it still have a function? If not, would it make sense to ignore the airpump, even if installed, and just seal off the airpump relay with a bolt and clamp?

Thanks a lot, and any responses would be greatly appreciated.



This post here on this thread:https://www.rx7club.com/3rd-generati...p-last-415169/

Essentially says that you won't be able to pass the sniff test for emissions for the old knight sport CAT, but I wonder if anyone who has the Bonez HFC without the airpump could provide insight on livability, smell and ability to pass just the sniff test portion of emissions? Thanks again

 

I've been running an SMB high-flow cat with no air pump for years. Knocks down about 80% of the stink, I think having an air pump would get the rest but I'm happy with that setup since I don't have to worry about emissions.

You will need a functioning air pump to pass emissions from what I understand.

There is normally a metal pipe that bolts to the back of the upper intake manifold kind of above the downpipe. It's a 2-bolt flange. That pipe runs down along the transmission towards the main cat, then eventually has a short hose that connects it to the main cat. Most likely the pipe was removed and a block off plate installed, you would need to get that pipe (which should be easy to find from someone who removed emissions) then just have a length of silicone hose going from that pipe to the nipple on the cat.

BTW that pipe is different RHD and LHD for whatever reason.

Dale

 

*Stares at tomsn16*


For now I'll just be done with it and install the Bonez HFC and new catback and block off the relay connection, and when I can find the appropriate pipe I will finish the pipe. Thanks, I saw people mention the SMB HFC (including you) in my search, but couldn't find which one it is. I assume since it's less restrictive than the Bonez HFC, its efficiency in reducing smell and pollutants is likely less? I'd be happy with 80% reduction for now, I don't mind the smell at all but will be having people who I take for rides with who won't be able to tolerate it at all lol

Still have quite some time before I got to do emissions again

 

Yeah I think you are on the right path. Get a short piece of high-temp hose, a bolt, and some clamps to plug that hole for now.

I don't know if the SMB cat is made any more, it's Australian-made, super high quality. I bought mine ages ago with a favorable exchange rate and got it for like $400 US. From what I understand it's probably not going to pass emissions though.

Dale

 

the pipe to the cat aka split air pipe isn't really needed, most of the air pump air goes to "port air" which is the exhaust ports and its internal to the engine

 

Thanks DaleClark and j9fd3s,

Luckily the Bonez HFC came with the T clamps needed and a short enough hose, just need the bolt which I have plenty laying around. Wish I just had installed it when I had it up yesterday, should have done more research lol. Will install it on Th or Fri now.