Rx7 fc

To cat or not, I have a stock fc completely stock. I disabled the air pump and run pre mix because the omp is bad.

I will probably put in a drop in k&n, and I'm getting exhaust on soon. If I delete will it lean out the engine? I want to get a 2.5" or 3" with a magna flow single exit.

Other than that I think the thermostat is failed possibly as the car gets warm but not hot the temp gauge sits just above the cold marks.

Some people have already told me (Stat) omg that will cause your engine to explode (I'm paraphrasing) but this car has good compression and 130k miles so I'm not keen on changing much.

I don't need the cat but I'm not entirely against it if it could lean out the car.

Disabling the air pump seems to help the car run better so thats funny as I was also told it would make it worse.

Krem

So, if i were you I’d think of it another way (about the cat)
the cat may hinder performance, slightly,
if you put on a high flow cat the difference to not having one would be sfa
lets look at the apparent reason for the cat in the 1st place (and yes, this is the old person with kids comming out of me)
The cat is there to help stop the carcinogenic gasses (that can cause cancer) comming out the exhaust,
i know there are many cars where the cat is deleted, but i mean really, are you willing to take the risk of deleting the cat for 2 extra hp to throw out carcinogenic gasses where your kids, cousins, partner, parents etc are breathing??
to me its a no brainer, just put on a high flow cat,!!
krem

Rx7 fc

I think with or without a cat your not going to want to breathe exhaust. I acknowledge your thought process, but it's 100% bad for you and a catalytic converter is a bandaid on a fossil fuel problem. So no I have no problem with everyone cutting the cats off of their cars. My lawnmower, weed eater and motorcycles don't have cats neither do millions of other ones right next to you.

That said I literally only care about reliability. The fact you have to run 2cycle pre mix in these engines and they burn oil from the factory.. These are literally the worst polluting things on the planet. Worse than diesel, diesel combusts completely my chemistry professor broke down diesel engine emissions and particle for particle 10 diesel trucks emmit less harmful chemicals than one regular automobile due to incomplete combustion. The only draw back to diesel is the particulate. The particulate can stick in your lungs so it's not great, but still part for part diesel is cleaner because of completely different chemical composition of emissions, gas second and 2 cycle by far the worst.

mazdaverx713b

iTrader: (91)

Disabling the air pump can cause catalytic converter failure. The air pump not only supplies fresh air into the cat for emissions but to aid in cooling the cat. You gain nothing but trouble by disabling the air pump and having the rest of the emissions equipment in place and functioning.

Also, the split air tube that is bolted to the main cat is required to operate the 5th and 6th ports. Your engine will have no top end power without properly functioning auxiliary ports. The stock exhaust is a great setup for the port actuators. If you replace the converter you will still need exhaust back pressure to operate the auxiliary ports to release the pressure stored in the dynamic chamber into the engine. Replacing the exhaust with a full Racing Beat unit will add power and still operate the 5th and 6th ports as designed.

DC5Daniel

iTrader: (10)

If you've ever been around a rotary without a cat, it gets old after a while always smelling like a poisonous lawn mower. If you had a highly modified car, it's one thing. The cat not only becomes a mild hinderance, but a liability at rotary exhaust temperatures and pulse strengths. But on a stock car, do yourself a favor and install a cat. You'll be glad you did.

WondrousBread

I just started my FC a couple times with the air pump removed (cat still present) and the exhaust stench is downright noxious. Even backed out of the garage, enough blew back into the garage that I had to get changed out of the clothes I was wearing, otherwise I'd bring the smell back in with me. It smells seriously bad, and the smell doesn't dissipate quickly.

Now imagine how bad it'll be with no cat at all.

I'd advise retaining the cat with the air pump, or moving to a high-flow if you're dead set on not having an air pump. It will smell bad if you don't have the cat, for literally no gains.

You'll also need to consider the auxiliary port setup, as was mentioned above.

j9fd3s

iTrader: (3)

save your $$ and just get a normal filter, the paper filter isn't a restriction, and they do filter better.

2.5 is all that you need for an NA, even 2.25" works. keeping the cat has a huge effect on emissions, but a small effect on power, so its nice to keep if the car is a daily

the S4 uses an actual gauge, and normal running temp is about 1/3 of the way up, the top line is 100c and the bottom is 65c. the S5 will be just under half between 65c and about 95c

Rx7 fc

Thanks guys, the cats had to go per my exhaust guy, they were fouled up too badly. 2.5 straight back and we found a muffler that's magna flow style no glass packing.

Sounds pretty good, super weird having no back pressure, letting off the throttle doesn't even slow me down now. I can already feel a power increase, I'm sure mpg too.

The 5th and 6th ports is there a mod for that?
​Edit: I just found I can weld an air nipple bung on the exhaust and it will still activate the ports cool

Air pump disabled, no restrictions it sounds decent little loud wot. I didn't really notice a power band change.

mazdaverx713b

iTrader: (91)

Yes you can weld an elbow and flange onto your mid pipe and have it work with the stock split air pipe. This will allow the port actuators to function properly.

Boner

Scour Ebay, and look for a Bonez midpipe (I assume this is an N/A) they are quality I had one on my N/A and it comes with a performance cat.

Delete the air pump, it is emissions garbage.

Rx7 fc

Update:
Car is running great, too loud.

I'm going to change to a larger Flowmaster metal gate muffler (non packing style) and add an elbow and nipple for plugging in the 5th and 6th ports.

Trying to figure out what I want to use for hardware at the moment. I'm thinking having an 02 bung welded on and then using a spark plug defouler / elbow then bringing that down to a nipple for the air vac line for 5th and 6th ports. I need to talk to my other welder buddy and hope he isn't too busy to help lol.

Dak

I have heard Flowmasters and rotaries don't work well together. I thought at one time they even said on their website something about it. Anyway from what I understand the exhaust pulses are so strong they eventually break the internal baffle plates loose.
As for the 5th and 6th ports just drilling a hole int the pipe and welding a tube or bung on most likely won't work. See this thread:
https://www.rx7club.com/2nd-gen-gene...ssure-1137769/

It's not cheap but if you want to quiet it down some and want your 5th and 6th ports to work I'd just buy the Racing Beat Pre-silencer.

j9fd3s

iTrader: (3)

the last time i heard a flowmaster on a rotary was in the early 90's, it was a stock 12A car with a straight pipe, you could hear that thing 2 miles away

Rx7 fc

Update: Exhaust V2.0 Flowmaster 2.5“ 50series.

Added a 50 series 2.5" Flowmaster in the center of the exhaust (about under the shifter) where the factory heat shields are for the cat.

That plus a resonator ( from 2012 charger) at the end of the tail pipe we left on and it sounds great. It's actually quiet! Only little sound wot at above 6k rpm.

Welded a spark plug defouler on the front of the exhaust with an elbow and a reducer fitting to the vac line for the 5th and 6th ports. They are working fine now.

My exhaust guy thought we should use a smaller series Flowmaster and I really disagree, the 50 series is a big muffler strong internals and solidly welded I'll let you guys know if I knock any baffles out but I highly doubt that have you seen how large a 50 series is? I think the muffler placement is allowing enough back pressure to work just fine free revving with no load the actuators work above 4k rpm.

I should really make a video for you guys this exhaust sounds great and it's ticket friendly they won't give me a ticket for this quiet thing, version 1 with just the resonator I would have given me a ticket.

Dak

Maybe the Flowmaster being of a chambered design it creates enough back pressure for the 5th and 6th ports to function. The people who had problems getting them to work were using straight pipes and/ or straight through style mufflers. Let us know how the Flowmaster holds up.

j9fd3s

iTrader: (3)

glad that its quiet, slow and loud is easy, fast and quiet is hard...

the rotary is like hitting the muffler with a hammer, time will tell...