Installing mid pipe question
 

Hey guys I removed the stock cat and stock mid pipe on my 93 fd rx7. The down pipe wasn't a problem but the mid pipe has another little piece that comes off of it and goes into the engine block I believe. If I put a aftermarket mid pipe what am I suppose to do with that extra pipe?

Before you go any farther.....
*If you have emissions, you will NOT pass without a cat.
*Running a midpipe with stock fuel and stock ECU can cause an over-boost condition called BOOST CREEP. That will make the engine run lean and cost you an overhaul. Go to the 3rd Gen section FAQ sticky, scroll down and read up about boost creep. Also note how it is different from BOOST SPIKE and is NOT affected by a boost controller.
*That small pipe, with a small rubber section is the air feed from the split air/air pump. Again, you won't pass a visual inspection if you have emissions, especially if you remove the airpump. Effects of running w/o an airpump and that pipe on the stock ECU tend to vary. Some report no effect at all, while others experience hesitation and idle problems.

Ahh thank you! Explanation!! Lol

So me running a down pipe and mid pipe pretty much risking to damage the engine. But is it a possible thing or a FORSURE thing that can happen?

Oh and how exactly do I plug up that spot that you say is for the air pump?

I get it. You probably bought one of the Ebay downpipe/midepipe kits and are just dying to install them. If you read and learn then you may not want to "plug up that spot for the airpump". It's not a "for sure thing", but it can happen and if it does it will cost you an engine...and a set of turbos as well.
While you're at it, there are also copies of the Factory Service Manual that can be downloaded in the FAQ sticky and are a great reference. But if you don't make an effort on your own, especially once you leave the New Member Section, patience here can run short.

Yeah I get you. I did what you said and read a bit last night on it. I was planning on putting a chambered magnaflow exhaust on it, would it help if I put like a pre muffler where the mid pipe was at with the new magnaflow exhaust?
And I'm not sure where the mp dp was bought the guy just gave it to me when I bought the car. They're both 3" and stainless steel.

Some more recommended reading--->https://www.rx7club.com/3rd-generati...9/#post5699718
https://www.rx7club.com/3rd-generati...-i-get-460562/

One other thing....running w/o a cat will make your car stink. The exhaust can make your eyes water and it even gets in your clothes. To put it in perspective, I smoke the occasional cigar and it even bothers me.

Yeah I think I may just stay away from their pipe until I have what I need first. I would still like to know though, would a premuffler then regular muffler work? Or it has to be the cat?

Ok so ill just wait on the mid pipe until I have what I need, but I still have the question of will a premuffler then a regular muffler work as well? Or it has to be either a cat or the upgrades.

Good thing i read this before installing my downpipe and midpipe. :)

If I was to install a good boost controller would it stop boost creep? If so what boost controller would you recommend?

A boost controller cannot lower boost past what would naturally be achieved by the wastegate.

In other words, nope, a boost controller won't help solve boost creep. Boost creep is only solved by increasing the wastegate size (porting it out) or restricting the intake/exhaust.

A boost controller would be used to raise boost past the natural spring pressure of the wastegate.

Ok.. so i cant just set the controller to 10psi? wouldnt the boost controller prevent it from going beyond 10 PSI?

No, not from boost CREEP.
CREEP is a condition experienced from too little back pressure in the exhaust system. A boost controller is only good for controlling boost SPIKE...a condition experienced from opening the intake side. Don't confuse CREEP with SPIKE. While both can result in a lean condition from too much boost and cost you an engine, they have two different causes... and two different cures.

Ok cool, good to know! Thank you!

If the wastegate is capable of holding the turbo at 10 PSI, then yes. However if the wastgate cannot bypass enough exhaust gas to keep the boost down (ie. it is too small) then no.

The wastegate on the stock twins is frequently too small for a 'full exhaust'. It can be ported, but it's internal so you have to remove the turbos to do it. On my street driven car, with the noise, smell and potential creep consequences I prefer to keep a cat (Hi-flow) on.