Hi guys,

I just got my new exhaust delievered. It is a 3'' turbo back system. My engine is totally standard so I was wondering it there was a restrictor ring to make sure the boost stays at stock psi.

If there is no such thing, would it be possible to leave my standard downpipe on and just install the rest of the exhaust.

You may think this is a stupid idea but I really needed a new exhaust as the stock one was falling to bits.

Really hope you can help

 

Leave the stock main cat. Install just the downpipe and catback portion. Also keeping the stock intake will help to keep your turbos at a near stock level. I would also look into rewiring your stock fuel pump or a aftermarket one.

 

I didn't think about it like that. That definately sounds like a better Idea. I haven't looked at the cat on it. I just hope it is in decent enough condition as the back pox and tail pipe has totally falledn to bits!

What do you mean by rewiring the fuel pump? What would this do?

Cheers

 

It will pump fuel quicker (higher flow) to the stock injectors so you don't run lean and blow your motor.

There are many aftermarket ones out there. RP makes a good one.

http://rx7.com/store/rx7/fdfuel.html

 

with an upgraded pump, does that mean you need to put on a ems or pressure regulator or is it just a bolt on no need to have to control it let it work

 

Their is the possibility that the FPR could be overpowered by the amount of pressure your running with a aftermarket pump. But with the stock one this should not be a problem. So no a EMS would not be needed but it is still recommended anyways. Anything over 10psi the stock computer will not add more fuel.

 

My AFR's on stock ECU w/ my mods run still a little rich for my liking. If you were to port you're wastegate, and see if your AFR's are okay I'm sure you could run a full exhaust.

Remember this is only if your able to keep 10psi.

 

I did a nice little drawing to explain the fuel pump rewire. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fuel-pump-rewire-drawing-773489/

 

You can either make your own or send a PM to the forum name of Jyro. Basically, you make a metal gasket the same as the current exhaust gasket. However, instead of leaving a 3" opening, you size it down to help control the boost (i.e. 2.5" or 2.75", whatever will work for your car).

 

Wow, I never thought about that either. I could easily make one of these. I got new gaskets with the set so basically I could use one as a template but when I make the hole, I will make it 2'' or something. This will enable me to install the full new exhaust

I will definately look at getting a new fuel pump aswell. looks like I will be spending more on this car than I 1st imagined lol. I want to get it serviced at WGT as soon as I can aswell but need them to also sort out a fuelling problem as it is running really rich. Sometimes it is even backfiring whioch can't be good

 

Well, I installed the nex zaust today and all is fine apart from 1 thing. There was a pipe going into the catalytic converter. I disconnected the pipe and when I rev my car, I can here air coming out of the disconnected hose?? Why would there be an air hose going into the cat?

Do I need to block this tube off and will this effect anything?

Cheers guys

P.S I ended up leaving the original DP on. it wasn't rust at all like the rest of the system was. I should still be boosting fine

 

If you still emissions to deal with yes, you need to connect that hose. It is pumping air into your exhaust for emission purposes.

 

The air hose your talking about just pumps air into the Cat to kind of dilute the readings coming out of the tailpipe, If you were to smog your car the CO and HC's would be lower with higher O2 readings....all it is for is passing emissions really.

 

So, let's see.....you want to put on a 3" system to open up the exhaust. But then you want to put in a restrictor so you don't overboost. Yeah, that makes sense.
It's all about the looks for you, isn't it?

 

Have you even read my thread??!!!

The 'ONLY' reason I bought the new exhaust was because the stock one was shot for ****. It had 2 golf ball sized holes in the back box and I have never seen anything so rusty. I got the new exhaust for a really good price but I can't afford to do everything else that comes with fitting a larger bore exhaust at the moment. When I can afford it, I will sort that out which will probably be in a months time.

Right, now to the guys that are actually helping.

If I don't put this pipe into the exhaust, would it be ok to block off or would this f*** my engine up?

Really appreciate the help.

 

If you're referring to the midpipe, then yes, if you keep the main cat you should not overboost. I am running a downpipe and catback right now and at WOT it does a 10-11-10 pattern. It only goes up for a split second so I'm not too worried about it. The ECU has the capacity to handle it.

As for the restrictor plates, if you get the right sizes you can run the full exhaust without having to worry as long as boost is under control.

 

you should get a boost controler. some have overboost problems with running near full exhaust.

i presently have full exhaust and intakes. i easily overboosted to 13 psi on my first test run while i was tuning my bc. others have with fewer mods than me.

the creep issue with full exhaust can be partially or completly solved 3 ways. restrictor plate(s)/wastegate porting/single turbo. many, and i mean many, are against the restrictor plate idea. i think its cause they either dont understand it or there snobs who can easily afford a pfc. whichever avenue you take just make sure you watch your boost, especially on colder days. it will creep in high gear even with porting.

 

For whatever reason, luck maybe, my car always passed smog without the air pump and/or the return air hose to the high flow cat.

 

Thanks for that Gordon. I'm glad I wasn't the only one that was annoyed by the pointless post above

Because I have replace the cat aswell as the back section (the only thing I haven't changed is the downpipe) I think I will invest in a decent boost controller. I get payed in a few days so I will just drive her steady and then buy the BC next week. I will also check out that auxilary section aswell.

Again, thanks

 

Be wary of boost controllers. If your wastegate is being overwhelmed, there's little they can do. Boost controllers primarily work to raise or lower your boost, they do not work to prevent boost creep or boost spike.

I'd highly reccomend keeping the cat. You haven't explained, why do you HAVE to replace the cat? Is it rusty or are the midpipe and cat-back on your new exhaust one piece?

Last comment here, I don't know if this has been brought up yet or not, I tried to skim but got bored and jumped to the bottom. Being in the UK, your car is RHD, correct? If that is the case, you do not have a stock precat. The stock DP is just fine, though a little smaller than some aftermarket DPs.

What brand is your new turbo back?

 

Thanks for that. I think I am going to put the cat back on next weekend. I will then put the aftermarket DP on.

I am not really sure what you mean but yes, it is right hand drive.

I have put the 3'' mid section on and the rear end section but I have left the stock downpipe on.

The brand is embarrasingly XS power buuuut my brother also has one on his Supra and his has been fine. I checked all the welds out and they are absolutely spot on and the fit is also perfect which I am chuffed about. It is a mandrel bent system aswell so I can't see it being a lot worse than the other makes?


Another small question to ask is that the car came with a silencer insert that goes into the back box. The tube coming out of this is only about 1'' so I took it out as I thought that there may be too much back pressure? Am I right or can you not really create too much back pressure. I would like to put it back in as it is a little loud without it and I am n ot a fan of really loud exhausts.

Really appreciate all the help guys. You are great

 

The rotary has much much higher exhaust temps than compairable piston motors and they tend to blow out or melt cheaper muffler insulators.

 

So... correct me if I'm wrong, but will a PowerFC be suffice in controlling boost creep or do you still have to port the wastegate

 

A Power FC can only control boost as well as the waste gate will allow. With a stock wastegate, you'll have the same problem with the PFC as you would with the stock ECU. What the PFC allows for is tuning for higher boost levels, provided you have the fuel system to support higher boost.

Really, to run a midpipe and control boost 100%, you have to have a ported wastegate. Anything else will be risking your motor.

 

LOL! I read quite well, thank you.

You, yourself, in your initial post speculated it might be a "stupid idea." Right the first time, Cyber.

You could have easily purchased a nice flowing exhaust system that wouldn't have required you to turn around, take a step backward, and restrict this new exhaust system of yours.