Just bought a 27,000 mile 93 RX7 with some mods.....K+N cold air induction, Blitz intercooler (not a lower front mount), Blow off valve, and Dragger Muffler. Had the compression checked and it's great, came in at above 115. The car is not loud enough and would like more power. I was going to put a down pipe and get rid off all the Cats and leave the Dragger muffler on. I was told that if I did that I would need to get the car tuned and add an aftermarket computer to piggy back the factory Ecm. I was also told NOT to run over 10 psi of boost because the motor won't last. So I would like some input on that. Also I went on youtube and listened to some cars with upgraded exhuast and they actually sounded kind of crappy. Any suggestions on removing the Cats and straight piping it (which my local muffler shop can make the pipes for me) or should I buy some type of name brand? Also will removing the Cats cause the boost to be too high?? Thanks in advance! Bill

 

The point about not running over 10psi is good safe advice. Remove the upper cat and install a downpipe. Leave the main cat. Install a boost gauge. Make sure it's still at 10psi. If it's not, install a boost controller and set it to 10psi.

Straight piping is the kind of modification that can lead to excessive boost and make your compression go from 115 to 15. That's why it's best to leave the main cat.

After you get the car running well and you know your boost level, you can consider your next mod.

David

 

you mean you have the little stock mount blitz intercooler?

I personally run an air pump and I have an aftermarket cat from rx7.com and a downpipe
you defiintely need a downpipe, because that precat can damage the vacuum lines
but there is no reason for you to contribute to smog if you don't have to
you are not pushing enough power to warrant removing the emissions, that's just my opinion

so what I would do, is get a greddy profec B boost controller and a downpipe
if you can afford it, get the rx7.com cat as well
and if you still have money to blow, get a power FC and a larger intercooler
a Vmount you can buy here in the groupbuy section for 1250$ supposed to be very reasonable
but, before you get a new intercooler, you must get a boost controller or PFC

edit:
btw, some guy on the WTB forum was paying money for used stock cats, so you might be able to get some money back as well

 

Welcome to the world of rotaries and congrats on scoring such a low mileage fd!

There's a couple of things to know about this,

The very first thing you should do before anything is buy an Apexi Power FC
You need this because you are running on the factory ecu which runs the car lean

Once you have the apexi in, then go ahead and get a down pipe...if you want to replace the secondary cat, you'll have to get either a high flow cat mid pipe, or a mid pipe with a muffler in it. your waste gate isn't ported so you can't install a straight through mid pipe

As for the sounds of a rotary, you gota understand that the high pitched scream of a rotary is an amazing sound that has been tarnished because of all the rice rocket hondas that put on fart cans for mufflers
The sound of a rotary is backed up by alot, so let her scream man, cus she's going to whether you like it or not lolol

 

Ok, I do have a boost guage in the car....forgot to mention that. Any clue what to expect from a downpipe listed on ebay...they are cheap, like less than $100 delivered. Thanks!

 

Yes it is a Blitz intercooler. It looks like it is an upgrade from stock. I am looking for a little more sound and of course more power is nice too. Thanks!

 

Does it take any special knowledge to install the Apexi Power FC, because there is nobody in my area that has a clue about these cars. What is involved with that install? Any input on those ebay downpipes that sell way less than $100.00?? Also you have to tell me what name brand and size wheels and tires are on your Silver RX7, they look amazing!! Thanks Bill

 

no special knowledge to install the Apex'i at all, plug and play installation, it simple replaces the stock ECU behind the passenger side kick panel
also do a search according to your region at the bottom of the forum home page for Apex'i tuners near to you...it is definitely worth it to take a trip and get the car properly tuned
poor tuning is the #1 reason why rotaries have gotten such a bad rap over the years
a well tuned rotary will give you less headaches than a piston engine, and a wholeeee lot more fun too

and it makes your life a hell of a lot easier if you buy an Apex'i with a commander

i would recommend buying one from rx7store.net...and then go to Autozone and buy exhaust header wrap (about $20) and wrap the downpipe

oh and one thing you also need to make sure you do is change your Air Separator Tank to an aluminum unit



and thanks a lot for complement man
they are Volk GT-U
sizes:
front- 18x9 (+34 offset)
rear- 18x10 (+44 offset)

 

IMHO, I'd rather buy a used name brand downpipe off this forum than anything cheap from eBay. Fit counts.

David

 

Ok I will see if I can find one on here somewhere. So will I not be safe if I just do a downpipe and don't do the other things suggested?? That Apexi computer with everything is over a grand.

 

You don't need an Apexi PowerFC if your boost stays at 10 psi. If boost goes up you can dial it back down to 10psi with manual boost controllers, which are cheap. I went fancy with my manual boost controller (JoeP inlines) and spent only $80.

One thing to watch for is boost at 4500rpm. If it spikes higher at 4500, install the manual boost controllers.

With the muffler and intercooler I'd guess you're on the border if you install just the downpipe. If you take out the cat too you'll certainly have major changes in boost to deal with.

 

Alright thanks I will keep an eye on it. Oh one other thing.....I saw a debate somewhere, where guys were saying up to 12psi is still very safe. Any thoughts on that?? This is a nice car and have no intentions of having to do a rebuild anytime soon.

 

The injectors and stock ECU do have mapping to support right up to 12psi, but that leaves no margin at all. The extra 2psi is padding to support minor boost control issues, so if you choose to use this you're taking more risk. This extra risk (less margin for error) is ok for some and not for others.

If you want to run more boost it is far more sensible IMHO to install mods that maintain or improve this cushion before going above 10psi.

 

Makes sense. Any suggestions on upgrades that I don't already have that will increase power?? What about removing the stock air pump and changing the pulley or any other fairly inexpensive tricks?? Also here is a dumb question but what does IMHO mean??

 

Take a step back and read through the FAQ thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

Pretty much everything you have asked is covered there. As for IMHO:

http://www.internetslang.com/IMHO-me...definition.asp

 

Thanks! I'll check it out!

 

At this point, information is your best modification. Search, read, learn... As mentioned, the FAQ thread is a great start.

You will learn quickly that fuel, ecu, cooling and instrumentation systems are very important on these cars.

Buy quality parts!.... You will save time, money and headache by staying away from knock-offs. Racingbeat makes quality exhaust parts.

 

You can run 14 PSi (the reliable limit of the twins, engine can do more with the right stuff) and a full catless exhaust. However, in order to do this you have to do some things first.

You need to pull the twins off and port the internal wastegate. You need get an electronic boost controller like the Greddy Profec B Spec 2. If your still running the stock intercooler, that needs to be upgraded. You need to get a PowerFC and when the car is ready get it tuned by a professional ROTARY tuner like Steve Kan. You will be able to run catless and safe this way. You do not need an injector upgrade on a stock motor with stock twins but might need a fuel pump upgrade and fuel filter should be changed if it wasn't recently.

I might be forgetting something so just use that as a baseline minimum. And yes all that costs money but that is the name of the game if you want to keep your motor happy.

Edit - If you want to get rid of your air pump, just get the Greddy pullies for that or ebay knockoff of it (no harm in this). However, don't eliminate the air pump unless you have removed your cat or your cat won't last very long. Also, you won't feel a difference with this power wise.

thewird

 

Thanks for the info!

 

Here is what I intend to do.....get rid of the precat for now and get rid of the airpump. At that point....depending on how it sounds, I may get rid of the main cat too. That is all I really planned to do. I really don't have anyone in my area that knows a thing about these cars, so taking it further means sending it out of state, (probably). So if I do get rid of all the Cats and airpump, as long as the boost stays below 12psi, should I be safe and not have to do anything else?? Thanks!

 

If you take the all the cats off your boost will not stay anywhere near 12psi. It will boost creep like a *****.

What your proposing will blow your engine in short order. If you want to keep it safe, leave the main cat alone.

thewird

 

Alright, then that is what I will do! Thanks again!

 

I am not sure where you live, but rx7world.net is in south carolina

anyway, I dont know what a dragger muffler is, but if you just want to change the sound there are different mufflers to choose from

 

I am in Myrtle Beach, does rx7 world tune and work on these cars or are they just an internet source for parts??

 

+1 to David and Mahjik's comments