floz

I've read through the tutorial here several times, and since I have my engine out for my very first rotary overhaul/rebuild, I've almost decided to go for it.

My two main concerns are reliability and fuel mileage. As the stock exhaust manifold was designed with an air pump in mind, I'm a bit wary of removing the air pump.

Could I keep my stock manifold for a while after removing the emissions equipment, or should I start shopping for headers immediately?

Also, should I see an improvement in fuel mileage from clearing out some of the vacuum routing mess and the air pump, or will it decrease my economy?


Aside from figuring out Mazda's funky names for certain parts, I'm loving this engine more and more as I take it apart.

dantheman

iTrader: (4)

My car ran a bit better, and got slightly better mileage after I pulled out the rats nest. I was running the stock exaust for several months before I came across a RB header. It isn't the header that will cause you problems, it is the cats. They are designed to have that air input, and will clog alot quicker without it.

If you are that concerned about it, you can swap out the main cat with a Magnaflow 4" round muffler. Just have your local shop weld 2 plates at either end of it exactly 18" apart, and it will be an exact swap.

harder 7

Let me get this straight -- "swap the main cat out for a "4 muffler"???--
that might just be the worst idea ive laughed at yet.
The stock exhaust consists of 3 cats, so why would you replace the "main" cat with a "4 muffler, especially when the stock exhaust diameter is "2.25 in.??

Hey Floz be on the lookout for people w/ bad advice...
1. the air pump has nothing to do with the oem manifold.
2. the air pump sends air to the air control valve- then to the cats- nothing more.
3.your 2 main concerns are mileage and reliability- what about emissions legality? if legality isnt a prob for you then I highly suggest removing: the airpump, ACV, Cat conv., and all the belts, bolts, and brackets connected with them.
4. you can either replace the ACV with a $15 block off plate- or just cap off the ACV hoses and leave it.
5. once you remove the airpump youll need a downpipe or headers and midpipe cuz youll burn up a cat with out the o2 from the AP. Rotary P sells downpipes for way less than a RB header sys. $100 and you can use the manifold with it.
definately be more reliable- better mileage- noticeable performance and lose a big chunk of xtra weight. The stock muffler is also a heavy ****. if you need any help hit me up- Im in Dallas also. good luck.

trochoid

iTrader: (6)

You are new, and I don't know what your experience is, but before you go bagging on people, maybe you should read up what has been done for cat replacements. The stock log manifold does a most of silencing on our rotarys, the cats do some, but create more of a restriction than anything else.

Once headers are installed, additional measures need to be taken to quiet the exhaust down. Installing a 4 or 6" outside diameter Magnaflow is one method that works well doing this. When installed in place of the main cat, they are also known as pre-silencers.

There is a very long thread on building a quiet exhaust, I recommend reading it.

trochoid

iTrader: (6)

Floz, as a side note, removing the emissions and air pump will have no affect on the stock exhaust mani. If you remove the cats and add a straight pipe in place of the 3 cats, the exhaust note is quite pleasant. It's when you add headers that the exhaust gets obnoxious, tinny and loud. Then it's time for a pre-silencer/mid-muffler.

harder 7

Are you serious? New? Experience Levels? Bagging People? Okay then show me the part where dantheman said "Presilencer" instead of "MUFFLER". Go ahead, show me. Oh thats right you CANT cuz he DIDNT. I recommened reading it again as a reminder to yourself not to put your foot in your mouth while claiming seniority. FYI if your in need of a BONEZ HFC w/ Psilencer I got an extra one Ill sell ya- I make special deal for you. I have no use for it as Im using a BONEZ downpipe which also happens to have a Psilencer attached to it. Personally I dont think you even sound like a REAL RX-7 owner with all your talks of Recommended reading of extra long threads of how to make a rotary xtra quiet and xtra safe. RX-7's are made for people with ***** and style. People who Redline a 8000 in every gear, religously. People who arent bothered by xtra SPL. People that enjoy BRAAP, instead of just AARP. If its too loud, you must be too old, pops. Adjust hearing aids accordingly.

harder 7

Wow trochoid your a genius! oh, wait a minute all you did was Playjorize my response to FLoz! Thats messed up man, especially given your extensive experiense. nice try.

Hey Floz be on the lookout for people w/ bad advice...
1. the air pump has nothing to do with the oem manifold.
2. the air pump sends air to the air control valve- then to the cats- nothing more.

t_g_farrell

iTrader: (1)

Hey harder_7, do us all a big favor and STFU!

harder 7

t g. I guess that stands for tough guy? you need to watch what you abbreviate to me tough gay. DSFAMF

trochoid

iTrader: (6)

harder_7, you are off to a very poor start as a new member on the forum. If you wish to question my skills or ownership of a 7, read the thread at the bottom of my sig. If you have the skills, or knowledge to build such a car on your own, post it up.

Of your 12 posts so far, 2 had erroneous advice, several more have an attitude that will not get you far here. We are a friendly group and attitudes such as your's don't last long.

Take a chill pill 'dude'.

rOtAryIsbEttEr

if you want to drive to texarkana, harder_7 id be willing to sell u sum pot. its good stuff. u need soemthing to mellow u out

dantheman

iTrader: (4)

Heh, I didn't see that this thread was bumped up.

Sorry, I ment pre-silencer, but since they are sold under the name muffler I figured it would cause less confusion for the person asking the question.

The muffler or pre-silencer is 4" around, but only has a 2.25" pipe running through it. This makes it so you keep your exaust velocity. If you get a set of flanges (the universal ones work) and weld them on exactly 18" apart it is a direct swap for the stock main cat.

You could easily make a down pipe to replace the two precats (and the main cat for that point) but you will see little proformance gain. Might as well spend your money on something that helps a bit.

The setup I am running works great for me. I don't like bugging everyone in town with loud exaust noises. I do like having a car that starts every time, and doesn't give me any issues. With the setup I have, I get that and a bit more power.

darkfrost

iTrader: (1)

Just to clarify to anyone else who might be reading and wondering what the 4" Muffler dantheman's referring to is...

here- http://www.hottexhaust.com/AluminizedRound.htm

t_g_farrell

iTrader: (1)

I think you better get back on your meds, they've worn off.

Kentetsu

Harder 7- Show respect where it is due and stop splitting hairs. Yes, it is a muffler, and yes, it is being used as a presilencer. Trochoid is a very well respected leader of this section, and has helped many owners solve their problems. When you show up as a new guy and start slamming people like him, I don't care what kind of experience you have, you will still come out looking like an idiot. And with that kind of attitude, we don't really need your experience (we have plenty already, with better attitudes to boot). Chill out and try again dude... Also, there was nothing at all wrong with the post by Dantheman...

dantheman

iTrader: (4)

Yeppers! I havn't had enough sleep to find the dang link to that sucker. I appreciate it.

harder 7

Rotaryisbetter- I appreciate the offer but txrcana seems a little far for a sack. anything I need that I dont already have is just a phone call away, unless...... do you have a sister? just joking

dantheman-Thanks for clearing up the situation w/ maturity- my intention wasnt to be a dick or to harass you or anyone else. However Ive been a member long enough to know that lots of members post bunk advice or just plain talk out of their Brown Eye! Thanks again. People are cooler in Texas anyway.

Trochoid- I like you,you make me laugh. You actually took the time to read my past posts so you could work up the nuts to challenge me to a duel of knowledge and skill. It matters not what your opinion of me, my past threads, my skill or experience level, or the amount of time that YOU think Ive been a member. So what? Ive been a member since long before your join date of apr 04-but so what who cares? Seems like you want to have a who's pecker is bigger contest w/ me. OK OK I get it- you have 5000+ posts- youre one of the founding fathers of rx7club-you have more skill and knowledge than any mere mortal should posess- WOW youre Hardcore 'dude'- a legend in your own mind. its pathetic someone with so much skill and knowledge would spend so much time focusing on BS. A piece of advice for you- spend less time squabing on the computer and more time driving your RX-7. Later Soca Whey!

Kentetsu

Obviously a slow learner....

Jozay721

hey i srtipped my emmisions yeaterday and noticed my choke and my cruise dint work, i knew it was gonna happen but how can i get the choke back, or what do u guys do when u start it, cuz i hate holdin the choke open with my hand. yeah i also noticed better gas mil;eage and my exhaust sounds a little better, now i love the rb setup with a cat.

gsterror

Down here we remove our chokes to save on clutter. Just bring the throttle down a little as it warms up. You'll learn when to let off. Keep it at 1200 or so (A little less than double idle).
Cruise, IMO never had a place in an RX7 anyway.

dantheman

iTrader: (4)

I don't know if my cruise worked or not when I was done with it. It is hanging there, but I never use it.

Your choke should work though. I use mine even here in 100 degree Texas just cause I am too lazy to just use the throttle. :P Check all the cables to make sure you didn't disconnect anything by accident. I do belive that it is manualy done by a cable, so a rats nest removal shouldn't have touched it.

dantheman

iTrader: (4)

If you are ever in the area, stop by. It sounds pretty good and runs nicely for the stock muffler and the pre-silencer.


btw, I have been here longer then both of you. :P

Jozay721

well my choke works it just doesnt stay like usual, but w/e i just pull it manually, also sometimes my car will crank over like 30 secs before it actually starts and when it does it want to shut off until i touch the gas,sometimes i got to try more than once. i used to just turn the key and start it easy, i dont know but im happy without the rats nest anyways.

dantheman

iTrader: (4)

That is very odd. There is definatly something wrong with your carb then. Make sure all of your linkage is correct. Might have just bumped something hard enough to upset it. Hopefully someone will chime in with a proper answer though.

trochoid

iTrader: (6)

If the choke doesn't stay out on it's own, check the temp sensor on the backside of the waterpump housing. That sends a signal to the ecu that in turn controls the magnet in the choke.