telephoto

i bought my 86 NA from the original owner at 100K miles still sporting all stock equipment. soon after, i had my fuel injectors changed to solve a major hesitation problem.

a couple months later my stock pre-cats went so i went to a local muffler shop and had them take out all three cats and put on a straight pipe to a single magnaflow high-flow cat.

the stock y-pipe looked okay from underneath, but mufflers were pretty bad already. both were left in place. the performance increase and response became amazing and the whole thing cost about $250. it had way more power than ever before. it was low, deep & throaty with a sharp intimidating note. but as i blasted down the freeway in joy that day, my mufflers were busy falling apart.

a day or two later i suddenly noticed a loud flapping coming from my muffler. i pulled over and realized my muffler tip on the driver side fell off. now i can look into the muffler housing and see what looks like a huge, rotted hypodermic needle. its now almost a week later and its so loud i wince when i pass cops.

SO...

I want to replace both mufflers & possibly the y-pipe.
no glass packs/huge ricer shitholes
Looking for something cost effective.
(read "under $350")

since i feel like i got such a huge performance boost with the
stock y-pipe/catback/muffler system paired with my
new straight-pipe to maignaflow main-cat to super mario warp-tube.
I dont know what the f*ck they did to connect the straight-pipe to the exhaust manifold, but...
IT REALLY DID FEEL QUITE AMAZING FOR ONE OR TWO DAYS.

So now I'm thinking I want to use stock specs for the openings and y-pipes fom the main cat all the way back, that i may ask them to fabricate. I suppose they are just cutting & welding everything. also, i have read alot of posts regarding NA's requiring backpressure to open 5th & 6th ports. if i am mistaken please correct me... but will i be okay with this or do i need to wire them open anyway?

I'm thinking I'll get the same place to make me a 2.5 single to 2.5 double pipe.
then buy two decent mufflers 2.5" input diameter to 2.5" output diameter.
funkspectrum has a couple for sale but i havent checked the diameters yet.
does that match spec or is my plan retarded for some reason?

oh, and if i dont pass emissions next year i will switch to full twin-muffler racing beat street system from engine to tailpipe

=survey says=

Ex-Eg-Driver

iTrader: (1)

More pics of girl in avatar.

telephoto

actually, i was looking the specs on the racing beat (bolts directly to stock) cat-back replacement....

here is the description:

-----------------------------
RACING BEAT
1986-92 Non-turbo Street Exhaust System
This street legal, cat-back exhaust system is the perfect replacement for your RX-7 - a durable assembly offering a real horsepower gain for your stock unit. Our system consists of a Racing Beat Y-pipe and two 2-inch (OD) 304-stainless steel Power Pulse muffler canisters. The replacement Y-pipe is manufactured using 2.5-inch (OD) tubing, splitting off into a pair of 2-inch (OD) tubes feeding the muffler canisters. (This Y-pipe can be used as a direct replacement for the factory Y- pipe.) Both muffler canisters are finished with a 3-inch, polished 304 stainless tips for an aggressive look.
-----------------------------

so should i just use that as a template
(since its been thought out)

i can pick up the mufflers for $100.
so i just need the Y-pipe fabbed and everything welded together and attached to the main-cat ?
im guessing i can keep the y-pipe & billed time under $250... ya think?

basically, this is it:
2.5" to dual 2" Y-pipe
dual 2" center input mufflers with a 2" offset output (magnaflow polished stainless steel - $100 each from Jegs - see links)

http://www.magnaflow.com/02product/s...e=main&id=7430

http://www.jegs.com/i/Magnaflow/642/...1/751040|10265

...and a couple 3" custom tips to finish it off.

does anyone have an opinion?

telephoto

<a href="http://picasaweb.google.com/richie.ortiz/Margaret/photo#5086873607778487714"><img src="http://lh3.ggpht.com/richie.ortiz/Rpg0mEjyTaI/AAAAAAAAA5E/Bkvnd4XYKV4/s144/DSC_0001.JPG" /></a>

click through

telephoto

$605 just for racingbeat's y-pipe & two mufflers, right?
so whats the big difference between magnaflow polished ss and racingbeat's polished ss?
and as long as the y-pipe has the same OD on all pipes whats the difference?
if i can get this stuff done for $350, did i effectively cut racing beats price almost in half?

also, i've been driving around alot with the exhaust flapping like this. is that bad for my engine?
it sounds like a a f1 car or harley or something hellish. i passed a cop in an unmarked car on the freeway
and he floored it to catch up and told me to slow down. im sure the sound was the dead giveaway though.

please advise.

telephoto

anyone?

petex

yea, stock mufflers are garbage. you wont hurt the engine driving like that, it's just annoying, the metallic sound. if you like single, get Apex GT spec, best sound ever. i had it on my rx7 and my 240. racing beat is okay, just too expenssive. there is also ebay.

telephoto

thanks,

i was worried i might choke up the engine with improperly timed exhaust paths at the Y-pipe

(since the drivers side exhaust is broken and the pressure of the exhaust flow coming out of just the open muffler feels stronger).

UPDATE:

so, i just called the muffler shop.

they said for $250, they will replace both mufflers with...
magnaflow basic round mufflers with 2.25" openings.

i guess i could keep the stock y-pipe or get it replaced with...
2.5 (OD) to dual 2.25 (OD)

will that keep my 5th and 6th ports open?

im assuming everyone is getting caught up on looking at the pics of my girlfrind that i posted and not reading any further

Roen

iTrader: (2)

Does your magnaflow have a backpressure pick up tube? If not, how do you know your 5/6 ports are still working?

Get headers, enjoy power.

telephoto

well i guess im assuming that the 5th/6th ports are working because just before my muffler tip on the drivers side fell off, the power felt like something i've never felt in any STOCK NA rx before.

i did some upgrades, but nothing special...

only upgrades from original equipment have been:

- new thermostat & black radiator with large openings & hoses (brand?)
- KYB Gas-A-Just rear shocks (new gr2's for the front just collecting dust in my room)
- 4 new belts
- new fuel injectors
- oil change

FINALLY:

2 pre cats & main cat removed & replaced with:
straight-pipe + magnaflow $75 high-flow cat (stock Y-pipe & mufflers)
^ BEST PERFORMANCE I'VE EXPERIENCED ^

then my already-rusted mufflers started falling apart inside
and the tip fell off of one. now it is back to being suppressed and sluggish, loud, nasty & obviously illegal.

the exhaust really seems to be the key.

i have looked at the magnaflow page and i think hes doing the 2 of the (basic 6" or 7" round) satin stainless steel ones (with 2.25" OD with a 2.5" or 2.75" or 3" tip).
i dont think that says anything about the backpressure pickup tube. would that be in the muffler or would the main cat do that already?

stock y-pipe? it looks okay... no splits.

Roen

iTrader: (2)

Is there a tube coming off the high-flo cat?

rotarygod

iTrader: (1)

There has somehow been a myth passed around here for a long time that a Y pipe hurts flow. I'm not sure where it or all the other bad info comes from but it's not true. There is zero performance advantage to a single exhaust. It's really a personal choice and nothing more.

The greatest performance benefit will be in getting rid of the stock cast iron exhaust manifold. It sucks. There are some people that say a header doesn't make more power but ignorance sometimes speaks before experience so ignore them. There is nothing wrong with the Racing Beat system. It's well made and muffles decently well. It's downsides are that it is heavy and that it is expensive. You get what you pay for. It's a great system.

The true dual system from RB is also very nice for a stock or streetported engine. Very nice gains. The exhaust note takes a little getting used to though. You'll find that people either love it or hate it. I'm one of the latter. I think it sounds like a cross between a lawnmower and a Harley and even that might be too complimentary. Either way it sounds like crap. The performance gains are nice though so pick your priority.

I'm not a fan of overly loud ricer mufflers. Many are. Again it's all personal preference. I personally don't think the Apex system sounds good at all but that's just me. To me bigger mufflers sound better. They aren't raspy sounding as a larger muffler will hit a wider range of frequencies. A larger muffler will have a deaper tone. A smaller, round muffler will have a more harsh "ricer" tone. Again it's all opinion and to each his own.

In the end just replacing the stock system is going to a gain. There is no one best system though. That applies to any mods. If you are going to have to pass an inspection with an emissions test, I strongly urge you to design an exhaust system around it. You'll be happier you did.

ericgrau

iTrader: (1)

The goal is to remove restriction. Heavy reductions in the cross-sectional area of the flow and sudden reversals in flow direction are major sources. Bends, even sharp bends, are minor sources. A high flow cat or removing the cat makes the most power, second are the mufflers. Piping is minor or negligible. It's not physically possible to remove more than 100% of the restriction, and thus - while they'll all still have a little restriction left - any good brand will work fine. Also be sure to test your auxillary ports per the guide at www.aaroncake.net.

Racing Beat is popular for their (relatively) quiet but nice sounding and durable mufflers, Bonez is popular for their cats' ability to withstand the high heat of a rotary. I'm sure some others are durable too, I just forget which.

Headers don't make significant power on two-rotor rotaries, and I am ignorant and unexperienced, so ignore me :P. Instead pay attention to what Racing Beat says about their own header, right on the web page where it is sold on their own web site (www.racingbeat.com). They recommend their header on carbeurated vehicles only. Otherwise they suggest a downpipe (bolted to the stock exhaust manifold) as a more economical alternative. Both bolt to a pre-silencer and replace the stock cat.

telephoto

ok, so its done (kinda)

from the front to the back, i have...
new straight pipe from the stock exhaust manifold (both pre-cats removed)
new magnaflow high-flow main cat (stock main cat removed)
stock 2" Y-pipe chopped about 12 inches after the split section
new 2.5 inch pipes running to the new mufflers
new magnaflow oval offset ss mufflers with 2.5 tips made of straight pipe

all of the above came to $500 grand total

sounds quiet close up, but you can feel it for several blocks
its got more power than stock, but just a bit less than when mufflers were falling apart.


should i replace the restrictive 2" Y-pipe with a 2.5"one that matches the rest of the system?

should i try wiring open 5 & 6 to see if power feels more free?

i wish i had a lift so i could take a picture...

Ex-Eg-Driver

iTrader: (1)

your gf is hot. Freckles FTW~

telephoto

her brothers and dad always had some 510's and Z's around the house as well.
she planned a birthday party for me and took me and 6 friends to the pro go-kart track in burlingame and bought us all practice time, pre-qualifying runs and a super race. she's the shheee-iiiiitttt.

telephoto

so i've ruled out wiring open ports 5 & 6 permanently, because the car needs aux ports closed below 3800 RPM for happy and continued economical benefit, but open at 3800+ RPM for upwards value of rx-7 smooth signature.

i'll do the clean & lube dab test to see if they open after some "spirited" driving.

if the 5th and 6th butterflies are flapping their wings past 4000 RPM...

then maybe i'll think about replacing the the Y-Pipe from the main (and only) cat to the two muffler-input pipes to free up that final bottleneck in my exhaust system.

they just cut the y-pipe to about 14 inches on all three sides and welded it back into the system. is that because they didnt want to fab one?

here's what it looks like now:

nvrdone

the smaller sized y-pipe might be helping you. Its like a ghetto megaphone. You squeeze air into a smaller space and out a bigger space makes it move faster. I know a lot of 2-stroke guys run something like this, as close to the port as they can get they go say 2in, to 1.5in, to 2.5in, and finish it with 2in, but its all a nice transition. I'm actually going to try this right after the header.

Roen

iTrader: (2)

As someone who had both the na downpipe and the header that racing beat talks about, the header definitely produces more power.

I only wish I had a dyno run of the car when it had the downpipe on, instead all I have is the before and after butt dyno.

If you think about it, the stock exhaust manifold is just a really short header, that's tuned for power at very high rpm's. The longer racing beat header brings the powerband lower to a more useable range.

Besides, who said racing beat exhausts make the most power, anyway?