RB TRUE DUALS vs APEXi
 

1)What Should i get..RB true duals?

2) Use 2 to 1 header with custom 2.25' straight piping into a single apexi n1 muffler?

Which will make more power? What is the disatvantages and advantages of both of these exhaust set-up's?

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I curently have truedual system on my S5 rx-7.. Sounds nice and quiet, and pulls like a bat out of hell.. I don't have any expereince with a Single apexi exhaust though.


My system consists of road race headers, two maganaflow 22" presilncer, rb rear mufflers.

I think that's because it doesn't really matter which you choose.

If this is for a street car, I suggest that you select a kit that is already proven to work. Too many people try to get slick or go cheap with a custom exhaust that doesn't work correctly because of poor design. For example, pre-silencers are ignored, turbo mufflers are used instead of the proper NA mufflers, header lengths are not correct, pipes are too large, etc. While a kit may cost a bit more initially, it is less expensive than screwing up a custom design several times until it finally works.

#2 will make your eardrums bleed, and I don't see it making any more power than the RB exhaust (may even make less)

I put together a long collected 2" into a 3" and then the Apexi N1 Muffler... Yes the LARGER one.. mediocre to decently ported 88 6-port.

It is the LOUDEST thing I have ever heard. It is actually louder than it was with the header alone.

COuple factors... it is long collected.. and hence tuned because I made sure the length was correct.. not just "hmm that looks like a good spot so I can go around the axles..." Nope.. It is two pipes under the rear subframe etc.. mandrel plumbing etc etc. Into a 3" collector. THen into the N1.

There is a guy that is from canada with a 12A bridge ported formula car that has a full body... I think it is a DSR car. It is TERRIBLY Fast... Mucha? mor Mouchha? SOmething like that.. Anyhow.. everyone comments on how loud this thnig is. The N1 on my 91 is MUCH louder.
My kids LOVE IT... I dont like it so much. I CANT drive it after the sun goes down for fear my neighbors will burn down my garage. My wife hears me over a mile away when I am coming home, or leaving.

Evilaviator laughed at me when I bought the muffler... but I put it together for the EP car to test its efficiency.. and its tune.. And YEP.. it is VERY well tuned. The N1 is a megaphone inside.. from 3" to 5".. Yep it pulls like a freight train. Yep it appears at this point to be much more efficient at scavenging than many other designs I have seen or used.. (Mufflers, and collection point mostly)
HOWEVER..... Not soo much for the street.

IF... IF I was going to do a street version... And tuned.. with performance was the point.. I would go long collected... ~112" with a muffler like a Ultra Flow.. or any other ceramic packed flow through muffler in 3" And a 3" down Spout on it.
The the kicker to keep it quiet enough? Do like RB does.. but two SS packed mufflers that are 2" in/out bullet style/cherry bomb style and put them int he runners that are going back from the uncollected header.
You can run it at 118" with the two cherry bombs and a street tuned motor because the pre-silencers will effectively increase your pipe lengths because of the dampened area in the mufflers. So the pulses/engine will "see" longer runners than are there.

That's because you put the turbo N1 muffler on your NA, lol.

Also, I think you may have been trying to beat out Capn' Wankel for the title of the loudest RX-7 in Florida. :)

HA HA HA HA

Maybe we should have a DB contest... Like they do for stereos.. LOL

NOT

my friend pat has a TII with 3" piping to a Apex'i N! muffler.

sounds mean, but is kinda loud...i dont mind it.

he dosent have cats also...and shoots flames like its his job :p:

yea i want the n1 mufflers that come on the apex duals for the fc n/a...there big!

N1's suck balls if you have any self respect for you and your street car. If you have a race car...great grab a 4" muffler and go make your tuned single.

Otherwise put the cash down for a true dual setup. Mine are closing up on 50k miles and still sound good(with the exception of a small exhaustleak due to a bad gasket) Large mufflers make you look like any ricebox/shitbox driving kid. The RB mufflers are atleast dignified looking and sound awesome.

... man, this gives me all sorts of bad ideas that would piss off the neighbors (even more than the race car already does!)

well i wanted 2 know the advantages and disavantages of both set-ups like power wise and stuff..not peoples opinions about how n1's suck or rb sucks...

his N1 is a single...not a duel. and if fits perfectly with the car....

if i get his permission ill post a pic of it shooting flames so you can see it..that is if you guys want me to though :cool:

YEA! i wanna see.but im starting to lean towards the duals now and i was wondering if any1 has that sound clip of the rb duals...i heard it before but cant seem to find it.. :(

I build a true dual system for my old FC, sounded great and still it was quiet due to the stock mufflers. I have driven a collected 2½" freeflow system. Highway cruising required earplugs :(

http://www.wankelkim.net/rx7/dyno%20(2).AVI

sounds pretty nice while driving...but the video i was actually looking for some1 2 post was a sound clip of the duals at idle then revvin it...

http://memimage.cardomain.net/member...75_32_full.jpg

sorry its so dark, but maybe you can make it out...its the only one i had.

nice flamage :bigthumb:

SWEET! i wonder if that hatch got scared :bigthumb:

I'll post a sound clip of my car and its TD's

www.aztechrotary.com/tduals.wmv

right click/save as.

I've got n1 duals on my TII. They look and sound awesome. Chris at Rotary Performance and I were talking and he even said that he thought the were the best exhaust made for the FC. 1987Rx7guy if you think they don't look good you are gay.

i like my apexi n1 duals on my NA... i dont even think there loud

OMG i want the rb duals now...

I am glad to know that I have no self respect for myself and my car. I totaly disagree with Santiago on the N1's and always will. I had a RB downpipe and presilencer with a N1 single and it sounds great, nice deep tone they aren't nearly as loud as everyone says they are.

I'm quite straight. I don't like the N1's because they aren't very good. 4.5" tip with half the size piping? give me a break. And I hate that exhaust note. Its just like any honda boy with their side turned exhaust can get from their N1 knockoffs.


I love the idea from a business stand point. Apex-i really struck gold with that one.


I can just hear that business meeting, "Hey I know lets make one cheap shit fart can muffler and slap it on EVERY fucking car we can find" and probably went on to, "and we can charge them insane prices for our shitty muffler design which is universal anyhow so we can mass produce it on the cheap side...."


The execs probably gave the man a promotion and raise with that brilliant idea.

he he
Going to work ATM.. but figured Id throw this out there for all the "True Duals" Fans.....

What is being done to Tune the exhaust pulses from the engine???

Are the Long and short collected systems collected at specific lengths cause joe-bob wankel worker decided it looked pretty there???? Or is there a better reason than looks or sound?

May want to think about your un-collected system, and why you want it? Sound? They do sound nice with the different pulses etc.
Performance? Hmmmm... Is it tuned length wise for your motor? Is it ported or not? Is the system made for ported or not? DO they say put it on anything and it will work great?

If you want it cause its Cool... Sweet.. No problem... If you want it for the superior performance... Well.. then I have to say you may want to research exhaust a bit.

The exhaust pulses (I am NOT going to go into detail much cause I do have to go to work LOL) The exhaust pulses in a rotary.. and a 2 stroke are critical to making power. IF the exhaust is the proper length and Tuned properly for the motor and a specific power band.. the exhaust will get proper scavenging. If not you can actually have a reversion wave hitting the exhaust port when it is trying to exhaust... and if it is timed incorrectly it will actually cause more problems than gains. Now... a thermo reactor to true duals setup is going to be better. THe thermo reactors are the suck. BUT... a long collected.. or short collected.. with proper tuning, and pipe sizes etc.. should out perform a slapped on true duals.. UNLESS... it by luck happens to have the correct length piping on the un-collected so that the pulses happen to create reversion waves when the exhaust hits the air at exactly the right time...

But then again... you dont have the OTHER rotor helping, by creating its OWN reversion pulse to act in conjunction with the 1st rotors pulses..

Anyhow.... If you want it cause it sounds good.. Sweet.. Go for it. If you want it for performance.. well.. go for it.. but it may not be the best method for performance.

(Picture all the race rotaries at the 787B level and below... there is a reason they have collected headers..)

Off to work

1. TItle of the thread= RB TRUE DUALS vs APEXi
2. True duals won't be improperly tuned because waves can't smack each other.
3. With a long primary you normaly have a nasty loud exhaust because of the lack of space for muffler(s)
4. The N1's ARE NOT TUNED to anything but stock.
5. The duals are tuned for a stock engine but peak power comes at 7k rpm unlike stock which is 6500?



I have close to 50k miles on my Mazdatrix uncollected duals and they are still kicking. The only rust is from bad scrapes from shitty roads around here. They come with some ceramic looking coating that keeps most everything spiffy. The mufflers are actually worth their price unlike N1's. The Duals even activate my S5's auxilary port and VDI systems without the need for an air pump or SAP. The Exhaust tips are normal sized not needing to add to the "i need to compensate for my inadequacy" like the N1's. BTW my friend's N1's did rust but it may have been the road salt. Either way N1's piping got rusty while mine is just scratched up. If he has a full blown purpose built race car then by all means get a tuned exhaust without mufflers and gut the shit out of the 7. But otherwise the duals pretty much own everything out on the market. Great quality, good looks, good sound(to most), and comperable price to piecing together a similar quality collected setup.

But if you bothered to actually read the first post, you would have noticed the initial criteria. ;)
"1)What Should i get..RB true duals?
2) Use 2 to 1 header with custom 2.25' straight piping into a single apexi n1 muffler?"
Note that #2 describes a custom short-collected system, not the Apexi N1 catback.

Even in the case of an independent pipe, the length and inside diameter of the pipe will affect the tuning. See the tuned pipe here on a 1-cylinder engine, where the tuning obviously has nothing to do with scavenging from another cylinder (because there isn't one, lol).
http://home.fuse.net/MDdesignsRacing/pipe.htm

A long-collected primary exhaust system usually mounts the muffler in about the same place as stock. My 1Gen RX-7 had the RB street port long collected exhaust, and it was extremely quiet. Maybe too quiet, lol.

Once again, I think you missed the custom specification of the N1 system as indicated in the first post.

Yes.

The Mazdatrix uncollected duals are designed only for stock-ported street engines. Uncollected exhaust systems have so far proven unsuccessful in higher hp applications.

The N1 mufflers are actually sized correctly. It is the customers who sometimes screw up and put the turbo N1 muffler on an NA, or vice versa.

I would reply to 1987 dude.. but Evil said it all... soooooo

yea all this talk now about how the duals dont give as much power as they seem...i think i just might run the custom set-up...im not sure yet

The duals do give the power that they seem, and actual results reported by members of this forum accurately match the performance indicated by the Mazdatrix advertising. It's just that you need to keep in mind their intended application, which is a street FC with a stock engine. Sometimes people on this forum are looking for the "best" exhaust system that performs better than all others under all conditions, but no such thing exists.

As for the RB true dual exhaust, it's rather new and therefore does not have the user base on this forum to verify results or compare them to other brands. I would imagine that the RB setup performs somewhat like the Mazdatrix system.

Quite honestly, nearly every custom exhaust system attempted by amateurs on this forum has resulted in sub-standard performance. I think you are better off just buying a bolt-on kit that you KNOW works, rather than guessing on your own and/or trying to go cheap.

well if i get the piping and see it welded on it "should" work properly with good power gains...all my freinds have custom and its just fine...but im just worried about ports opening with the straight pipe...but i have the rb header and presilenser and they open fine and i have no cats...cause of the header so it shouldnt be a problem right? And straight pipe gives u more power so the custom might be a win win situation maybe? :confused:

Ah I didn't see the part about custom setup.

And the "not inproperly tuned" statement on my part was about having one exhaust pulse hit the one from the other rotor. That is kind of impossible with separate pipes. I know that you can still work with pipe diamiters and lengths. Most motorbike people know this anyhow. :) I'd still say go with the duals if you plan to drive on a road.

And don't long primaries eliminate one muffler? That means you cut the muffling cap. by half if not more because you might not use silencers.