rxspeed87

ok I was reading around and it seems many ppl do not really like the true dual after installing them on their car

guess the sound was loud as hell
powerband sucked hind tit
and the upper end it just fell flat on it's face
guess part of it was lack of scavenging

but I'm curious here

how would an x-pipe stand up against a true dual?


that way you have the pipes collected so each bank can help pull on the other side


and this way you do not get stuck with the stock y-pipe setup which don't think woudl be the greatest design?


any ideas or first hand experience


also if anyone does have a true dual mind giving an x-pipe a shot to see what it's like?

DelSlow

iTrader: (2)

i had a mazdatrix true dual system on my na, and it was awsome. kinda loud at WOT, and it didnt have much of a low end, but the upper end was great.

Icemark

An X pipe would work the same as the stock y pipe.

On a rotary you need to keep the rotor outputs apart for best HP. You will loose top end by any joining of the exhaust paths.

This has long been proven, since the late 70's. I don't know why you (rxspeed87) are so convinced any sort of joining of the exhaust will work to produce more HP. It won't. It has been proven not to long ago. The rotary engine just does not follow a 4 stroke piston engines exhaust operation.

rxspeed87

wasn't that is why I was asking
aslo saw a few experiences by others though yes I know haven't tried it myself so can't say for sure



and I keep trying to think about how it might work with the huge overlap on the exhuast between each side but eh I donno

xfeastonarsex

iTrader: (5)

What about with the stock turbo II? Should you keep them collected? or split it?

Icemark

The Turbo has too much turbulance after the turbine, to take any advantage for split pipes.

If you ran two turbos, each independent on each rotor there would be gains using a true dual, but you would loos so much low end it wouldn't be worth it unless you were building track car that never saw anything under 3000 RPM

SureShot

My NA had a full duel setup.
With working aux ports the whole power band went up, especially above 6500.
It is the easiest power gain on an NA.
Slightly more peak power can be gained from a collected header, but you have to know how to tune it.
The pics & a sound clip are linked in my sig below.

rxspeed87

icemark don't mean to doubt you but do you have anything to show the difference between a true dual vs a y pipe vs x-pipe setup?

rotarygod

iTrader: (1)

rxspeed87: All I have to say about this topic is that it will be the same as every other question about which works best. There are so many different "opinions" rather than "facts" that get posted on here and everyone gets really violent against others. I've stated my personal firsthand accounts with various different systems on numerous other threads in regards to this topic so I won't continue to start another debate here. I will tell you that someone here has already posted some seriously flawed bs. You'll get people on here that know what they are talking about and you'll also get people on here that don't have a clue what an exhaust system is supposed to do. It is up to you to sort through all the bs and when it is over you'll probably have more questions than when you started.

SureShot

NA exhaust - If you really want the best tune I trust this advice:
For a stock ported NA 13b you should have 3" of straight pipe from the engine that flows in to your header(or is a part of it) and that collection should happen @ 27" from the block. From there you want to gradually open up the exhaust ie... 2" header, 2.25 pipeing, 2.5 inch piping, 3 inch outlet or resonator.

1987RX7guy

iTrader: (3)

Ok I am not going to get into the fight but post up what I feel should be.

#1 The True duals do not sound like anything bad or good. If you like the sound thats what YOU think. If you hate the sound thats again what YOU think. Sound can not be made a one tone fits all thing here. Take ricers with fart cans for one. They think their car's sound good. While generally everyone else doesn't.

#2 They are not loud by any means. You could have a louder exhaust on a TII or another N/a. My bud's TII with ApexI N1's and a high flow cat can be FELT at idle. You can bearly hear my car at idle with true duals. My business partner's N/a with Twin magnaflow 3.5" tipped cans is louder than my car at 7k rpms when he is doing 3k rpms. And I am talking about VOLUME not tone.

#3 The power band does not suck at all. It is a wonderfull improment over stock. It also is better than compared to a Collected header/silencer with a ghetto fab cat-back. Neither the top end nor the bottom end are sacrificed. In fact I would go out on a limb and say that I have more low end than a turbo below 3k rpms.


#4 Scavenging is a very usefull thing when you know what your doing. But if your going to get a bolt-on exhaust they are not tuned for the MAXIMUM power you can get.



If you want max power your not going to get it legally sound wise. You should talk to some of the more knowledgable members on here for tuning strategies if you chose collected. Other than that I can't help you. But

IMO the true duals are not a crap exhaust at all. They may or may not be the best but we have no hard evidence in the real world to proove it. Only theory which would suggest that collected is better when done properly. But many run true duals on heavily ported engines which goes against the grain.


Santiago

If you want sound clips look for them they are on here. I have some vids of my car and there is another car with true duals on here with vids. Actually two other cars. One has posted here already.

Aaron Cake

iTrader: (1)

This has been covered countless times before. Unless there is somthing NEW posted, this topic is over. We seem to go through the same thing every week.

rxspeed87

I have read through a lot of the post

gues what I was trying to get at by making this post was does anyone have actually dyno papers showing what happened?

as you can see from the times of many of my post I am up kinda late

not trying to start an arguement or anything

MrDirt

Whoa whoa whoa... you do NOT want the exhaust to taper out. Exhaust gases cool and become more dense as they travel through the exhaust. Meaning they shrink and slow down. To keep the exhaust gases flowing fast, and to improve scavenging, you want the exhaust to taper to smaller and smaller sizes as they exit. This will give the gases less space to occupy, making them flow out even faster.

mazdaspeed7

For this very reason, Im not getting into it. If you want to know my opinion, search.

Icemark, do you actually have something to back up your claim? Exhaust tuning has progressed a little since the 70's... Can you actually back that up, or are you just regurgitating something you read?

Icemark

Just regurgitating and also basing it on how I understand the rotary engine to work.

And if a X pipe or H pipe worked... wouldn't RB or someone else be selling it saying look at all these gains, since many people like RB have been playing with rotary engines and their exhaust longer than I have been driving.

mazdaspeed7

The exhaust pulses, and scavenging work in general work in the same way on a rotary as on a piston engine, and actually it is more effective. The lack of valves blocking the ports allows the pulses to be stronger, and cleaner. Tuned intake and exhaust works better on rotaries than on piston engines. But all the basic principles still apply. As for RB and their true duals, its a great exhaust for a mild street car. It is not tuned at all, and therefore very insensative to changes in the motor/intake. But to make it quiet, they have to use heavy pipes and restrictive mufflers. So as the airflow goes up, the advantages of the RB true dual specifically, but similar setups as well, go down. My true duals are NOT coping well with this ported motor.

1987RX7guy

iTrader: (3)

Just goint to say some stuff here.

Racing Beat does not make the True Dual setup. Mazdatrix does. You should know that.

Heavy pipes perhaps it is a bit of weight but a small % of the overall weight of the car that could account to something as trivial as removing a spare tire from the rear. Ofcoarse if they made it out of 100% SS it could be lighter.


Do you have any proof that the RB or HKS mufflers offered by Mazdatrix are restrictive? Both are Straight through. I know the RB cans are straight for a FACT by my own methods. I stuck a hose length in the tip and it came right out the other side where it hooks up to the rest of the piping. The HKS should also be straight through if I am correct. The pre-silencers are also a straight hole with a gun silencer style design.


Santiago

PS-If you ever dyno the car get us those sheets with a before and after will ya. I am interested in how much more power you can yank out of it with that tunning. Exhaust tunning that is.

mazdaspeed7

Brain fart. I know Mazdatrix makes the true dual. Oops.

I really thought the RB mufflers werent straight through, but I guess Im wrong. But I still believe its very theres a bigger trade-off between noise and power with true duals than collected.

I may have come comparison numbers next week, but we'll see. At best, i only expect to show how bad my true duals were chocking down my motor.

1987RX7guy

iTrader: (3)

Yep go on their site. It states it clear on their mufflers link that it is a straight thorugh design.

Icemark

No the exhaust pulses do not work the same, they are radically more intense and exit timed almost exactly the same as well as...

and you know what, I am not going to post again why they don't work the same... I have done it too many times. Believe what you want. If someone wants to waste thier time and money, its not my place to tell them what they will find.

mazdaspeed7

How does a 180 degree difference between the pulses from the 2 rotors qualify as the same time? Thats EXACTLY how tri-y headers on a 4 cylinder are tuned...

And why arent you going to post here again? I challenge you to prove your beliefs.

rotarygod

iTrader: (1)

All I have to say is that if the exhaust pulses are "radically more intense", which they are, then shouldn't proper tuning by collecting yield radically better results? I know the answer but am just not going to get into it here.

You guys better watch it, Aaron Cake is going to shut this down pretty fast if this keeps up!

rxspeed87

yeah come on guys keep it clean

hey rotary god I just noticed how many post you have

rotarygod
No Life.

Status: Offline!
Registered: Jul 2002
Location: Houston
Posts: 1320

kinda like that number for soem reason

but does anyone have actual dyno sheets from them?
does anyone actually any proof other then ideas on if this works?


and this is for icemark and mazdaspeed
yes the rotors expell gasses 180* apart from one another.
the thing is though they also have a lot of overlap from one rotor to the other with the design of them

the exhuast port doesn't really ever close just opens up to the next chamber

SureShot

OK - Here is what we are dealing with.

You guys pipe it any way you want: