aaah i love this forum

 

For starters, the Y in an FC's dual exhaust is far from abrupt, with the pipes diverging at an angle less than 30deg. And if you really did read what I posted, you'd know that I never said the Y doesn't cause any restriction. In fact I mentioned the restriction it causes numerous times. I also said that a well-built Y is less restrictive than most people tend to think. I know this because I use technical manuals at work that show how to calculate the losses in duct and pipe systems. I also went to great lengths to explain that the extra restriction from the Y is balanced out by the fact that if the pipes are sized correctly, the restriction caused by two pipes will be much less than the restriction caused by one. Some people have this totally unfounded idea that the Y is such a huge restriction that it doesn't matter what you put after it, which is a load of BS.

The other point I've repeated again and again is that pipe sizes are more important just the configuration. If you truly believe that "single flows better" no matter what, then you must believe that a single 2" pipe flows better than a 3" pipe that splits into two 3" pipes. But that is obviously not the case. A system that consists of a 3" pipe splitting into two 2.5" pipes will flow as well a single 3" system, but not nearly as well as a single 3.5" system.

It will not rob you of power unless you install or build a crappy system. The tiny bit of extra weight is not redundant, because it results in far more effective muffling.

If that's the best engineering argument you can come up with, I don't think you should be calling others simple minded...

Go back and read what rotarygod said about muffling. Most people would never notice the 1% (or less) difference in the car's total weight, but the lower noise level could be a difference between ticket and no ticket, particularly for an NA.

Please stop flogging this dead horse. You're blowing it way out of proportion.

Exactly. If your exhaust has a Y that causes a lot of restriction, you need to find a new exhaust builder.

I guess you haven't seen a lot of high-power NA rotaries. You can easily run a 3" exhaust if the collected part of the system is tuned properly. Once you're past the tuning point, you can go as big as you want. The reason people don't is because most collected rotary exhausts are not properly tuned.

Nobody ever said it could. See above about the horse...

 

NZ has got it all figured out! Listen to him.

 

Amongst a bunch of other stuff you said I don't agree with...

You did, actually. Repeatedly.

 

...screw it...

This is all opinion. I think a 30* "Y" is pretty abrupt. You don't? Fine. It's opinion.

See above statement, and you never answered my question.

I'm sorry, tuning has to work around set perameters. You can not set a particular tune then change things around at whim.

See previous post.

 

nz wins!!!!

however its news to me that 3" exhaust would be beneficial on an n/a. they need some restriction (smaller diameter tube) to develope decent torque rigth? or are these setups just going for top end?

 

Depends on an unlimited number of variables. Displcement, tune, where you want the power, aspiration, etc. In a sense, the exhaust needs to be restriction free. Only thing tubing diameter really does is govern how fast and how much is flowed...which is where the tuning comes in play. You have to tune to a set goal. You figure out where you want the engine's power to be fully utilized and build an exhaust that will flow the most gas at the high rate possible at that specific point.

But the exhaust is only one thing in what can be a REALLY big picture.

 

I'll put it like this, though...if you're putting down the kind of power to utilize a 3" exhaust on a NA 13b, you probably don't need any advice from any of us...

 

Prove it. Show me where I said (or even implied) that "a Y could be made adequate enough to perform as well as a straight pipe" (your words). Show me or admit you're wrong. If you want I'll find all the times I said it couldn't. A couple are even in this thread.

My "opinion" is based on my training in mechanical engineering and my experience as an HVAC design engineer. What's your based on?

What's funny is that you think a Y with an included angle of 30deg is abrupt, yet you say the bend in a single system is "smooth and fluid", despite the fact they're about the same shape. Look at this pic of the Y in the RB system. Looks pretty smooth to me. How is the change in pipe angle at the Y different to the bend in a single system?



WTF are you talking about?

 

ONly once in this thread did you imply that it couldn't. You've said countless times that (all else being equal) a "Y" pipe "could" flow as well as a single.

You said a "Y" pipe doesn't have to be abrupt. I'm sorry but sticking a splitter right in the path of movement is "abrupt" in my opinion. In yours, it is not. What does that have to do with your experience as an HVAC design engineer?

Applied knowledge, experience, research, and education.

A single pipe with a smooth fluid bend does not have a splitter stuck right in the middle of flow.

you said...

You have that backwards. You can not set a vehicle to run a particular way with a particular setup and then go altering things and expect it to still all run in prime condition without re-tuning...or I guess "you" can expect that, but don't tell other people that they can, too.

 

I asked you to show me where I said that, so put up or shut up. I have never said a Y flows as well as a piece of straight pipe. I've said a dual muffler exhaust system can flow as well as a single system if sized correctly. Totally different. Stop making **** up in a lame attempt to salvage your argument.

Well the engineering data used to calculate pressure drops in pipe and duct systems says your opinion isn't worth much.

Knowledge of fluid flows (air in ducts, water in pipes, etc) is a fundamental part of HVAC design. Pretty obvious really...

Who mentioned altering anything? Not me. More made-up ****...

 

People peolple let's go a little easy huh!

I think it's time to put this to rest once and 4 all.........someone write MYTH BUSTERS on the discovery channel and let them take care of this he he.
Would be VERY interesting to watch! I'm sure all of us would be glued to the tube if it ever did happen to make it to the show. ha ha

But.....my personal pref.....I like the look of a SINGLE with a nice slight angle of the muff and other whole patched up.

 

You just said it again. I'm not trying to salvage any argument...

clever

That doesn't change opinion...

Read what you wrote

But, whatever. You got at it how ever you want to.

Have a nice day

 

Way to get butt-hurt over the internet.

 

You guys sure know how to turn a mole hill into a cluster ****.

 

lol

 

I still hope he has a nice day

 

Said what again? WTF are you on about?

 

Sorry...I read that wrong. You said "if sized propperly"...which I can agree with in some ways and disagree with in some ways. Several times, though, you've said that if everything else remains equal (ie, tubing can displace same volume, mufflers same volume, etc) a dual catback would flow as well as a single...or that's the way I understood it.

...I may have misunderstood you. Which is why I asked, repeatedly, if that's what you meant.

 

Single exhaust:

less weight
no obstructions in exhaust flow/straighter exhaust flow path
leaves empty gap in stock rear bumper
looks ricey


Duel exhaust:

more pipe volume for less exhaust flow restriction
better front-rear weight distribution
looks more intimidating
its what the original RX-7 engineers designed for




Im going with duel exhaust

 

i say dual...but both of them together in the center...kinda like a viper gts..

 

this is just my .02, but I am currently going to school for nuclear power for the navy. All we do in a reactor plant is move water, steam, and heat to make power (don't worry I'm getting to my point). we have to take a class called heat transfer and fluid flow. Exhaust is a fluid, so all the same priciples and properties apply. what you put into the pipe is obviously goin to come out. With a single pipe, you have less bends, but Mazda made the car with 2 mufflers for a reason. That reason is that if you have a 2 exits instead of one, you can dispel more gas at a faster rate then trying to cram it all in one pipe. I would preferrably go with duals, but I don't make enough to make my own system. no matter if you run N/A or turbo, your car will benefit from a free flowing exhaust. N/A's just need a little backpressure. my point is that duals are better, because you have more room at the y pipe to move more gas, which makes more power.

but that's just my take on it.

 

1) an exhaust system is only as good as it's wakes point.
2) a single pipe could flow just as much as a dual becaust teh piping is usually bigger, after the Y duals usually decrease in pipe diameter

 

If I'm sounding annoyed, it's because I hate being misquoted, whether delibeately or not. I've never said anything about "tubing displace the same volume" (WTF?) or "mufflers same volume". I don't know where these ideas come from. If you're going to quote me, quote my exact words, not your interpreation of what you think I meant.

It should be pretty obvious that to directly compare single and dual muffler systems, the mufflers have to be of the same basic design. If you replace a dual system that uses restrictive triple-flow mufflers with a system that uses single a straight-through muffler, or course it'll flow better.

 

^ditto. It's all circumstantial.