I agree, what I meant was just a single pipe as in no muffler or resonator.

 

- just got shivers....

 

Rick: Through teaching? I've seen sponsors properly defend their position w/o being dicks. Even if your opinion is slightly more accurate than mine, HyperSprite's, and the rest of us, you lost more than you gained. That doesn't mean I won't do business with you in the future, but I certainly don't think much of you as a person.

 

Regardless of platform, your basic premise of "you need _____ (fill in with whatever) backpressure" is incorrect.

You can write as many words about it you want but if they are not correct, more words wont help. The need for backpressure is a myth and you are simply perpetuating it.

Chris

 

Quite honestly - since you and Hyper stoppedposting - the junk in this thread stopped, and now you come back to start again.

1 - I didn't lose anything - if anything, I actually gained and you lost. I'm sure members will think twice about getting invoilved in certain conversations when your on threads.

2 - There's no business to do with me. not sure where you get that from. If you mean Fast Intentions - well I don't work for them or profit from them at all. I'm just a customer who helped create their catback system.

It doesn't matter how you think of me as a person - really it doesn't. The fact that you came back to further expand on what nobody else here wants to deal with, really shows your ways.

Perhaps you should just gracefully accept that you didn't have all the information, instead of blasting your way into a thread trying to be God...trying to show someone up with improper information.

Really man...back off already...just say " hey, I learned something, and thanks Rick!"

Your the one with the problem here...have you even looked at your first post in this thread, a response trying to call me out (when your wrong), and you expect someone to be NICE to you??? ..yea...OK!

Rick

 

And you, dude...what have you ever done, other than read some web articles and quote them word for word to make your point? Whether that point is wrong or not?

So - for the 3rd or 4th time, lost count, what have you done R&D-wise to know any better than what you have read somewhere?

Experience does count...do you have any? If not, that's cool..but don't keep doing what your doing. Like Undrgnd - either you learn something or not. The backpressure debate has been around for a while.

Like I said and others - why don't you actually go and try it for yourself, so you can realize that SOME backpressure is not only needed, but inevitable.

Other than that...

 

To all -

I have no issue admitting when I'm wrong - but when I'm right and know it, and have experiences to prove it - I am PASSIONATE about what I do know.

Hands down...this is a learning place, for many. When I know something isn't right, and I actually fall upon the thread, I will do what I can to show the right way, as easily as possible, without blasting into a thread trying to deface every character there.

Again...you can look at my posts and see what I do here, and how I help here, when I can.

On that note: I will now bow out of this thread altogether...PM me if you still want or need any info.

Rick

 

Good riddance. I don't need to be talked down to by a ***** like you in 15 different posts to hear about backpressure. I can get it from more and better sources than you provided - oh wait, you didn't provide any sources, you just told us you know everything and we should believe you.

 

Sorry - I forgot to unsubscribe fast enough.

If you want to hear about HyperSprite and how he seemingly likes to go after exhaust vendors publicly...go to the link....wow..some people NEVER learn.

http://www.hypersprite.com/z/auto/default.htm

Bye now...

 

Wow, surprised how many idiots we have on this forum.

 

No, I'm right, as usual. Check post 23 ***-hat.

 

Exhaust velocity I think its called. Not backpressure.

 

Sadly you are the only person on this whole forum that actually thinks that. lol.

 

Looks like a couple others agree with me, namely HyperSprite and undrgnd. Both who backed up thier claims with 3rd party data. You however continue to spew ****.

 

They agree with you?! I don't see that at all. And you on this whole forum have posted nothing but wrong info.

 

What?

https://my350z.com/forum/showpost.ph...0&postcount=23
and you can Check post 25 as well.

My word you are a Fu(king moron.

 

Backpressure: The myth and why it's wrong.

I. Introduction

One of the most misunderstood concepts in exhaust theory is backpressure. People love to talk about backpressure on message boards with no real understanding of what it is and what it's consequences are. I'm sure many of you have heard or read the phrase "Hondas need backpressure" when discussing exhaust upgrades. That phrase is in fact completely inaccurate and a wholly misguided notion.

II. Some basic exhaust theory

Your exhaust system is designed to evacuate gases from the combustion chamber quickly and efficently. Exhaust gases are not produced in a smooth stream; exhaust gases originate in pulses. A 4 cylinder motor will have 4 distinct pulses per complete engine cycle, a 6 cylinder has 6 pules and so on. The more pulses that are produced, the more continuous the exhaust flow. Backpressure can be loosely defined as the resistance to positive flow - in this case, the resistance to positive flow of the exhaust stream.

III. Backpressure and velocity

Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. I'm sure that all of you have at one time used a garden hose w/o a spray nozzle on it. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much much faster rate.

The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity. Backpressure in it's most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your powerband is located 2-3000 RPM you'd want a narrower pipe than if your powerband is located at 8-9000RPM.

Many engineers try to work around the RPM specific nature of pipe diameters by using setups that are capable of creating a similar effect as a change in pipe diameter on the fly. The most advanced is Ferrari's which consists of two exhaust paths after the header - at low RPM only one path is open to maintain exhaust velocity, but as RPM climbs and exhaust volume increases, the second path is opened to curb backpressure - since there is greater exhaust volume there is no loss in flow velocity. BMW and Nissan use a simpler and less effective method - there is a single exhaust path to the muffler; the muffler has two paths; one path is closed at low RPM but both are open at high RPM.

IV. So how did this myth come to be?

I often wonder how the myth "Hondas need backpressure" came to be. Mostly I believe it is a misunderstanding of what is going on with the exhaust stream as pipe diameters change. For instance, someone with a civic decides he's going to uprade his exhaust with a 3" diameter piping. Once it's installed the owner notices that he seems to have lost a good bit of power throughout the powerband. He makes the connections in the following manner: "My wider exhaust eliminated all backpressure but I lost power, therefore the motor must need some backpressure in order to make power." What he did not realize is that he killed off all his flow velocity by using such a ridiculously wide pipe. It would have been possible for him to achieve close to zero backpressure with a much narrower pipe - in that way he would not have lost all his flow velocity.

V. So why is exhaust velocity so important?

The faster an exhaust pulse moves, the better it can scavenge out all of the spent gasses during valve overlap. The guiding principles of exhaust pulse scavenging are a bit beyond the scope of this doc but the general idea is a fast moving pulse creates a low pressure area behind it. This low pressure area acts as a vacuum and draws along the air behind it. A similar example would be a vehicle traveling at a high rate of speed on a dusty road. There is a low pressure area immediately behind the moving vehicle - dust particles get sucked into this low pressure area causing it to collect on the back of the vehicle. This effect is most noticeable on vans and hatchbacks which tend to create large trailing low pressure areas - giving rise to the numerous "wash me please" messages written in the thickly collected dust on the rear door(s).

VI. Conclusion.

SO it turns out that Hondas don't need backpressure, they need as high a flow velocity as possible with as little backpressure as possible.

Turbo Exhaust Systems:

Some of you asked for a better explanation about restriction in a turbo exhaust, so here 'goes. To sum it all up, on a turbo car, the tighter and more restricted the exhaust housing of the turbo is, the faster you're going to spool your turbo... because the restricted gasses escape through the exhaust housing with more velocity (much like the garden hose description quoted above)... but with this restriction comes the downside. Less exhaust volume will be able to fit through that turbine housing once the turbo is spooled and starts squishing more air through the intake.

This is where the wastegate comes into play. The wastegate is actuated BEFORE the exhaust wheel in the exhaust housing. When it opens, whatever the diameter of your wastegate is gets added to your exhaust piping. Effectively increasing the capacity of the exhaust provided that everything downstream is large enough in diameter to handle it the extra flow. The main reason it does this is to prevent over-spooling the turbo. Once the turbo reaches its efficiency, it doesn't need to flow all the extra gasses through the turbine wheel, so the wastegate allows you to route the exhaust around the turbo... if it can't route enough exhaust around the turbo (restricted wastegate) then too much exhaust gas will be forced by the exhaust wheel and BOOST CREEP will occur as your turbo over-spools.

One way to prevent boost creep is to port the wastegate housing (if you have an internally gated turbo) or to replace the wastegate with a bigger unit. If that still doesn't work, then the problem is likely going to be a restriction in the exhaust downstream from the wastegate. Many overboosted car owners prefer to vent their wastegate dumps to the atmosphere. Not only is it illegal to bypass your catalytic converter, but it's loud as hell, gets your engine bay filthy, and clogs up your K&N like nobody's business; however, it nearly eliminates boost creep. It's a cheap and easy solution that fixes boost creep on a race car.

The best solution to boost creep is to route your wastegate dump past the catalytic converter and back into the exhaust. It will be a custom setup. Nobody makes this. Make it look clean and you'll pass emissions because they don't run your car hard enough to open the wastegate when doing emissions testing. You have to reach full boost for the wastegate to open, and since the exhaust runs through the cat until the wastegate opens, it all gets "cleaned" before it reaches the sniffer. With this setup, the wastegate will also be much quieter because it still runs through the muffler, and you won't trash your engine bay with black caustic funk.

Putting a separate catalytic converter on your wastegate dump is a stupid idea because you'll never get it hot enough to "light off" and start converting the carbon monoxide... so don't get any crazy ideas and create unnecessary exhaust restrictions.

Once compressed air comes into the mix with an engine, exhaust tuning has much less to do with making power. So what if you can milk another 3-5 hp out of a car with a tuned exhaust... the benefits of making an engine sustain an insane final compression ratio (boosted air x compression in the combustion chamber) has much more affect on making power if you can just get rid of the extra gasses it produces. Bigger is almost always better on a turbo setup. The only place where it isn't good is on the exhaust wheel where too big can = no chance of spooling your oversized turbo any time this year.

 

How about you post something useful instead of name calling everywhere you go?

 

Whatever the case may be.

The point of this thread was some people were arguing that just having two pipes going back would make power and others were arguing having two mufflers and resonators would make a better distribution of power. Who is right? Number two of course on a standard VQ engine, if not turbocharged/supercharged, nitrous fed, or fully built, the VQ engine will not benefit by just having two big exhaust pipes going all the way back because it won't make power until too high of a rpm. You can argue about this till your head explodes buddy.

If you don't believe me, go disconnect your exhaust on a dyno and show me a gain. It'll never happen! Have a great day.

 

Because you are stupid, and have no idea what you are talking about. If you would submit, and actually adimt you were wrong (as well as work on your reading comprehension skills) maybe I would treat you like a human being. Until then, I'll continue to treat you like the sub-human piece of $hit you come off as.

For instance

"The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity"