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u bend resonator delete...

  #1  
Old 10-15-2008, 10:46 PM
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Default u bend resonator delete...

What are the expected gains of a u bend/resonator delete on an 07 ss? or would a 3" dp be better?
 
  #2  
Old 10-16-2008, 04:26 AM
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Default RE: u bend resonator delete...

You look underneath?
You shouldn't have a U-Bend.
3 inch down pipe will kill more on the low end than the tiny bit it grabs on the top end negating usable power.
You exhaust problem lies with the resonator more than anything else and has been the case for years.
 
  #3  
Old 10-16-2008, 08:12 AM
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Default RE: u bend resonator delete...

yeap, you hear us talk about the u-bend alot but it's only on 00-05 Monte Carlo's. GPD has a picture of what hte bottom of your car looks like. the resonator and muffler delete (or changing the muffler) would be hte biggest part of your gains. about 80% of hte little bit of horsepower gain you get from a cat back system comes from the mufflers.

and BTW, don't change your mufflers and the such with horsepower in mind. you won't gain THAT much from them. change them only with hte idea of a nice sound coming out or you will probably be disappointed.
 
  #4  
Old 10-16-2008, 06:37 PM
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Default RE: u bend resonator delete...

Since I couldn't get beyond the basics in another post, I will for you continue.

First will look at the rear exhaust.
If you have dual outs, your system has pretty much taken care of restrictions, but it has one problem.
Now we've all seen these exhaust companies show charts, graphs etc of how pipes, h.p, per pipe and mufflers flow in CFM right?
These duals were made for one premise only. A sporty car looks better, meaner and so fourth if it has dual outlets, correct?
In the process of doing this the dual outs solved a problem called flow restriction.
OEM mufflers have a average of 225 CFM flow abilities as advertised by these exhaust companies.
The same premise applies to the pipe.
Having 2 mufflers instead of one gives you 450 CFM flow ability and also double on the pipes.
450 CFM in a single system is more than enough for a pretty stout V-8 which flows a much higher amount in CFM of exhaust gases.

Do you really need more?
Mufflers in our cases only produce sound, no power what so ever.

The one problem of the rear section which I haven't mentioned yet is the Y pipe section for the dual outlets.
Dam thing is a "T" in shape and will create all kinds of problems with flow, not to mention it also has a secondary problem lying within it.
First the Y must be shaped similar to a Y itself and the tips of the Y should be as close and possible together so the exhaust doesn't make a wild turn. Secondary to it, it also should be smaller in diameter. Leg in 2 1/4- 2 1/2, 2 legs out 1 3/4-2 inch, why?
Velocity, scavenging, which will look closer in a minute.
These 2 terms work in conjunction which each other, without one or a light act by one the second will not exist or be at a minimum.
You just had the exhaust traveling at lets say 100 mph, if it splits into a section that doubles its size it also halves its speed. You want to try and maintain that speed as close as possible and the only way to do it is with smaller pipes that when doubled have the same ability as the single.

After velocity, scavenging must be looked at.
What is it in simple terms, a vacuum created.
Simple looks at how it may work, think fluid dynamics.
Ever siphon???
Understand how it works???
Same exact principles is in order here. The exhaust escaping under velocity is sucking the gases behind it, just like with siphoning of water etc.
Now for a test at home you can do if you really are having a hard time understanding is to take 2 garden hoses. Clear plastic milk bottle with a hose fix it kit to make it so the bottle can be added inline to the hoses.
WHY?
It will show you what a resonator, a larger internal pipe like a 3 inch downpipe does to a exhaust.
When you do this you will notice a light trickle at best once the initial suction if applied and it will never flow anywhere near the volume and velocity a single size hose will. WHY?
As simple as the size cannot fill under the vacuum pressure made by the smaller diameter without getting to technical.

Oh yeah, wild claims are made, but why.
Because the exhaust has a .......... push to it, no vacuum created and if it had vacuum________________.
Low CFM makes it more like . . . . ., higher CFM's ........., but never____________.
Low RPM where stock cams make torque, it just drops out.
Higher rpms where the dots are closer to perfect maybe making just a tad of vacuum, the motor starts to come alive and make more power. Its a trade off, because the stock size does have a limit CFM wise to it and can't even under vacuum move enough versus the large pipe, but the larger pipe flows slower and lower CFM volumes.
The only way to make a 3 down system begin to work is having it all 3 inches all the way back, but that arises some other issues and I'm done for now.
 
  #5  
Old 10-16-2008, 07:18 PM
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Default RE: u bend resonator delete...

Simply, don't change the exhaust. It is good as it is.
 
  #6  
Old 10-16-2008, 07:49 PM
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Default RE: u bend resonator delete...

So i shouldnt remove the resonator or swap out the muffler (except for sound maybe)? Then what about heat wrapping the exhaust pipes? i heard hotter air moves faster ie more CFM's? Also, if the exhaust isn't the weak end then what is? What can i improve upon for the most gain? Because right now my p/wratio is worse then a gt mustang???
 
  #7  
Old 10-16-2008, 08:56 PM
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Default RE: u bend resonator delete...

members here claim there SS V8 can rape a 05+ Mustang GT, but i've never seen them race personally so i'd have to say its a tough call. the best wya to get power is to go over to one of the other sections, like the Engine & Internal or maybe the Supercharger, Turbochargers, and Nitrous sections.

and yes, hot air moves faster than cold air and therefore you want to keep exhaust gases as hot as possible as they leave the car to get htem out ASAP. therefore, a bigger pipe isn't always better.

change out your mufflers if you want a nice sound. magnaflows are the only dyno tuned muffler for your car, so your best bet for power is them. however, the difference is minimal, barelly noticable with maybe a hair of mpg gain. the only reason to tamper with exhaust is sound. i've learned it the hard way. i've got time slips that show barelly any difference at all.

 
  #8  
Old 10-17-2008, 01:34 PM
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Default RE: u bend resonator delete...

3 inch down pipe will kill more on the low end than the tiny bit it grabs on the top end negating usable power.
I disagree- the 3" DP is a good mod, even on an otherwise stock L67. This thing is making ~60 more hp, and moving almost 1.5L more air- so that would lead me to believe that it would be at least equally as beneficial on a 5.3. I just don't know how big the stock DP and manifold outlet are on the LS4's, I would imagine they might've redesigned the DP a bit from the one they used on the 3800s.

You exhaust problem lies with the resonator more than anything else and has been the case for years.
I also disagree with this. The resonator on my 96 monte was literally a smooth bore, straight through piece of pipe with a single small tube sticking up in the center from the outer wall- it wasn't open all around like a glasspack is. I'm not sure what the inside of the resonator looked like on my gtp (they tossed it before I had a chance to see), but I only dropped 0-1*KR, so it couldn't have been much of a restriction. I dropped a good bit more KR doing the 3" downpipe/cat delete/ubend delete.

however, the difference is minimal, barelly noticable with maybe a hair of mpg gain. the only reason to tamper with exhaust is sound. i've learned it the hard way. i've got time slips that show barelly any difference at all.
x100 You won't feel any power difference anyways, so just buy it based on what sounds good to you.

 
  #9  
Old 10-18-2008, 05:47 AM
Join Date: Sep 2008
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Default RE: u bend resonator delete...

I dropped a good bit more KR doing the 3" downpipe/cat delete/ubend delete.

The cat is finally out outta the bag. ( Pun intended )

Bumpin here has claimed the 3 inch D.P. deal to be, well Cats A$$, but now he has let out a very valuable piece of information.
Look at any other of my posts dealing with the exhaust and a cat is the #1 killer of power loss in the exhaust.
It being in a system, acting like a expansion chamber leads to a 1 PSI increase in back pressure.
1 PSI back pressure has been equated to 7-10 H.P. in loses.
No wonder he feels that this U-bend delete, 3" D.P. mod is so trustworthy and not a killer of low end power because he also removed the biggest problem while doing it.

I would also bet that if he had just removed the cat from the stock system then he would not be all for the 3" down, U-bend delete, because then it would not be a big deal as he has mentioned with the rest of the system. The rest of the system adds more problematic back pressure issues than the stock down and U-bend without a cat.

But not everyone will want a 50 State illegal exhaust system.


Now back to the resonator.
What kind of resonator does your car have?
Does it look like a bullet muffler that is only a inch or two larger than the pipes and under 24 inches long?
If it is, its actually not a resonator and more like a racing bullet glass pack. It will take away some power, but its design isn't a very big killer. It can be cut out and replaced with a stainless pipe section for less than $60 and you'd gain maybe a horse or two.

If its a true resonator like my GP and Monte have that are 04+ models and its 5-6 inches in diameter, 30+" long, believe me it is now a seat in the pants feel after removal. This style is a sound cancellation device that acts like a expansion chamber, much like a cat and takes away roughly 4-6+ H.P. on its own. Same $60 or so to lose it. We have a 04 GP that has a bullet style maybe 14 inches long so I know they used variable types. It'll also when removed add some throatyness to the exhaust note and its not a drone inducer many have claimed. Any time a exhaust is louder its going to add some cabin noise over previous and drone is a mid rpm annoyance that is created by bad piping or lousy mufflers.
 
  #10  
Old 10-18-2008, 04:01 PM
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Default RE: u bend resonator delete...

No wonder he feels that this U-bend delete, 3" D.P. mod is so trustworthy and not a killer of low end power because he also removed the biggest problem while doing it.
Its not just on my own cars, I've done a 3" dp w/ whatever HF cat they come with on other gtps, and I've been pretty impressed as well (as have many others). IMO, I've seen better gains even with a 3" DP w/ cat that just a resonator removal. It seems like the resonator becomes a restriction a little bit higher. Keep in mind that I've worked onseveral wbodys besides my own- especially when you're talking just single bolt ons and such.

My point is that if a 3" DPis the major aftermarket offering- and what makes the most power on a240 hp 3.8L, then why would it be too big for a 300 hp 5.3L?

To the OP, do whatever you want- I'm tired of this joker...

 
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