Konnan101

So I'm looking to completely redo my exhaust from the headers back, but I really don't want my car much louder than stock, so the question I have is: are resonators just mufflers farther up the exhaust or are they a completely different thing...

My plan was to use these - http://store.summitracing.com/partde...5&autoview=sku for my mufflers

and then these - http://store.summitracing.com/partde...5&autoview=sku after the x-pipe to cut down on the noise.

cats--\ /--#--#-
X
cats--/ \--#--#-


does this seem like a good setup? or are there better things out there for noise reduction (with the same flow)? Sorry again if this was an obvious question...

forcefed86

It's a good setup but it would be louder than stock.

If you want stock sounding exhaust why not just remove the cats and leave all the OEM equipment? Or get an electric cutout so you can have the best of both worlds without spending an arm and a leg on fancy exhaust systems?

Blizzy

iTrader: (-1)

What you have proposed wil be significantly lounder than stock, most notably due to the increase in pipe diameter to 2.5". The larger pipe will present fewer opportunities for sound waves to reflect off the walls of the exhaust system on the way out the tailpipes. Each sound wave reflection diminishes the amplitude of that sound wave, decreasing the sound intensity.

Independent of the sound argument, a 2.5" dual exhaust is significantly oversized for a 250hp motor. Even under WOT conditions, you will not be producing enough exhaust gas velocity to produce efficient air travel through such a large pair of pipes.

Standard convention says that exhaust piping will flow 115CFM for every square inch of pipe cross sectional area and that 2.0-2.2CFM are required for every horse that is being made by the motor. Let's do the math:

2.5" pipe has a 1.25" diameter. The cross sectional area of the pipe is (pi*radius*radius) 4.91 square inches. At 115CFM per square inch, that is 565 CFM of flow capacity. At 2.0-2.2 CFM per horse, the 2.5" pipe can flow 257-282hp without restriction.

I know what you are thinking: that number is perfectly in the range of the 1UZ, right? Well, it would be if you only had one of them. But, with two 2.5" pipes, you double the cross sectional area. There is no sense putting an exhaust capable of moving 500-550hp of exhaust air efficiently unless you are making 500-550hp. At 250hp, your exhaust gases will only be flowing at 50% capacity and 50% efficiency through those pipes. Imagine how inefficient the system will be when you are not making peak horsepower (which is most of the time you are behind the wheel).

Keep in mind that a 2.5" exhaust pipe can flow more than 282hp. In fact, it can flow way more. It simply can flow at most 282hp without restriction. Using the conventions above, a 3" pipe can flow ~400hp without restriction. Any horsepower made over 400 will have to be done at the expense of unnecessary exhaust back pressure from overflow, but it can be done. Eric from TTC Performance made 891whp on a 3" single exhaust on his 2JZ-GTE. Every horse beyond 400 was made in the face of backpressure, but if the motor can push the air, it will.

Moral of the story: if you are doing a dual exhaust and want to keep the system quiet, pick a smaller pipe diameter. If you want to maximize efficiency of exhaust gas velocity (and thus performance), pick a smaller pipe diameter. In addition, I would look into a quieter muffler. Borla and Gibson are somewhat well known for making high flow mufflers that are quieter than the competition. Gibson's slogan is "Turn down the sound, not the power."

In reality, a single 2.5" pipe can flow all of the horsepower of the 1UZ without restriction. If you want to lower sound intensity, maintain peak performance, and -heck- drop some weight while you are at it, a single 2.5" pipe would do the trick. With a simgle 2.5" pipe, you could minimize exhaust restrictions as well, as a single muffler would likely be enough to keep the system as quiet as stock.

A final note: the standard exhaust convention of 2.2CFM/hp does not necessarily apply to a turbo application. Because of the inherent backpressure presented by a turbocharger in the exhaust piping, exhaust choke is more easy to accomplish. It is hard to say exactly how much higher than 2.2CFM/hp should be needed, but a turbo is certainly more well suited to a slightly oversized exhaust than a slightly undersized one. Nevertheless, consider that Eric at TTC made 891whp on a 3" single when you are making your exhaust pipe diameter decisions.

durtysc300

^^^whoa i never new any of that haha

Konnan101

thanks for all the info, and the crash course in exhaust...I still don't quite understand what kind of back pressure if any is optimal for the best performance, but what I understand now is, and please correct me if I read this wrong, that this setup might not do anything but change the sound of my car, and possibly hurt performance...

Like I said earlier I'm just getting into this whole car modification thing, and this setup was just what I came up with having done very little research...so I guess my question is what would be better? Would a 2" dual exhaust with more restrictive, quieter mufflers, like a pair of Borlas be a better route for my car...or should I go even smaller?

Also if I go with the Borla or Gibson 2" setup would I only need one muffler on each tailpipe, or would an extra set of mufflers be necessary to turn down the sound?

As far as the single exhaust set up goes...would this be a better choice (money, performance, and sound) over a 2" dual setup? Also would a single exhaust setup be a problem later on down the road when I started adding horses to the engine?

thanks again for all the help, and I hope I'm not being to lazy asking questions like this...also if this helps to get a better picture of my setup, I'm trying to get a pair of Tex headers and high flow carsound cats for in front of the x pipe.

durtysc300

i would think that a 2 1/4 inch woudl be good w/ borlas

Blizzy

iTrader: (-1)

Imagine you and a long line of people are at one end of a long, dark hallway, and you all need to get from one side to the hallway to the other. This would be easiest to accomplish in a hallway with nothing in your way that is narrow enough for each of you to reach the walls both sides. You could put your arms out to each side, start running, and not stop until you reached the other side. This is similar to an exhaust that is properly sized without back pressure: easy to manuever quickly, and nowhere to get lost.

Now, imagine that hallway is ten arms widths wide. In the dark, it would be easy to get disoriented. You would probably run into one side of the wall and then the other on your way to find the doorway at the far side of the hallway. In the meantime, you would run into others whowere disoriented as well. Eventually, you will get out, but in no way as fast of a time as your would in the situation above. This is similar to an oversized exhaust. The backpressure that is present in this system is the disoriented people (exhaust particles) getting lost on their way from one side of the hallway to the other.

Finally, imagine that first hallway but filled loosely floor-to-ceiling with crumpled newpaper. Unlike the most recent scenario, you would not get disoriented on your way through the hallway, but you would have to work harder to travel a given distance because of the newspaper that you are forced to overcome. This is similar to an undersized exhaust. The backpressure present in this system is the newspaper that is forcing you to move more slowly than you would be if it were not there.

Now, what if you had a couple couches randomly placed in the hallway, blocking the clean path from one side to the other. Even if you were in the first scenario with a proper hallways size, getting over the couches would cause congestion and slow down the time it would take to get from one side to the other. Adding a muffler or resonator that flows less than the corressponding unobstructed pipe will result in intermittent patches of back pressure, which will slow down the performance of the people trying to cross the hallway (like a muffler would the exhaust gas partciles trying to get out the tailpipes).

Any backpressure is destructive to performance. However, back pressure is unavoidable. No exhaust pipe can be change its size based on engine load. No muffler/cat/resonator can be chosen to have the exact flow dynamics of the pipe preceding it. The goal is to minimize exhaust back pressure without affecting peak performance. This is primarily accomplished by choosing the pipe diameter that presents the smallest cross sectional area of pipe without choke (back pressure from being undersized). However, when it doubt, with any non-turbo street car it is often more correct to be undersized than to be oversized.

I can't tell you what to do. You have to make your own decisions. I can only give you the information to work with: If you run the numbers, a 2" exhaust has 3.14 in^2 of cross sectional area. That is 361CFM or 164-181hp.

If you look at the GS400 exhaust system (later model 1UZ making over 300hp and doing 0-60 in 5.8s in stock form), the beginning section is 2" mandrel bent piping. Most of the GS400 guys who purchased the RMM Supercharger kit and are making upwards of 400hp have retained that piece of the factory exhaust because it is mandrel bent and not presenting a serious restriction.

Mandrel bending is a process by which the inner cross-sectional area of a pipe is maintained, even at the bends. Conventional exhaust shops crush bend the exhaust piping, which dents the metal and causes an inconsistency in the diameter of the pipe, causing backpressure. The additional attention paid to the GS400 exhaust in this regard makes it efficient enough to retain, even in a souped up application where thousands of dollars have been spent to better performace.

The GS400 stock exhaust includes both resonators and mufflers like our stock SC exhaust. It is mild in intensity but strong and refined in tone. Resonators would help to turn down the sound, but they may or may not be required depending on your muffler choice and your requirement for what is loud and what is not. Ultimately, that is your decision as to what suits your needs.

The only viable way to add significant horses (more than ~40) to the 1UZ is through forced induction (turbocharger, supercharger, or nitrous). You are not going to make 20hp off a cone filter intake; the stock systems are too well designed to offer that much room for improvement.

I would stick to a dual exhaust because it works with the stock body. The rear bumper looks strange with only one tailpipe unless it is fiberglassed to make that other exhaust outlet area disappear. I also think the dual exhaust looks better, and it hints at the V8 under the hood moreso than a single (if you notice, the Camaros/Firebirds/Mustangs, it is often easiest to tell the number of cylinders under the hood by the number of tailpipes off the bumper: 1 for V6, 2 for V8).

Carsound cats are now badged Magnaflow since Magnaflow bought them out. When you are buying a Magnaflow cat, you are buying a cat made at the Carsound factory.

As for the Tex Headers, they can be found at Rush Imports website. They need to be shipped from Australia. After shipping and paypal fees, the $550 headers will cost you $824 to get to your doorstep. S&S Headers, made in America, run $600 plus ~$30 shipping.

The Tex Headers suffer from a design/manufacturing flaw at the collectors. Due to poor pipe cutting/welding, there are protrusions of pipe in thecollectors that create pockets where air can get trapped and cause backpressure. You will also struggle to avoid a Check Engine Light since the EGR system will be hard to plumb with the long tube header style. While they are more well designed than stock headers, they leave a lot to be desired. Here is a simple illustration of the inefficiency of the Tex Headers.

The S&S Headers boast a 1.5" primary pipe diameter, 1/8" smaller than the primaries on the Tex Headers. 1.5" primaries are very well suited for a 4L motor. The smaller primaries will keep peak torque closer to idle, making the car more fun to drive on the street. The larger, 1.675" primaries of the Tex (and EK Tuning) headers will pushpeak torque closer to the redline, making the engine need to be revved harder to make the same "seat of the pants" feel.

The S&S Headers are less money, more easily adaptable to work with the factory EGR (no check engine light), and they are more properly sized for the stock 1UZ motor. In addition, they lack the inherent design/manufacturing flaw of the Tex Headers. I would favor them over the Tex/Rush Headers.

unreal-

Excellent post Blizzy, never realized exhaust tech was so technical. Very informative.

/Subscribe and save.

Konnan101

wow man thanks, that answers a lot of questions...I really appreciate you taking the time to make the long post

SC4_FI

blizzy, what if i want to run duals and dont care about sound and want to run just 2 cats, 2 mufflers, and no res. on a 1uz, what would the optimal setup be in your opinion

Blizzy

iTrader: (-1)

In my opinion, I would just delete the stock resonators (~$40 at the local exhaust shop) and repaint the stock mufflers with 1200*F black engine paint and 500*F clear engine paint (~$10 for one can of each at Walmart).

If you do something custom, you are going to be putting on lesser quality parts (especially at the cat) and you will be disappointed with the marginal results for the large amount of money spent.

By the way, I currently have done exactly what I suggested doing above. It cost me $50, the car sounds a little better, it looks a lot better without the chipping paint on the mufflers, and I get to keep as many genuine Toyota parts on the car as possible to maintain reliability.

SC4_FI

i ment keeping the stock cats at the exhaust manifolds and the stock mufflers...now that you say that about painting....painted
.....



cats--\ /-----#-
X
cats--/ \-----#-


but if i keep all that stock, what size pipe would be most efficiant from cat to xpipe to muffler

J:M

Nice posts, very great info. So this leads me to this question. If you're sitting on a stock 1JZ, should new mufflers be even on someone's list of mods? I was hoping to do a 2" pipe cat back to 2.5" to the dual mufflers (Magnaflow). But now your previous posts make me think I'm just throwing money away if I re-do the piping from the cat all the way back with new mufflers. FYI, can't remove CAT, I live in California, sucks I know.

Blizzy

iTrader: (-1)

Not being able to the remove the cat is hardly the end of the world. The stock cat is metal substrate and of very high quality. It will flow nicely so long as it is not clogged.

Magnaflow mufflers do have a few design advantages over the stock mufflers, even though the stock mufflers are of a straight-through design. Magnaflow plus sizes the interior muffler piping ~1/4" in most of their mufflers.

If you order a 2.25" Magnaflow muffler, the interior pipe diameter will be 2.5". Because of the inner pipe is perforated (to allow the sound dampening material to do its thing), flow is less smooth than a straight pipe. The extra diameter of the internal pipe helps regulate the flow capacity from inlet to outlet with lower back pressure. This is a good thing for performance.

How much a difference would this have over a stock muffler? The difference is marginal in terms of performance if you are comparing the stock 2.25" muffler to the Magnaflow 2.25" muffler. The Magnaflow muffler could get the scale tipped in its favor when considering the increase in curb appeal and more preferred exhaust tone.

Another note: If you re-read my posts, I made mention that turbo cars are inherently different from the non turbo cars in terms of pipe sizing. Standard exhaust conventions do not really apply as directly due to the back pressure caused by the turbocharger restricting the exhaust flow right out of the chutes. Generally, for a turbo application, you want to miss on the high side of the pipe sizing if your exhaust goals put you on the fence between pipe sizes because of the backpressure of the turbocharger(s).

If you are replacing the stock crush bent pipe with crush bent pipe from a muffler shop of the same diameter, expect extremely marginal results. The advantage to replumbing the exhaust at a shop will be felt non-marginally only if larger/smaller pipe is used, if mandrel bent piping is used, and/or if the geometry of the stock exhaust is altered significantly.

Hopefully this information (in addition to what I have previously shared) has helped you to feel more comfortable about making an informed echaust decision.

Good luck!