1989GTATransAm

iTrader: (3)

Ok here you go from PipeMax and this is just ballpark. With real dyno information we can dial it in pretty close.

A. 4th harmonic is 18.4". Highly recommended and best torque curve.
B. 3rd harmonic is 36.8". More bottom torque.
C. 2nd harmonic is 73.7". Longest recommended with mufflers.

Orr89RocZ

iTrader: (20)

hmm highly recommended we go with the 4th harmonic.. i wonder just how much i'd be givin up if i went with the 2nd instead?

skinny z

It just has to be determined if the mufflers of choice behave in the appropriate way.
I lifter this from a Super Chevy article written by Vizard.

SOME HEAVY-DUTY QUOTES FROM ENGINE MASTERS WINNERS

John Kaase: "I used a straight-through glass pack muffler design specifically because of the high-flow they can deliver. My dyno testing left no doubt as to how important collector length was and that a straight-through glass pack contributes to that length. By getting the collector/muffler length right, which in our case was about 40 inches, the torque at 3,500 was increased substantially. That gain is probably what won the Engine Masters deal for me the first time. I have seen an incorrect length along with less than the critical minimum flow cost 40 hp. Short change efforts on the collector/secondary and it will short change you."
Joe Sherman: "If you are building a serious performance system, then assuming you have a near-optimal header set-up, the place that is most critical when it comes to avoiding power loss is from the collector back. Also, don't be fooled into thinking that big tailpipes contribute to power. In all my years of dyno testing, I never have seen that work. For me, the straight-through Magnaflows when used as part of the collector length, show only very small losses in power over an open pipe. It's all about the right length and sufficient flow. I have seen mistakes in this area cost 85 horsepower."

Do Ultra Flos perform like a glass pack? By glass pack I assume they're talking about the classic Cherry Bomb.
I'm not familiar with the chambered tubes you refer to. GMMG.

Orr89RocZ

iTrader: (20)

dynomax ultraflo is basically a straight thru core muffler and is packed with fiberglass to sound deaden the exhaust

its like the race bullet but the bullets have no insulation...and is just straight thru. Powersticks/chambered tubes are straight thru but instead of just holes inside the cases, they look like a cheese grater, with flipped up pieces of metal that get in the way of the flow path to create that sound

They still flow good but not quite as good as a ultraflo or bullet


sounds like he tuned for the mid length 3rd harmonic and picked up massive torque amounts. I wonder if that hurts hp as much? Cuz i could do this easier than the 18inch length and probly gain massive torque, but i dont want too much torque lol. An 11 to 1 383 should make massive torque as is

skinny z

Remember too that the Engines Master builds are for area under the curve and not just peak horsepower. In fact many will sacrifice those big top end numbers for larger amounts of torque and more average power.

Orr89RocZ

iTrader: (20)

thats what i figured... question remains does that car run faster with more average power? I'm trying to get good hp numbers but track times are abit more important to me than a dyno queen

1989GTATransAm

iTrader: (3)

My vote is for more average power under the curve.

Orr89RocZ

iTrader: (20)

well i hope to drop the motor in by tommorrow night so we'll see if i can get that done

if i do, i can get a much better look at how the exhaust runs down and if need be, i'll make a best torque overall exhaust just to be brutal on the street and track

skinny z

Drag racing engines tend to run in a narrow power band and the area under the curve dosen't matter quite so much because you don't use much of the curve. You tune for peak power and try to keep the engine at maximum power as much as you can with your gearing. Do you use 3000 rpm at the track? My 3000 stall and 6000 red line keep me to that. With a close ratio trans, the band can be even less. However for a more dual purpose vehicle (or anytime you run on the street) it's a different story. Seems that the smart money is on the broad range of power approach.

skinny z

Here are a couple of interesting pics. You can see how the 4" pipe could easily be modified to act as a resonator box.

Orr89RocZ

iTrader: (20)

If i was to do that exhaust i'd just keep it a single 4 inch and throw out the box idea. nice looking system tho

skinny z

You would lose the tuned collector length in that case.
It seems like more trouble than it's worth however I would like to know what the possible gains could be over a more conventional design.
Still working on mine. Looks like my fabricator is putting me off for another couple weeks.

Orr89RocZ

iTrader: (20)

for a single 4 inch system like that, it be harder to make a box than a dual setup or a smaller exhaust like a single 3.

but shows you can have 2 pipes from the headers go into a single LONG box. If you could make it long and wide enough you could make a single termination box joining 2 banks

skinny z

I would think that would be the plan all along. One terminator box like Vizards corvette piece.
A 4" pipe would need to be about 60" to get 800 cubic inches. Thats 8 times the cylinder volume per bank times two banks.
Not a lot of room.

Orr89RocZ

iTrader: (20)

it wouldnt be a single, you'd have to make it like 7 inches wide by 3.5 inches tall to join two 2.5 or 3 inch collector pipes from the headers. Then it would have to be 32-33 inches long to achieve 800 cubic inches. If you could fab that box it would fit i'm sure if you angle it right

still cant get 18 inch total collector length if you do that tho.. you'd have to shoot for 36 inch for average power or most torque.

skinny z

The short collector lengths (18"+/-) were always going to be problematic. That's part of the reason I'll go the open header route for track days. At least for now.
If I can experiment, maybe I'll find that a 36" collector will perform just fine. A terminator box can be built to suit at that point. I'd really like to be able to drive to the track and not have to do much more than put on the slicks instead of uncorking the pipes and tuning the fuel curve. Having the open header power available all the time ( with the terminator ) would also be sweet.

Orr89RocZ

iTrader: (20)

Ok now that the motor has been in the car for a few week, i need to get this exhaust done so i can start using the car

I have no idea what i'm gonna run. I'd love to keep this exhaust science stuff going but i'm having a hard time figuring out what I will beable to do with this car

I got s-extensions for my headers and they will not work to get around the frame or crossmember so i will have to cut and custom fab up a piece to get around the Spohn member. Shouldnt be too bad i would think but we'll see

After that i'm looking to make a quick setup where its dumped before the axle. Cant decide on mufflers, but i'm leaning towards dynatech split flows. I was thinking dynomax ultraflo rounds but at 6inch diameter thats losing clearance. I dont want the car to be super loud but i dont wanna lose power The Split Flows will be loud but flow awesome and give me some good power numbers. Pretty expensive tho

The other option is magnaflo 4x9 x 14inch long case mufflers. They flow good and are alot quieter but still pretty loud

I also dont know whether i want x pipe or H pipe

i got to check to see how much room i have under the car. I will have a good idea what i can do with this system now that the headers and motor are in place. Motor is 95% done, awaiting exhaust and oil/coolant/priming tool

Orr89RocZ

iTrader: (20)

well its not looking good at all

there is simply NO room under this car to do anything worth driving on except maybe a single 4inch system. I dont know how others have done true duals. My car sits too damn low. my car underneath seems to be different than most. I just dont see how other systems on other cars will work with mine

I will not beable to do a terminator box at any length. So this sucks. I may be able to do a cutout but even thats pushing it room wise under this car....AT 18-19 inches it would sit just in front of the trans pan, and i need a custom bend just to get around the crossmember/trans pan so i'm not sure i can fit a cutout there.

I could still do true dual 3inch running down the stock location but its gotta be perfect and staggered to work. Mufflers will HAVE to be located behind the axle which i did NOT want to do. Driveshaft loop on the spohn crossmember will 90% more than likely need cut off. Possible relocation but i doubt it. Maybe a rear mount one? idk, i got to do something to be legal. i'll have to custom mount one. But nonetheless, the drivers side i believe has to move back over to the passenger side. Else it will sit pretty low and run right against the fuel lines and i dont want the exhaust heating those lines.

magnaflow x pipe will be necessary and both tubes will have to run down stock location. In order to go over the axle, i think the one pipe will have to run over to the drivers side again underneath the torque arm. Should be enough room i think but its hard to say

Now the problem arises with the mufflers i wanted to run, the car will now have LONG collectors and suck on the top end.... its well over 90 inches of pipe and probly closer to 110-120. this is horrible.

I'll have to think about this longer and really get the car in the air and plan this out. I only jacked up the front end and played around for alittle while with some spare 3inch pipe. Just isnt looking good at all

Single 4inch would be the best way out at this point i think

1989GTATransAm

iTrader: (3)

I think a single 4" pipe will do you quite well with your combination. I'm running a single Mufflex 3.5" on my car. After my results I have decided the exhaust is good enough. With your long tubes it should be even better.

So run 3" after the headers into a 3"x4" wye and then run the 4" in the stock locations. I don't think this will hurt you at all if done correctly.

Orr89RocZ

iTrader: (20)

i'm kinda torn right now..i really wanted duals for the sound but i was hoping i could get away from running in the stock location. But its cheaper to do the single 4 inch so I believe i'm gonna go that route

Plus seeing your results gives me hope i'm not losing much and will make the power i planned. But then again if you ran cutouts at proper length, how much will you gain?

now heres the thing. i'll run a single 4 inch I pipe over the axle and split it like i did before. so thats 3inch tubes into a long single 4 and back out to 3". So in effect will that long 4inch somewhat act like a resonator? i'm estimating the length would be closer to 70 inches, making volume of about 880 cubic inches. Single box about 8 times 1 cylinder then times 2 for both banks would be 766 inches SO would it act like a box?

skinny z

Do you have the flow capacity of any of the mufflers you're considering?

Orr89RocZ

iTrader: (20)

i dont know yet on that... but i'll tell you the 3 i'm considering at the moment

Borla XR1 in a 4 inch
Dynatech split flow in a 4inch if they make it i havent checked

Dynomax Ultraflo welded round, 4inch inlet 6 inch body


thats what i'm thinking. i need 1100 cfm of flow at least. More on the spray. Each of these should flow around 1100 i would think. they are all straight thru and being 4 inch they should flow near 1400 like 4inch straight pipe does

skinny z

What were you results?
----------

Orr89RocZ

iTrader: (20)

else i can do this

split it over the axle again as i do plan to do inorder to have dual exits again then run a muffler on each of the 3 inch legs like a GMMG or something

should easily cover the flow i need then. i would consider magnaflow 4x9's then


dynatech split flow is just like the borla but cheaper. ultra flow i've seen advertised at 1000 cfm for a 3inch version i think

skinny z

If you pay attention to the entry and exit details I don't see why it shouldn't. It's just difficult to bring two 3" pipes into one 4" and accomplish that. One 3" into a 4" looks more feasible although that means dual pipes from front to back including over the axle.
You could then run a pair of mufflers at the back either in the stock location or where the tail pipes usually are.
Think there's room for parallel 4" pipes?

Orr89RocZ

iTrader: (20)

see i'd be running a y pipe collector... smooth transistion from two 3inch pipes into one single 4inch exit

skinny z

Unfortunately, I don't think that will work as a resonator. The tuning we're looking for would be lost at the point where the two pipes transition into one. It's all about pressure waves and that would be altered by the y pipe collector.( I'm using a similar piece between my collector extentions and single exhaust pipe.)

Orr89RocZ

iTrader: (20)

interesting idea i seen was this magnaflow muffler, a dual 3inch in and single 4 out... maybe that work? but its on back order so i dont believe i'll be gettin it, just an idea

whats this talk about reflective surface to throw the wave back at the header? how does a small chambered flowmaster type mufffler accomplish this? They arent THAT big to act like a huge volume change i dont think, but do have walls inside that deflect sound and exhaust waves around. If i was to use a muffler at the 36 inch mark, would it successfully act like a resonator?

skinny z

Although I'm not entirely certain, I believe an open case muffler (is that what you mean by chambered? ) behaves differently from a 'tube' type muffler.
You've read this before but I'd like to copy a couple of paragraphs from the article that started all this.


When we dealt with collector length it was emphasized that it was, in most cases, more critical than the primary pipe lengths. Adding a muffler (even one with zero backpressure) to a system with already optimized lengths can alter the pressure wave response such that the tuning is now out of phase with what is required and as a result, power drops. The trick here is to install mufflers such that they don't alter the tuned lengths of the system. Let us assume that the test muffler is attached directly to the end of the collector. A pressure wave is reflected either at the end of the exhaust pipe or when a sizable increase in cross-sectional area occurs. Open chambered mufflers such as Flowmasters often appear to the pressure wave much the same as the end of the pipe. This means the pressure waves see no change in length and reflection occurs largely as it did prior to the fitment of the muffler.

A glass pack muffler can act significantly different. It does not appear as a pipe end but as a substantial increase in collector length. Result: a reduction of power even though there is no measurable backpressure involved. From this we can see that many comparative muffler tests were in fact "pseudo pipe-length" tests. Although many invalid conclusions were drawn, these tests still demonstrated some important facts. The most important is that the engine's needs in terms of flow and pressure wave length tuning must be isolated, one from the other. This is easy to do by means of the pressure wave termination box (resonator box) mentioned earlier. Incorporating a resonator box into a system produces a layout along the lines seen in Fig. 9. With enough volume, the resonator box makes everything down stream appear invisible to the header's primary- and secondary-tuned lengths. With a flow capability of 2.2 cfm or more, the muffler appears virtually invisible from a flow standpoint. As a result, we have a muffled system that produces virtually the same power as an open exhaust.

So it would seem that an open case chambered muffler at the end of the collector would see that collector as the tuned length. A glass pack at the end of the collector would see the collector extended by the length of the muffler.
That's why I think the picture of the dual exhaust with the two muffler tubes just about under the seats may represent an effective system. Post #196 in this (your) thread.

1989GTATransAm

iTrader: (3)

Here is the thread to my results.

https://www.thirdgen.org/forums/tpi/...lp-runner.html

I know that DynoMax and Magnaflow both make hi flowing straight through mufflers.

Orr89RocZ

iTrader: (20)

yeah, so its just the open case design that acts like a volume/cross-sectional area change, rather than a reflective surface of some sort? I wonder why is it that they recommend a large box of 8 times one cylinder when some of those flowmaster types are not that big. interesting nonetheless

skinny z

Here's some info for you. Now that my buggy is in the air ( I've posted a pic of the current status on a new thread in the exhaust forum: LT Headers to 3" single) I can measure a few components. My flowmaster muffler in the stock location is 5x10x17. That's 850 cubes. More than enough to satisfy the 8 to 10 times cylinder volume requirements for BOTH banks. In my photo, you can see the magnaflow 2 into 1 y pipe adapter. I think there may be enough room to accomodate a full size empty muffler case and get a resonator box at the appropriate distance from the collector.
Looks interesting.

Orr89RocZ

iTrader: (20)

I got my exhaust components in today..atleast most of it so far. my muffler i abit bigger than i thought and i'm not sure i'll beable to mount it infront of the axle but i'm gonna try my hardest to get it to work, i want it there so i can have dual outlets again

ps. 4 inch pipe is CAVERNOUS

1989GTATransAm

iTrader: (3)

"4 inch pipe is CAVERNOUS"

That is horsepower in the making. No back pressure allowed.

Orr89RocZ

iTrader: (20)

hope i can fit it up in there..its still pretty tight trying to keep a big muffler like my split flow in that location. I just want as much ground clearance as possible. I should be ok tho

skinny z

Step one is complete here.
New LT headers into a single 3".

87LS7GTARIDER

Need help does anyone know where i could get some custom fab headers for a 3rd gen with ls7 swap every thing is real tight under the hood already and i dont have a pipe bender or a welder handy as of now so id like to know if any one knows any where you can buy these at

Orr89RocZ

iTrader: (20)

very nice! i'll be doing the same type of thing here in a few days... got my exhaust stuff here and waiting on the mig welder to start fabbing things up

skinny z

TIG welding. It's the only way to go!
This is a shot of the inside of one of the collectors. It was purge welded with TIG. The welds inside are as good as the welds outside.
Stainless welding at it's finest. The guy that did the work is an absolute master.

Orr89RocZ

iTrader: (20)

That sure is pretty! My last system i had made with stainless pipe i had tig welded..but this setup i'll be using regular exhaust pipe. Mig should do it and i'm not really concerned how it looks.

Orr89RocZ

iTrader: (20)

Started my build and so far i like it

No pics as of yet since i dont have the camera with me this weekend, but it is coming around. i got one pic of the crossover with my phone, its an ok pic

the setup consists of modded hedman s-bend xtensions. I had to shorten the mid section and slightly twist the end to point outward alittle to get it to celar the spohn crossmember. Worked great, clears nicely and gives ok ground clearance

from that i have extensions going into a flowmaster y pipe collector. Passenger side is just about straight shot to the y pipe. the drivers side has about a 90 bend then a straight to bring it thru the crossmember where the torque arm attaches but above where the driveshaft loop attaches.

see pic


then i got that y pipe going into the muffler. I plan to then go over the axle into another y pipe to have 3inch dual exits like i had before


Only thing i'm worried about is the torque arm and that pipe. its close to hitting the arm, but if that arm pivots forward alot on the pivoting mount, it will hit the pipe. I'm not sure how far it pivots. Also the full length of travel on the rear it may swing the arm down and get close to that pipe but we'll see. I plan to make the DS loop detachable so the y pipe can be removed

mw66nova

iTrader: (13)

sounds alot like mine! except for a couple of obvious differences...mine is 3.5" and doesn't go over the axle.




good luck with it justin! make sure to get sound clips, etc. once it's running!

Orr89RocZ

iTrader: (20)

yep my y pipe sorta looks likes that

how much clearance you have with that? i know your car sits higher than mine tho with those tires i bet


And yes once its running i'll have clips

mw66nova

iTrader: (13)

you sure your car is lower than mine?



anyhow, i have ~3.5" of clearance or so. you can see in that pic pretty much exactly what's going on.

Orr89RocZ

iTrader: (20)

well you dont have ground fx, so it looks like it sits higher. if anything your rear sits higher than mine but the front is about the same or lower. Oh well, it does sit low enough, and my car looks to have about that clearance. I will only know once i finish this system later this week and get the car on the ground

i just finished my plans on how to make this y pipe detachable from the car and basically i had to make the spohn DS loop detachable as well. I cut it off and welded a bracket to it that will allow it to bolt on again. should work just fine

Rayzor32

iTrader: (1)

yo what size tire is that in the back? did u lower the front at all? wutever u did it looks ****in awesome

ssean92

iTrader: (10)

I love the Ypipe on your car matt I should have done the same one....

mw66nova

iTrader: (13)

29x9 hoosier, it's lowered 1 coils worth up front and 1.5 coils worth out back.

skinny z

Here's another look at the almost finished product. It still requires an intermediate exhaust support.
Road trip to Virginia and back. 1500+ miles. Zero ground clearence issues.
The biggest difference from the seat of the pants is the incresed power starting around 3000 rpm. That's undoubtedly the result of the change from shorty style headers with a restrictive factory style y pipe and catalytic to LT headers with modified 2.5" collectors (from 3").
A few problems with lower octane fuel on the trip. I use 94 up here (Sunoco) but once or twice on the trip I had to use 91. Quite a difference.
There are a couple of cross member pics in my LT headers to single 3" exhaust thread in this forum.

skinny z

Looking good!