3G Go Kart Project , Exhaust

[FyreDaug]

See this thead for the project: https://www.3geez.com/forum/showthread.php?t=52936

Okay, what I think ive decided is that the pacesetter currently on my hatch will come off and go on this, and then replace the header with one of the factory manifolds I have, and get it welded to the 2.5" all the way back.

Now, the pacesetter I have is in decent shape (just doesnt have the main-to-downpipe gasket in there) so Ill probably just re-coat it (its coming off a bit).

I'm gonna keep it 2" pipe all the way. Ive got 2.5 on the hatch and its too big, and 2" is simple enough. Especially when theres less than half the normal amount of piping, its not like the exhaust has enough chance to de-velocitize as it would with a longer pipe.

Okay, first question cat or no cat? If its any cat at all, itll be a high flow, no stock shit here.

The muffler will be pretty much right next to the motor, so its not like theres a whole lot of pipe.

I want a quiet exhaust on it, but also free-flowing.. Itll maybe put out 140hp when im done with it, so its not like its flowing like an h22 would, but something decent.

Im a little scared though, I really really dont want a buzzy sound, but I dont have a whole lot of room to put anything, pretty much right after it goes under the motor its coming back up, and out. I like what glasspacks do to the sound, but they are quite long. Id probably throw out the cat if a resonator makes a better change in sound, and they are about the same size as cats normally anyways. glasspacks (cherry bomb) around here are like 26" length... I might be able to fit one if I cut the down pipe where it levels out and weld it to the downpipe (no flex in here anyways... that means no pacesetter flex either... literally righth where the 2 go into 1 is where the cut would be made)

As for muffler, like I said, something better than stock flow, but quieter than some of those really high flow ones.... With significantly less pipe, I thinking it makes this battle even harder, and itll be louder on this car than on my hatch with more piping....

A formula 1 kinda sound would be nice too, but still something with a little bit of throat to it if you step on it.... Im sure the weber (or DCOE's if I have the cash) will make a little bit of intake noise anyways... so basically 2" headerback with about 30" total piping from where the 2 goes into 1 on the header.... thats 30" to the tip, including all bends and muffler/whatever lengths.

What can I do?

[halxi]

skip a muffler and go for the biggest possible resonator+high flow cat you can get in there (biggest resonator, as in longest)

[Hash_man_Se_i]

why you would put a cat in is beyond me... I say a magnaflow high flow resonator and muffler... cheap and will sound good.

[FyreDaug]

Cat because of the subtle sound change it makes, trying to stay away from things that pop and buzz..
And no, this isnt on the accord, its on the kart. My ehxuast is done on this car, ill just have to swap out the header.
Okay, thanks for the dia. Why 60"? Is that the best size? What happens if its smaller? longer?
As for that straight pipe section, what about putting a glasspack in there? Its "basically" straight pipe, but instead of dead pipe, it can be used to reduce sound.
I dont know if there will be enough room for 60". I cant draw right now, but picture this
Engine mounted in back of car, you are looking at the back (therefore if you are looking directly at motor, you are seeing the intake side). The header will travel down and under the motor, then come up and right a little near where the intake mani is (exhaust will be wrapped. Ive got like 12ft of good wrap around here anyways, might aswell use it). So its come from under and come up about half the height of the motor as it gets to the far right side. Then the horrible near-U bend that is gonna have to be in, will be there, so it essentially curves back over horizontally. Like if a muffler were mounted right there, it would be horizontal. Thats not a whole lot of pipe, but theres not a whole lot of room. Unless I U-bend it over again to come back from left to right, but that just seems like more restrictions, especially since I dont have access to anything mandrel around here, that 1 U is bad enough.
Any recommendations on specific mufflers? Itll probably be hooked with a 50 shot down the road too, but typically NA im expecting 140 tops. maybe 180 with a bottle. Should be quick enough...
Im not expecting exhaust to have a huge impact on the power of this car, but why the 2.75" resonator and 2.25" res-back? I was thinking simply 2" all the way to steer clear of different velocitized areas. Im no exhaust guru, and im sure you know more than me in this case, but could you explain?
Okay thanks for the info, your always full of something.... atleast this time its info just messin.
Okay I understand the whole thing about the secondaries and the velocity a bit better, but would the length after the secondaries matter if it was straight pipe or a glasspack? Glasspack is still straight through, and it "vents" open into a bigger tube, like the resonator, after still.. After they merge its a 2" diameter with about 10" of just pipe, so with that 10" cut off, I could throw a 24" glasspack on there... I dont know, im not trying to argue, just wondering if its possible to use some sort of noise reduction unit instead of the straight pipe after the secondaries... aslong as its still straight through I dont see a problem
and maybe that U bend I said it a little more like a C bend when I think about it, but either way, big bends like that scare me a little
They could be, but I have 0 experience with any of them so I dont know how they sound, have you used any of the 3?
Also, quick question, would exhaust technically be a little louder with less pipe? Raspier? or anything

with bends.... bends are typically bad, but I like this thread. Very useful information.
(btw we pulled one motor/trans today)
well there is a little more space to be used, I was thinking kinda where that pipe "tips" at the very end would be where a U bend would be, and put a big oval muffler exiting the opposite end
Well technically what I was thinking was the ehxuast would come over at an angle and by the time it were to come up it would already be on the transmission side, then it would bend over the other way (180*) and have the exhaust go that way... But hell if this way would be reletively quiet then by all means ignore what I said

[smufguy]

So you are pretty much doing what we did in SAE about a good 4 years back. WE ran Bike mufflers since they were small and easy to fit. Ill find a pics of what i took and maybe i could attach it for ya.

[A20A1]

PART I. SHORT EXHAUST SYSTEMS FOR LIMITED SPACE

my exhaust was never raspy and I had next to no pipe and a chambered muffler. It sounded deep like a performance truck/motorcycle (not sport bike).
The chambered muffler was there because I didn't want to add extra length to my tunned lenght. Even thought the physical piping was longer then the tunned length, the opened chamber of the muffler I had on allowed for the expansion pulse to act much the same as it would if I ran an open header.

Exhaust leaks will cause funny exhaust noise and pops
I would suggest a chambered muffler instead of the packed mufflers.

The aerochamber muffler from hooker has both packing and chambers. Even though it has some packing, it will more then likely act like a chambered muffler and can be used as one.

Flowmasters are a clear example of a chambred muffler. But you should go with 2.5" + on the flowmaster... it flows about 290 CFM

Most of the good packed mufflers still can get raspy in the upper rpms. Round styles more so then the larger oval ones.

It will be louder with less pipe;
But pipe more or less contains the sound and moves it around... there isn't much there that is either doing something to deflect or absorb the sound waves to keep it from exiting the pipe. Pipe diameter and shape will change the tone/note? of the exhaust. but not really how loud it is.

Straight through packed mufflers act more like a collector, so you'll be adding length if you add the muffler after your tunned lenght.
So you'll need to make everything really short so it all fits into 30" or add other 30" with the muffler incuded in the length.

You'll end up with 60"-72" with everything, from the exhaust valve to the end of the muffler if you want to go with a glass packed muffler; everything will be 2" Diameter. Sad part is about this setup is that you have to pick a muffler that is the right length.
With a chambered muffler setup you have more length options becase the chambered muffler lenght isn't being considered a part of the tunned lenght.

Minumun lenght: 60"
Sound: Fair

Chambered mufflers acts like an open pipe which is the effect you want to have after the 30".

You'll end up with 30"-36" from the exhaust valve to the end of your resonator if you use a chambered muffler. The chambered muffler should be at least 0.50" larger inlet.outlet diameter, most mufflers fall at about 24" long; you could end up with a total length of about 60" from the valve to the end of your exhaust.

Chambered doesn't mean you will have more backpressure, as long as you find one that flows what you need.

It more plausable you'll need the full 36" if you use the resonator, then you're out of room and must stop using 2" pipe.
After that will be the Chambered muffler.

This setup does put limitations on the length and possible use of any resonator.


Minimum length: 30" (no Resonator) + Muffler Length = aprox. 50"
Minimum length: 36" (Resonator) + Muffler Length = aprox. 56"
Sound: Good

It's your choice though if you go chambered or straight through/packed.



I was looking at summit;
Flowmaster 40 Series
length 19"
36" (Exh. valve to end of Resonator) + 19" (muffler) - 0.50" (lenght of 2" outlet overlaping inside 2.50" inlet) = 54.5"
30" (Exh. valve to end of 2" pipe) + 19" (muffler) - 0.50" (lenght of 2" outlet overlaping inside 2.50" inlet) = 48.5"
Where as the Packed muffler system would have to be at least 60"
I'm not recommending flowmaster for the accord... but in this instance it is quite useful as a tuning aide.
Here is the other option
Hooker Aero Chamber
lenght 18"
you could have 47.5" with no res.
After the chambered muffler you're pretty much free to do whatever... just make sure if you decrease the outlet diameter of the 2.50" muffler you merge it like in the image below.
Dropping to the smaller diameter pipe will help with sound as well.

Now to shine the spot light back on the Packed muffler option.
Where the Chambered muffler has to keep the pipe straight, you can go ahead and add in curved pipe between the res and the muffler or the res and the header and still be okay as long as the total length is still between 60"-72"
So really if space is you're concern go with the Packed muffler and compact the exhaust routing with bends.

Focus on getting the lengths setup so you keep your torque.
If you have more room for pipe try the option below.

[A20A1]

PART II. COMPLETE EXHAUST SYSTEM FOR LIMITED SPACE

What about 60"-72" from the exh. valve to the exit of a 2" pipe, then add on a 2.50" chambered muffler?

It should give you more room for pipe and the resonator.




Basicly you measure the center line of each pipe and curve from the exhaust valve to the end of the 2" pipe and it should be as close to 60" as you can get it... if you need it longer then try and get it under 72" long.

After that you go into a chambered muffler 2.50" diameter... a straight through packed muffler will not work the same.

After the muffler do what ever you feel like.

...well there is a little more space to be used, I was thinking kinda where that pipe "tips" at the very end would be where a U bend would be, and put a big oval muffler exiting the opposite end.

Well technically what I was thinking was the ehxuast would come over at an angle and by the time it were to come up it would already be on the transmission side, then it would bend over the other way (180*) and have the exhaust go that way... But hell if this way would be reletively quiet then by all means ignore what I said

I don't want to ignore you... you're the owner. I can try and work a system out that will give you what you want and still do what I recommended.

I'd say the last diagram is the quietest and hopefully looks the way you want it while still meeting the requirements I would want to see in there.

My Megan Racing 4-2-1 Header is about 33" from the valve to where 2 merge into 1.
That will give you 27" to make all the bends and use up with the resonator.
Usually you'd want a bit of straight pipe before the exit into the 2.50" muffler I'd like to say 10" but I'm sure you could cut that down to maybe 4"
so lets say that will leave you with 23" now the two major bends might each take up 4 inches so now you have 15"
if you get a 12" resonator you'll have 3" left to do minor bends.

04" Straight pipe before muffler
12" Resonator
08" U Bend
03" Minor Bend
33" 4-2-1 (Valve to 2-1 Merge)
60"
And that is your 60" long 2" diameter system.

Just remember you can go over 60" but not by much.

So which muffler are you getting?
Flowmaster
Hooker
Other?

140 hp will need to flow about 308 cfm for minimal exhaust loss.

My vote is for the Hooker Aero Chamber 441 cfm and much better construction good for 200 hp.
If you were to add a pipe after the muffler.
2.00" 164 hp
2.25" 207 hp
2.50" 256 hp
Go with the smallest possible then choose a reducer that will bring the 2.50" muffler outlet down to the size you selected.

Flowmaster 40 Series comes in just under the nose offering 290 cfm but with a little more sound deflection/cancelation
still okay to 160 hp with the 2" pipe, but the Flowmaster will be a backpressure gremlin past 130 hp.

[FyreDaug]

Wow. Had to read it all twice. I like what you did with the thread, im assuming it was you.

Okay, verdict: still undecided for now, but I do have another question. In the last diagram you just did up, you are suggesting the 2" pipe all the way to a 2.5" muffler... what about the 2.75" res to a 2.25" muffler like it was going to be before? You even got rid of the diagram, was it not a good idea to do now? But what you just drew is basically what I was trying to derscribe anyways, with the curve and the bigger muffler. I dont want to limit my exhaust to just the specs I said, Im thinking with the money left over from this project we will tear apart the other motor and start building it a little. Maybe plans for higher revving and nitrous. possibly upwards to 140 na, and up to a 50-75 shot.... so maybe a slightly better flowing muffler to keep things safe. What about stepping up to 2.25 for the resonator, then keeping that size to the 2.5" muffler? Would that be good for about 210?

EDIT: Keep in mind im slihgtly purposely bloating these numbers to be on the safe side

[A20A1]

nah, the 60" of length from the valve to the end of the 2" pipe is all secondary length, its supposed to be small as in 2" because that is determined by the pipes on the header, unless you change the header I would keep it 2" to the muffler.

Basicly you're using two exhaust system factors isolated from one another.
Two factors are: ( The two Systems are: )
1) Pressure wave tuning with length/diameter selection. ( Header )
2) Minimizing backpressure with mufflers flow capacity. ( Muffler )

The Hooker would start making backpressure past 200 HP.
you can make 210 HP and not have backpressure problems as long as the muffler or mufflers flow a total of 462 CFM.
The hooker flows 441 CFM, you have to ask yourself if you want to make up that lost 21 CFM and 10 HP.

You will probably need two muflers, and that just adds more complexity and other issues.
1) more cost
2) finding appropriate muffler as close to 231 CFM as possible.
3) by introducing a Y to have two mufflers you alter what you're trying to achieve with the header system.

I suggest you keep it as it is and just not put anything smaller then the exit diameter after the 2.5" muffler...
thought you can go down to 2.25" after the muffler and still be very close to 210 HP.


Also consider not using a resonator prior to the muffler since really most things sold as resonators are just packed mufflers.

Go straight 2" pipe to the first muffler ( Hooker Aero Chamber ) see how it does.

If you find that its too loud, add on a ( round straight through magnaflow in 2.5" )

For a tip use a reducer from 2.5" to 2.25" or leave it 2.5"

[FyreDaug]

how do you know all this?

[A20A1]

I don't I just spent 3 years of my life reading about what works and what doesn't as well as playing with exhaust on my own. I learned more in the last year then in the first two and had some preconceptions knocked aside in the process.

Anywho these are conclusions, close aproximations, reoccuring themes, and educated guesses.

along with some crossed fingers as well

Aside from that you can always see some of the equations at work.
here:
https://www.3geez.com/forum/showthread.php?t=6466

[A20A1]

Here is some good info on the cat listed
http://www.team-integra.net/sections...p?ArticleID=24
http://honda-tech.com/zerothread?id=1128725

http://sms-products.com/Converters.html

A fair price... this'll be nicer then the res to drop out sound.
Looks like they only come in a few sizes... I would suggest 2.5"

I really don't know what it will do to the tuning though... so just to be safe I would say stick it after the muffler but then it might be too far away to do any good. If you make below 150 HP and run the cat it'll still act like you don't have one... once you push beyond 150 you may start to lose a little but so far from those dyno results you wont even lose that.

I'm also thinking that in order for the cat to perform and flow well it needs to be close to the header.
So I'm at a loss untill I know how far the stock cat is away from the exhaust port... then I can safely say if having the cat so far away is a good idea or not.



If the cat is no good after the muffler you can always remove it and install it before the muffler.

Seriously though scrap the res and go with the high flow cat.

That was after all you original plan.
- Muffler
- Header
- Cat
- 2" piping

Oh and thru all this I forgot to mention this in response to the very first post, Stay away from Glass Packed Mufflers!
If you want a packing material make sure its stainless steel.

[FyreDaug]

Why stainless steel? I currently run the pacesetter on my hatch upsizing to 2.5" and keeping 2 glasspacks and pipe straight through. Sounds pretty good actually.... whats so bad about glass?

How does the sound of that hooker sound compared to stock?

Im sure you are fully aware that those really annoying buzz cans people use are typically just replacement mufflers and they dont use any resonators/glasspacks or anything and they sound god awful. Lets say this horrible sound is a 0 and stock is 10, where would you approx place that hooker? And how much better would it be with say a 12" 2.5" res like you had planned before in that other pic you removed with the straight 2" going into the 2.5" and just padding it and making it work so it would expand, and then going to a 2.25" hooker, or even 2.5" hooker, it doesnt matter to me. If I do eventually plan to build it up, it wont go past 8000rpm after some head work. I just want a little more motor out of the gears. So if I use the 2.5" res and a 2.5" hooker then ill throw on a 2.25 or 2" tip as a reducer to keep the expanded gas going at a good velocity....

Am I on the right page here? Does that sound like an acceptable setup?

The hooker flows 441 CFM, you have to ask yourself if you want to make up that lost 21 CFM and 10 HP

2cfm = 1hp? If its gonna hurt me 10hp if I use this muffler, then ... well that kinda sucks, but acceptable sound is what im after. itll be fairly quick to begin with, but if I step up the diameter of the muffler it would technically flow x% better right?

[A20A1]

Glass ( Fiberglass ) will burn out after a while then you have to repack it or buy a new muffler.


You wanted 210 HP... Say you make 180-200 HP
The hooker flows 441.... If you make 210 HP which you can make, you'll be flowing more then the hooker can handle AFTER you go past 200.

So where ever in your RPM range that you peak at 210 is the only place the muffler should show any resistance.
Let’s say you only get 210 hp at 6,800 rpm... well the rest of the time you are below that you should be fine.
200.4545454545 hp needs about 441 CFM of flow.
Or 441 CFM is good for 200 HP

You're not constantly flowing your peak CFM though, you don't have 200 HP at 2,000 RPM
So I said IF you plan to make over 200 HP then you might consider dual mufflers or finding a single chambered muffler that flows more.

You can find straight through mufflers that flow more but then you don't get any tuning advantages unless you use a straight thru as part of the pipe length. Which mean a 2" straight thru before the first real change in cross-sectional diameter or expansion into a greater volume, IE: the atmosphere or a large chamber.

No stepping up a diameter of the hooker does not always mean you'll gain any more CFM from the muffler. It’s usually the internals that are the restriction not the pipe itself. That’s why you first determine your pipe diameter. This pipe diameter is only after the first expansion/first change in cross-section to make sure your exhaust flows... this is not a part of header length or diameter. Now this doesn't mean you can't make more HP then what is shown, it simply says you'll be building backpressure as your HP exceeds the Max CFM of the exhaust system.

1.75" Single Exhaust pipe flows about 275 cfm good for 125 HP
2.00" Single Exhaust pipe flows about 361 cfm good for 164 HP
2.25" Single Exhaust pipe flows about 457 cfm good for 207 HP
2.50" Single Exhaust pipe flows about 564 cfm good for 256 HP

The Hooker I selected for you is 2.50" inlet and outlet
Why?
1) Because 2.50" is good for 256 hp
2) It is as close to 1" larger than 2" it forms a collector and an anti reversion dam when installed correctly over the 2" pipe.

While it does make sense on some level that the company would increase the flow of the internals to any increase in pipe inlet and outlet diameter... that is not always the case.

Lets say this horrible sound is a 0 and stock is 10, where would you approx place that hooker?

Sound Quality Idle ( 10 Stock / 0 Crappy Can )
- 7 - 
- 8 - With a good Resonator 
Sound Quality WOT ( 10 Stock / 0 Crappy Can )
- 6 -
- 7 - With a good Resonator

 
Sound Volume Idle ( 10 Stock / 0 Loudest open pipe )
- 5 -
- 6 - With reducer after muffler 2.50" to 2.25"
Sound Volume WOT ( 10 Stock / 0 Loudest open pipe )
- 3 -
- 4 - With reducer after muffler 2.50" to 2.25"

I still say a Cat is Better then a Res, espicially one that flows well, If you do install a true Helmholtz resonator you'll only get so much from it. The Magnaflow Resonators are packed though they may have some angled linings inside the pipe to deflect sound waves back into the incoming sound waves. With a cat you'll disrupt the sound waves more. I have made exhaust systems before with no res but kept the cat, using your scale:
With Cat : 8 at idle and 6 at WOT for sound quality
No Cat : 7 at idle and 4 at WOT for sound quality
This is with a PT Muffler

[FyreDaug]

Awesome, alright one last thing. Since the glasspacks will burn out over time (Ive put a good 15000km on these 2 and they sound about the same as they did before) If I did put one in place of that straight 2" tube going to the muffler and didnt weld it but used coupler clamps (tube that fits over the 2" opening on both sides, and dually clamped down) that even after time, I could swap it out no problem. But are there any downsides to those clamps? Are they common to leak? Even with muffler tape?

I know I keep saying this, but I do like the way those cherry bomb glasspacks make it sound compared to open header.... especially with 2 of them on there, its acceptable volume. I would like a little quieter with this though, which is why I keep harassing you for information out of this thread. That cat is quite pricey though, and for the subtle change in sound they would make compared to what I KNOW a glasspack could do for it, a glasspack is less than 1/5th the price. And your tellin me these hooker mufflers will sound good, and thats pretty much all I need to know. Right off the bat im gonna have pretty much 98hp + the vacuum removal bonus. Thats it. Were gonna build it get it working, then throw this exhaust system on it, dcoe's and a stage 2 cam. Leave the rest stock until it gets built. But even with dcoe's, a good flowing exhaust and a good cam, I should peak at around 130-135 anyways, which would be good for a 75 spray. Hell, smufguy if boosting on a stock motor making over 200, I dont think I need to do a whole lot. And I can always build the other motor too... blah blah blah getting off topic.


Either way, thanks for the info, I will probably do what this thread says. :thumbsup:

[A20A1]

I would certainly go that route, there are plenty of good clamps out there.

Just change things around and see what works best for your motor.

if you don't like the aerochamber give it to me

nah I can buy it off you when I get some money.

[FyreDaug]

Yeah trial and error I guess... Ive read up on a few reviews and stuff and it doesnt sound like it would be a bad muffler at all. I think this is what its gonna be, Pacesetter header, chop the merge after secondaries on the pipe and throw a glasspack in there, immediately after the pack there will be the up bend and curve into that 2.5" aero chamber (this one right? http://store.summitracing.com/egnsea...4&autoview=sku) and then a 2.25" tip? Or just keep it 2.5"?

[A20A1]

You can even prefab this piece with:

1) 2" pipe
2) 2" to 2.5" exhaust adapter

That way you just clamp it to the muffler and everything is centered nicely and the 1/2" overlap is built in.

This is for the inlet side of the muffler




Yup those are the hooker aerochambers,
2.5" center in / center out would be the best.
Hooker 2.5"


something like these reducers
2.5" to 2"


As for keeping it 2.5" or 2.25" after the muffler that is up to you...

But I would say go down to 2.25" it will help with sound.

[FyreDaug]

Sweet, thanks alot mike, ill keep you posted. Any idea where you can buy those mandrel donut things? Its just a big mandrel circle x big with a certain size OD. Any idea what im talking about? Ive seen them before..

EDIT: Also, my pacesetter doesnt have a gasket between the 2 parts, is it neccesary? Its installed just metal to metal right now, just thinking it may be leaking pulses a little inbetween... Where can I get them if I need it?

[A20A1]

Here you go
http://www.roadraceengineering.com/mandrelbends.htm


You realize that any bend that isn't mandrel drops the cfm by nearly 100.

[FyreDaug]

I do, well didnt know it was a hundred. Damn, im gonna pick up a mandrel bend for sure, only really need 2 bends

okay, so if I can manage to get a glasspack in there somehow, itll be in, otherwise itll be a 2" resonator and the 2.5" hooker. I think space for that cherry bomb glasspack will be eaten up by the secondaries, so probably only room for a 12" resonator, but we'll see soon enough.

Quick question, think I could get away with using 1 single mandrel U bend? A very very slight bend to one side right after the secondaries, then bring it up (about 90*) and then over again almost 90* again, looking on ebay to get all my stuff, and the U bends are fairly cheap, just wonder if its enough bend

And damnit, that site with those mandrel donuts only accepts credit card, a problem because I dont have one.

[A20A1]

they don't accept money order? ask them. most will because it's just like cash.


Ebay sells the bends? are they any good?

Problem with the gauge of pipe is that thin gauge pipe say 20 gauge will burn through with a regular mig if you're not careful.
Move down to thicker pipes like 14 gauge and they are easier to weld but they add more material on the inside so in effect it's a smaller pipe, unless it's measuered in Inner Diameter ID then you don't have to subtract the gauge.