Stock exhaust system

[barnett468 418]

13 minutes ago, Mach1 Driver said:

That's what I was hoping for and why I originally asked about the resonators. So maybe 2-1/2" pipe into Walker mufflers and a transverse in the rear. BTW I'm definitely not happy with the existing power (250 hp) and will upgrade to 400-450 hp as part of the restoration. This is all part of the plan for the "quiet" Chris Straub upgrade we discussed last year.

oops...you do not have 450 hp now?

yeah, the resonators are primarily there to reduce drone and not specifically intended to reduce noise although they do to a small degree.

i forgot about last years thread...getting a bit old but thank god i'm not as old as rpm is.

it will definitely be a challenge to cool if you use a very restrictive exhaust. my initial thinking (which may change a little after further contemplation) is 2/1/2" exhaust with some type of crossover with 2 3/4 - 3" dual walker style mufflers into the same size transverse muffler but the problem may be finding a 2 3/4" - 3" transverse muffler but i can look around and make a couple calls as well.

another problem will be noise from the thin headers. hedman elites use some of the thickest tubing but you will still get a good deal of noise from them so you may very well, want to insulate the interior after you get it up and running.

now, it may be that this type of system will still have some drone, and if it does, you can add "anti drone" pipes to the system because you probably won't have room for resonators.

just don't tell chris what you are doing, lol.

 

 

 

 

[Mach1 Driver 560]

Lots of sound deadening is planned. I was thinking of using ceramic coated FPA headers. Yeah Chris said I should use 3" pipes, but I don't see how that would work.

[barnett468 418]

you can get 2 3/4" but that is still a tight fit but it can be done.

https://www.jegs.com/i/Dynomax/289/49195/10002/-1

[barnett468 418]

35 minutes ago, Mach1 Driver said:

Lots of sound deadening is planned. I was thinking of using ceramic coated FPA headers. Yeah Chris said I should use 3" pipes, but I don't see how that would work.

One of the best sound deadeners is the dynomat because it is thicker than most others and denser than some others.

 

[barnett468 418]

this muffler may be one possibility for a transverse muffler. the shop can enlarge the pipe you use to fit the 3" openings or even insert the pipe  inside of the muffler.

https://www.summitracing.com/parts/mpe-12469/overview/

 

heres another but the magna flow is higher quality.

https://www.summitracing.com/parts/jex-mf2468/overview/

[barnett468 418]

something like this with a transverse muffler added if there is room for it. depending on your shock set up it might be a challenge but they make short dual mufflers also

 

[1969_Mach1 333]

Three mufflers with 2-1/2" tubing is going to be a mess under the car, if it even fits very well.  I wouldn't consider a transverse muffler.  With the horsepower goal.  To have it sound stock might not be possible.  I know late model cars are not very loud and some make over 450 hp.  But don't forget they all have catalytic convertors on each side.  Some have two and three catalytic convertors on each side.  Those, by themselves quite the exhaust some.

I would set it up with one muffler for each side like shown above, but for 2-1/2" tubing.  Use the 2-1/2" tubing, an X-pipe, and keep the exhaust tips about the same diameter as the tail pipes, not smaller and not those large diameter megaphone type tips.  And be finished with it.  Stock sounding exhaust will be negated by the use of long tube headers, a longer duration early exhaust valve opening camshaft, and higher cylinder pressures.  Sorry to sound negative, but you might be going down a rabbits hole.

[barnett468 418]

32 minutes ago, 1969_Mach1 said:

Three mufflers with 2-1/2" tubing is going to be a mess under the car, if it even fits very well.  I wouldn't consider a transverse muffler.  With the horsepower goal.  To have it sound stock might not be possible.  I know late model cars are not very loud and some make over 450 hp.  But don't forget they all have catalytic convertors on each side.  Some have two and three catalytic convertors on each side.  Those, by themselves quite the exhaust some.

yes, it is obviously counterproductive to have a 450 hp engine and then reduce the hp by installing a restrictive exhaust system, but hey, i'm just trying to make suggestions that will best meet his unusual goal.

the stock systems on many new cars is a "mess" underneath them as well but since nobody looks under them, the appearance is not that important but it will take a very good exhaust person to do it. bear in mind that the system i am suggesting is not much different than the stock system that ford used on millions of cars with the exception that i am suggesting mufflers in place of where ford used resonators like they did in the system below.

[Mach1 Driver 560]

2 hours ago, barnett468 said:

you can get 2 3/4" but that is still a tight fit but it can be done.

https://www.jegs.com/i/Dynomax/289/49195/10002/-1

If they sold mandrel bent 90 degree sections in 2-3/4 that might be worth trying- I'll have to look

[Mach1 Driver 560]

2 hours ago, barnett468 said:

One of the best sound deadeners is the dynomat because it is thicker than most others and denser than some others.

 

2 hours ago, barnett468 said:

this muffler may be one possibility for a transverse muffler. the shop can enlarge the pipe you use to fit the 3" openings or even insert the pipe  inside of the muffler.

https://www.summitracing.com/parts/mpe-12469/overview/

heres another but the magna flow is higher quality.

https://www.summitracing.com/parts/jex-mf2468/overview/

Thanks, noted

[Mach1 Driver 560]

1 hour ago, barnett468 said:

something like this with a transverse muffler added if there is room for it. depending on your shock set up it might be a challenge but they make short dual mufflers also

 

My single exhaust has one long muffler on the passenger side in the same location that is 19" long- probably a little longer than those, so there is plenty of room.

[Mach1 Driver 560]

50 minutes ago, barnett468 said:

yes, it is obviously counterproductive to have a 450 hp engine and then reduce the hp by installing a restrictive exhaust system, but hey, i'm just trying to make suggestions that will best meet his unusual goal.

the stock systems on many new cars is a "mess" underneath them as well but since nobody looks under them, the appearance is not that important but it will take a very good exhaust person to do it. bear in mind that the system i am suggesting is not much different than the stock system that ford used on millions of cars with the exception that i am suggesting mufflers in place of where ford used resonators like they did in the system below.

Agreed- the original Ford drawings in the Osborn Chassis Assembly Manual show the same dual exhaust set-up for 1969 351 and 390  and 428 Mustangs std and GT. They ran up to 335 hp- which is 75 to 84% of my current goal. I've seen new resonators that are 2-1/2, so one possibility is to bump the pipe size up from 2-1/4 to 2-1/2 and expand it at the 3" transverse Magnaflow. If its too loud then replace the resonators with straight thru mufflers.

[barnett468 418]

11 minutes ago, Mach1 Driver said:

Agreed- the original Ford drawings in the Osborn Chassis Assembly Manual show the same dual exhaust set-up for 1969 351 and 390  and 428 Mustangs std and GT. They ran up to 335 hp- which is 75 to 84% of my current goal. I've seen new resonators that are 2-1/2, so one possibility is to bump the pipe size up from 2-1/4 to 2-1/2 and expand it at the 3" transverse Magnaflow. If its too loud then replace the resonators with straight thru mufflers.

well the initial dyno testing in the 60's was crank hp done with no accessories, an open air filter etc. as soon as they put the engine in the car it automatically lost maybe 10 - 15% of its power.

[Mach1 Driver 560]

1 hour ago, 1969_Mach1 said:

Three mufflers with 2-1/2" tubing is going to be a mess under the car, if it even fits very well.  I wouldn't consider a transverse muffler.  With the horsepower goal.  To have it sound stock might not be possible.  I know late model cars are not very loud and some make over 450 hp.  But don't forget they all have catalytic convertors on each side.  Some have two and three catalytic convertors on each side.  Those, by themselves quite the exhaust some.

I would set it up with one muffler for each side like shown above, but for 2-1/2" tubing.  Use the 2-1/2" tubing, an X-pipe, and keep the exhaust tips about the same diameter as the tail pipes, not smaller and not those large diameter megaphone type tips.  And be finished with it.  Stock sounding exhaust will be negated by the use of long tube headers, a longer duration early exhaust valve opening camshaft, and higher cylinder pressures.  Sorry to sound negative, but you might be going down a rabbits hole.

All good points. I hadn't considered the additional sound from long tube headers, and had planned on them. Who makes shorties that really fit a 351w? Cylinder pressure will be kept to 10:1. I'll have to ask Chris Straub about the cam- its already custom, since I don't want a lot of lope. He was confident he could make it smooth and quiet and over 400 hp, but I see the exhaust is definitely an issue. Chris will supply all the engine parts for my assembly. This will be fun.

[barnett468 418]

17 minutes ago, Mach1 Driver said:

Agreed- the original Ford drawings in the Osborn Chassis Assembly Manual show the same dual exhaust set-up for 1969 351 and 390  and 428 Mustangs std and GT. They ran up to 335 hp- which is 75 to 84% of my current goal. I've seen new resonators that are 2-1/2, so one possibility is to bump the pipe size up from 2-1/4 to 2-1/2 and expand it at the 3" transverse Magnaflow. If its too loud then replace the resonators with straight thru mufflers.

it will be pretty loud that way i guarantee you. that magnaflow muffler is a straight thru design, and as i mentioned, the resonators will not make it nearly as quiet as quiet mufflers will.

 

 

[barnett468 418]

Just now, Mach1 Driver said:

All good points. I hadn't considered the additional sound from long tube headers, and had planned on them. Who makes shorties that really fit a 351w? Cylinder pressure will be kept to 10:1. I'll have to ask Chris Straub about the cam- its already custom, since I don't want a lot of lope. He was confident he could make it smooth and quiet and over 400 hp, but I see the exhaust is definitely an issue. Chris will supply all the engine parts for my assembly. This will be fun.

you will kill off even more power with mid and shorty headers. i don't think chris meant the engine wold be "quiet" by any means but he may have meant it won't be obnoxiously loud and have a big lope but only he can say for certain.

[Mach1 Driver 560]

2 minutes ago, barnett468 said:

it will be friggen loud that way i guarantee you.

with resonators or straight thru mufflers- or both?

[barnett468 418]

1 minute ago, Mach1 Driver said:

with resonators or straight thru mufflers- or both?

the system i posted a photo of is a stock system with resonators . if you do it like that with the magnaflow muffler as the transverse muffler it will be loud . you simply can not really make it quiet without killing off a lot of hp.

[Mach1 Driver 560]

6 minutes ago, barnett468 said:

the system i posted a photo of is a stock system with resonators . if you do it like that with the magnaflow muffler as the transverse muffler it will be loud . you simply can not really make it quiet without killing off a lot of hp.

sigh, yeah. A lot of engineering goes into making Vettes smooth and quiet. Its integral to the design. 

[Kaspar 21]

How much HP would a mon straight thru mufflers like the Walker lille, compared to a straight thru Magnaflow? Am thinking of doing that swap also, because of the noise.

[lanky 44]

I have some input on this topic. I have spent a lot of time trying to figure out if a non-restrictive exhaust can be quiet...IMO it's impossible *with classic mustangs* because of the space available in the exhaust system. Especially once you're above ~300hp.

I once thought turbo mufflers were the way to go, and they are definitely a good option. However for the volume they do have significant restriction at higher rpms and since they are NOT quiet I have decided high quality straight-through mufflers are my choice.

Optimally (for me) would also include either with glasspacks at tailpipes, glasspacks before the mufflers (only really short ones would fit here), some kind of dual in/dual out muffler added behind axle (transverse) etc etc. 

Some cars with space for larger (or more) mufflers can produce high power and remain relatively tame, but I think with our cars it's more difficult. I agree with the post about sound deadener, that makes a huge difference. 

[Kaspar 21]

I understand. It's the lack of space that is annoying me too. I  have 14" Summit straight thru mufflers on now, but maybe I can add a transverse muffler if that might help? I'm also thinking of swapping to 18" Walker, but don't wanna restrain the engine.

I wish it could sound like a modern sportscar that is quiet when exiting the driveway and passing the neighbours and then once I floor it in the highway it roars.

[1969_Mach1 333]

I am aware that some would like their classic car to sound more like a modern day muscle car.  That's not me, I like the exhaust sound of 60's and 70's muscle cars.  Anyway, keep in mind the exhaust systems on modern day muscle cars are loaded with catalytic convertors.  Usually two or three per side.  Depending on the design of the catalytic convertors, they can quite the exhaust as much as a muffler.  Also, the motor itself contributes a lot to the exhaust note.  Long duration cams with early exhaust valve opening that are more commonly used on our classic cars will make the exhaust note louder because more of the combustion explosion is heard in the exhaust.  Todays motors with variable cam timing can work around that and create a completely different more mellow exhaust note.  My 2 cents on this topic. 

[lanky 44]

I forgot to add one thing: I strongly recommend against Walker mufflers. I had a brand new one last less than a year before exhaust was coming out of the pinch seams. Not sure if they have welded one's, but they manufacture for dynomax and I think some of those are welded. 

There are also those mufflers with valves that open and close based on either vacuum or exhaust backpressure. I would never use one, but worth looking into maybe.

With a 2.5" system routing the exhaust for 3 mufflers (2 reg 1 transverse) would be difficult to say the least. You wouldn't be able to run very long of a transverse muffler due to the curves of the pipes, maybe a 14"er would work...not sure.

If I can't do the above when I have a system made, I will definitely run some sort of resonator/glasspacks (however small) right after the rear axle. They wouldn't do much, but with straight through design mufflers any extra can't hurt. 

I really won't debate this last part if anyone disagrees, but everything I have read with actual data shows that during cruising x-pipes typically are a little quieter than h-pipes (with everything else the same).

[mqu02 30]

On 5/20/2018 at 5:02 PM, Mach1 Driver said:

All good points. I hadn't considered the additional sound from long tube headers, and had planned on them. Who makes shorties that really fit a 351w? Cylinder pressure will be kept to 10:1. I'll have to ask Chris Straub about the cam- its already custom, since I don't want a lot of lope. He was confident he could make it smooth and quiet and over 400 hp, but I see the exhaust is definitely an issue. Chris will supply all the engine parts for my assembly. This will be fun.

Just throwing this out there as something to think about.  JBA makes a complete shorty exhaust system with 2.5" SS pipes that is designed to fit our cars.  It probably won't make as much power as a long tube header system, but will be close, and should handle 400 hp pretty easily.  It has a great, deep sound, that isn't obnoxious like many out there (you will have no problem having a conversation inside the car).  I installed it on my 351, and I have no regrets whatsoever.

I am sure you can find this system significantly cheaper than Amazon, and it was just what came up first on my search:

https://www.amazon.com/gp/product/B0040Z8XRI/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B0050SI59U/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B000N5JNTG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1