Sidepipes--Want Your Perspective

[Stentor]

I am getting ready to have a less restrictive pair of sidepipes made for my car (I know the restrictive stock pipes I have are killing serious HP and TQ). I wanted to poll guys on the forum to see what your experiences have been in this area.

• What type and size muffler did you go with?
• Which way do you have the louvers of the muffler facing (toward or away from the flow of the exhaust)?
• Do you experience the infamous flapping noise upon deceleration? If so, please describe the issue and what you think can be done to avoid this.
• How loud are your pipes (i.e., sound good, loud but still good, too loud)?
• How much HP and TQ do you estimate you gained by switching to less restrictive pipes?
• If you had it to do all over again, what—if anything—would you do differently with the pipes?

Thanks,

Stentor

[xracerbob]

I have Classic Chambered mufflers substituted in place of the standard ERA muffler. I have the louvers facing away from the source of the exhaust (toward the exit). The pipes are loud but not obnoxious and have a deeper tone than many I have heard. I started with this set up so I don't know what the gain would be over the stock pipes, but they are definitely less restrictive than the standard ERA units. I don't think I would change anything as these cars should be loud and rumbly, not ear piercing and popping and thats just what I got.

[Dwight]

I replaced mine last winter with Classic Cobra Pack. I had 2 1/2" x 24" long muffler and I replaced them with 3" x 28" Cobra Pack. The 24" mufflers had the louvers facing away from the motor. And they were loud at 4000 rpms! I installed the 28" mufflers with the louvers facing the motor. I made a lot of motor changes so I don't know what horsepower I gained because of the mufflers. I did gain about 80 hp to the rear wheels.
Now I can cruise at 70 mph and talk to my passenger in a normal tone. I have a deep rumble at idle and a Cobra tone at speed.
With the old pipes, cops could hear me 3 blocks away and I have the pictures to prove it.
I love the sound of the new pipes and I think they gain me a little hp.
The sound/tone is perfect!

Dwight

[twobjshelbys]

My winter project is to change mine out for some black pipes.

[MaSnaka]

Stentor,
I changed mine to Classic Chambered Cobra Packs 2 1/2" x 30" with packing. Louvers face away from the engine. A much deeper tone than before, andI do get the flapping air noise. At first I thought they were too loud although they sound great. Now that I've had them awhile, I'm use to them and I like them. The shop that installed them into my existing pipes said that mufflers with holes were less restrictive than the louvers and insisted the louvers should face the rear to create less turbulance. I did pick up about 35hp and about 50tq. I dynoed the car before and after but also upgraded my intake manifold. My engine is a 390fe.

John

[DocDirk]

My kit came with severely restrictive 1 7/8" ID stock baffles and I had the car dyno'd before and after changing to 2.5" ID baffles, louvres facing the rear. The gain on that change alone was about 45 HP but then I'd been choking my BB with the mufflers that came with it. I think I'd pull up a few more ponies with 2.75 ID pipes but I never race anyhow...and I've already got more under my foot than I know what to do with

The sound with the restrictive pipes was brash and irritatingly loud, the sound with the larger baffles is more of a rumbly growl, a far more pleasant tone which invites many an inquiry as to "what've you got under there?"!

I found and used an exhaust pipe diameter calculator that took into account the Engine CID etc. but I can't find it now, just Googled it luckily.

Regards!

Dirk

[badrich]

I like my 18" race lobacs. Moderately loud, but much more mellow than my original burnt out glasspacs! Rich

[Ron61]

There was nothing remotely original looking about my car, but I used stainless pipes with a 4" inside diameter and had a single collector of the same diameter welded onto a plate that bolted ton the headers. Then I used a long, high flow glass pack muffler in each pipe. It was a little on the loud side, make that I used ear plugs if I was driving more than a few blocks, but I gained almost 12 horsepower over the 4 into 1 collectors and the smaller original side pipes that came with the car. Only problem is the stainless heats up quickly and will burn if you touch it. But I had no discoloration except some gold in the elbow of the collector.

Ron

[mdross1]

After listening to a friends FE for a while 3' from right ear then having to climb out over the hot muffler.The choice was easy for me,undercar exhaust,2 1/2" all the way.The 460 has no breathing problems. Have to say though,the flat back side exhaust looks right!

[KarlCSX2498]

Hello, I had the 2.5" packed cobra pack mufflers installed on my side pipes by Nick at Acton Custom. I'm not sure which way the louvers are facing, Nick will know. The car sounds great, I would do the exact same thing again.

Since my car is a completely new scratch build, I can not compare it to anything from before. The pipes are reported to be off an original car but when they were cut open there was a big transition from collector to the muffler and the passage was very small and they were rusted and sounded like a baby rattle before the change.

Give Nick a call or PM and he can give you all the details on the mufflers, he is a dealer for Classic Chambered mufflers.

good luck, karl

[dont]

I replaced the stock SPF 2.5" with 3" x 20" cobra packs with the louvers facing the air flow. The fluttering sound is brief and only when I depress the clutch for gear changes. The over all sound is deeper but louder under hard acceleration. My dyno results were 15hp and 16tq gains on the same dyno with almost identical weather conditions. The only thing that I would do different would be to change the collectors for a smoother air flow. My engine is a 460 BB.

[RedBarchetta]

-What type and size muffler did you go with?
Went from factory 2" SPF (perforated core wrapped in steel wool) to a 3" Stainless Specialties (perforated core wrapped in ceramic blanket material).
351W punched and stroked to 392 with very healthy Comp hydraulic roller cam.


-Which way do you have the louvers of the muffler facing (toward or away from the flow of the exhaust)?
They are unidirectional with their perforated core.


-Do you experience the infamous flapping noise upon deceleration? If so, please describe the issue and what you think can be done to avoid this.
Yes. And I find it annoying. A better transition from the collector into the mufler section would probably fix this. See my gallery for a drawing of how I would accomplish this.


-How loud are your pipes (i.e., sound good, loud but still good, too loud)?
They have gotten louder with age. My guess is that the ceramic blanket material gets clogged up with exhaust soot and that is why. Overall they still sound quite good, but I'd like to get back to a "tighter" sound at some point (I feel they have lost that edge since new). WOT will still wake up every cop within 1/2 mile of my location.


-How much HP and TQ do you estimate you gained by switching to less restrictive pipes?
Have no idea. Probably lost a little torque as a result though. Car still drives like a scalded dog.


-If you had it to do all over again, what—if anything—would you do differently with the pipes?
Given the cubic inches, would have compromised a bit and gone slightly smaller with either 2.5" or 2.75" inner core. I also would have spent more money on the transition portion and the factory collector to smooth it all. Someday I will throw more money at it, but keeping what I have for now.

-Dean

[Rick Parker]

I designed and fabricated the entire system using 1 5/8" 25" long primaries, merge collectors, 24" long, 3.5 diameter mufflers with 2.75 bore into FIA type side pipes on a 289, loud (?) absolutely! No regrets.......

[mickmate]

I have put the Stainless Specialties mufflers in a SPF like Deans. The exhaust seems to have a lower rumbling sound to it now. It sounds good and is comfortable in the car. It is the single biggest performance mod made to this car to the point it gave traction problems. The original SPF exhaust was crimped across the inside tube so there was a 3/4 x 1 5/8" slot left open. Horrendously restrictive.
I have put several sets of Classic Chambered in to Cobra side pipes. I have heard the 2.5" with the louvres facing towards the motors one of them being Karls above. I can still easily chat with my daughter while we ride around in these cars. They seem to make good power. There is no comparison to the 1.75 or 1.625" ID's these cars had. The customer of one set says he wants to reverse the mufflers as the flapping noise is driving him crazy. On the other hand they sold me who is a street car undercar exhaust fan on side pipes, to the point where I carry these mufflers in stock.
The 3" Classic Chambered I have also used with the louvres facing forward, we haven't heard those run yet. Classic Chambered recommends the 2.5" good for up to 450 HP and they become restrictive after that. I am using really nice transition cones at the front of the mufflers so it doesn't create turbulence. The performance specs are on the site and some sound clips of Cobras too http://www.classicchambered.com

[RedBarchetta]

Stentor, two more tips for you that many overlook:

1. While you have your pipes off the car and performing all that surgery, weld in an O2 bung on each collector (pointed at around 4 o'clock driver's side / 8 o'clock passenger's side, towards the inside of the car). Plug them for regular use (no one will see them at that angle). But they are always there and functional if you ever want to hook up a sniffer to tune for the proper A/F ratio. I'm still kicking myself in the fanny for not doing this simple mod while I had them out.

2. Check the side support straps/brackets and reinforce them with another strip of steel. Speaking for the SPF version, they are prone to cracking. Again, you have them out and apart...might as well beef them up here and there (and before you make them purty).



Regards,

-Dean

[patrickt]

Originally Posted by mickmate

I have put the Stainless Specialties mufflers in a SPF like Deans. The exhaust seems to have a lower rumbling sound to it now. It sounds good and is comfortable in the car. It is the single biggest performance mod made to this car to the point it gave traction problems.

You can hear the SS "Turbo Tones" by clicking my signature lines down at the bottom. I like them, and I've heard quite a few big block Cobras that were simply too loud for my liking.

[Frank Messina]

I have the headers and sidepipes from Kooks on my car that use 24" auger style mufflers. The sound is good to my ear and not at all objectionable in either tone quality or loudness. Unlike packed mufflers the volume doesn't change with these and the tone actually improved noticeably as I got the air fuel mixture sorted out. It was funny too because I at first thought it was the sidepipes that were responsible for the weird tinny tone and couldn't figure out why everybody had been raving about how good they sounded. Once I began tuning the motor I realized that as I got closer to optimum the sound quality steadily improved from tinny to a deeper more full sound. This turned out to be helpful getting secondary mixture dialed in. Wow, an audible tuning aid that actually works! Who knew?
While I'm happy with what I've got, I have to say that when Dean first drove over to my house with his new sidepipes, I was immediately jealous. They were about the sweetest sounding pipes I'd ever heard. But as he indicated, they're different now. The augers stay the same. HTH.
Frank

[Rare Iron]

Originally Posted by RedBarchetta

Stentor, two more tips for you that many overlook:

1. While you have your pipes off the car and performing all that surgery, weld in an O2 bung on each collector (pointed at around 4 o'clock driver's side / 8 o'clock passenger's side, towards the inside of the car). Plug them for regular use (no one will see them at that angle). But they are always there and functional if you ever want to hook up a sniffer to tune for the proper A/F ratio. I'm still kicking myself in the fanny for not doing this simple mod while I had them out.

2. Check the side support straps/brackets and reinforce them with another strip of steel. Speaking for the SPF version, they are prone to cracking. Again, you have them out and apart...might as well beef them up here and there (and before you make them purty).



Regards,

-Dean

O2 Bungs: Walker/Dynomax #88103. The plug for these is #35299. You can order these at any NAPA store.

[scottj]

Built my own exhaust from header flange to turn-out. 1-7/8 to 3-1/2 collector, w/tapered transition into a 3" x 18" perforated core straight through muffler, and 3-1/2" turn-out. I wouldn't do it again (too much work)... next time I would have somebody else build it, only with merge collectors.

Motor drives and responds to tuning same as with open exhaust. This is on a 430" motor with a very large solid roller, a single DP 4 barrel, and locked timing (670hp). Original sidepipes were Lobak spiral cores. Although quiet, throttle response was terrible. In fact, I ran more timing to compensate for the diluted intake charge caused by the excessive (for my combination) backpressure.


Re: "flapping noise" on decel; I dont have any with this system. But, FWIW, I have louvered baffles in a 2-1/4" pipe on my Harley and it "flaps" like crazy. Remove the baffles and it goes away??