[Tom Hand]

After reviewing the other muffler cutaways and text, this muffler will make lot of sense to you all. These are some built from spare parts leftover from VOE and Crossflow trials. I decided to use the parts constructively and since Dad did not need them on his wagon, and Cliff was still using his old chambered ones, I figured he would be a good test person to install and run them for me at that time.

1) The body/shell and end caps are an 11" by 5" by 16" oval. This is the maximum you can fit safely under a Firebird or Ventura (later one). The fibrous material is ceramic fiber, chosen for its wonderful acoustic property and its ability to resist damage from heat or chemicals in the exhaust gases. It is the same material used in the VOE mufflers I built early on and it works very well absorbing the high frequency tones, getting rid of a lot of the resonation, and lowering the overall sound level.

The inlet and outlet bushings are made from a 45 degree mandrel, 3" section from Dr. Gas.

You'll note that I left over an inch on both sides of the bushing and center tube as it traverses through the 5 by 11" body. This gave lots of room to pack the muffler to a higher density with the fibrous ceramic which is a good way to get all the benefits you want from a muffler.

The perforated st. st. was chosen for its optimum transparency and porosity. Test after test, report after report, and muffler after muffler prove that this helps provide great sound control, a nice tone, and acceptable gas flow. The sound energy can pass through it, the energy is absorbed in the fiber, and you end up with a nice smooth tone. I did it differently than most others in that I extended the perforated pattern almost from one end to the other. I chose to give up some air flow capability to get better sound level control at lower speeds. These mufflers are quieter than many of the other straight through mufflers that have only short (6") sections of perforated tube inside.

The st. st. sock material is for 2" pipe as the 3" had not arrived yet but it is in the muffler. This material adds a lot to the cost but keeps the fibrous ceramic in and makes the mufflers' tone and sound level stay consistent.

2) After some careful review of offset offset mufflers and looking at lots of OEM version specs., I chose the minimum center to center distance that would still work with most F-body cars. This also provided more of a straight-through path but not so little that the exhaust sound was too loud or crackly.

3) These are the mufflers after being black high temp. powder coated. Cliff has them on his car now and can shoot some more images some day when the car is up and the weather is warm.

4) It is hard to judge but these are BIG inlets and outlets (3" ID) and you just can't believe how quiet they are on a powerful engine. I was pleasantly surprised and happy.

How do they work? Very well. They flow like straight through, silence like a SuperTurbo, have a nice tone, minimal resonance, and fit pretty darn well. I was never able to sound test them on our test engine but I had them on Dad's car and they provided some really good sound numbers. Slightly louder than the SuperTurbos, about equivalent to the UltraFlos, and not much different than the 22" long XLERATORS. Air flow potential-wise, I seem to recall they were in the 95% range so there is no comparison with any of the chambered mufflers, regardless of inlet or outlet configuration.

Too bad I am out of parts. But, mufflers similar to these are available from most reputable companies, just that the size I used is not typical (gave more volume for sound absorbing material) and the offset was less (gave more flow capability).

[ponjohn]

WOW, awesome project.

Do you think the insulating material can be purchased?

John

[Tom Hand]

How much you need?
I have lots of similar stuff.

[Laguna454s3]

Thanks Tom

I always enjoy your insight of the muffler world.

Any thoughts on the now discontinued Edelbrock RPM muffler ?

I bought a few sets when they went on deep discount. I like the idea of the split flow path as in theory there should be some sound cancellation when the pulses collide through the perforations and again when they rejoin. The flow path isn't completely smooth as they are constructed in 2 stamped halves as a top and bottom and additionally the perforations are in the curves.

John

[Tom Hand]

John,

Those are the old Jim Fueling patented ones I am pretty sure. We had one to play with and I recall it was different than a normal straight-through but not sure how much I could really tell at the time.

I have a patent image I will search for and get posted.

Must have been high cost to build because they disappeared pretty quickly. They also may have been from Cyclone (Sonic Turbo) who got bought shortly thereafter??
Tom

[Tom Hand]

Here is one image from Jim's patent.

[Z Code 400]

Tom,

I thought you might appreciate this.....

Back in the 1960's, Dad produced a rectangular shaped, dual inlet/single outlet muffler for his Ford Flathead Lakester that had a spring-loaded trap door inside of it. The two inlet pipes were perforated and the front of the muffler contained an acoustical chamber that was stuffed will stainless steel wool. A triangle-shaped baffle split the exhaust flow and directed it toward the sides of the muffler.

There was a second chamber (actually two small chambers packed with wool and a blank cavity in the middle that housed the trap door) in the muffler with a trumpet-shaped, perforated pipe on each side that collected exhaust gas and routed it towards the outlet. Diamond profile gas directors were slipped through slots in the case and the tabs were welded over, which eliminated any chance of the baffles coming loose.

Under normal driving, gas exited the inlet pipes, passed through the 'trumpets,' releasing sound into the two chambers, then exited the center outlet. Once the exhaust gas flow reached a certain velocity, the trap door would be pushed down and open a direct path for the exhaust.

It sounds complex, but when Dad drew me a sketch, it seemed very simple...Robert

[Lee]

Tom,

Here is an odd one for you.

Years ago, I came across a fellow, who had some REALLY out of the box ideas. Older gentleman, the sort you want to dismiss as a kook when you first meet him. Stories about how A.J. Foyt had a small nitrous system hidden in his back brace, Wayne County stuff.... But the guy had a Honda Civic that ran low-11's, and this was back in the 90's!

On the topic of reducing exhaust noise, his "idea" was a length of PVC, which had "golf ball"-esque dimples on the inside. I never got to hear an example of this, but never forgot it!

Have you ever heard of such a concept?

Lee

[wheelspin]

Originally Posted by Lee

........On the topic of reducing exhaust noise, his "idea" was a length of PVC, which had "golf ball"-esque dimples on the inside. I never got to hear an example of this, but never forgot it!......Lee

Back in the early 90s when I was still riding bikes, BMW brought out a new wind tunnel tested full face helmet and the exterior was covered with golf ball sized dimples. The advantages were touted as less interior noise and reduced wind turbulence @ speed (less of a "speed bag" effect @ high speeds).

Les

[Jack Gifford]

"Chambered pipes" came stock on... darn it, can't remember for sure. I think some Studebakers of the early sixties. The scale of the dimples was much larger than those of a golf ball- the pipes had "pinches" every few inches. Anybody remember the details, or do I need to look it up?

[lust4speed]

Wasn't that an option on the early or mid 60's Oldsmobile Cutlass?

[b-man]

Closed per the thread starter's request.