"Of Flowmasters and Super Traps"

[David Vizard]

The first time I put a set of Flowmasters on an engine destined to go into my Trans Am I was horrified at the power loss. After testing a few other mufflers I was only slightly less disappointed by the slightly less of a power drop. After having purchased at least 5 sets of 'turbo' mufflers and found they were turbo capable in name only I decided to design my own muffler. Up to this point in my life i was only experienced in the design of straight through high temp glass pack mufflers for professional grade Rally competitors in Europe. The one for Mini's (the original) could quieten down a 130 hp race 1293 to below street legal noise with absolutely no loss of power. That was over 40 years ago and it is still the best out there.

But an efficient muffler design for a V8 was going to be something new for me so I started researching what was needed and what was already out there. After a few weeks of testing and tearing mufflers open I came to the conclusion that up to that point, every brand of so-called performance muffler manufacturer fitted into one or other of two categories that being- either did not know how to design a good muffle or did not care to design anything better because the low grade tech they offered the public sold because no-one had anything much better.

All that sounds like a pretty big condemnation. At this point I had to ask myself if I could do any better. With virtually no hesitation 'YES" sprung to mind.

Within about 2 weeks I and a friend who was an automotive acoustics engineer (I worked on the airflow and he worked on the sound reduction and where we met in the middle - that was our design) had a pair of 2-1/2 inch prototypes made up. On the flow bench internal flow design out-flowed every muffler the same size even if they were straight through glass pack (and some of those supposedly hi-po mufflers were worse that a stock factory offering. As for noise reduction my friends efforts paid off handsomely as noise was way less than any glass packs and only a little louder that stock mufflers. I remember the best turbo mufflers of the day dropped the output of my otherwise 404 hp motor by 28 hp and some of those very noisy glass packs were among the worst for power loss. The home built prototype mufflers dropped the output by 2-4 hp and were way quieter.

Now here is where this story gets really good to the tune of some $985,000.

Just as the dyno tests were drawing to a close a friend of mine, who had been privy to a lot of this testing, walks into the shop and tells me that the boss of Cyclone headers (and mufflers) was interested in seeing the performance of the new mufflers demonstrated. So that was duly arranged and the tests put out the low power loss numbers and the high sound reduction just as I said they would. Well the short story here is Mr. Cyclone Boss bought the rights to the design and covered the costs of the seven patents involved in that design. I am sure there are some out there that bought and used this design. It was sold under the name of 'Sonic Turbo'.

But the story does not quite finish here. I got a call from Cyclones PR man who told me the Hot Rod magazines then editor - Lenny Emanualson (who, to this day, does not know of my involvement with this mufflers design) was, in conjunction with Gale Banks, going to run power and noise tests on every 2-1/2 inch performance muffler they could lay their hands on. The trouble was our design had to be put in a case that Cyclone had just paid big money for the tooling. It was also decided to make a 2-1/4 inch version first as that was deemed to be the biggest market. What Cyclones PR guy wanted to know is could we design and make a 2-1/2 inch muffler in a week. Well the answer was no. But I suggested that because our 2-1/4 inch muffler was so good it would probably out perform any of the rivaling manufactures 2-1/2 inch designs. With this in mind I told our PR guy to swedge a 2-1/4 inch muffler's intake and outlet diameters up to 2-1/2 inches. In other words make a 2-1/4 inch muffler fit into a 2-1/2 inch system.

The test, done at Gale Banks shop, would feed all 8 cylinders of a 468 inch BBC through one muffler. So here is the deal. Our 2-1/4 inch design was taking on everyone else's 2-1/2 inch design. Well guess what - that muffler came out #1 by a very clear margin and in terms of sound suppression was about 3rd or 4th on the list to the best of my recollection. The Sonic Turbo was the best selling turbo muffler for may years. That is where the $985,000 came from - even split two ways it still looked like a good number!

At the end of the Sonic Turbo design saga I had a pretty low opinion of most of the mufflers on the market and the design skills that went into them.
But then another turn of events led to me having a great deal more respect for one company but that's a story for maybe later down the road. Next post will be with my experience with Super Trap mufflers.
DV

[GARY C]

I still have the ones from your T/A, probably the first and last set in existence. I haven't put an engine in it so I don't know their condition.

[MadBill]

... Next post will be with my experience with Super Trap mufflers.
DV

Here's a Sonic blast from the past: https://books.google.ca/books?id=h9QDAA ... er&f=false

PS: I'm not expecting a ringing endorsement of Super Traps David...

[pdq67]

I know they cackle and are way loud, but imho, the old smooth perforated inner pipe W/D/T REAL glass packs will flow almost as much as a same sized straight pipe! They used to be made like rolled seam, "cans", but now I think are, "hydro-formed"...

And I am NOT talking about sawed/pressed louvered inner pipe glass packs like Cherry Bomb and others here! They choke badly due to the louvers being in the way of the flow thus causing back pressure.

And through the years, I think that I might have read one muffler test that included the old W/D/T glass packs in the test!!

It's kinda like NOBODY ever tested Holley's old 300-36 true dual plane high-rise in an intake manifold test!

pdq67

PS., Walker/Dynomax/Thrush mufflers..

[Circlotron]

I know they cackle and are way loud, but imho, the old smooth perforated inner pipe W/D/T REAL glass packs will flow almost as much as a same sized straight pipe!

If we are talking about smooth flow then I expect they would too. But I think part of the problem is if they are up close to the header collector where there is a strong pulsating flow then they effectively add a bit of length to the collector and cause it to be off tune with consequent power loss. A muffler in this position with a large open cavity just inside it's entrance would show less power loss I would think, provided it flows okay.

[MadBill]

Yes, that's exactly the premise of a DV article ~ 15 years back!: http://www.superchevy.com/how-to/exhaust/0505phr-exh/

[pdq67]

On my '67 Camaro car..

I would try to install two shorter W/D/T as resonators under the rear seats like stock and then two longer ones one on top of the other sideways between the rear end and gas tank and then try to go out like stock just behind the rear tires.

I would end up with a true straight through exhaust system, although with some curves in its pipes.

pdq67

[af2]

On my '67 Camaro car..

I would try to install two shorter W/D/T as resonators under the rear seats like stock and then two longer ones one on top of the other sideways between the rear end and gas tank and then try to go out like stock just behind the rear tires.

I would end up with a true straight through exhaust system, although with some curves in its pipes.

pdq67

Turn them backwards and the flow excels out the rear!!

[pdq67]

On my '67 Camaro car..

I would try to install two shorter W/D/T as resonators under the rear seats like stock and then two longer ones one on top of the other sideways between the rear end and gas tank and then try to go out like stock just behind the rear tires.

I would end up with a true straight through exhaust system, although with some curves in its pipes.

pdq67

Turn them backwards and the flow excels out the rear!!

I have heard and read that, but doubt it because the sawed/pressed louvers still stick out into the exhaust stream. Thus the overall ID is smaller than the smooth perforated inner pipe glass packs, imho.

pdq67

[David Vizard]

On my '67 Camaro car..

I would try to install two shorter W/D/T as resonators under the rear seats like stock and then two longer ones one on top of the other sideways between the rear end and gas tank and then try to go out like stock just behind the rear tires.

I would end up with a true straight through exhaust system, although with some curves in its pipes.

pdq67

Turn them backwards and the flow excels out the rear!!

I have heard and read that, but doubt it because the sawed/pressed louvers still stick out into the exhaust stream. Thus the overall ID is smaller than the smooth perforated inner pipe glass packs, imho.

pdq67

pdq67 - BULLS EYE!

The product data to build a 'no - loss' quiet but authoritative sounding exhaust system is out there. Just check out Walkers mufflers. They have, printed right on the box, the cfm flow and the HP they can deal with while containing losses to %1 or less.

Your exhaust system R&D has been done for you - take advantage of it.

DV

[Erland Cox]

I have a 2,5" exhaust with 2 straight thrue mufflers on my track Volvo.
It has to be below 96db passing bye.
I have no hp loss above maximum totque versus open exhaust but a loss below maximum torque.
And the loss goes away if I stick the 2,5" header into the first part if the system that is 3" without a transition.
Even if the header sticks deep inte the 3" pipe.
I am busy trying different header configurations that are good everywhere but the exhaust loses 10hp around 4000 rpm.

Erland

[David Vizard]

Erland,

Can you sketch that --- I am not sure I am visualizing it the way you describe it to be.
Thanks
DV

[pdq67]

Turn them backwards and the flow excels out the rear!!

I have heard and read that, but doubt it because the sawed/pressed louvers still stick out into the exhaust stream. Thus the overall ID is smaller than the smooth perforated inner pipe glass packs, imho.

pdq67

pdq67 - BULLS EYE!

The product data to build a 'no - loss' quiet but authoritative sounding exhaust system is out there. Just check out Walkers mufflers. They have, printed right on the box, the cfm flow and the HP they can deal with while containing losses to %1 or less.

Your exhaust system R&D has been done for you - take advantage of it.

DV

Thank you David!

I take this as a compliment.

As funny as this seems, I have 4 CHEAP JC Whitney turbos under my car from when I had my hopped up 406 SBC in it.

(2), 2.5" x 12" long under my front seats and (2) 2.5" x 18" right behind them under my rear seats and then out like a stock '67 Camaro.

(4) cheap turbos were still noisy!!! And I did have an, "H", pipe just off my collectors.

pdq67

[BradH]

I don't know how far back "Super Trapp" goes, but DiscoJet Corp (Davis, CA) was selling "Trapp" 2-stroke silencers in the early 1970s. Instead of the traditional "silencer" design of a straight perforated core with fiberglass packing around it, the Trapp design had a perforated core that was NOT straight, it was more like a sine wave.

The Trapp did a very good job of cutting down the ear-piercing crackle of an open 2-stroke exhaust, but it also corked up flow enough to cause a noticeable power reduction on the Yamaha YZ125 (yeah, the original strap-down-tank / twin-shock YZ) a friend of mine tried one on. I loved the sound, but it definitely softened the power.

There are a couple of them on eBarf right now. Here's one that has a couple of picture that just barely show the core isn't straight through when looking in either end: https://www.ebay.com/itm/Yamaha-DT1MX-2 ... :rk:8:pf:0

[makin chips]

Thanks for posting this, David. I had never heard of Sonic Turbo mufflers before this. Some quick internet searching shows nothing but rave reviews about their sound. Everything I found was the same. Nothing compared to Sonic Turbos, before or since.

Maybe it's time to put em back on the market. Who owns the patent?