I've met comparatively few people (outside these forums of course...how's that George? )that seem to have more than a passing understanding of exhaust backpressure and how it relates to a 4 cycle exhaust system. If a conventional muffler (turbo or otherwise) is trully "restrictive" It is logical that you would be able to measure positive pressure against the walls of the muffler case because the gasses can't get out as fast as they are coming in. We've probably all seen 'blown out' mufflers or cases that have been swollen (if only slightly) by excessive exhaust pressure.

Also, more surface area (which includes the pipe walls themselves and absorbtion is evident because the pipes get hot) there is in a system can actually aid power because by absorbing the exhuast heat you are cooling and slowing the energy that remains in the system until it exhusts to the atmosphere. EX On a Big B or E body with a 3" system there's a LOT of pipe upstream of the mufflers that aids in reducing the remaining energy before it ever gets to the case. Also, the net effect is really at what point does the exhuast slow the rate of acceleration of the motor? Assuming no tire slip, a given car/motor going from idle to
WOT with 3.55 gears vs say 4.30 gears, a more restrictive muffler will have less of an effect on acceleration because the peak volume of air moving through the engine meters through the system CFM per second at a lower rate.

Some People erroneously assume that flowmasters are 'restrictive' because they flow less CFM in a side by side 'free flow test'; this really has little if any bearing on what an actual 4 cycle exhaust system does), a Flowmaster (and similar designs) operate very much like a check valve in that they are designed (in theory) to capture and channel the FORWARD moving" exhaust pulses while reducing the reversion effects of the vaccuum created behind each exhuast pulse as the valve is closing behind a high velocity stream. In an open pipe atmospheric air naturally fills the void and as we know air has mass that must be 'pushed' through the pipe before the exhaust exits the system.

I don't mean this as a 'dissertation' at all, I'm just pointing out there's a lot of HYPE and "seat of the pants" testimonials that don't always stand-up 'real world' to sound engineering logic ....and timeslips. On a race car, sure but on the street...

opinions vary of course

THanks for reminding me how dumb I am Bobby

I have run the Super turbo in one form or another on all my vehicles for the last 20 years(except the vette-Corsa).

Have one on my V6 Dakota and does'nt sound terrible with the V6 rasp.

I need to reword it I guess, I didn't mean it to sound that way, it's just I know so many people think Bigger is better, open and LOUDER is ALWAYS an impovement (regardless of engine size, weight or gearing) and they (through misleading advertising) correlate pressurized ambient temerature "free flow" airflow to what's actually going on in a 4 cycle exhaust system.

Well, I'm not a fluid dynamics genius or anything, but by the way you describe it, it sounds to me the ideal exhaust would be a larger single pipe / single muffler. Correct me please if I'm wrong becouse this kinda thing facinates me.

Neither am I, not by a long shot! But I think it's been proven (especially with the turbo crowd) that a properly merged big single system can make as much power as a dual and typically can be made lighter or more strtegically routed to aid weight distribution.

Many of the mid 90's early 2000's F-BOdy GM's still run big 3 1/2 - 4" single systems because (and having owned one and worked for SLP on Many of them) the underside of those cars doesn't lend itself to running a true dual system...it's doesn't seem to hurt he performance at all.

Look i didn't want to get everyone all pumped up i just wanted to know if anyone has used the Dyno max super turbos on there cars and how they liked them.!

Mark,

No worries mate! It's all good! We're all friends in here so we just say what's on our minds.

So How's the 431 shortblock coming? Just talked to Hollis last week about my Rocky, you still thinking about sending your E-heads to him for a little 'respiratory enhancement'?

I'll be up in Oak Ridge next week, shoot me your number maybe I can come by and meet ya.

Another practical thing about Backpressure is (generally) the further the resistance occurs from the exhaust valve the less impact it has and there is a distinction between backpressure which effectively slows the acceleration rate of the piston on the power stroke and Dilution/reversion (which generally is where exhaust that can't escape the port is 'trapped' in the combustion chamber dilutes the incoming charge during overlap.) Also, even atmospheric pressure is 'backpressure' ...but as it is a phyisical constant (a fact of life) it's effect is sometimes 'ignored'. but the negative pulses behind each high pressure 'slug' of exhaust is key to achieving a basic understanding the flowmaster (and similar designs) exhaust theory.

Sounds good will send a PM to you.!

i have them on my 74 duster with a mild 400. 3" x pipe, i reduced it after the X, before the mufflers, 2.5" super turbos. i like the way it sounds. sometimes i wish it was louder, but when i take it for a long ride, with the windows up you hear some drone in overdrive, and im happy then its not louder. its not bad though. i like to change up my exhausts, sometimes i wish i went with the full 3" superturbos and reduced it after them, so maybe ill have to try them. im running stainless 2.5" a body tips.

Love them!
Had flowmaster 40's with full 2 1/2 exhaust on my Charger thanks to the PO and the drone was terrible at 40-50 and too damn loud all the other times. I bought the long Super Turbos and no drone, nice sound and the wife will now ride with me! Good price to boot!

I just put my favorite little single chamber mufflers back on my car the other night. I LOVE IT!!! No drone and totally 110% obnoxious.

I was running the 2 1/2" Dynomax Super Turbo mufflers. They sounded good but had 2 1/4" passages on the inside and with a center outlet restricting flow on the first turn they stunk as far as performance went. I had a thread on this a while back and the older versions of the Super Turbos did not have the smaller internal passages. Heck why not run a restrictor plate on your carburetor too? Switched to Ultra Flos and car pulls way harder. Its just a tad louder then before and no drone:

http://billsgarage.info/BarracudaVideos.html

My 71 cuda has header and 50's series big block original flowmasters. Thay are great sounding mufflers. Drone is some other problem associated with 40's and muffler placement.

My 85 c10 has headers and dynomx super turbos. They are not quiet as advertised. Mounted under the cabin they have as much resonance as any muffler. They were half the cost.

A friends 350/350 impala has summit turbo mufflers that were $12 a peice and sound fantastic.

Good luck. Happy motoring.

Just wanted to say thanks for the reply and the car sounds great in your video.!

But i have to disagree with you i just had them installed and the car is way queiter and has a great sound at idle and i don't see any performance diff in my car there is almost no drone noise at all and cruising now is a pleasure and they are cut off at the rearend 3" pipe in to 3" inlet & 3" outlet plus i had a H-pipe installed & the cars sounds better to me now ((plus lots of noise don't make it faster.!))

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I was running the 2 1/2" Dynomax Super Turbo mufflers. They sounded good but had 2 1/4" passages on the inside and with a center outlet restricting flow on the first turn they stunk as far as performance went. I had a thread on this a while back and the older versions of the Super Turbos did not have the smaller internal passages. Heck why not run a restrictor plate on your carburetor too? Switched to Ultra Flos and car pulls way harder. Its just a tad louder then before and no drone:

http://billsgarage.info/BarracudaVideos.html

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I agree i had a new system put on today 3" to the rear and a h-pipe man that car sounds great.! I love it

i had the 21/2 super turbos on my dart 440 with a 528 solid cam sound awesome not real loud like flowmasters which i dont like. i can hear my car radio with the super turbos!! they gets pretty loud when you stomp on it but quiet at idle and not too loud cruising

I agree mine are the same it really sounds good driving or at idle i am very glad i did go with the Dynomax Super Turbo Mufflers i used the 3" in & 3" out i should have done this along time ago.!

The 3" hemis are hard to beat and they are a larger case ( length, width And Height) than the 2 1/2's, and they flow a whole lot better. If you look at the 2 1/2's the case is pretty skinny and as such I'm willing to bet the 2 1/4 internals help the flow. If the case were as tall as the 3" theyed be much better.

Mopar muscle did s test between 3" old rusty hemi turbos and brand new ultra flows and the 67 coronet with a 630+ HP 493 ran like (IIRC on it's best run) .17 seconds faster in a less than true Apples to Apples testing. They were also several dbs louder. With new muffs I think the results would have been closer. I love the hemi turbos they're quiet enough and perform well enough to make a 700hp 12:1 motor quiet enough to drive through my neighborhood at any time of night, and I couldn't do that with flowmasters or ultraflows. As for feeling the mufflers holding my motor back, well I cant feel it and I'm packing some pretty respectable power levels.

Yea i looked at those after i had already got my Dynomax super turbo mufflers that is what i had on my 67 GTX back in the 80! But i must say these dynomax super turbo mufflers sound very good and as far as i can tell my cars pulls just as hard but alot quieter.! And yes your car is a killer street ride very nice.!

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The 3" hemis are hard to beat and they are a larger case ( length, width And Height) than the 2 1/2's, and they flow a whole lot better. If you look at the 2 1/2's the case is pretty skinny and as such I'm willing to bet the 2 1/4 internals help the flow. If the case were as tall as the 3" theyed be much better.

Mopar muscle did s test between 3" old rusty hemi turbos and brand new ultra flows and the 67 coronet with a 630+ HP 493 ran like (IIRC on it's best run) .17 seconds faster in a less than true Apples to Apples testing. They were also several dbs louder. With new muffs I think the results would have been closer. I love the hemi turbos they're quiet enough and perform well enough to make a 700hp 12:1 motor quiet enough to drive through my neighborhood at any time of night, and I couldn't do that with flowmasters or ultraflows. As for feeling the mufflers holding my motor back, well I cant feel it and I'm packing some pretty respectable power levels.

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