Well at least the offset in and center out suck. There is a MAJOR restriction in the layout of these mufflers, MAJOR. First off the inner pipes are only 2 1/4" on a 2 1/2" muffler. Second, and a much bigger problem, is when the exhaust comes into the offset side the first flow director sends the exhaust right into the center-out pipe and the exhaust has to go over and under that pipe to get to the other side. This is a MAJOR restriction. This muffler should not be on a performance car!!!

I just took these off and put some Ultra Flows on and instantly felt better throttle response and an insane increase in top end pull. Was not expecting that much of a power improvement so I took the Super Turbos apart to find out why.

I would imagine the offset in and offset out Super Turbos flow pretty good though.

Another pictures. Note how exhaust rams right into that pipe. It has to go over or under to get to the other side and there is not much room. Flow director on the other side is not really gonna help much.

This part of the muffler not too bad. The offset in offset outs would be laid out like this on both sides.

Here is a pic of the muffler layout.

The reason I run the Ultra-Flows is because they are a straight thru muffler and since I race thru the pipes they are one of the best mufflers performance wise you can get. The Super Turbo's sound nice but will hurt power a little compared to the Ultra-Flows. Ron

looks like a sacrifice in performance for optimum in/out locations...must be for certain cars? but for all that muffler is, why not replace sections of straight pipe with 3 glass pack resonators!

I wouldn't say they all suck...In your case the center/offset 2 1/2" are pretty restrictive mainly because of the obvious neck-down and the case width being too narrow to allow the over/under flow around the center tube. But the Larger 3" ( ex #17769) Dmax ST of the same design has a taller and wider case and actually has eqaul to or slightly MORE cross sectional/flow area around the top and bottom [roughly 2X(3 1/2 x 1 1/4) or 8.75 sq in vs 7.068 sq in for a 3" pipe) of the center tube than the cross section of the pipe ID itself so the weak point you make is not a serious flow restriction issue. What you have is a compromise of overall case size.

I like the large case 3" muffs but not the necked down small case 2 1/2" like your example, there are some very good flowing Super Turbos that give up comparatively little performance vs the ultra-flow compared the considerably lower DB levels. Whwen properly sized the flow of the ST is more limited by the reverse flow than by the internal volume.

http://www.dynomax.com/mufflers.php?muffler=superturbo

I like the ultra-flows but on my 700+hp 12:1 roller motor with a ton of overlap....so for my motors they're simply just too Loud for the area I live. When my car goes by people look for the right reasons...which is worth giving up (maybe)a tenth to me any day.

Arguably a better design (in terms of DB reduction) was the Edelbrock stainless muffs that have the UF straight through but the pipe splits into 2 and rejoins inside the case...like 2 y's joined at the top....this gives you more perforated area to reduce the db's. I have a set of the 14" on the 414 Rocky and they're not too loud, seem to be better made and and are noticably quieter than the Ultra-flows.

On the muffler I took apart there is 3/4" between the center-out pipe and the upper and lower outter case of the muffler.

Bill

Yeah I guess that's the point I was making....but if you take 2( 3/4" x ~3") that's 4.5 square inches of open flow area which is really only about 10% less than the cross section of a 2 1/2" ID open pipe which is 4.91"....acually it's less than that cause the id of a 2 1/2 is smaller than that. If the case was only 1/2 taller overall (which would give you +1/4" on either side of the tube) the flow area would exceed the open pipe. so that case is properly sized for a 2 `1/4 inlet/outlet, what you have is a marketing/cost compromise. Ironically that muff would probably work better as a 2 1/4 with customer provided 2 1/2" neck downs.

Bill, That's a beautiful car by the way, I think I might have mentioned that before...but just in case

my challenger went 10.50s at 126, 3800lb, rpm heads, pump gas with those mufflers and full exhaust

Video of car running with Ultra Flos. It does not do a good job of capturing how good the car sounds in real life but it gives you an idea:

http://www.youtube.com/watch?v=ZDTmQBxn0gU

I agree Bill that you have a very nice Cuda. And I can understand what you mean Wize that even though my pipes go out to the rear bumper with the 3" pipes and Ultra-Flows its a bit louder then I thought but not as loud as some of these cars I see running around the streets. I dont know how some guys get away with it as some cars sound like open headers on the street. Ron

Thanks for compliments guys. Mine is not real loud with the Ultra Flos probably because I run 2 1/2" exhaust. With the super turbo mufflers it was quiet like a stock exhaust car.

When did they do this??

Mine are 3" all the way and I always check... of course they've been on there for several years.

And you are right, if that's the case it is False Advertising and they need to be called out on it.

Here's the old Mopar Muscle artical where they back to back the old 3" 20" case Hemi muff against the new ultraflow. You can see a cutaway where the Hemi is clearly 3" all the way through.

http://www.moparmusclemagazine.com/techa...ents/index.html

Interestingly they compared the 20" Hemi Case to a shorter 14" case Ultraflow which really isn't 'apples to apples' in terms of size....backpressure or obviously weight

I know the old Dynomax used to be owned by Maremount (which now make the Cherry Bomb Line) but maybe the new owners (who also own Thrush) sold us out and now go a smaller/cheaper route?? That's a real shame

I am not sure when the change was made but from what I have personally seen, it was around the later mid ninties-late ninties. Of course you also have the senerio where old stock is still on the shelf too.

Maybe there are still certian numbers that are the true size, but I have been off of using Dynomax Super Turbo's for so long I just haven't kept up with them. IMO, they are not worth the price for what you'll pay for something much better.

Here is the quote from the thread on the other board I go on.

Quote:

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After a lot of searching last year on mufflers for my car,I chose the large case hemi 3 inch turbos.I read good reviews on them everywhere.I ran a [Email]6.99@102mph[/Email] with these back in the spring and have not had a chance to go back since.Tonight,I took the pipes and mufflers off for the last test and tune of the year at Holly Springs Motorsports tomorrow.After loading the car and going over everything,I took a light and looked up in the muffler and what I saw really pissed me off!Why would anybody manufacture a 3 inch muffler and neck it down to 2.5 inches inside?Dont make sense to me.I gave dang near 100 bucks a piece for these.Anyway,we'll see what it does tomorrow with no mufflers.

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not to stir any crap here but i did some very basic kind of measuring on a #17769 muffler where i work just a few days back and i can tell you for sure that its not 2½" internaly the measuring was done in a very simple way and not realy all that accurate but i would say about 2 3/4" internaly, unfortionaly that muffler is sold now but when they are on the shelf again i will have another look and do a better measuring that will be within 0,1mm,cant do any destructive check but can check the tubes that can be reached from the outside.

have in mind that a internal measurement of 2 3/4" isnt very far from the internal measurement of most 3" aluminized tubing that is measured O.D.
a simle formula in metric is 76.2mm od (3")tubing usualy has a wallthicknes of 2mm and there is two walls to count making it a total of 4mm of wall. 76.2-4=72.2 compared to 69.85mm (2 3/4") id measurement inside the muffler 72.2-69.85= 2,35mm

2.35mm of tubing thicknes is not a big loss in my opinion,its not right but its far from as bad as this thread may make it look, i bet there is bigger losses elsewhere in most any prebent exhaust system. ofcourse the loss gets bigger if you use thinner wall tubing. but there is probably bigger losses from the tubing being bent around small radiuses and at great angels.


edit sorry for all the metric numbers,im pretty comfortable with the imperial system but its just so much quicker and easier in métric for me to explain it in this case

And all header tube/exhaust/muffler pipe is measured by OD so a 3" nominal pipe is <3" I/D or 3"-2 X the wall thickness. 3" ID would be a bit larger (maybe .15" or so) than 2 3/4" OD which is 70MM and a common European size and very hard to tell visually (at least at a glance) from 2 1/2....right FAST guys

Surely somebody has one on the shelf somewhere.

I am not trying to stir the pot either, but it is worth noting that whatever the measurement is, It is indeed off. I did find it worth mentioning and if I still had the proof (I dumped all my old catalogs a few years ago), I certianly would scan it in. But none the less, it is an intersting topic indeed. And I am sure it actually covers more than just one manufacture.

Like I said before, nowadays researching before buying is always best.

Interesting post. I have had my DynoMax Super Turbos on for 11 years. I chassis dynoed them against open headers. We watched for drastic changes in the A/F, in between jetting and timing, it did not warrant racing it with the muff's off. It maybe time to get something on there a little more up to date, though. We'll see..

I talked to a guy who bought some 3" Super Turbos are few years back and he said he had the option to choose between 3" all the way through OR smaller internal pipes. He said back then they could be had both ways. Don't know if that is still true? I bet the 2 1/4" mufflers are 2 1/4" all the way through but who knows.

I drove my car around a few hours today. Its louder but not bad at all and no drone. One thing for sure, it idles better with the Ultra Flos. My cam has a 108 Lobe Separation Angle so I guess the exhaust gets out of the engine a little easier compared to the Super Turbos. But no doubt about it the idle is better.

Another thing I noticed is after the exhaust comes in, slams into the center-out pipe and squeezes around it, then the exhaust has to find its way into a straight cut internal pipe. And that flow director does not do anything. The exhaust just went above and below the center-out pipe and the flow director is not wide enough to catch the exhaust so wam into the side of the case and then into a smaller straight cut pipe. No wonder the car runs so much better now.

Now on the other end both internal pipes have tapered edges. It looks like the one pipe is put in backwards: tapered edge on exit and straight edge on the inlet side.

I have 2 street cars. One is a 360(9-1,224 hyd roller,LD340,650 holleyDP) 4 speed Challenger that runs Dyno-Max 2 1/2". Runs 12.50@110 thru the mufflers. The second car is a Volare with a blown 340 that runs Ultaflows. it runs 11.00@122 thru the mufflers. Both seem to do their intended job. The Challenger is fairly quiet,The Volare is NOT. I've never uncapped either one.
Doug

My dad's road runner has a healthy 440-6 w/ 3" exhaust. It originally had Ultraflows on it, but he thought they were too loud so I put on a pair of super turbos. Sounds good and he's happy, but now it is noticeably slower. Ran much better w/ the ultraflows.

A 20" case Super Turbo has 3 x 14" or 42" of baffled tubing compared to about 22" in an Ultraflow, actual backpressure within the muffler could be measured by putting a pressure gauge through the shell of the case....I'm willing to bet that on most motors you wouldn't see very much if any pressure reading until a 440" motor got up over 5000 rpm or so, and even higher with an X or H pipe on it. On a 416" stroker smallblock in a B or E body I doubt you would see any ET difference if you used a true 3" Hemi reverse flow and very little ET loss, maybe .05 or less in a 0-60 run even on a 500" high compression motor.

The Muscle Motors test of a 3800 pound very low 11 second approx 550 hp car saw .14 seconds and 1.29 mph in the 1/4 going from a rusted out 7 yr old 20" Hemi turbo to a 14" ultraflow back to back, but the DB's went up (from 93 to 100)substantially. And that was on slicks, so with most cars and on street tires I doubt the real world difference would be as noticable as the seat-of-the pants meter might indicate.

Obviously a perforated straight pipe is going to outflow a reverse flow of the same pipe od....My only issue with them is anybody can buy them and for every well-tuned nice sounding Mopar there's a more than a hundred "hey look at me!" Boy-racers who really just make a lot of noise

These days I think I'm more impressed every day with the FAST guys doing it (reasonably quietly) with 2 1/2" duals and manifolds. The best sounding mufflers to me are the Corsa's but they don't seem to do well with big overlap motors. To me on the street I/ve always prefered a more stealthy low deep rumble that allows you to hear the 'chirp' of the high compression roller motor over what pretty much a generic loud 'open header' cackle type sound which just reminds me of walking around the pits for 40 yrs. I don't mean that as a insult to glasspack style mufflers but us guys that have been around a while can tell you they could tell the difference between a Ford from a Mopar or Pontiac just by the tone....from a half a block away....and that all goes away with a glasspack...so for me I guess it's more a nostalgia thing I guess...and maybe that's worth a tenth or so . But opinions vary, I guess.

Being that we're all older than dirt around here, hopefully some will realize a "DYNOMAX SUPER TURBO" is nothing more than a 1960's Chevy Corvair Turbo muffler with 1. less packing to make it louder and 2. two little stamped "flow directors"?

And due to Walker/Dynomax's marketing genius, they have been able to sell them at triple the price of the original Corvair muffler since day one.

They do sound nice! And they are indeed slightly better than the original turbo muffler (or at least they used to be.....before they reduced the pipe sizes internally).

But they aren't a race muffler, and never were.
They are based on an OEM Chevrolet part, so it's not really fair to expect much from them.

You're right Zippy, Their popularity on the street was actually an unintended consequence...as anyone who has had a Turbocharger knows the snail knocks so much of the DB's and exhaust pulsation and reversion out of the system ( the turbine acts like a check-valve) that you need very little in terms of actual 'muffling'.

My point was that the reverse flow design is pretty good and even a big motor like a 500" is really only 250" motors worth of airflow on a dual exhaust system. A well designed 3" low restriction system doesn't cost you very much power and when it does it's mainly at WOT and at the top of the RPM range, 95% of the time on the street it never comes into play.

I tell a lot of people that for every 10th an exhaust system is allegedly costing their performance, I can find them 3 in tweaking their carb and ignition tuning, or by swapping them to the right intake manifold

I have run these for years.I have had the 20" case 2.5" hemi super turbos on my Polara for years.They sound great with the dr gas x-pipe in front of them.