I'm going to be installing two new mufflers on my chevelle this winter. I backfired the car earlier this year when the throttle hung open and had to shut off the ignition. I swelled both mufflers and both are leaking. Has anyone ever tested mufflers for performance to see which performed better. I found some direct comparisons on Hooker's website which compared flowmaster's, Dynomax and Hookers against straight pipes on the dyno. The hookers performed better. Does anybody have any other direct comparisons or thoughts on how to compare?

Is there an industry standard for testing mufflers for flow like there are with cylinder heads?

Clyde

AFAIK, there isn't a atandard. Dymonax's site has flow numbers for their mufflers. I'm partial to the Dynomax UltraFlows. Their SuperTurbos are good, too, for lower HP (up about 350 or so) and are quieter.

It's been proven by a couple of old tests through the years and I have the old mag's somewhere to back it up that good old W/D/T Continental, smooth, perforated inner pipe, GLASSPACKS rate RIGHT under STRAIGHT PIPES!!!

BUT not everybody likes their "Cop-calling" cackle or the loudness and sound change due to blow-out due to age!!

I personally love them..

And I bet if you take a real close look at some of the so-called modern, hi-po, (read, expensive), mufflers, you will find out that they are actually a different shaped version of a good old glasspack after all is said and done...

pdq67

I like Dynomax Race bullets, but I had to take them off because they were too loud.

dynomax ultra-flows.

68SS and bowtie,

Are you just basing that on sound or do you have anything to show that they have improved performance?

Pat,

You mentioned that the Dynomax Super Turbo's were good for up to 350HP. What is this based on, just a gut feeling or is it based upon data?

We used a set of 2-1/2" Dynomax Super Turbos on a 331" 65 Vette - it made 380 rwhp or about 450 fwhp at 6000 rpm.

Originally posted by Clyde_Maston:
I found some direct comparisons on Hooker's website which compared flowmaster's, Dynomax and Hookers against straight pipes on the dyno. The hookers performed better.Hookers always perform better,because they have to ;) :D (sorry-couldn't resist)

...Anyway,I'm sure their marketing and R&D Dept. has something to do with that.I think it was CC or Hot Rod that did a pretty good muffler comparo test awhile back.Might want to check their websites.My vote would be Dynomax Super Turbos or the Ultraflows or Summit Turbos if on a budget and still want a good flowing muffler.

There are basically two types of performance mufflers. Those with a straight flow path and those with a 'deflector' or 'chambered' flow path. Here is a list of mufflers that would have applications for Chevelles.

Straight flow path:

Dynomax Ultra Flow various models
Pypes Race Pro
MagnaFlow XL
Goerlich's Xlerator
Straight Line Performance (may not be made anymore)
Borla
Basani

Chambered/Deflector style;
Dynomax SuperTurbo
FlowMaster (all models)
Hooker (several models)
Pypes ProV & Street Pro
Midas Ravin
Full Boar
SpinTech
and probably a dozen others

If you have a street car ALL of these mufflers are going to improve the sound and performance of your Chevelle. Anywhere from 5-10 hp increase over a stock oem muffler all else being the same. I would almost guarantee a maximum swing of a couple of hp on any one of them. For higher hp applications things get a little trickier. (400+) you will be more likely to see a few extra hp out of the 'straight thru' mufflers but not always(it depends on your drivetrain combination) On lower hp cars(300-) you could actually see slightly lower hp gains and low end torque on the 'straight thru' mufflers. All the above straight thru mufflers flow close to that of staight pipe. All the others flow between 65-80% of straight pipe. So start thinking about things like sound, price and warranty to help you make your decision easier.

And btw, well designed pipes utilizing mandrel bends and add on's like headers and X-crossovers will have a much greater positive affect on performance than any mufflers you could install.

I guess Dynomax took down the flow numbers for their mufflers :( . A couple things I like about the SuperTurbos is they have curved pieces (called flow directors (http://www.dynomax.com/superturbo.stm)) that directs the exhaust around the bends. Plus, they have the same size internals as the inlet and outlet. Not all mufflers do. Some may have a 3" inlet and outlet but are internally the same as 2" or 2-1/2" muffler.
Most anything you get will be better than FlowMasters.

LOL Chris. :D

Ccass, I recently replaced the old 307 2 inch crimp bent system with a 2,5 inch Flowmaster American Thunder with H-Pipe. How much HP gain do you think that will bring on my 400 SBC? I haven't had the chance to drive her since and from what i heard I should feel quite an improvement. I'd just be interessted in approximate numbers (10-20hp, 20-30hp?).

Thanks,
Olli

I just went through this same exact thing. drove me nuts, i wanted the highest flowing/ quietest muffler. It turned out to be the dynomax super turbo 20" case. It supports 380 HP and is just a touch louder than stock. It actually flows more than the 14" case super turbo. I choose this muffler because i found a test on it from a guy with a Pontiac wagon. I'm very happy with them.

Dynomax still has the flow #'s and HP #'s , you have to go to the specifications page on the brand muffler your interested in.

I really like the Dynomax welded Ultraflows. I'm using a large case version that is 20" long not including the inlet/outlet pipes. I wanted a super free flowing exhaust that was quiet as possible. I also included an X-pipe to knock the sound down a bit more.

Does anyone have anything to say about the Borlas? I've no opinion really, so just curious.

Originally posted by OUChevelleSS:
Does anyone have anything to say about the Borlas? I've no opinion really, so just curious. Expensive and "European" sounding, probably would appeal to the Import Tuner crowd more than the musclecar crowd. I've no idea how they flow.

I put Magnaflows on the truck (with an H-pipe and 2.5 pipe I didn't have before) with stock manifolds. I love the sound and I do believe they increased my low end torque just a bit. I previously had 2.25 pipe, no cross over and a no-name set of turbo mufflers.

If you are after the most flow possible, the straight-through style mufflers have to be at the top of the list. If you want to keep it quiet and add a touch of performance, a cross over will help.

my ultraflows have a flow rate chart on the box they came in comparing their flow to "blow master"mufflers.(sorry,couldnt resist).it is widely known among gearheads that the ultra flows rate very high as far as flow.i'm going to be working on my project for a very long time before it is complete due to health problems,i.e.,strained budget,so i cant vouch for the sound or anything.my only complaint was they looked a little rough out of the box due to heat and a few little tiny b.b's from the welding process but a can of high heat aluminum spray paint shined them up just fine.

Do flowmasters really flow that bad?

Chris.

Originally posted by OUChevelleSS:
Does anyone have anything to say about the Borlas? I've no opinion really, so just curious. A friend of mine runs a pair of 2.5" XR1's and an H-pipe behind the 377 in his '66 Chevelle, and they sound VERY good. The idle/cruise is reasonable in volume (on par with if not a bit quieter than my Dynomax Ultraflo's) but they are pretty loud under heavy throttle. They're built very well too.

FYI, the Borla's are basically straight through perforated core mufflers similar to the Dynomax Ultraflos and Magnaflows, only Borla uses stainless wool packing compared to Magnaflow and Dynomax using fiberglass/ceramic wool packing.

Troy

While up on the dyno, my 3" offset/offset dynomax super turbos were replaced with some other MUCH louder higher performance mufflers.. netted zero hp/tq anywhere in the RPMs. So, back on the super turbos went..they aren't the prettiest mufflers, but they work just fine. I put down ~460hp to the wheels, so I don't think they are a huge handicap at higher hp levels. But, this may not be entirely fair because I have an x-pipe, full 3" tubing all the way, and the mufflers are huge.. 20" case, 3" in/out.. so its maybe not a good small muffler comparison.


Matt

Another option might be the Dynatech Split flows. I've been looking at those to replace my bullets as I'm needing something a little quieter. I'm tired up making the little old neighbor lady mad everytime I fire the car up. Their 4" inlet/outlet model weighs like 7-8lbs and is make of steel. A little cheaper than the Borlas but very similar design.


http://www.secureperformanceorder.com/DynatechStore/splitflow.cfm

505Nova,you should have run straight headers from the beginning.that way when your neighbor complained you could have "made an honest effort" by installing the race bullets.heh!heh! :D

how about the Hooker Aerochambers? anyone using them? i'm going to be shopping for some 3" pipes and mufflers this spring and i have pretty much made up my mind AGAINST buying Ultraflows, because it seems that everyone and their brother has them now. kinda like when everyone used to have Flowmasters, now it's Ultraflows. i want my car to sound a little different than most others. i like the sound of the Aerochambers from what i heard on a sound byte, as well as the Spin Tech Pro Street mufflers, although the Spintechs seem kind of loud.
Also, my buddy had some Ultraflows on his 65 Elky and they were less than 3 years old and were blowing alot of fiberglass packing out the pipes. anyone else have that problem?

I'm using a 3" Hooker w/Aerochamber(3" inlet/2.5" dual outlets) catback. With my old stock 305(LO3) motor it sounded great. Low quiet idle but roared well under any acceleration over 1/3rd throttle, plus no drone on the highway up to 3500rpm or so. Now with the 406(XE284 cam) and 1 5/8" shortie headers its totally noticeable(low non-tin sound) from a distance at idle and very barky when revving or under acceleration. Still has the same sound mannerisms. Can't say what it does for my performance with the new motor as I'm running a 3" highflow catco cat anyway(and havn't run with a different exhaust) but with no cat and going from stock exhaust with the old motor I picked up 3mph in the 1/4(86-89mph).

I love my Hooker Aerochambers...only 2.25 inch pipe though, knid of anxious to see what it's like with 3 inch. True duals.

Funny thing... a friend of mine with an 87 350 TPI GTA had 2.5" duals with aerochambers and headers and they were quieter(than my 305) at idle and even when on it and his were even dumping under the car instead of out the back.

Hooker MaximumFlows are a straight-through type. Tests I've seen show them to flow 595 cfm at 28", the Aerochambers only flowed 440 cfm.

Originally posted by 71velle_malibu:
LOL Chris. :D

Ccass, I recently replaced the old 307 2 inch crimp bent system with a 2,5 inch Flowmaster American Thunder with H-Pipe. How much HP gain do you think that will bring on my 400 SBC? I haven't had the chance to drive her since and from what i heard I should feel quite an improvement. I'd just be interessted in approximate numbers (10-20hp, 20-30hp?).

Thanks,
Olli Replacing the 2" compression bends with 2.5" FM AT system would have probably not done a heck of a lot for that 307. Maybe 10-15 but the 400 SBC will probably appreciate the 2.5" mandrel bends and gain 30+ over the same SBC with that scimpy 2" system. The X crossover instead of the H could give you another 10-15hp and increased high end torque with only a slight loss of low end torque.

Originally posted by Chris R:
Do flowmasters really flow that bad?

Chris. No.

I went from an H pipe/2.5 Flowmaster delta flow's to an X pipe/2.5 Ultra Flows. Difference at the track is about .05.

This is in a 3415lb Camaro going 12.0's.

I don't see the packing blowing out of the tailpipes but the Ultra Flows are louder than they used to be. And yes they are a glorified glasspack. The X pipe kills the "glasspack" sound thank God.

At 500 hp I'll guess the ET difference to be .1 with 2.5", probably no diff with 3".

Originally posted by 91 Camaro:
Funny thing... a friend of mine with an 87 350 TPI GTA had 2.5" duals with aerochambers and headers and they were quieter(than my 305) at idle and even when on it and his were even dumping under the car instead of out the back. just out of curiosity, what does the 406 powered car in your sig ET?

i like the Full Boar mufflers dont remember for sure what part number i have on my car but they are the 2 1/2" inlet outlet design and they was rated for something like 415cfm flow rating and they recommended them for up to like 375 hp motor running a true dual exhaust with 2 1/2" pipe.

i had these mufflers installed on my car with 2 1/4" tail pipes. which replaced the 7 year old or so california turbo mufflers that was about 15 bucks back in the day.

it sure felt stronger thru the rpms and sounded way cooler.

along with a few other mods my car went from 97 mph in the 1/4 to what it is now with the full exhaust under it at 107.19 mph

i would say this is pretty sweet and the mufflers and standard type bent exhaust works well for my bbc.

I like the Borla XR-1s. Fairly quiet and perform almost as good as open headers. My son's Chevelle is reasonably quiet and the mufflers only cost 5 hundredths in the quarter, even though the exhausts weigh 40 more pounds.

Originally posted by m71:
</font><blockquote>quote:</font><hr />Originally posted by 91 Camaro:
Funny thing... a friend of mine with an 87 350 TPI GTA had 2.5" duals with aerochambers and headers and they were quieter(than my 305) at idle and even when on it and his were even dumping under the car instead of out the back. just out of curiosity, what does the 406 powered car in your sig ET? </font>[/QUOTE]Not sure yet, never got it to the track after the swap.

Dynomax Ultraflo

Harold you got any idea what the Borla's weigh? Are yours the 3.5" or 4"?

I run the Borla XR-1 oval 16" 3.5 in/out mufflers on my 548 and made 676 RWHP on pump gas. I have not tested them w/o the full exhaust system so I cannot say what they cost compared to open pipes, but the straight thru design (actually 3 tubes) suggests the loss is minimal.

They have a nice sound -- deeper sounding than the Moroso spiral mufflers I previously ran.

The only downside I see to the Borla's are the price.

Take care,

Mark

Originally posted by Rich-L79:
[QUOTE]Originally posted by OUChevelleSS:
[qb] Does anyone have anything to say about the Borlas? I've no opinion really, so just curious. Expensive and "European" sounding, probably would appeal to the Import Tuner crowd more than the musclecar crowd. I've no idea how they flow.

Gotta disagree there, Rich. I had them on a '69 396 w. Hooker Headers and I felt they gave a " classic " musclecar sound, no euro, believe me. Framer also has them on his 67 SS, and they sound great.

As far as flow, they are a straight through design ( the Borla Turbo ) and I would imagine they are right up there with Dynomax Ultra Flow.

I don't find them priced that badly at about $110.00 US@. They are stainless and have a 1 million mile warranty. What more could you want?

My friend has them on his '68 Camaro. Sound great, I would say closer to muscle car sounding than say Flowmaster or anything. But, a little too rich for my blood, I guess I'll stick with my Aerochambers. I was just wondering what others had to say about them, performance, etc..

Hi John, The mufflers, exhaust pipes and tail pipes with turns weigh about 20 pounds per side in the 3 1/2" size and exit just ahead of the rear axle. I'll ask my son about the exit method. It seems like the car has more low end torque with the exhaust on.

The best mufflers in the world are NO MUFFLERS!!!

Hmm - that's a bit heavier. My 4" setup weighs 11 lbs per side - overall length is about 49" with turndowns. Maybe the ol' neighbor lady will just have to live with the noise LOL.

my dynomax ultra 14" case mufflers were 14lbs each.

Are the flowmaster 40s really that bad, I put them on my suburban and love the sound..But I dont want to put them on the Malibu if they are going to kill my HP..Hope to be around 400-450 horsepower mouse motor

TROY

I replaced a ratty 2.00" header back system on my '59 with 2 1/2" compression bent pipes turned down over the rear, with Dynomax large case Ultra Flow mufflers. My new exhaust is actually quieter than before, despite running the larger pipes. I love the sound.

For the '65, which my girlfriend will be driving, I went with a 3.00" "X" pipe kit from Pypes with 3.00" Gorlich (sp?) mufflers. I was told they would sound similar to the Ultra Flows. Given the "X" pipe, I hope the exhaust will be as quiet as the '59.

I see Flowmaster is coming out with a new muffler that looks something like a Dynomax bullet. They had it at the SEMA show but nothing on their website yet. The info I saw on it says it has no packing material - has sound rings in it. Might be interesting...

MagnaFlow is the quietest with straight through performance. No chambers, no neckdowns. If the inlet is 2.5", than the entire length of the tube inside is 2.5" dia. If you want great power, cheap price, a little quieter than the Flowmaster (just a little), then go with MAC Products mufflers. MAC has been doing the 5.0 Mustang and Camaro stuff for years and is finally going into other makes. Their mufflers feature a multi passage design without packings that can blow out and retail for;
2.25, 2.5, or 3.0" for $59.50ea for painted steel or $74.50ea for stainless.
I have been selling the heck out of them and no complaints.

Found these flow numbers, the MAC Flow Path FP734 2.5" in/out offset in and offset out;

Flow Path DynoMax Flowmaster
FP734 17734 42553
361.06cfm 315.81cfm 257.73cfm

test specs @ 25" H2O - 71% humidity - 84deg temp