Muffler or Not?

[Virg464]

Just wondering if anyone runs mufflers on their "race-only" car? I don't have any experience with (sanctioned) racing on a actual track, my fun has always been on the street. So, if mufflers are used, what do you use? Chambered/Baffles/Glass-paks? I'm finding out that the exhaust system has a very big impact on performance, so I want to try and get things at least close before I go flying down the track.
The car is just for a good time at the track, I'm not looking to compete for monies (famous last words?)

 

[rumblefish360]

Straight through will perform the best.
Hooker Aero Chambers are the only chambered muffler I myself would use. Center in & out.
Hooker Max flow or the Dynomax Ultra flo or the like are glass packed for a lack of better words. Sometimes companies will use a stainless steel wool in place of fiberglass.

You should be running a header extension pipe the same size as the collector into a pressure wave cancellation box that matches the cubic inches of the engine on each side, then funnel it down to the exhaust pipe, then into the muffler.

 

[RemCharger]

You can certainly enjoy the car more with open exhaust.
And if your competitor is the same, it won't drown you out

 

[topside]

Years ago, Sears Point had to have a Db rule for weekday bracket races. On my SB Duster (low-10s footbrake car), from its 3" collectors we added a 3.5" X-pipe and Dynomax race Bullets, and turn-downs at the rear axle that slightly faced each other. Quieted the car down but it still would be a loud street car (it was strictly track). Didn't slow the car down, but I could actually hear everything better and the system made it sound like it was spinning much more RPM, which was amusing.

 

[33 IMP]

I always race with mufflers, even if open is allowed. I like to hear what is going on. I use 3 1/2 Flowmasters, 3 1/2 hooker aeros, and 3"magnaflow straight thru. Since I never race without mufflers, I don't know if it would be quicker opened up (other than the full length 3 1/2 Flowmaster set-up. Probably pick up a tenth just from the weight loss if I removed it.). 6.30s eighth thru the aeros, n/a small block. Like topside, turndowns in front of the axle, 45° angle toward each other.

 

[Jerry Hall]

Doesn't anyone use cutouts on street/strip cars anymore? They even have them in electric now.

 

[kiwigtx]

Doesn't anyone use cutouts on street/strip cars anymore? They even have them in electric now.

Cut-outs are good fun on the street (open road)....and sometimes necessary when at the strip - mostly to hear your own vehicle above the sound of the guy in the next lane.

 

[drhill]

I put them on mine. Using Dynomax 17676 mufflers with electric cutouts.

 

[Bighouse]

I put them on mine. Using Dynomax 17676 mufflers with electric cutouts.

View attachment 1335283

I like that!!

 

[Darter6]

I raced with Dynomax Race Bullets on several cars over the years.

 

[Dodge 330]

I use Dynomax Ultraflows and 3" exhaust. Very quiet. I haven't tried pulling the exhaust but really doubt the car would slow down. Been 10.0 @ 133 with that setup.

 

[440rb]

Our street/strip '69RR runs with full exhausts@the track, 4" collectors, 3" tubing with large mufflers, not sure which type, just blew one out and having to redo.
Motor dyno'd@695hp, its been 10.30@130, at 3800lbs that works out to around 688fwhp so not much of a loss, however with open hdrs I reckon there's 1>2 10ths in it with re-jetting carb and weight loss perhaps.

 

[Cheapsunglasses]

Mufflers? We don’t need no stinkin’ mufflers!

There fixed it @Photon440

 

[Photon440]

Mufflers? We don’t need no stinking mufflers!

If your mufflers stink, you may have a carb problem.

 

[biomedtechguy]

I have a 3" system, Doug's electric cutouts added and 3" 40 series Flowmaster mufflers with a X pipe crossover.
I like running with the cutouts open at Cruisin the Coast and at the drag strip, but I don't think it affects performance, and that's mainly because the exhaust is so efficient.

 

[cdr]

3 inch Magnaflow are straight through & pretty quiet, have them on my 68 Charger , most all chambered mufflers will hurt power.

 

[33 IMP]

Just wondering if anyone runs mufflers on their "race-only" car? I don't have any experience with (sanctioned) racing on a actual track, my fun has always been on the street. So, if mufflers are used, what do you use? Chambered/Baffles/Glass-paks? I'm finding out that the exhaust system has a very big impact on performance, so I want to try and get things at least close before I go flying down the track.
The car is just for a good time at the track, I'm not looking to compete for monies (famous last words?)

It kinda depends on if you just want to take the uncorked edge off, have to meet a noise standard, or want it quiet enough for occasional street use. I drive a couple of the cars I race on the street too, so I went for something that would actually muffle some sound.
If you just want to take the edge off, and lose virtually no horsepower, a couple dynomax bullets, or similar, will get that done.
My theory for quiet power is this: get the proper size head pipe, and through pipe in the muffler, and then put on the biggest, longest, muffler that will fit under the car.

 

[Budnicks]

My old car silver 68 RR 479/383 1-7/8" to 2" 32" step headers,
with Flowmasters 3" Delta-Flow 50 series
in their old 'American Muscle car', line of mandrel systems
& FM Scavenger 4-2-1 x 2" tube entering & 3" collectors
(heavy *** collectors & exhaust system) all the way out the back
I lived in an upscale Country Club/gated community
it needed it to be a lil' bit quieter
with the H-pipe about 20" back in the system...

It would run 9.77 @ 135 'best' pass N/A thru the mufflers
I ran with & without mufflers, normally ran around 9.90-10.0 @ 130-132-134
thru the mufflers, depending on what combo
all day long
no matter the RAD (Relative Air Density),
the track prep was really more important
with the Drag Radials
it really depended more on RAD of the day, or prep of the day
in good air, it didn't make much difference, if at all
that if I had mufflers off, only noticeable difference was really
just the weight of the exhaust system,
like 80#- 100#s
about 1/10 - 2/10ths max faster,
uncapped on it's "best ever" pass, had different lower gears too

PITA to take the whole system out
&needed to be fattened up a tad, 3 jets front & 2 jet sizes rear for WOT
Reading the plugs after a pass 1st

I ran them with N2O too, it didn't do much to affect the power
it went (best of) 8.58 @ 156 thru the mufflers on a 300hp shot
it's run 8.70's @ 151-52-ish on N2O all day long too

I made over 100 passes on that car & combo, usually at a Test & tune
(not the best track on T&Ts or air density in Sacramento in the summer)
car was too fast for 'it's build', needed more cage, only had a 4 pt roll bar

I saw an episode of 'Engine Masters' show,
their #'s showed '12 hp loss' thru the whole system, with a 40 series
(on like a 550hp (?) combo IIRC)
it wasn't even the best system & headers/collectors 'like I had'
I doubt the loss is as much as many (people) claims it is
(cheap "Hemi 'turbo' mufflers" were by far the worst, for HP loss, in the 30+ ranges)

My old buddy long time head porter Mark Rowe (at Gerolamy)
he'd clean up my work & fine-tune the ports
& I did a test with that system/on the flow bench, after finishing the heads
& 1 header & 1 side of the exhaust hooked up, PITA to set up
anyway, it didn't hurt the flow at all
it actually had a scavaging effect, when the exhaust was on it,
a few flow #s higher, could be + or - the tests from time of day (RAD) to
has/had something to do with just an 'opening into the open air'
vs going thru an actual tube, only measures 1 cylinder at a time
"allegedly" heat possibly would/could show an extra draw/scavaging too,
but it'd be nominal #s at best, according to Mark (RIP)
it convinced him he started to run them on his racecar

I'd rather have the mufflers & save my 'what's left of my hearing'
be able to hear the engine (or other noises) better
for + or - 12 hp on a 700+hp combo

your result may vary, that was mine

most all my racecars had no exhaust at all,
just open big tube headers with (12"-15") extensions after the collectors
or zoomies

I debated on putting cut-outs on it, never did I sold it, back in 2007

 

[Virg464]

Thanks to everyone for all the info. Mufflers it is, I like idea of hearing whats going on with the motor, that makes a lot of sense.

 

[Kern Dog]

I'm amazed that one of the delusional old timers didn't chime in to tell us that all engines need backpressure to function.