formula_novice

iTrader: (1)

Hi Guys,

I'm finally getting to the end of my latest build (see sig). I anticipate the motor will put out somewhere between 475-500 horsepower at the crank.

I've been reading A LOT on here and other sites regarding mufflers, etc.
Like everyone else, I want to lose as little HP as possible from the exhaust. The only catch is I want the car to sound deep and strong (i.e. like a classic muscle car) without being too loud.

Here is what I'm going with at the moment...

I have Doug's 1 3/4" long tube headers,
3" true dual exhaust
3" X-Pipe
2-Hooker Aero Chamber mufflers 3" in/out
No Cats/EGR

To quote this article, http://www.superchevy.com/how-to/exhaust/0505phr-exh/#
"For instance, a V-8 making 500 horsepower on open exhaust will require 500 x 2.2 = 1100 cfm. Two 550-cfm mufflers will get the job done and contain the backpressure-induced power loss to 5 horsepower or less."

"This is what Hooker's Aero Chamber muffler looks like inside. Our tests showed these well-made 2.5-inch units to be good for no loss on a 375hp engine while delivering a conservatively sporty, yet authoritative, exhaust note"

Obviously I'm not running open exhaust nor 2.5-inch but everything I've read about the Aero Chamber mufflers shows flow rates between 320-370cfm. Do you guys think the Aero Chambers will cause me to lose a lot of power? Any other suggestions?

FYI - I also have some 3" cutouts but I read somewhere that those can cause a loss of power due to removing backpressure?

Thank you!

Ron U.S.M.C.

I don't know about flow but the Hooker Aero Chamber would be my choice of sound if I did not like the 80 Flowmaster. If it can sound good on a 305 I'm sure a larger displacement would sound even better. At least to me.

formula_novice

iTrader: (1)

Thanks Ron! I appreciate the feedback!

customblackbird

iTrader: (15)

I guess I will chime in.

I wouldn't be looking so much into muffler design for exhaust back pressure. Your always want to design the system for max flow with slight backpressure given your HP and RPM range. What you don't want is a high flow setup with a very restrictive muffler as it will create more of a velocity issue than a back pressure issue. Muffler design will dictate exhaust tone/sound but so does exhaust tubing DIA and length. Given your range the 3" dual exhaust is a smidge large but I wouldn't say its going to be a huge impact like it would be on a stock 305/350.

You want a quality muffler that will not restrict flow but absorb sound waves/resonance. The only way to do this is with a fiberglass/steel wool/roving fiberglass packing around a perforated tube. Chambered mufflers like flowmaster,Thrush chambered etc will just echo the exhaust pulses and sound waves giving it an awful tone on the throttle and tend to be much louder than fiberglass packed mufflers.

One thing to consider is that high flow mufflers can also have great sound deadoning qualities. Inner design (angles, flow paths etc) plays a big part in how much a muffler can flow, and ususally case SIZE will determine the effective area that can absorb sound waves and make the muffler more quiet. So a given muffler of 3" inlet and outlet of 14" case length will be louder than the same muffler/brand but with a 18" case length, since the muffler has 4" more area/length to absorb sound. This does NOT mean it flows less.

Chambered mufflers tend to stick large metal blockaids in the flow path to direct exhaust pulses to help with noise but mainly they just distrubt flow while not effectively decreasing noise.

flowmaster (dronemaster/crapmaster) design. Exhaust is clearly restricted as its forced to go around all the obstructions.
http://image.mustangmonthly.com/f/13...er_chamber.jpg

Inside of a magnaflow/Jones max flow muffler. They will outflow a flowmaster or chambered style muffler every day of the week while providing much more sound control.
http://i338.photobucket.com/albums/n...en-ed-WM-2.jpg

New Corsa design
http://www.speednik.com/files/2011/09/IMG_6820.jpg

Borla design
http://image.trucktrend.com/f/910473...e+cutaways.jpg

Other quality mufflers with great design are Borla, Corsa, Dynomax, Jones, Magnaflow, etc But you see 1 common design between all of them. A very nonrestrictive perforated tube surrounded by a sound deadening packing material.

I used to run 14" chambered mufflers on my exhaust which is close to yours. BUt I have a 521 BBF, 2" primary into 3.5" collector reduced to 3" mandrel exhaust into 3" Xpipe into dual 3" in/out Jones Max flow 18" case length mufflers dumping at the rear axle. And I can tell you going from the 14" chambered to the 18" perforated tube with glass packing has really changed the tone and sound of the exhaust positively. I really like the sound and its much more tolerable even though its still loud bc of the engine size and pipe DIA lol. This is a video of my 521 when I changed out the mufflers, doesnt do it justice but its a deep throaty tone. I've now since run the exhaust over the axle to the rear bumper and hope Ive changed the tone/reduced noise alittle more.

customblackbird

iTrader: (15)

BTW Cutouts are great for the strip, as they allow full flow for MAX high RPM HP. but you will lose low end power as you bypass most of the exhaust length. But even then a well designed exhaust should overall perform better than a cutout. Cutouts nice bc you can run a full OEM style "quiet" exhaust 99% of the time and open the cutout when your ready to be loud and spin very high. I don't run them bc I like the sound of a well designed exhaust.

formula_novice

iTrader: (1)

Thanks a million Customblackbird! Car sounds great btw

I'm going to send the Aero Chambers back and order a set of Jones mufflers.

Are these the ones you went with?

http://www.summitracing.com/parts/jex-mf1259/overview/

Thanks again!

customblackbird

iTrader: (15)

No problem. The magnaflows are a better construction from what I've heard but also like 3x the cost. My only issue with the max flow was the case is 409SS so it rusts kinda quickly (did a muffler swap on my 2014 ram with the hemi) and it was on for 1 winter and had a good bit of case rust. I didn't paint that one but I did paint the 2 thay u posted on my firebird with high temp 2k header paint and they still look good. I don't drive thay car in the rain or winter so they should last much longer. A 304SS case would be a better choice if u want good looks and longevity.

Those are the ones I run but I'm in the HP zone of needed dual 3" exhaust. These mufflers flow extremely well and u might feel a loss in low end tq (I did on my ram). Your pipes are a bit large for your output.

formula_novice

iTrader: (1)

So for the street use, do you think I should keep the Aero Chambers? I guess the trade off would be I lose a little more HP but keep the low-end TQ?

customblackbird

iTrader: (15)

That's up to u, while I feel the low end loss would be slightly noticable I think the mid to high rpm would prob Rev alittle quicker. Really depends on ur driving habits and where u spend most of ur rpm time.

Honestly I think u'd benefit more from a slow transition from ur 3" collector to a 2.5" and run it all the way back to a Jones style muffler. Your exhaust velocity would be very high and you would still keep the low end while being able to rev. The only downfall is the cost and time/fabbing to replace all the 3" with 2.5". That's if u don't plan on bumping crank hp to about 600hp down the line but then I think ur 1 3/4" primaries would become a restriction.

I would price out ur options and see what's worth it to u. A dual 2.5" system will be quieter than a 3" system as well so it helps u there too.

customblackbird

iTrader: (15)

Post some pics of the exhaust, I would like to see what u got and how u did it.

formula_novice

iTrader: (1)

Ok... I've only started on the passenger side but will post a pic shortly... keep in mind this is my first attempt to create an exhaust

Would going from my existing 3" into say a 2.5 or 2.75" Max Flow help with the velocity? Or would that just become a bottleneck?

Thanks again!

formula_novice

iTrader: (1)

Here are the pics... have pity on me

customblackbird

iTrader: (15)

Doesnt look bad! Nice work thus far. U might be surprised when u get the car on the ground and see what ground clearance ur gona have lol.

As far as the mufflers go with the smaller size it would create more of a bottleneck. You want to keep tube DIA constant and consistent to keep velocity high. Running a smaller muffler with the larger dia pipe will only flow as much as the smallest part. Think of it as restricted to that size without the benefits of the consitent dia piping. Kills ur velocity and unbalances the volume of the tubes while creating backpressure. If your going to run the exhaust over the trans crossmember u might want to look into oval tubing or flatten it out a bit for added clearance. Just don't crush/collapse it.

formula_novice

iTrader: (1)

Thanks! I'm still learning to weld, so it's a bit of an experiment
Ha! Yeah I was wondering what kind of ground clearance I would end up with... If I could get about 2.5" I think I'd be thrilled


Ok that makes sense. I will probably finish running the 3" and see how it performs. If needed, I can always swap the mufflers out for the Jones.

Thanks again for all the advice! It's much appreciated!

Night rider327

iTrader: (13)

Very nice start.
Your ground clearance is going to SUCK routed like that.

Being mine was a daily driver when I done the dual 3" pipes, I needed all the ground clearance I could get.

After thinking about my under the crossmember dual 2.25" setup, and doing a few measurements I can up with this idea.

Lower the crossmember down 2", Space transmission back up 2", and run my 3" pipes over the crossmember.

I used some 1x1 square tube welded together and holes drilled in it to space crossmember down (used longer bolts)

Then I used a pc. of 2x3 tube between crossmember and trans mount.

Then mounted the mufflers (dynomax ultra flo) in the very rear of car, on each side of the trunk storage well.

My lowest point, I can still fit a 12 oz coke can under it with maybe 1/4" between top of can and bottom of pipe.

formula_novice

iTrader: (1)

Thanks for the info Night Rider!

I've seen people make their own tranny mounts to gain some clearance but never thought of lowering it down. Would you happen to have a pic you could share?

RedLeader289

iTrader: (2)

It's running a little rough in this vid (cold start) but I love the sound I get from my true duals (2.5") and the thrush welded mufflers that I have. dumped just before the rear axle.

customblackbird

iTrader: (15)

I'd be interested to see the pics too but I see u have dual 2.25" pipes now. Dual 3" would be very tight at the back of the trans.

Alot depends if the car is lowered or stock (sagging) or actual new raised ride height. That affects the clearance mostly.

2.5" is going to scrap on just about everything lol... unless u got some very flat roads and no speedbumps.

formula_novice

iTrader: (1)

I haven't had time to check yet but I was wondering that too...

I did put new "lowering" springs in the car... i think it was a 1.5" drop in the back and 1" in the front... but I really don't notice much of a difference... I guess my old springs were pretty worn.

LOL! Sounds like I need to raise my expectations a bit

RedLeader289

iTrader: (2)

a 28" tire in the rear would help with clearance issues, of course then you couldn't rotate them.

formula_novice

iTrader: (1)

customblackbird,

I thought about everything you said and went ahead and ordered 2 of these mufflers...
http://www.summitracing.com/parts/JEX-MF1259

I want the car to sound deep but as quiet as reasonably possible. But it seems silly to build a custom 3" exhaust for a 383 and then limit it with a lower-flow muffler design.

I would imagine the minor loss of low-end TQ wouldn't be that bad on a 383

Forgot to ask... I connected an X-pipe to my exhaust (see pics above). Is there any special distance/placement it needs to be installed with relation to the headers or muffler? Or is what I did ok?

Thanks again!

formula_novice

iTrader: (1)

LOL. I like the way you think

RedLeader289

iTrader: (2)

lol

Night rider327

iTrader: (13)

No, my old exhaust was dual 2.25", I upgraded to dual 3" and is what I have now.

I run 28" rear tires (Nitto 555R 275/60-15) and 26.10" front tires (yoko avid 235/60-15)

Ride height.. Front is 1/2" lowered and rear is about 1.5" higher

Yeah I got pictures... Don't laugh, It was done with a lot of flex pipe.. The idea was to make up the system using flex pipe for the bends and have a custom exhaust shop copy the bends... But life got in the way and that has not happened yet.

formula_novice

iTrader: (1)

Very nice Night Rider! Love the dual mufflers in the back and the stance!

customblackbird

iTrader: (15)

You will like the mufflers. They will be a deep mellow tone, no rasp but they flow really well. U will see when you get them and look through them… basically a slightly bend mandrel tube

You might notice it, can be easily solved with a higher stall tq converter. I noticed it on my brand new 5.7 hemi truck and they are conservatively rated at 395hp at the crank. Plus I had a ram air intake and some other goodies. I noticed it with just the jones muffler swap. But you got more tp and a lighter car so maybe not so much. EIther way I think you'll like the tone. If not they are cheap enough that you won't feel like its a huge mistake. I used to run flow tech Afterburners as my dad swore by them and they sounded pretty good… actually still have them sitting in my garage.

WEll technically when you use a crossover pipe like a Hpipe or Xpipe its suppose to be in a certain spot. Easiest way is Before welding or cutting into the exhaust to run true separate duals, then run the b@astard hard and get it hot, the pipe will actually burn/discolor the pipe at the hottest point and thats where you want to put the Hpipe or Xpipe for maximum effectiveness. On our cars your really limited on where to put them so its really up to you if u want to get the most out of it or put it where its easiest for you.

customblackbird

iTrader: (15)

Why not just run 28" tall tires on all 4 and then you could rotate them!

I actually just purchased and put on some 20x10s front and rear with 295/35-20 Nitto Invos. It jacked the car up nicely (about 1.5" with just the rims) while giving it the look of being lowered 1.5" at the same time. The car now sports front and rear weight jacks but I'm running taller springs bc I want the most active coils so I would say I'm lowered like 1-1.5" over stock. Then the wheel takes away 1.5" so Im closer to 2.5 - 3" lowered than stock in the wheel wells but I'm around stock height from the undercarriage to the ground. So its like having your cake and eating it too lol. Sure the wheels are heavy but I have rims and tires for the strip just for that reason.

customblackbird

iTrader: (15)

THats and interesting way of doing it. Looks like you have good clearance too. try to get some pics of the ride height, maybe a side shot showing ride height but also how the exhaust looks from the side of the car. And I would like to see how you did it over the rear axle as well.

customblackbird

iTrader: (15)

Since were posting pics or ideas of exhaust. Here is mine. I just finished the pieces that go over the rear axle.

You can kinda see most of the exhaust and the Xpipe.


Here it was before the rear muffler back pipes over the axle, I ran it like this for 1 year with the Jones max flow.


Here is a pic of the Xpipe with the old 14" thrust chambered mufflers (too frigin loud) and the jones max flow right next to it.


This is what the inside of the jones max flow looks like. Like I said basically straight through.

mmadden55

Hedman full length reducers 2.5 to 2.5 in out 18 inch glass pack out the side ahead of the rear wheel, both sides.

customblackbird

iTrader: (15)

no pics?

mmadden55

Not at home and car is so no. Not much to see, hanger in front of and behind glass pack and at end of pipe. Nothing fancy but it works and is cheap. I used the same setup on a 440 Charger, 440 Sebring + and my 440 six pack Dart which had close to 600 hp. Flowed like a champ was nice sounding and not really loud in till you got in it. Nice v8 rumble. You can do it in 3 inch if you want to but 2.5 is more than enough in this set up.

Used the Walker I think hanger staps perforated metal with like a 2 inch rubber strap and a hook to hold a standard ubolt clamp, other nice thing about it is glass pack is only like 4 inches in diameter.

Night rider327

iTrader: (13)

Thanks guys...

I went under the rear axle, not over. Getting two 3" pipes over the axle wasn't gonna happen w/o an offset mount and brace. Under axle works fine for me though. Still great ground clearance.

I don't have a good side shot of the car w/ new exhaust on it... Here is a couple old ones with the OLD EXHAUST SYSTEM, 2.25" PIPES, NOT THE DUAL 3"

https://www.thirdgen.org/forums/atta...icture-575.jpg

https://www.thirdgen.org/forums/atta...d-dscf3555.jpg

Ride height has not changed, but I have changed the exhaust and other engine parts.
You can see a muffler case under car in front of rear wheel on one of those pics, and can see how close to the ground it was.

I'll get some side pics of the car with new 3" pipes for yall soon.