3 inch exhaust

[33 IMP]

It was an informative, interesting show. Too bad they didn't do a dual 3", too. Would have been interesting to see how that compared to the single 3".

They did do that, quite a few shows back. They tested a complete 2 1/2 system with straight thru (wanna say dynomax, but could have been something else) and an identical 3" setup, and compared to open exhaust, on a very stout bbc, somewhere around 600hp. The 2 1/2 cost about 25hp compared to open, the 3" cost only about 5hp. I dont know how much this relates to those of us who have only 400-500hp.
Edit: it was magnaflow mufflers, and the whole episode, #9, is on you tube.

 

[BSB67]

They did do that, quite a few shows back. They tested a complete 2 1/2 system with straight thru (wanna say dynomax, but could have been something else) and an identical 3" setup, and compared to open exhaust, on a very stout bbc, somewhere around 600hp. The 2 1/2 cost about 25hp compared to open, the 3" cost only about 5hp. I dont know how much this relates to those of us who have only 400-500hp.
Edit: it was magnaflow mufflers, and the whole episode, #9, is on you tube.

And going from memory, it was like 15 hp on a 620 hp engine with headers. The 3" exhaust proponants are usually excited by the results. The 2 1/2" proponants see the same results differently. Kinda funny.

Get what you want. Unless you have 600 hp, and you go to the track and control all the the variables that effect track results, you'll never know the difference.

 

[Ron H]

Question - I posted on this thread earlier about the 3" exhaust system on my medium built poly. I have Flowmasters that sound nice; but want to go with a more muted sound. I was pondering on having 2.5" mufflers installed to create a little more resistance given the size of the system is more than what I should have agreed to install. Anyone have any thoughts on if this is a bad or an ok idea? Thanks.

 

[747mopar]

Question - I posted on this thread earlier about the 3" exhaust system on my medium built poly. I have Flowmasters that sound nice; but want to go with a more muted sound. I was pondering on having 2.5" mufflers installed to create a little more resistance given the size of the system is more than what I should have agreed to install. Anyone have any thoughts on if this is a bad or an ok idea? Thanks.

I originally built a side exit 3" exhaust with an X pipe then went full length with the same setup, the added length created a bit of drone so I'm going to add resonators... Might be a real easy option for you? They're basically a straight through muffler but from what I've read they get rid of drone and quiet the exhaust a bit. Seams like an easy fix, get a small diameter one as long as will fit between the header and muffler? Haven't done it yet but plan to before spring.

 

[33 IMP]

Question - I posted on this thread earlier about the 3" exhaust system on my medium built poly. I have Flowmasters that sound nice; but want to go with a more muted sound. I was pondering on having 2.5" mufflers installed to create a little more resistance given the size of the system is more than what I should have agreed to install. Anyone have any thoughts on if this is a bad or an ok idea? Thanks.

Just my very humble opinion.....
Unless your poly is a 400+ inch stroker, with really good heads and a stout cam, a 2 1/2 system would have been plenty. But you already know that. If you like the flowmaster sound (and i do), i see nothing wrong with going to a 2 1/2 muffler. I am guessing you have 2-chamber if they are too loud. Simple solution is get a three chamber. Much less noise volume, less chance of drone, and still a flowmaster sound, just more subdued. I had a 70 series bigblock flowmaster (3" in/out, but a single) that was barely louder than stock, and a couple 50 series that are HUGE, but no drone and relatively quiet.
Unfortunately, all the cheap flowmaster clones seem to be two chamber, and the mufflers i bought are now at least twice what i paid. Nothing is cheap anymore, sometimes you have to spend to get what you want.

 

[Ron H]

I originally built a side exit 3" exhaust with an X pipe then went full length with the same setup, the added length created a bit of drone so I'm going to add resonators... Might be a real easy option for you? They're basically a straight through muffler but from what I've read they get rid of drone and quiet the exhaust a bit. Seams like an easy fix, get a small diameter one as long as will fit between the header and muffler? Haven't done it yet but plan to before spring.

I'm likely antiquated on this; but always thought resonators were set after the mufflers rear of the system recalling the systems on some of our old cars...?

 

[33 IMP]

They did mount after the muffler. Now i think they are recommended before the muffler. Frankly, i think either location will help, and i would install them where its easiest, has the most room, in a straight section of pipe.

 

[747mopar]

I'm likely antiquated on this; but always thought resonators were set after the mufflers rear of the system recalling the systems on some of our old cars...?

What I've been reading says before the mufflers.

 

[BSB67]

And going from memory, it was like 15 hp on a 620 hp engine with headers. The 3" exhaust proponants are usually excited by the results. The 2 1/2" proponants see the same results differently. Kinda funny.

Get what you want. Unless you have 600 hp, and you go to the track and control all the the variables that effect track results, you'll never know the difference.

I went ahead and watched the video again. I had forgotted that the motor was a solid roller cam motor with peak power at 6200 rpm. There was a 13 hp difference between the 3" exhaust and the 2 1/2" exhaust. 614 hp verses 601 hp.

Here is the other thing that becomes apparent in the video. They did not re-tune the carb from the open headers run. The motor liked an AF ratio of 12.5 - 12.75-ish, but it was running down at 12.0 - 12.25 with the 2 1/2" exhaust. If you want to kill power, run a motor richer than it wants to be. Rich kills more power than lean. I wonder what the results would look like if they did a full-on tune with the 2 1/2" exhaust and then did the pull with 3" exhaust and open headers pulls without any additional tuning.

Keep an eye on the data, not their words.

 

[Dan64]

Anyone know of any dyno test that have been done with a 3" to the muffler than 2 1/2" tailpipe type of system?. I'm in the process of laying out my 64" Polara's exhaust system ( 629 hp 496) I can get 3" to the muffler pocket pretty easy ,use Dynomax Ultra flow welded with 3" offset/offset which would set my up for using a Tti tailpipe section ( can't use their mid pipe section due to Gear Vendors unit). I have springs moved inboard appr. 3" and a stock fuel tank, it's tight, 3 1/2" between the frame rail and tank. I'm going to need to steal every little bit of space i can to get a tailpipe in there, would love to do all 3" but maybe 2 1/2" is good enough?.

 

[33 IMP]

From what i have read, the further back a muffler is, the smaller it can be, because the exhaust gas cools the farther it gets from the motor. The same theory would apply to tailpipes smaller than the headpipes. Heck, my factory 440 car used 2 1/2 into the muffler, and 2 1/4 tailpipes out.
(If it was me, i would just do the 3" headpipes and mufflers, run it without the tailpipes, then put the 2 1/2 tailpipes on and see what happens. But then, i love playing with exhaust sound, i think it can change the whole personality of a car).

 

[hunt2elk]

Anyone know of any dyno test that have been done with a 3" to the muffler than 2 1/2" tailpipe type of system?. I'm in the process of laying out my 64" Polara's exhaust system ( 629 hp 496) I can get 3" to the muffler pocket pretty easy ,use Dynomax Ultra flow welded with 3" offset/offset which would set my up for using a Tti tailpipe section ( can't use their mid pipe section due to Gear Vendors unit). I have springs moved inboard appr. 3" and a stock fuel tank, it's tight, 3 1/2" between the frame rail and tank. I'm going to need to steal every little bit of space i can to get a tailpipe in there, would love to do all 3" but maybe 2 1/2" is good enough?.

This was my plan. 3" though the mufflers and then go down to 2.5". Or I was thinking of 3 to the muffler and then bushing down. Called TTI about it. They said they would make it for me, but I was crazy to do it. Told me it would add to much restriction and power loss. So I went 3 all the way, unfortunately.

 

[Dan64]

I think for now i'll do the 3" and put dumps after the muffler. I'll probably forget about the Tti tailpipes and take it to a shop to see if they can sneak 3" tailpipes in or not. I really do want to get it all the way out back, may have to transition to 3" oval between the frame and gas tank,idk.

 

[That_Tall_Dude]

This was my plan. 3" though the mufflers and then go down to 2.5". Or I was thinking of 3 to the muffler and then bushing down. Called TTI about it. They said they would make it for me, but I was crazy to do it. Told me it would add to much restriction and power loss. So I went 3 all the way, unfortunately.

exactly what I asked except I was going to do a 2.5” system with 3” (quiet) mufflers; they were like.... “yeah, that’s weird but we can do if you want it”

did 3” the whole way... it’s uber overkill on mine, but they didn’t talk me into though

got some cheap glasspacks, gunna just slip them on the end of the tailpipe and see if reduces DBs before cutting them in (next to the tank)

I guess I could get a reducer and a few feet of 2.5” and slip that on to the tail pipes... see if that does anything too