360 la headers & straight pipe

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Ironracer said:
Ok wait, he has straight pipes? A muffler won't make it louder, then. Whoops! I just had took a short nap. Probably fogged out still.
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Sound is weird. A 'muffler' can actually louden an exhaust..
Tone has a lot to do with it too. Certain tones can have the same SPL (sound pressure level), and yet feel or sound quieter. Change the tone, and even at a dB lower it can 'sound' louder.
Wave reflections can amplify this, and the way the classic flow masters are baffled, they do exactly that.

Of course, it all depends what's making noise. A low compression, small cammed 360 with proper timing and AFR will be pretty dang quiet. Fatten the AFR, retard the timing way back, and it'll start to sound like a Harley.

Better yet: put some flat tops in it, get it to 11:1, cram in about [email protected] on a 105-106 LSA and it'll sound bitchin no matter what kind of exhaust is on it.
 
Didn't say he wanted it fast- just loud!
s-l500.jpg
 
First video is 360 with Flowmaster Super 44's, second video is 360 with Cherry Bomb header mufflers



 
Your low PO 360 from truck van won't be that cool with no muffs
Be loud but not like a HP with compression and cam.
And the needs muffs for backpressure was covered on Engine Masters.
Headers with extensions was best. The formula was, painted a pipe and someplace at 16 to18 or 19 inches the paint burned off. That's where to end the pipe coming off the collectors
I think I would grab a bolt on from Summit set up if on the cheap. Or Pypes , or Flowmaster of ya like drone for street use.
 
Assuming your headers have 3" collectors, and your using reducers for the 2 1/2 pipes..... ditch the reducers, put on straight 3" tubing.
Just be advised, most people (well, me at least) think an uncorked stock low compression motor sounds like ****, besides being too loud.
Fast and sneaky quiet is MUCH better than slow, and loud. (and I have definitely been both.....)
 
My one time at Band Camp story.
12.3 to 1 340 large cam open headers 16 inches pipe. Towed to car show at a place that serves adult drinks and has bikers.
So sat all day, I went to get truck-trailer parked on side street.
My wife as I pull up starts car up. A lady with 2 of her friends jumps like she was shot out a cannon. I look and see she tossed her drink and her pants are wet.
I tell my buddy who knows her ask what she was drinking so I can buy her another. He says my wife already asked and that's not drink on her pants!
That cars loud and loopey
 
340six said:
Your low PO 360 from truck van won't be that cool with no muffs
Be loud but not like a HP with compression and cam.
And the needs muffs for backpressure was covered on Engine Masters.
Headers with extensions was best. The formula was, painted a pipe and someplace at 16 to18 or 19 inches the paint burned off. That's where to end the pipe coming off the collectors
I think I would grab a bolt on from Summit set up if on the cheap. Or Pypes , or Flowmaster of ya like drone for street use.
Click to expand...

Engine Masters also disproved the burned paint mark test. Each dyno pull they did, the paint just burned farther up the collector extension until eventually the entire mark was burned.

Collector extension (or same-diameter pipe as collectors with full exhaust) needs to be at least 18" long and generally the longer they are the farther down in RPM the torque is retained.
 
Sorry i ment at least 16 to 19. In the idea of open and nothing was good.
And the mandrel vs crushed in a mid level was no different was a surprise
The single 3 inch doing as good as the 2 pipes in that HP range the engine was also good to see.
 
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Don't know why we're talking power-producing here... OP just wants "obnoxiously loud". Never said fast.
Take a cue from the new Dodge EVs: Make a recording of a Top Fueler and play it through your amped-up sound system. Crank it up to 11.
 
You want it louder? Remove the exhaust and replace it with 2" pipe, preferably mandrel-bent. More compression would help quite a bit, but smaller pipe is both louder and more obnoxious-sounding.

Every obnoxiously-loud truck around here is 2" straight pipe on a low-compression '90s 5.7 Chevy K1500 or 5.4 Fjord F150. The Fjords are louder due to higher compression.
 
Professor Fate said:
Don't know why we're talking power-producing here... OP just wants "obnoxiously loud". Never said fast.
Take a cue from the new Dodge EVs: Make a recording of a Top Fueler and play it through your amped-up sound system. Crank it up to 11.
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That recorded/synthesized "exhaust" on that prototype Charger sounded like Paul Lynde being raped with a cactus.
 
340six said:
Your low PO 360 from truck van won't be that cool with no muffs
Be loud but not like a HP with compression and cam.
And the needs muffs for backpressure was covered on Engine Masters.
Headers with extensions was best. The formula was, painted a pipe and someplace at 16 to18 or 19 inches the paint burned off. That's where to end the pipe coming off the collectors
I think I would grab a bolt on from Summit set up if on the cheap. Or Pypes , or Flowmaster of ya like drone for street use.
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In my humble opinion, after over 30 years of playing, it seems to me that you Need BP, to have any bottom end on a street car
 
Ironracer said:
In my humble opinion, after over 30 years of playing, it seems to me that you Need BP, to have any bottom end on a street car
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Myth, been proven otherwise a few times, here’s the deal.

Headers or not, the amount of pipe after the collector or the manifold or header should be dyno tested to provide the best possible length to provide the best possible amount of torque possible. After this, a pressure wave cancellation box equal to a minimum of the C.I.D. of the engine should be installed on each pipe.

From here, if one should choose to use a muffler or not, the engine is now making the best low end torque and will retain maximum power throughout the rest of the dyno run.

Any back pressure is just performance limiting. Period. It is exactly the same as me limiting you exhaling while you’re running. You can breathe in as deep as possible, no problem. But I’ll only allow you to exhale so much. Just by this alone, not exhaling all that you can, there is now a limitation on the amount of air you can breathe in. Your overall performance in running is now curtailed. Apply this to the engine.

Silencing an engine after the pressure wave cancellation box is another topic since the OP wants maximum sound.

To this end, after your header extension length is found, cut your cars exhaust there and let it run like that. Running a full length exhaust pipe to the rear of the car/bumper could very well be reducing power since the pressure wave tubing is nullified and engine breathing is cut short as described above.

Adding a pressure wave box for maximum torque and continuing the exhaust pipe without a muffler may indeed possibly reduce sound. I don’t know for sure. I’ve never done that myself. Nor do I know of anyone that has.

The header extension pipe should be the same size as the pipe diameter of the header collector where all 4 pipes come together. Normally this is 3 inches on small blocks. Keep that size throughout the rest of the exhaust system. This should produce maximum sound. Stepping up to a 3-1/2 or larger pipe to run the length of the car may help in more obnoxious sounds.
 
You want loud?
you need high-energy in the exhaust. It's just that simple.
A trumpet on the end of the pipe is gonna make it ugly.
To get loud, you need;
high cylinder pressure together with
an early-opening exhaust valve;
or a really really short, small-diameter exhaust pipe.
My car has a 3" full-length dual system. I am a streeter.
I have run 3 different cams at three different Scrs, 4 different Dcrs, 3 different cylinder pressures, and 2 different exhaust opening angles.
they were all loud at WOT.

But when Not at WOT,
I'm gonna say, the loudest was with the earliest opening exhaust.
The cylinder pressure varied from 176 minimum to 195 maximum.
the combo that made 195psi had the latest opening exhaust (108*) and it was the quietest.
the other two opened at 102/103, with cylinder pressures between 176 and 179 psi, and they were both louder, altho I can't say which cuz they were 3 or 4 years apart.
The loudest was after I cut the H-pipe out.
The least Dcr I ran was 8.77, and the most was 9.27, and the difference, IMO while not remarkable, I'd say was very very noticeable.

My feeling is that in your 360;
with barely 8.1 Scr and a factory 2bbl cam, if that's what you have, the exhaust valve does not open until 116* ATDC and the cylinder pressure is likely to be less than 126psi with a measly Dcr of ~6.77 .
Point being, there is NOT much energy being created on the compression stroke (126psi), and nothing left in the Exhaust, when it leaves the cylinder (at 116After), nevermind when it comes crawling out the tailpipe, having been cooled by some 24 total ft of steel pipe.

For power production,
any back-pressure at all, will negatively affect the strength of the scavenge signal, and reduce the tug on the plenum during the overlap cycle. For an engine with enough overlap to count, Back-pressure is bad for power.
However, while cruising on the hiway; a lil Back-pressure will help reduce the efficiency of the overlap cycle, and that will increase the potential for decreased fuel-consumption; atta time when max torque is not required.
But IDK how you would go about engineering such a system. Well I do but............. when I mention that I once got 32 mpgs with a 335hp 360, people usually call me a liar, so I won't say. The point being; that with headers, overlap is bad for fuel-economy, BUT WORSE;
is an early-opening Exhaust valve. For economy, that 360 2bbl cam with 116* of extraction is right where it needs to be.
 
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To re-answer the question since the responses went sideways. Get a cheap Summit or Flowmaster 2.5 bolt on system, then add a Y-pipe cut out to manually open. Later get cheap China eBay electric one's but keep then clean so tget close all the way.
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Small exhaust pipe for loud sound?

I’ll take the big pipe. The bigger the trumpet, the bigger the sound.
Otherwise I’m with AJ. IDK about altering cam timing for the cause. Seems a bit much to do for noise.
 
rumblefish360 said:
Small exhaust pipe for loud sound?

I’ll take the big pipe. The bigger the trumpet, the bigger the sound.
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Agreed, I changed my exhaust last Fall going from a 2" and 2.25" in some spots to a complete 2.5" exhaust right out the tailpipes reusing my existing mufflers. Car got louder not quieter.
 
Just keep those that live by you and the cops off your *** with

Exhaustdumps3.jpg
 
AJ/FormS said:
To get loud, you need;
high cylinder pressure together with
an early-opening exhaust valve;
or a really really short, small-diameter exhaust pipe.
Click to expand...
Guys, to clarify;
I did not say to put a small-diameter full length pipe on a HotRod! that's just totally wrong.
What I said was, and I quote;
"or a really really short, small-diameter exhaust pipe" I mean, I even emphasized the "really" part.
You know, like a Zoomie or an open-header without anything behind it; or you know, like a roto-tiller, lol.
The earlier you open the exhaust valve, the more energy will be in the exhaust, and the louder it will be; and,
the bigger the TAILPIPE is, specifically the last couple of feet, the more it will act like a trumpet. I mean,
I thought we all knew that.
I'm sorry if my post got too complicated, lol, but it looks like at least three guys, maybe 3.5, were able to figure it out.

To further clarify, Notice, I said
"to get loud you need;
high cylinder pressure together with
an early opening exhaust valve."
I wrote that in a way that I thought would force the reader to figure out the "together with", part.
In other words; Neither the high cylinder pressure, NOR the early opening exhaust valve, by themselves, will create the Loud part. You need BOTH.
The more cylinder pressure your engine is able to make while cranking, the higher that pressure will be multiplied to,
by the heat of combustion, under load.
The theoretical maximum expansion ratio, of gasoline, inside the cylinder, without detonation, might be around 9 or 10 to one. Lets use 9/1; but it will depend heavily on the efficiency of the engine.
Lets say your 7.8Scr 360 is at 60%, and it makes 120psi cranking. That would math out to;
120 x 9 x 60%=648psi
let's say your Eoa (Exhaust opening angle) of 116*, sucks so much energy out of that, that it leaves the chamber at I'm guessing, 188psi, and by the time it hits atmosphere out the back, the exhaust system has cooled that right down, and so there is very little heat left in it.
Now lets wind that cranking cylinder pressure up to 190 psi, and lets set the Eoa to 102*, and thus figure the engine efficiency at 80%
Now the numbers look like;
190 x 9 x .80= 1368psi, . So then, imagine the cylinder pressure is down to 400 psi just before it exits the cylinder, and then, it exits the 3" pipes pretty darn hot!
Heat is energy, so, it's gonna be a lot louder.
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All psi number are made up on the spot, and are for effect. I may have exaggerated but you get the idea. The thing to remember is that exhaust heat, is energy, and the driving force behind the level of loudness.

And that is why I have 3" duals all the way. Which is to provide more radiating area, to suck more heat out of the gasses as they are on the way to the back bumper, which was a move for to have less remaining energy in the exhaust around town, and therefore less obnoxious noise. Plus, you know, I ordered those pipes with turn-downs, which slams thos hi-frequency soundwaves into the gravel
From 2.25 to 3 is plus 33% radiating area. On 16ft of exhaust, that adds up.
Happy HotRodding.
 
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340six said:
My one time at Band Camp story.
12.3 to 1 340 large cam open headers 16 inches pipe. Towed to car show at a place that serves adult drinks and has bikers.
So sat all day, I went to get truck-trailer parked on side street.
My wife as I pull up starts car up. A lady with 2 of her friends jumps like she was shot out a cannon. I look and see she tossed her drink and her pants are wet.
I tell my buddy who knows her ask what she was drinking so I can buy her another. He says my wife already asked and that's not drink on her pants!
That cars loud and loopey
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I good thing it was not something else in her pants!!!! When I had my Dodge Van with a 70' 340, 2.5" chambers with 2.5" pipe, welded to the flanges with Walker Turbo mufflers with the tail pipe extending out in front of the rear tires. I had to pull into my driveway and not back in, because my neighbor's home would rattle, I was told.
 
The OP seems to have vanished, but I'll take a shot...
I can't imagine wanting a car to be as loud as possible, considering all of the negative attention it would draw. Not to mention the negative physical effects on your body.
But, if you want noise, run zero exhaust. Nothing, I mean even remove the headers. Then, add about a 200 hp nos system and tape the button down. Use with a bottle (or several bottles) big enough to last a good long time. Long enough to be sure that everyone near you is thoroughly pissed off, and your hearing is completely destroyed. And don't forget to save some money for all of the tickets you'll get. :realcrazy: :realcrazy: :realcrazy:
 
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