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Discussion Starter · #1 ·
I have a 79 Camaro with a 350, long tube headers #882 smog heads, true duals with Super 44s and mustang lx tail pipes all 2 1/4. What would preform better turn downs or tail pipes?
 

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Performance wise you probably won't see a difference. Noise and resonance wise, full tailpipes are a better choice. Tailpipes also don't blow dust and dirt all over other cars if you are cruizing through a car show.
Do a search on "X"pipes also. You may want to invest in one of those before you finish up your exhaust.
Mark
 

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I have a 79 Camaro with a 350, long tube headers #882 smog heads, true duals with Super 44s and mustang lx tail pipes all 2 1/4. What would preform better turn downs or tail pipes?
Astro has it right, its amazing how pssd off guys get when your kicking up dust all over their cars lol, and you won't see a difference at your power level. If your redoing the exhaust I would step up to a 2 1/2 myself for future power upgrades.
 

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I've wondered that myself. Makes me wonder on the new vehicles though. I see a lot with the pipes out the back, or bumper. And others, with a turn down by the bumper. I'm talking new production cars. Has me confused. :confused:
As far as pipes though. The straighter you can make them flow, the better it is.
My marquis has turn down tail pipes at the rear bumper, but I believe the law is something about exiting past the pass compartment and not nessicarily out of the body itself.
I racked up a few tickets with my last dd grand marquis as it had single chamber flows and turndowns in front of the rear axle.....and was ignorant inside the car because of them...I learned my lesson on turndowns lol.
 

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Just my opinion, Cars sound so much better with tail pipes than turn downs.
You'll never miss the 2 HP(only @ WOT) increase that tail pipes might cost you.
 

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Discussion Starter · #8 ·
Well it had old school super turbo mufflers with no tailpipes or turn downs and it was much louder then the 44s with tailpipes. I only put tailpipes on to stop it from popping when i took my foot off the gas.
 

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I have a 79 Camaro with a 350, long tube headers #882 smog heads, true duals with Super 44s and mustang lx tail pipes all 2 1/4. What would preform better turn downs or tail pipes?
There's the legal and a safe answer which is behind the rear wheel whether that's inside mud slinging range of the tire or under the bumper it gets the noise and more importantly the carbon mono oxide away the air you breath.

The techncial answer is not as easy as the average hot rodder would suppose, there may be less back pressure with a shorter pipe or maybe not.
Consider a couple/three things that affect back pressure and establish pulse timing between the atmosphere and the exhaust valve.

- Behind the moving vehicle is a low pressure area by ending the exhaust under the bumper you can take advantage of this to reduce the amount of atmospheric pressure trying to push the exhaust back into the pipe its trying to get out of. The faster you go the larger this pressure depression becomes. Anyplace else the flow and pressures may not be helpful and might atcually be a hinderance air can actaully flow from rear to front in local reactions, if the exhaust ends in one of those places you loose power.

- Tuning length, this is even tougher to solve. There is a length of exhaust system that is ideal for timing of negative pressure waves to arrive at the exhaust valve as it opens, this alows a pressure reduction at the valve that helps not only pulling the exhaust out but mixture in during overlap. This can be so strong that David Vizard calls it the 5th cycle of a 4 cycle engine. But this is a variable tuning that is exhaust temperature and RPM sensitve so you try to time this for the RPM band and its harmonic frequencies that produce the most power at the most useful RPM. This can be apporximatly calculated and there are web sites that have the math. As to whether that will be a short pipe or a long one is the math you have to run.

- A third consideration that comes to mind for a street vehicle is mass flow, it is difficult to get mufflers with sufficient flow capacity so dual exhaust systems are tied together somewhere in their length by an H or X pipe to gain some flow share on both sides of the system since the flow is pulsed not continuous so there's a big slug then a gap than another slug and gap that the system has to manage so some load sharing helps the mufflers digest these large slugs, in the case of most V8s there will be two cylinders unloading with only 90 degrees between them which makes a really big slug with six slightly smaller ones. The big slug tends to be on the same side of the engine (5/7 or 2/4) for the Chev numbering system, so one pipe is always working harder than the other without a crossover.

Bogie
 

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I had a 1966 Galaxie 500 at age 18, and stuffed a 351C-4V into it. This was a low budget swap.

Exhaust manifolds, dual exhaust with glasspacks and turn-downs at the rear axle.

Hated it!

Having a conversation inside the car with the engine idling was like beating your fist on your chest while talking. The girls complained that it vibrated the barrettes right out of their hair. (I'm showing my age ... this would have been 1975.)

"Do the tailpipes" would be my advice.
 

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Some lower performance engines actually lose power from a lack of back pressure, so a complete exhaust system often helps the car's torque and low end response. On very high performance engines the less restriction, the better they usually run.
 

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As it was mentioned earlier, on a street engine the back pressure helps. I have turndowns just before the rearend on my 55. You do get a bit of noise but it was the easiest thing to do and besides, it's a HOT ROD it should have some rumble ! When I finally install the other interior components and a carpet pad, it should be just right !
 

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please,someone,anyone,SHOW ME??? a dyno sheet where an engine loses power(properly tuned) with a large exhaust system over a smaller exhaust system,,, or any enginethat makes less power with open headers compared to anyexhaust system????
 
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