Can bigger mufflers really add more than 10 ponies?

[Howard]

Wait... Let's define our terms.

"When a pump is working to move air, it must overcome the forces that resist air movement. These forces include things like gravity and air density, internal pump/motor friction, resistance caused by the length and diameter of the tubing used and the resistance caused by any medium that the air is drawn through, such as filters or chemical sorbents. The sum total of all these forces is called backpressure, and it is a measure of how hard the pump has to work. Any time a pump is working, it is always working against some level of backpressure."

That particular definition describes pumping losses in general. Backpressure in the automotive sense is usually just referring to resistance caused by pressurized exhaust gasses.

Backpressure is resistance that your engine has to fight against in order to make power--having more backpressure is not what might give you more power at low RPMs.

- gittso on mnsportcompacts.net

 

[Gyrene]

You can bring science into this all you want, you can say what should happen when such and such occurs, but the fact of that matter is that dyno tests have proven that backpressure increases low-end torque, which is needed in street cars. I've seen with my own eyes a car put up on a dyno with nothing but straight pipes...low end torque decreased and high end torque increased, no matter what the laws of nature say, I know this to be true. You need to finely tune your exhaust system so that you have enough freedom for gasses, but also enough restriction, ask any racer who participates in the street-class drags.

 

[Howard]

I've seen with my own eyes a car put up on a dyno with nothing but straight pipes...low end torque decreased and high end torque increased, no matter what the laws of nature say, I know this to be true (sic)

And how, may I ask, are you going to reach the high rpm torque unless you have low-end torque

Well, two conflicting opinions.

 

[BreakApart]

"Can bigger mufflers really add more than 10 ponies?"


Yes they can, but will they? No guarantee.

The only way new mufflers can add that much power is if the engine was already designed for that level of power, but the mufflers were restricting the potential already. All your doing is un-capping the exhaust.

Now if the engine was ALREADY working at it's designed-(at the factory) peak power levels, changing the exhaust will have little effect. However, MOST automobiles in the U.S. are using restrictive mufflers and fuel settings to lower the power and noise so that they meet the EPA standards.


My SV650s motorcycle has the EXACT same engine, camshaft and specs as the euro model, but the U.S. model was fitted with smaller carb jets to meet emission standards. Once you put the same jets in the euro's use you gain BACK the lost torque/ponies. So in this example the engine power was lowered below the DESIGNED specs, same thing applies if a restrictive exhaust is installed.

 

[Howard]

Read this dtyn

 

[BreakApart]

Originally posted by: Yucky
Read this dtyn

A different set of geeks on a different message board. Ohh that adds sooo much more credibility. lol...

 

[DDCSpeed]

This thread has became a long discussion. I just want to insert my opinion.

I agree with Eli that the general idea is that the better your engine "breathe" the better your car goes. The general idea is getting headers, muffler and air intake.

I dont know how many hp headers can get you. Muffler are rumored to give you 15-20 horsepowers but thats advertisement. Just the mufflers add 3-5 HP if any. Muffler is all about the piping to the header so if you get the fullback then you are in the ballpark and swing. The fullback will give you the airflow you need to add 7-12 HP i believe. Air intake will add about 3-5 HP at certain RPM. I have an AEM Cold Air Intake on my 01 Accord. Magazines say it adds 5-7......but they are just helping AEM sell stuff. Combining all 3: headers, muffler (full-back) and air intake, you may get about 20 HPs. However, your car is polluting the air like a 1950's car

 

[Howard]

BreakApart, why don't you explain whatever it is that doesn't make sense? Or are you just blathering about something you don't know about?

 

[Howard]

OK, now I see what you're talking about. I posted the wrong link in the beginning. Read the link in my post again.

 

[Howard]

However, your car is polluting the air like a 1950's car

Not true. Not unless you're gutting or removing the cat.

 

[Gillbot]

A muffler will not, a full cat back can add as much as 15-25hp to the crank and headers can add as much as 35hp to the crank. I have seen people add headers and a catback and gain as much as 50hp at the wheels though.

 

[Howard]

headers can add as much as 35hp to the crank

This is not F&F... LOL

Was the previous manifold made of straws?