Exhaust experts pls share some knowledge pls...

[Ken4555]

hi all...

 

i need to know does a mid muffler effect power?...

 

ok i know the tail muffler straight through will probably add 1-2 maybe 2-3bhp over a stock muffler...

 

lets say the tail muffler is already straight through... will a mid muffler affect the exhaust flow and decrease bhp? or no difference even if it was a straight through from the extractors to the tail muffler...

 

thanks...

[Ken4555]

i always thought that a mid muffler will not affect power output... now i know it does... noticeably....

[Ykf899]

click this link got alot of reviews about exhuast's

 

 

http://www.carreview.com/cat/exhaust/cat-b...LS_1580crx.aspx

[Readonly]

hi all...

 

i need to know does a mid muffler effect power?...

 

ok i know the tail muffler straight through will probably add 1-2 maybe 2-3bhp over a stock muffler...

 

lets say the tail muffler is already straight through... will a mid muffler affect the exhaust flow and decrease bhp? or no difference even if it was a straight through from the extractors to the tail muffler...

 

thanks...

 

Hmmm actually it is a misconception that a straight thru exhaust system will give all rides more power.

For some cars, having a straight thru exhaust system actually drops in hp and also low end torque.

 

Some people operate under the misguided notion that wider pipes are more effective at clearing the combustion chamber than narrower pipes. It's not hard to see how this misconception is appealing - wider pipes have the capability to flow more than narrower pipes. So if they have the ability to flow more, why isn't "wider is better" a good rule of thumb for exhaust upgrading? In a word - VELOCITY. I'm sure that all of you have at one time used a garden hose w/o a spray nozzle on it. If you let the water just run unrestricted out of the house it flows at a rather slow rate. However, if you take your finger and cover part of the opening, the water will flow out at a much much faster rate.

 

The astute exhaust designer knows that you must balance flow capacity with velocity. You want the exhaust gases to exit the chamber and speed along at the highest velocity possible - you want a FAST exhaust stream. If you have two exhaust pulses of equal volume, one in a 2" pipe and one in a 3" pipe, the pulse in the 2" pipe will be traveling considerably FASTER than the pulse in the 3" pipe. While it is true that the narrower the pipe, the higher the velocity of the exiting gases, you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity.

 

Backpressure in it's most extreme form can lead to reversion of the exhaust stream - that is to say the exhaust flows backwards, which is not good. The trick is to have a pipe that that is as narrow as possible while having as close to zero backpressure as possible at the RPM range you want your power band to be located at. Exhaust pipe diameters are best suited to a particular RPM range. A smaller pipe diameter will produce higher exhaust velocities at a lower RPM but create unacceptably high amounts of backpressure at high rpm. Thus if your powerband is located 2-3000 RPM you'd want a narrower pipe than if your powerband is located at 8-9000RPM.

 

For instance, someone with a civic decides he's going to uprade his exhaust with a 3" diameter piping. Once it's installed the owner notices that he seems to have lost a good bit of power throughout the powerband. He makes the connections in the following manner: "My wider exhaust eliminated all backpressure but I lost power, therefore the motor must need some backpressure in order to make power." What he did not realize is that he killed off all his flow velocity by using such a ridiculously wide pipe. It would have been possible for him to achieve close to zero backpressure with a much narrower pipe - in that way he would not have lost all his flow velocity.

 

So dont just change exhaust items for the sake of changing it.

 

[Jenggowenggo]

hello brudder

 

Will a larger exhaust as compared to a narrower exhaust affect Fuel comsumption ?

Which is better more good F/C ?

 

Thank u.

Byebye.

 

[Readonly]

hello brudder

 

Will a larger exhaust as compared to a narrower exhaust affect Fuel comsumption ?

Which is better more good F/C ?

 

Thank u.

Byebye.

 

will higher bhp result in better FC?

if you want the ponies to run, they got to eat the grass, at least thats how the saying goes :)

 

i believe the best mod for FC is to tweak with the ECU.

else change to hybrid

[KkMICHELIN]

Like to clarify that I am no exhaust expert but based on my own exhaust `upgrade' experience, changing to hi flow cat and straight through muffler does improve the power quite a fair bit but only if u tune up yr ECU...

[Mini-itx]

hello brudder

 

Will a larger exhaust as compared to a narrower exhaust affect Fuel comsumption ?

Which is better more good F/C ?

 

Thank u.

Byebye.

 

Narrow pipe for better FC of course.

[Mini-itx]

i always thought that a mid muffler will not affect power output... now i know it does... noticeably....

 

You need the mid muffler if you are already using a straight thru and/or . Else your exhaust will be too loud. Sometime 1 muffler is also not enough, I have seen a Swift fitting 2 because its exhaust is too loud.

[Watwheels]

Actually, TS for this issue you should look into fluid(gas or liquid) dynamics. But it requires some reading to understand.

 

Bernoulli's principle

 

You can see that what ppl so call straight thru exhaust is not very ideal.

Edited September 14, 2010 by Watwheels

[Watwheels]

This is an extract on the link:

 

"Fluid particles are subject only to pressure and their own weight. If a fluid is flowing horizontally and along a section of a streamline, where the speed increases it can only be because the fluid on that section has moved from a region of higher pressure to a region of lower pressure(See attached pic); and if its speed decreases, it can only be because it has moved from a region of lower pressure to a region of higher pressure. Consequently, within a fluid flowing horizontally, the highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest."

 

 

Looking at the pic exhaust gas moving from a bigger pipe(higher pressure) to a smaller pipe(lower pressure) is faster dan say moving thru a constant diameter of big pipe. What car manufacturers did is already in its optimum but ppl's misconception of having a constant big pipe of moving more exhaust gases is wrong. And ppl like to give this example as "back flow" is also wrong. The correct way of saying should be moving across high to low pressure.

Edited September 14, 2010 by Watwheels

[Ken4555]

 

my own logic has always been...

 

too big muffler you lose power as the same logic as your house tap you install a tap double triple times bigger in size... same amount of water comes out of a bigger hole... cause the water pipe that enters your house is still the same size...

 

[Watwheels]

The example I gave is most relevant cos it shows how a gas or liquid flows horizontally, very much like an exhaust pipe.

[Moredhel]

Hi, been reading up on the replies in the exhaust section.

 

I think that it's a common misconcepton that bigger exhausts = more power.

It actually depends on the car you are driving and the kind of setup you want.

Different engine displacements and burn rate results in different ranges required.

 

Don't ask me about technical thresholds. I only know and tested for my own car.

 

But e.g., I'm driving a Japanese B&B 1.6cc car. Generally, if you look at the ECU

settings, the advance and inj timings are actually at a very safe, even rich level. Such that you

can probably drive the car for 20 years before something goes wrong with the engine.

 

Exhausts are actually restrictive if you consider the intake being 3 inches and the header

a mere 1.75". Hence, the resulting pressure differential from the cat is such that a choke is restricting

your exhaust flow, resulting in not so good FC and an overall underpowered car.

 

 

Hence, I thought about the solution and decided to do a modest upgrade to a 2" pipe

with a proper header and semi muffler(I'm not into the loud exhaust and stuff). Being

relatively eco and lta friendly, I decided to leave the cat as it is.

 

Resulting effect from a racing team designed exhaust setup along with a larger intake resulted

in the EMU trying to catch up with the now increased air flow at both ends, when checked, the

advance has increased somewhat and I'm getting better power and mileage from the same inj timing.

Means: Improved power and Better FC!!

 

Might sound unbelieveable to some, but it works for inline 4 NA. Turbo....not so....

 

Power and torque has improved throughout using my 4-2 2-1 -2" - SFM, releasing back-pressure and

improving overall flow concept. Have not done a dyno. But then, have also not done a add-on chip.

Happy with the results overall. Tuning will come when moolahs come in.

 

 

 

Anyway, the general idea is that you have to know what is restricting your car's performance

and the current programming of your vehicle and tweak the physical setup within reasonable

limits. For mine, I've calculated that the upper limit would be a 2.25" pipe, but with an open pod

and increased capacity injectors. But deciding to save the cash for the UCQ, I went with a reasonable increase

while getting a better flow filter with SRA.

 

Bigger is not always better. But slightly bigger is good when you know your setup is running rich.

 

 

[Watwheels]

1.6cc is quite a small engine you have there.

 

Seriously, it's either 1.6L or 1600cc.

 

And the thing about your claims, IMO it's no dyno no talk. Car owners like to claim about the feel of increased power is doubtful. Just my POV.

[Moredhel]

1.6cc is quite a small engine you have there.

 

Seriously, it's either 1.6L or 1600cc.

 

And the thing about your claims, IMO it's no dyno no talk. Car owners like to claim about the feel of increased power is doubtful. Just my POV.

 

Apologies, it's 1.6L

 

I do know that after the IE, no T, FC increased a respectable +3.5km/L and I could win a 1.8L NA car, lagging behind 2.0L

is much lesser too.

 

My previous post is simply to share what I've identified as a problem and what I"ve done to improve it. I ain' a WS with something

to sell, so I don't have to provide 'happy tuner graphs' to prove my point. It's trial and error for each driver and vehicle.

 

And who does the tuning before the hardware anyway....as I said, I'm driving a B&B car and don't have that much

cash to spare doing dynos to prove anything...

 

 

In any case, what would you recommend for a car running rich on stock EMU?

[Watwheels]

I would leave it as stock condition. IMO exhaust mods for NA engines are a waste of time & money. The money spent vs the gains, I rather spent it somewhere else.

[Moredhel]

I would leave it as stock condition. IMO exhaust mods for NA engines are a waste of time & money. The money spent vs the gains, I rather spent it somewhere else.

 

True, but some people are not modifying for the power, I'm modifying for the FC and the driveability available to a 1600cc.

Some people modify to fit their tastes and preference.

 

Based on your theory, it's pointless modifying a 3.6L V8 because the percentage gains would be about the same.

So everyone should drive a heavily modded turbo incl P&P, compression tuning, engine block reworks and hi-boost?

 

Have you tried sitting in a hi-comp reworked 2.0 NA car?

 

 

Of coz if you're one of those elites driving an Enzo around then I'll just keep my mouth shut coz you're not allow to mod your cars.

 

 

Anyway, money spent vs gains?

 

Customised exhaust header, midpipe and op muffler incl install - 350-600

Open Pod or Hi-flow Air Filter - 100-150 + d.i.y

Tuning and Chip(Portable to new car) - 850

 

Total: $1600

 

Fuel Savings over 6 years: $10 x 4 top ups/m x 12 months x 6 years = $2880

Minus inspection fees: $ 150 x 3 = 450

 

Shows a gain of $830 bucks over 6 years.

 

Plus driving and modding experience: Priceless.

Taking down that lancerlution with oversized and eardrum piercing exhaust: Priceless.

Keeping pace or overtaking that car with a slightly larger cc: Priceless.

 

 

Worth? To each his own ba.