Deleting resonators and muffler?

[SPEED3TYPE2]

i was thinking about going straight pipe and putting one of these on....http://images.google.com/imgres?img...rev=/images?q=+spiral+exhaust&um=1&hl=en&sa=N

???... i just welded in straight pipe

 

[dparm1984]

it is if its a smaller N/A four cylender type of motor, smaller engines need backpressure to create better torque

This is a myth.

Larry from Endyn Motorsports had some interesting research and findings about this:



from 21st Century Performance Book:

Few tests have been done that clearly show the effect of changing back pressure. Most muffler and exhaust comparison tests change more than one parameter simultaneously, making the identification of exhaust back pressure as a culprit difficult.

However, Wollongong (Australia) mechanic Kevin Davis has done extensive testing of varying back-pressure on a number of performance engines.

These range from turbocharged Subaru Liberty (Legacy) RS flat fours to full-house traditional pushrod V8s. In not one case has he found any improvement in any engine performance parameter with increased exhaust back pressure.

The tests came about because Kevin has developed a patented
variable-flow exhaust that uses a butterfly within the exhaust pipe. He initially expected to use the system to cause some back pressure at low loads 'to help torque.'

However, he soon changed his mind when any increase in back pressure proved to decrease torque on a properly tuned engine. What increasing the back pressure does do is dramatically quieten the exhaust.

One of the engine dyno tests carried out by Kevin was on a modified 351 4V Cleveland V8. Following the extractors he fitted a huge exhaust that gave a measured zero back pressure. Torque peaked at 573Nm (423 ft-lbs) at 4700 rpm, with power a rousing 329 kW (441 hp) at 6300 rpm. He then dialed-in 1.5 psi (10.4 kpa) back pressure.

As you'll see later, very few exhausts are capable of delivering such a low back pressure on a road car. Even with this small amount of back pressure, peak torque dropped by 4 per cent and peak power by 5 per cent. He then changed the exhaust to give 2.5 psi back pressure. Torque and power decreased again, both dropping by 7 per cent over having zero back pressure. These results were achieved on a large engine with a large overlap cam - one of the type some people suggest is 'supposed' to like back pressure.


If, in fact, power does increase with increased exhaust back pressure, it is most likely the air/fuel ratio and/or ignition timing that are no longer optimal for the altered state of engine tune."

Larry Widmer at Endyn comments on the above textbook quote:

At less than WOT and peak power rpm, the diameter of the tubing
should change in ID. Just as with intake ports (unless we're just
running off port volume), cross sectional area should be only sufficient to supply the flow rate necessary to feed the engine.

High velocities, that don't incur pumping losses are the rule.


The exhaust system is much the same. Just changing back pressure is a bogus way of trying to create the "ideal" pressure in the system. The exhaust system should work like a correctly conceived header. It should extract the exhaust from the header, to minimize pumping pressures.

The only way to create a system that will serve as an extractor is to properly size the tubing to allow the flow velocity to create a sort of "vacuum" behind it.

Just as with headers, creating a system that will provide the best of all worlds at all throttle positions and rpm ranges is impossible. It's all going to be a trade-off. You can tune for the throttle positions and rpm ranges where you desire the greatest performance, but you'll sacrifice performance at the other end of the rpm range.


Building a system to divert the flow into a smaller system can help
bolster lower rpm power, just as with today dual runner intake
manifolds, but you'll never find a dual runner intake on any engine that's targeting the greatest performance potential possible. I should also add that such systems are inefficient from a standpoint of weight and surface area.

For mid-performance applications, these type systems will be as popular as their costs will allow.


In our quest for "more", we seldom work to achieve mid-level
(mid rpm range) performance, so just as the gentleman who wrote the book in the post from above, we prefer to tune with the least amount of backpressure possible. We do have to observe rules and regulations (noise levels and EPA regulated emissions) and the systems must fit the vehicle in question without dragging the ground, so there will always be compromises.

I suppose that I should mention that cost is another consideration. If it wasn't, a lot of our street systems would have greater area and they wouldn't necessarily be circular in configuration either.

In the stock Integra Type R, backpressure becomes a power "liability" by the time the engine's making 210 flywheel HP. Relative to wheel HP, if you're making more than about 11 HP more than "stock", the system's costing you....and yes, detonation can be caused by excessive back pressure.

The other problem you face with excessive back pressure is one of reversion. The higher the back pressure, the more inert exhaust components re-enter the cylinder. A few of these bad-guys can really steal big hunks of power in a hurry. If you don't believe me, just run a pipe from your exhaust tip up near the air cleaner on your next trip to the dyno. A little sniff of the exhaust will absolutely kill your power.

 

[samsel450r]

i heard ppl with the ms6's putting on a cutout and blowing there engines???????

 

[SPEED3TYPE2]

This is a myth.

Larry from Endyn Motorsports had some interesting research and findings about this:



from 21st Century Performance Book:

Few tests have been done that clearly show the effect of changing back pressure. Most muffler and exhaust comparison tests change more than one parameter simultaneously, making the identification of exhaust back pressure as a culprit difficult.

However, Wollongong (Australia) mechanic Kevin Davis has done extensive testing of varying back-pressure on a number of performance engines.

These range from turbocharged Subaru Liberty (Legacy) RS flat fours to full-house traditional pushrod V8s. In not one case has he found any improvement in any engine performance parameter with increased exhaust back pressure.

The tests came about because Kevin has developed a patented
variable-flow exhaust that uses a butterfly within the exhaust pipe. He initially expected to use the system to cause some back pressure at low loads 'to help torque.'

However, he soon changed his mind when any increase in back pressure proved to decrease torque on a properly tuned engine. What increasing the back pressure does do is dramatically quieten the exhaust.

One of the engine dyno tests carried out by Kevin was on a modified 351 4V Cleveland V8. Following the extractors he fitted a huge exhaust that gave a measured zero back pressure. Torque peaked at 573Nm (423 ft-lbs) at 4700 rpm, with power a rousing 329 kW (441 hp) at 6300 rpm. He then dialed-in 1.5 psi (10.4 kpa) back pressure.

As you'll see later, very few exhausts are capable of delivering such a low back pressure on a road car. Even with this small amount of back pressure, peak torque dropped by 4 per cent and peak power by 5 per cent. He then changed the exhaust to give 2.5 psi back pressure. Torque and power decreased again, both dropping by 7 per cent over having zero back pressure. These results were achieved on a large engine with a large overlap cam - one of the type some people suggest is 'supposed' to like back pressure.


If, in fact, power does increase with increased exhaust back pressure, it is most likely the air/fuel ratio and/or ignition timing that are no longer optimal for the altered state of engine tune."

Larry Widmer at Endyn comments on the above textbook quote:

At less than WOT and peak power rpm, the diameter of the tubing
should change in ID. Just as with intake ports (unless we're just
running off port volume), cross sectional area should be only sufficient to supply the flow rate necessary to feed the engine.

High velocities, that don't incur pumping losses are the rule.


The exhaust system is much the same. Just changing back pressure is a bogus way of trying to create the "ideal" pressure in the system. The exhaust system should work like a correctly conceived header. It should extract the exhaust from the header, to minimize pumping pressures.

The only way to create a system that will serve as an extractor is to properly size the tubing to allow the flow velocity to create a sort of "vacuum" behind it.

Just as with headers, creating a system that will provide the best of all worlds at all throttle positions and rpm ranges is impossible. It's all going to be a trade-off. You can tune for the throttle positions and rpm ranges where you desire the greatest performance, but you'll sacrifice performance at the other end of the rpm range.


Building a system to divert the flow into a smaller system can help
bolster lower rpm power, just as with today dual runner intake
manifolds, but you'll never find a dual runner intake on any engine that's targeting the greatest performance potential possible. I should also add that such systems are inefficient from a standpoint of weight and surface area.

For mid-performance applications, these type systems will be as popular as their costs will allow.


In our quest for "more", we seldom work to achieve mid-level
(mid rpm range) performance, so just as the gentleman who wrote the book in the post from above, we prefer to tune with the least amount of backpressure possible. We do have to observe rules and regulations (noise levels and EPA regulated emissions) and the systems must fit the vehicle in question without dragging the ground, so there will always be compromises.

I suppose that I should mention that cost is another consideration. If it wasn't, a lot of our street systems would have greater area and they wouldn't necessarily be circular in configuration either.

In the stock Integra Type R, backpressure becomes a power "liability" by the time the engine's making 210 flywheel HP. Relative to wheel HP, if you're making more than about 11 HP more than "stock", the system's costing you....and yes, detonation can be caused by excessive back pressure.

The other problem you face with excessive back pressure is one of reversion. The higher the back pressure, the more inert exhaust components re-enter the cylinder. A few of these bad-guys can really steal big hunks of power in a hurry. If you don't believe me, just run a pipe from your exhaust tip up near the air cleaner on your next trip to the dyno. A little sniff of the exhaust will absolutely kill your power.

its not a myth, you gain power up top but in a small motor like a 1.8 honda you loose a whole bunch of torque and power down low. I used to have an integra gsr I experianced this firts hand. now on a turbo motor this does not apply the less backpressure the better, or on a bigger motor this does not apply..

 

[kraz3y]

yeh some cars need back pressure on my pops v6 mustang we ran no cats and dumped at the muffler it ran like s***....so we took the dumps out and ran tail pipes there was way more torque

 

[dparm1984]

Well trusting your butt dyno is a bad idea, you really won't be able to detect small changes.

I own an Integra GS-R too. And frankly, I worried about making the horsepower up top. My car was geared for power up top, and if you want a fast GS-R you build the motor to generate its power up high. How much time do you spend at 2000rpm when racing? NONE.

But back on topic...

 

[SPEED3TYPE2]

i used to race a gsr when i had my flowmaster and you could literally see what was happening his better lowend compensated for my better highend. I put the stock muffler back on car felt MUCH faster.... there is a reason for this I read about but I can't remeber it was something like "scaleing" that is cuased by backpressure when you have a small non-turbo motor. With out the "scaleing" affect you get worse gas milage, worse lowend power, worse overall torque..

 

[samsel450r]

i just went to the shop today and had them take off the resonators... and with already having the test pipe it sounds great... but now i have loud vibration noise coming from the inside of the passenger door panel when i slow down?????

 

[MADTIG]

heres mine with the 2 resonators removed i think imma removed the muffler too soon its sounds really nice but not loud enough for me

http://www.youtube.com/watch?v=i7MPJUpYsvI

Got a question and might be a lil hard to understand what i mean, but did removing the 2 resonators only change the sound or did it change both sound and loudness(bass) of the car??

 

[kraz3y]

Got a question and might be a lil hard to understand what i mean, but did removing the 2 resonators only change the sound or did it change both sound and loudness(bass) of the car??

mostly louder sound changed a bit can you more of a growl sorta like a mix of a muscle car and exhaust on a wrx

 

[MADTIG]

Thanks. Sound is between muscle car and wrx?? sounds like a winner! haha.

Btw...has anyone compared this mod to an after market cat-back? not through vids, but in person?

 

[dparm1984]

Ummm, a WRX sounds strange because of the flat motor design. The tubes on the exhaust manifolds are extremely unequal in length, so you hear the individual pulses a lot more.

 

[UHATEIT]

Anyone know if deleting the 2 middle resonators with straight pipes would void the warranty??? I have checked youtube and it sounds pretty sweet I just want to make sure that i don't get screwed by the dealership

 

[SPEED3TYPE2]

Anyone know if deleting the 2 middle resonators with straight pipes would void the warranty??? I have checked youtube and it sounds pretty sweet I just want to make sure that i don't get screwed by the dealership

na it won't void your warenty. shoudl't it didn't mine i would also delete the resinator by the muffler it perfects the sound i tried 2 then the 3rd the thrid was the best for sure. makes buble sounds, plus louder when you floor it but at idle-cruisineg its normal.

 

[tru-boost]

i removed the 2 resonators and kept the muffler. it sounds sweet ! the only thing the dealership could do is refuse to repair any exhaust related problems downt the road. they cant void your entire warranty.

 

[SPEED3TYPE2]

i removed the 2 resonators and kept the muffler. it sounds sweet ! the only thing the dealership could do is refuse to repair any exhaust related problems downt the road. they cant void your entire warranty.

i did the same and i'm tellin you when you remove that 3rd one it is MUCH better! but if you have a dp or mp you may have the same affect, cuase i still have both cats..

 

[tru-boost]

i assume you are refering to the muffler ???
the car has 2 cats, 2 resonators, and 1 muffler. there is no 3rd resonator.

 

[SPEED3TYPE2]

i assume you are refering to the muffler ???
the car has 2 cats, 2 resonators, and 1 muffler. there is no 3rd resonator.

you can say what you want its a straight thru resinator like the ohter 2 its just has a square shape instead of round..

 

[wisniaPl]

Im with you tru- boost when you look under car you can see 2 resonators and 1 muffler 2 resonators look diffrent than last muffler ...even blind guy can see diff

 

[SharkDiver]

i assume you are refering to the muffler ???
the car has 2 cats, 2 resonators, and 1 muffler. there is no 3rd resonator.

Everyone knows this besides speed3type2 for some reason..He dosent understand that there is such a thing as a straight thru muffler.I tried explaning this to him for months now.Just let him think what he wants and move on.