"Delete Loop" pipe safe for Pentestar?
08-11-2014, 08:54 AM
#21
JK Junkie
Performance and road car exhaust
08-11-2014, 09:22 AM
#23
JK Junkie
Edit: A lot of work but should work I would guess.
Last edited by 14Sport; 08-11-2014 at 09:27 AM.
08-11-2014, 10:31 AM
#24
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THink about if you were a smoker and blew a smoke ring. The reason the ring curls in the air is the same.... there is a vaccuum pulling it in like that. So that vaccuum in an enclosed pipe will pull the subsequent exhaust making it so there is less work on the engine to push it out. If there is a collision... there is a wave of pressure moving back towards the exhaust valve which sort of pushes back on it and causes the engine to work harder. To visualize that, think of two people on opposite sides of a pond dropping large rocks in it. The waves hit each other and lessen the initial size but still continue towards the other side causing a bit of a wall of energy that the next wave has to push through as well.
Backpressure isnt really pushing back on the exhaust, its the amount of pressure on the backside of the exhaust pulse creating the vaccuum. You get into the same arguments when you discuss exhaust tube sizes. Larger isnt always better... it may allow less restrictive flow but the lack of backpressure means your engine is using more power to push the exhaust. A single exhaust is still in the same restrictions but doesnt have to worry about turbulence (aside from at the header which is why you see uneven header tubes).
08-11-2014, 01:19 PM
#25
The radius of bends, number of bends and their placements, together with the pipe length of one of the pipes, have to work as a system with those of the other pipe.
Last edited by GJeep; 08-11-2014 at 01:26 PM.
08-11-2014, 02:33 PM
#26
JK Junkie
Well I guess Jeeps bring the suck then. Any other car and you can swap the exhaust with a ton of different systems. Touch it on a JK and it's done.
08-11-2014, 05:00 PM
#27
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wow...
having unequal length pipes before the collector causes ripples in the Volumetric Efficiency (VE) of the engine. At certain revs it harms performance, at others its an advantage, all depending on a large amount of variables. On a 5.3L chevy engine the offset Y causes about a 7% drop in airflow from 1600 to 2000 revs. If you are pretty sensitive to the performance of your vehicle, you will notice the difference in performance.
This is what my corrected VE table of my 5.3 looked like after headers and a Cat delete. For that engine and cam, it wanted added back pressure at low RPM to compensate for the longer duration cam, which boosted power at high rpm. I can attach pics of before and after if you want to compare, but airflow was down slightly below about 2800 rpms after the headers and deletes, however the drop was less drastic at 1600 and 2400, and at 1600 I confirmed the pulses were colliding in the collector; increasing back pressure. Also to note, the peaks and valleys were not as drastic with the stock exhaust.
//Picture shows the percentage of air filling each cylinder with each stroke//
On an engine as small as the 3.6 Pentastar, you want to eliminate as many valleys as possible because it has practically no low end to start with. And... keeping the exhaust pulses timed with the loop pipe keeps the traditional straight 6 sound, which I personally like. It is essentially the same effect as a crossover header setup on a a V8 with a cross-plane crankshaft, which makes it sound similar to the flat plane crank design Ferrari uses.
The loop is not/was not/will not ever be responsible for damage to your engine. Removing it won't tear anything up either, but the airflow calculation to determine spark advance will be incorrect. Fueling will be compensated over a fairly short time by the long term fuel trims
having unequal length pipes before the collector causes ripples in the Volumetric Efficiency (VE) of the engine. At certain revs it harms performance, at others its an advantage, all depending on a large amount of variables. On a 5.3L chevy engine the offset Y causes about a 7% drop in airflow from 1600 to 2000 revs. If you are pretty sensitive to the performance of your vehicle, you will notice the difference in performance.
This is what my corrected VE table of my 5.3 looked like after headers and a Cat delete. For that engine and cam, it wanted added back pressure at low RPM to compensate for the longer duration cam, which boosted power at high rpm. I can attach pics of before and after if you want to compare, but airflow was down slightly below about 2800 rpms after the headers and deletes, however the drop was less drastic at 1600 and 2400, and at 1600 I confirmed the pulses were colliding in the collector; increasing back pressure. Also to note, the peaks and valleys were not as drastic with the stock exhaust.
//Picture shows the percentage of air filling each cylinder with each stroke//
On an engine as small as the 3.6 Pentastar, you want to eliminate as many valleys as possible because it has practically no low end to start with. And... keeping the exhaust pulses timed with the loop pipe keeps the traditional straight 6 sound, which I personally like. It is essentially the same effect as a crossover header setup on a a V8 with a cross-plane crankshaft, which makes it sound similar to the flat plane crank design Ferrari uses.
The loop is not/was not/will not ever be responsible for damage to your engine. Removing it won't tear anything up either, but the airflow calculation to determine spark advance will be incorrect. Fueling will be compensated over a fairly short time by the long term fuel trims
Last edited by wheels777; 08-11-2014 at 05:07 PM.
08-12-2014, 07:43 AM
#28
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wow...
having unequal length pipes before the collector causes ripples in the Volumetric Efficiency (VE) of the engine. At certain revs it harms performance, at others its an advantage, all depending on a large amount of variables. On a 5.3L chevy engine the offset Y causes about a 7% drop in airflow from 1600 to 2000 revs. If you are pretty sensitive to the performance of your vehicle, you will notice the difference in performance.
This is what my corrected VE table of my 5.3 looked like after headers and a Cat delete. For that engine and cam, it wanted added back pressure at low RPM to compensate for the longer duration cam, which boosted power at high rpm. I can attach pics of before and after if you want to compare, but airflow was down slightly below about 2800 rpms after the headers and deletes, however the drop was less drastic at 1600 and 2400, and at 1600 I confirmed the pulses were colliding in the collector; increasing back pressure. Also to note, the peaks and valleys were not as drastic with the stock exhaust.
Attachment 570708
//Picture shows the percentage of air filling each cylinder with each stroke//
On an engine as small as the 3.6 Pentastar, you want to eliminate as many valleys as possible because it has practically no low end to start with. And... keeping the exhaust pulses timed with the loop pipe keeps the traditional straight 6 sound, which I personally like. It is essentially the same effect as a crossover header setup on a a V8 with a cross-plane crankshaft, which makes it sound similar to the flat plane crank design Ferrari uses.
The loop is not/was not/will not ever be responsible for damage to your engine. Removing it won't tear anything up either, but the airflow calculation to determine spark advance will be incorrect. Fueling will be compensated over a fairly short time by the long term fuel trims
having unequal length pipes before the collector causes ripples in the Volumetric Efficiency (VE) of the engine. At certain revs it harms performance, at others its an advantage, all depending on a large amount of variables. On a 5.3L chevy engine the offset Y causes about a 7% drop in airflow from 1600 to 2000 revs. If you are pretty sensitive to the performance of your vehicle, you will notice the difference in performance.
This is what my corrected VE table of my 5.3 looked like after headers and a Cat delete. For that engine and cam, it wanted added back pressure at low RPM to compensate for the longer duration cam, which boosted power at high rpm. I can attach pics of before and after if you want to compare, but airflow was down slightly below about 2800 rpms after the headers and deletes, however the drop was less drastic at 1600 and 2400, and at 1600 I confirmed the pulses were colliding in the collector; increasing back pressure. Also to note, the peaks and valleys were not as drastic with the stock exhaust.
Attachment 570708
//Picture shows the percentage of air filling each cylinder with each stroke//
On an engine as small as the 3.6 Pentastar, you want to eliminate as many valleys as possible because it has practically no low end to start with. And... keeping the exhaust pulses timed with the loop pipe keeps the traditional straight 6 sound, which I personally like. It is essentially the same effect as a crossover header setup on a a V8 with a cross-plane crankshaft, which makes it sound similar to the flat plane crank design Ferrari uses.
The loop is not/was not/will not ever be responsible for damage to your engine. Removing it won't tear anything up either, but the airflow calculation to determine spark advance will be incorrect. Fueling will be compensated over a fairly short time by the long term fuel trims
08-12-2014, 04:13 PM
#29
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10-24-2014, 11:42 AM
#30
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Equal Length Exhaust
Equal Length Exhaust
Assuming that an exhaust system is otherwise properly designed, equal length pipes offer some benefits that are not present with unequal length pipes. These benefits are smoother engine operation, tuning simplicity and increased low-to-mid range torque. Strangely enough, Formula 1 engine use equal length pipes, but with increased mid to high range torque.
If the pipes are not equal length, both inertial scavenging and wave (resonance) scavenging will vary among engine cylinders, often dramatically. This, in turn, causes different tuning requirements for different cylinders. These variations affect air/fuel mixtures and timing requirements, and can make it very difficult to achieve optimal tuning. Equal length pipes eliminate these exhaust-induced difficulties. "Tuning", in the context used here, does not mean installing new sparkplugs and an air filter. It means configuring a combination of mechanical components to maximum efficiency for a specific purpose and it can not be overemphasized that such tuning is the path to superior performance with a combination of parts that must work together in a complimentary manner.
In an exhaust system that is properly designed for its application, equal length pipes are generally more efficient. The lengths of both the primary and main section of pipes strongly influence the location of the torque peak(s) within the power band. In street and track performance engines with longer pipes typically produce more low-to-mid range torque than shorter pipes and it is torque that moves a car. The question is... Where in the power band do you want to maximize the torque?
Longer pipes tend to increase power below the engine’s torque peak and shorter pipes tend to increase power above the torque peak.
Large diameter pipes tend to limit low-range power and increase high range power.
Small diameter pipes tend to increase low-range power and to some degree limit high-range power.
"Balance" or "equalizer" chambers between the exhaust pipes tend to flatten the torque peak(s) and widen the power band.
Equal Length Exhaust
Assuming that an exhaust system is otherwise properly designed, equal length pipes offer some benefits that are not present with unequal length pipes. These benefits are smoother engine operation, tuning simplicity and increased low-to-mid range torque. Strangely enough, Formula 1 engine use equal length pipes, but with increased mid to high range torque.
If the pipes are not equal length, both inertial scavenging and wave (resonance) scavenging will vary among engine cylinders, often dramatically. This, in turn, causes different tuning requirements for different cylinders. These variations affect air/fuel mixtures and timing requirements, and can make it very difficult to achieve optimal tuning. Equal length pipes eliminate these exhaust-induced difficulties. "Tuning", in the context used here, does not mean installing new sparkplugs and an air filter. It means configuring a combination of mechanical components to maximum efficiency for a specific purpose and it can not be overemphasized that such tuning is the path to superior performance with a combination of parts that must work together in a complimentary manner.
In an exhaust system that is properly designed for its application, equal length pipes are generally more efficient. The lengths of both the primary and main section of pipes strongly influence the location of the torque peak(s) within the power band. In street and track performance engines with longer pipes typically produce more low-to-mid range torque than shorter pipes and it is torque that moves a car. The question is... Where in the power band do you want to maximize the torque?
Longer pipes tend to increase power below the engine’s torque peak and shorter pipes tend to increase power above the torque peak.
Large diameter pipes tend to limit low-range power and increase high range power.
Small diameter pipes tend to increase low-range power and to some degree limit high-range power.
"Balance" or "equalizer" chambers between the exhaust pipes tend to flatten the torque peak(s) and widen the power band.
http://www.formula1-dictionary.net/e...road_perf.html