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I've read countless of forums with mixed reviews on doing headers with a 4.7 and I'm looking for actual opinions from those who have done them. I have an 04 4.7, 08+ Intake, H.O cams, tuned, cold air intake, ignition and injector upgrades, 70mm TB, 3" to dual 2.5" exhaust and getting ready to do 4.56 gears. Would I benefit any from headers or should I stay away? Also how hard were they to install.
 

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I really don't see how they wouldn't add some power. The stock manifolds are so stubby, that there has to be a gain in power with even a short set of headers. Install shouldn't be too terrible. I'd pick up a set of new bolts beforehand, in case you end up breaking some off in the process.
 

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I put shorty ceramic coated Gibsons on my Stampede. High quality and perfect fit. Expensive but I had the engine out so it was the best time to do it. I didn’t drive the truck prior to swapping in a modded 4.7 so I can’t say how much of a difference the headers made in power output. My understanding of shorties is that they add to your high end where as long tubes add more to low end. The stock headers are pathetic looking so I’d say gains are absolutely guaranteed. As for installation I did mine with the engine out but I have put shorties on a 5.2 Durango and there was plenty of room to install them with the engine in. The 4.7 has a wider V than a magnum but still accessible.
 
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I've read countless of forums with mixed reviews on doing headers with a 4.7 and I'm looking for actual opinions from those who have done them. I have an 04 4.7, 08+ Intake, H.O cams, tuned, cold air intake, ignition and injector upgrades, 70mm TB, 3" to dual 2.5" exhaust and getting ready to do 4.56 gears. Would I benefit any from headers or should I stay away? Also how hard were they to install.
Just shorty headers, I would say not worth it. However with your mods you should pick up more performance from them. From my experience with the 4.7 it is a matter of several mods that all add up. Check out my dyno results from the dyno video in signature.
 

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I have not installed headers on a 4.7 Dakota, but I have installed headers on many other engines and vehicles. My info for you is general. Header installation can vary from easy to "I-wish-I-never-attempted-this!" It's going to depend on the header brand and style. Some headers are really pain to install simply because they have to pass between the engine and frame which is the tightest space in an engine compartment. I've had to lift engines to snake a set of headers into a truck before. Next, headers can make access to other parts, like a starter impossible to reach and finally headers can dump a ton of extra heat into the engine compartment.

As far as performance, headers can contribute to making more horsepower because they allow for better breathing, but mostly at high rpms, when an engine is trying to shove out a lot of exhaust in a short period of time. Factory cast iron exhaust manifolds actually flow more than enough for normal driving conditions which for an engine is anything between 2000 to 3500 rpms. Headers work best at higher rpms and at less rpm they don't really increase hp. Theres no doubt that headers look much better than cast iron manifolds, but if your engine is going to operating mostly at normal everyday rpms, they would just be a waste of money, time and hassle. If OTOH you're going to spend time on a track at WOT, headers will help make all the hp you can get at those rpms

Ed
 

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You will get two responses to this question. Some will say NO they dont make a difference and some will say YES they do make a difference.

They are both right!

Short answer is -YES, headers do make a noticeable difference on the 4.7L>>>>> but only IF you address (replace) the restrictive factory "Y" pipe with a high flow "Y". Simply adding headers to a stock exhaust system with the factory "y" pipe does not address the most restrictive point in that system and will make for disappointing gains.

Those who say NO, headers dont make a difference tend to install headers on their 4.7L without addressing the restrictive factory "Y" pipe. Sure they may have added a CAT back system which does little but change the sound and make your pockets lighter... but they are still forcing everything through the restrictive factory "Y" pipe. Very little gains will be noticed if the factory "y" pipe is left untouched.

Those who say YES headers did make a noticeable difference on their 4/7L have replaced the factory "Y" pipe with a high flow "Y" pipe and upgraded to a true 3" single exhaust.

If a customer calls me and asks what they should upgrade on their exhaust system, I ALWAYS suggest the first mod should be to replace the factory "Y"pipe with a high flow "Y" and have it merge into a true single 3" exhaust from the the "Y" back. So you would need a (2.25" dual in / 3" single out) "Y" pipe and then EVERYTHING past that point must be single in single out 3" Pipe/CAT/Muffler...

If you convert your system into a true single 3.0" system with high flow "Y"... adding headers at that point WILL add noticeable gains to the 4.7L.

If you have any questions or concerns please feel free to reach out, I can help you get the most out of your 4.7L.

And now you know the rest of the story...

SPEED SAFE, AIR RAM PERFORMANCE
 

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I had my exhaust enlarged to 2.5" downpipes, to a 3" Y, to a single 3" pipe that goes into a Magnaflow and then dumps under the bed. No cats. No headers yet, either. It's about as short and open as you can get. I've had a couple of oldschool guys claim that it's too big of a pipe for a 4.7, but they didn't feel the increase in power like I did. And the sound... it's glorious.

The old argument that "it's only good for a certain RPM and if you drive normally, you won't feel the gains" is bullshit. I don't know anyone with a desire for more power, who doesn't open up the throttle on a semi regular basis, just for the purpose of enjoying the power delivery. If only racecars needed performance parts, then there wouldn't be such a huge industry in the first place. Daily driven vehicles can absolutely benefit from power adders, regardless of the affected RPM range.

If you want more power, buy the headers. If you want the most power, buy the headers and replace the rest of your exhaust. It all makes a positive difference in sound and delivery. Do what you want and have fun.
 

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I had my exhaust enlarged to 2.5" downpipes, to a 3" Y, to a single 3" pipe that goes into a Magnaflow and then dumps under the bed. No cats. No headers yet, either. It's about as short and open as you can get......but they didn't feel the increase in power like I did. And the sound... it's glorious.
And it's illegal without the cat. But hey, if you can get away with running without a cat, more power to ya. Since the question is about headers and not exhaust systems upgrading, I would still stand my my original points. Headers (alone) will not contribute that much power. To really get the most out of headers you need to address the entire engine as a whole.

The old argument that "it's only good for a certain RPM and if you drive normally, you won't feel the gains" is bullshit.
It is bullshit. But you could try to prove that arguement wrong with actual numbers, not with butt dyno impressions.

I don't know anyone with a desire for more power, who doesn't open up the throttle on a semi regular basis, just for the purpose of enjoying the power delivery.
But it's a completely different thing to argue for certain parts without backing up that claim.

If only racecars needed performance parts, then there wouldn't be such a huge industry in the first place. Daily driven vehicles can absolutely benefit from power adders, regardless of the affected RPM range.
Comparing race cars to daily drivers is a lot like comparing apples to oranges. There are many "racing" parts that don't work on a daily driver, yet kids are still dumb enough to buy into them thinking it's going to make an improvement. When I was young, I fell for the hype too. In retrospective, I just wasted my money and the gains were tiny if any.

If you want more power, buy the headers. If you want the most power, buy the headers and replace the rest of your exhaust. It all makes a positive difference in sound and delivery. Do what you want and have fun.
If you want more power, address the entire engine before you buy headers. But the challenges are higher with the 4.7 because these engines have been neglected in the aftermarket world. Chrysler has already worked against us by taking an OHC engine then tuning it for truck duty.

Ed
 

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Horsepower mods tend to feed off of each other, especially when it comes to airflow. More air in will necessitate more air flow out. It all works together. So claiming that one has to work on the engine before doing headers is moot. Everything helps, at any point in time. Sure, you'll gain more from the headers in combination with other flow mods, but the order doesn't really matter. The guys wants headers, so I say go for it.

And people need to be smart about the parts they buy. Full racecar parts rarely work out in a daily driver. That wasn't my point at all. The guy has a 4.7, so there really aren't any race parts to worry about in the first place. Any bolt-on he buys will work just fine and there's really no risk of over-building it, given the lack of aftermarket support. If you actually want serious power, swap in a Hemi and have fun with that.
 

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I had my exhaust enlarged to 2.5" downpipes, to a 3" Y, to a single 3" pipe that goes into a Magnaflow and then dumps under the bed. No cats. No headers yet, either. It's about as short and open as you can get. I've had a couple of oldschool guys claim that it's too big of a pipe for a 4.7, but they didn't feel the increase in power like I did. And the sound... it's glorious.

The old argument that "it's only good for a certain RPM and if you drive normally, you won't feel the gains" is bullshit. I don't know anyone with a desire for more power, who doesn't open up the throttle on a semi regular basis, just for the purpose of enjoying the power delivery. If only racecars needed performance parts, then there wouldn't be such a huge industry in the first place. Daily driven vehicles can absolutely benefit from power adders, regardless of the affected RPM range.

If you want more power, buy the headers. If you want the most power, buy the headers and replace the rest of your exhaust. It all makes a positive difference in sound and delivery. Do what you want and have fun.
While I agree with some of what you are saying... some of it is debatable. I dont feel 2.5" is too large at all... However I do not feel its not ideal for low end torque production. So by increasing the left and right sides to 2.5"... you will most certainly feel gains and most likely, you will also make more peak HP over someone who has kept the factory 2.25" left and right and merged into a single 3" as you did... Bottom line, your high flow "Y" and single 3" is the true hero in the exhaust equation. However, a 4.7L that retains the 2.25 pipes and full length 3.0" system will make more low end torque but slightly less upper RPM HP than a 2.5 system dumping short. The 2.25 into a single 3 will equates to better overall MPG and slightly better towing ability... I am not saying you cant tow with your set up, I am sure it does it better than the factory crap... just saying the 2.25 into a single 3.0 full length will do it better.

And this does not in any way mean you did something wrong... your application and needs are different than others... So there is no one size fits all and everyone should take the time to consider the application and intention the vehicle will be used most. Every mod you do comes with a gain/penalty. As long as your willing to accept the penalty for the gain, its the right mod for you.

There is a huge difference between purposely built race cars and cars/trucks purposely built to be daily driven vehicles. They ALL share the same theory of operation principles. So they ALL work the same way and the theory of operation aplys to them all equally. Having a good understanding on the theory of operation arms you with the ability to understand how mods effect any given application BEFORE spending your money on it. Having a firm gasp on the theory of operation also allows you build and improve given areas which add to overall gains due to increased efficiency. Basically that's what we are doing with factory built engines... we are only increasing the efficiency of operation by swapping in more efficient parts...

This is why we can only gain so much with a cold air intake and 30+HP is no longer the claim from big named manufactures... back in the day, when we got started, all the big name intake manufactures all claimed 25+hp gains... however, we only advertised 10-12HP gains. With that said, with back to back testing both on DYNOs and the track, our intake outperformed those bigger name intakes who claimed more. How, Why? Because we had a better understanding of the theory of operation than they did and we proved it over and over again for years. We always said that there is only approximately 10-12 HP of efficiency left in the factory filtration systems... Anyone who claims more is lying to you.

Anyway, I just like to discuss stuff... I dont think anyone is wrong here...

SPEED SAFE, AIR RAM PERFORMANCE
 

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Horsepower mods tend to feed off of each other, especially when it comes to airflow. More air in will necessitate more air flow out.
It's not that simple. Yes, some mods tend to feed off each other, but the wrong combo of parts can rob power. Many people will go and buy individual performance parts thinking that each part they add will increase power, yet not realize that some parts may not work well with others and they end up disappointed and blaming the parts rather than placing the blame on themselves for building an engine with incompatible performance parts. People who are fully into building performance engines, tend to experiment with various parts combos to see what combos work best for their application. It is usually a lengthy and expensive process.


There is a huge difference between purposely built race cars and cars/trucks purposely built to be daily driven vehicles. They ALL share the same theory of operation principles. So they ALL work the same way and the theory of operation aplys to them all equally.
The theory of operation is easy to understand, but many have a hard time grasping it because there are so many different views on the subject. I view "theory of operation" this way. We can all agree that HP is good and more is better. But we first need to understand a fundamental of HP, -and that is, what exactly is HP? By definition HP is work/time. In an engine, work is torque whereas time is measured in terms of RPM. Hence we get the formula for HP as; Torque X RPM /5252

Torque and RPM must coexist. It's impossible for one to exist without the other, BUT there can be various degrees of each. For example you can have massive amounts of torque with very little RPM or high amounts of RPM with very little torque. This also means that we can have almost an infinite combination of Torque and RPM values to reach any particular HP figure. (Example you can have a 500HP engine by tons of torque with low rpm, or very little torque spun at high RPM)

In an engine, torque is the direct result of burning air/fuel. The maximum amount of air/fuel that can be burned at any given moment is limited by displacement.
RPM is how often you can burn that air/fuel (Volumetric Efficiency) over time.

So how do we make more HP? As far as torque, we are limited by displacement, so if we want to make more torque (which would increase HP according to the formula) We would either have to increase the displacement or add forced induction via the use of either a turbo or supercharger.

The other aspect of HP is thru RPM, or spin the engine faster so that there are faster burn (torque) events in time, and this goes to breathing or volumetric efficiency. To understand this, lets look at an engine spinning at 6000 RPM, in theory it should breathe in twice the amount of air then it would at 3000 RPM, but at 6000 RPM, the valves are opening and closing at twice the speed and therefore open for half the time then at 3000 RPM, so basically it wouldn't really "breathe" any more at 6000 RPM then it would at 3000 RPM. This is why Cams are often chosen especially in RPM ranges. A performance cam will hold the valves open longer and deeper so more air can fill the cylinders at RPM. Further improvements to breathing involve getting the column of air to flow faster thru the intake system and vacating the spent gases out the exhaust as quickly as possible using scavenging theory.

Basically that's what we are doing with factory built engines... we are only increasing the efficiency of operation by swapping in more efficient parts...
We often give no credit to how well manufacturers are building engines these days despite the constraints of cost, efficiency and emissions. But the other side of that coin is performance upgrades are harder to attain because the manufacturers are already incorporating what we would normally add to our engines. Even the factory exhaust manifolds flow quite decently, for a mass production product.

Ed
 

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Ed, theory of operation is not an opinion, Its literally "The Science" behind how a 4-stroke engine operates.

So I would not be so quick to discredit how parts work together in the process of making HP/TQ.

Without a good understanding of engine theory of operation, we would be unable to improve that engine better than what was given to us. Engines are NOT magic and its more than throwing AIR FUEL SPARK xRPM into them, although that is a small part of the equation. Engines are mechanical and therefore predictable and when you understand how they operate, modifications done to them also become for the most part predictable. You have chosen to focused on one part of the equation, and it happens to be the reactionary side. I am not saying what you said was wrong, just saying it was just the effect side of the theory of operation.

So without turning this into a school lesson on "engine theory of operation"... I know I dont need one from you... I highly suggest you dig in and do some research. There is more to engine performance than the effects of AIR/FUEL/SPARK/ HP/TQ. <--- All important stuff sure, but its just one part of the equation and it happens to be the last part of it.

You suggested the only way to increase HP was to increase CI & RPM... I am not sure where you where going with that... That's common sense in most preschools. Most stock 4.7L engines belt out 175-180RWHP... all while retaining the factory short block and doing nothing to increase the CI and using bolt on mods (Ported heads are considered bolt on's in this example) and custom tuning we can get that number up over 320RWHP NA... All from improving on the efficiency of what the manufacture gave us.

One example of theory of operation many people just have zero to very little understanding on is exhaust systems and the effects of exhaust flow/velocity and its interaction with camshaft overlap. You almost touched base on this with your above comment... I was almost impressed, as very few understand this is where low end torque is made or lost. And just to give a hint, its not back pressure... no engine on the planet was ever designed to bennifit from back pressure. No need to increase the size of the engine to increase efficiency.

Understanding the theory of operation and how to build an exhaust system that will take advantage of and work with camshaft overlap goes a long way with bolting on exhaust mods that will enhance torque production rather than lower it. (Why is this so important.....?) In order to do this, you would also need to an slight understanding of fluid dynamics and apply that to exhaust flowing through a system. (No degree needed, just an grasp on the basics... and some math to figure required volume). The reason all this is very important is because for one, the factory exhaust system is NOT set up best for performance and there are a ton of exhaust parts available for sale and many of them will hurt low end torque. So just because they are available and are claimed to improve performance, not understanding how things work make it impossible for anyone to reasonably validate the claims and make wise decisions on the mods they chose.

We dont need to spin an engine at 6,000 RPM to know if a part is going to improve or hurt performance. We can look at a part and apply what I know about theory of operation and come to a general conclusion as to if a part will hurt or has the potential to improve performance.

Also, headers on a 4.7L engine do in fact work very well when the greatest restrictions in the system are addressed either first or at the same time. The greatest restriction on the factory system are the factory "Y" pipe back system.

Adding headers to an otherwise stock exhaust system will lead to disappointment.

Most 4.7L engines making up to 0-400HP will bennifit from a true single 3.0" exhaust starting from a high flow 2.25" dual in "Y" merging into a single 3.0" out. Making everything single 3.0" in/out and dumping it at the rear bumper is best in order to retain the exhaust flow which keeps velocity high which increases cylinder fill which equates to increased low end torque... We are talking about daily driven heavy trucks here...

Anyway... good luck withever it is that your doing.

Say it out loud with me..."Engine theory of operation is NOT a random opinion... its science!"

SPEED SAFE, AIR RAM PERFORMANCE
 

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Ed, theory of operation is not an opinion, Its literally "The Science" behind how a 4-stroke engine operates.
Does this mean that you were expecting a discussion on thermodynamics? If it was lost on you, allow me to clarify, my 'opinion' was based on theory of operation fundamental principals and is applicable not only to 4 stroke engines, but also 2 stroke engines, engines that have spark plugs and engines that don't, etc.

So I would not be so quick to discredit how parts work together in the process of making HP/TQ.
At no part of my response did I discredit how parts work together. If you go back and re-read my post, what I said was, not all performance parts are compatible with each other. Big difference!

Without a good understanding of engine theory of operation, we would be unable to improve that engine better than what was given to us. Engines are NOT magic and its more than throwing AIR FUEL SPARK xRPM into them, although that is a small part of the equation. Engines are mechanical and therefore predictable and when you understand how they operate, modifications done to them also become for the most part predictable. You have chosen to focused on one part of the equation, and it happens to be the reactionary side. I am not saying what you said was wrong, just saying it was just the effect side of the theory of operation.
Or you didn't grasp that I wasn't talking exact specifics but rather in generalities, meaning that what I was discussing could be applied to any engine, be it 2 stroke, 4 stroke, gas, diesel, or otherwise.
As such, by discussing it in generalities, it allows me to point out engine theory from a different point of view which should be beneficial to those who are open to discussion

So without turning this into a school lesson on "engine theory of operation"... I know I dont need one from you...
I must have misunderstood you when you stated; "Anyway, I just like to discuss stuff..." But I'm sure you don't need a school lesson, you're the resident 4.7 guru here and we both know your business here depends on selling performance parts in a highly niche market.

You suggested the only way to increase HP was to increase CI & RPM... I am not sure where you where going with that... That's common sense in most preschools. Most stock 4.7L engines belt out 175-180RWHP... all while retaining the factory short block and doing nothing to increase the CI and using bolt on mods (Ported heads are considered bolt on's in this example) and custom tuning we can get that number up over 320RWHP NA... All from improving on the efficiency of what the manufacture gave us.
It was clear that you didn't grasp the point that I was discussing in general terms and any points I made were applicable to all internal combustion engines. But lets quickly recap. What is HP? I say it is work/time. Am I correct or is that wrong? Next point, I said "work" in an engine is "torque" whereas the time element is measured in terms of 'RPM'. Is that right or is that wrong? So what was the point? It goes to engine theory, if you want to raise HP, you have to address one or both of the two elements of HP. And there are many ways to address them. I made no suggestion that the only way to increase HP was to increase CI & RPM though it could be one of many routes to more HP, so long as you use parts/machining that complement each other.

One example of theory of operation many people just have zero to very little understanding on is exhaust systems and the effects of exhaust flow/velocity and its interaction with camshaft overlap. You almost touched base on this with your above comment... I was almost impressed, as very few understand this is where low end torque is made or lost. And just to give a hint, its not back pressure... no engine on the planet was ever designed to bennifit from back pressure. No need to increase the size of the engine to increase efficiency.
In terms of conversing in generalities, there was no need to get bogged down in a myriad of specifics like for example, a detailed discussion of thermodynamics. But to quickly comment, many people believe that once the piston reaches BDC on the end of it's power stroke, it's all over. The exhaust valve opens and the upward force of the piston pushes out the exhaust. But nothing could be further from the truth. At BDC there's still quite a lot of thermal energy present in the form of expansion. When the exhaust valve opens, that superheated gas "expands" out thru the exhaust system. In turbo charged applications, it's this untapped expanding energy which is harnessed to compress air for the intake charge (and which is why turbos are inherently more efficient than superchargers)

I am in total agreement with you, in that no engine was designed to benefit from back pressure. Unfortunately, back pressure is a compromise specific to daily drivers which must operate with long pipes of some given diameter, with mufflers and cats. It's unavoidable! Therefore the compromise is the engine is tuned to run with a given amount of back pressure. If you look at it this way, applying the definition of efficiency, we aren't gaining HP with headers and freer flowing exhaust, we are capturing what was lost to flow resistance. This is essentially why there is little to gain with just a header swap.

Understanding the theory of operation and how to build an exhaust system that will take advantage of and work with camshaft overlap goes a long way with bolting on exhaust mods that will enhance torque production rather than lower it. (Why is this so important.....?) In order to do this, you would also need to an slight understanding of fluid dynamics and apply that to exhaust flowing through a system. (No degree needed, just an grasp on the basics... and some math to figure required volume). The reason all this is very important is because for one, the factory exhaust system is NOT set up best for performance and there are a ton of exhaust parts available for sale and many of them will hurt low end torque. So just because they are available and are claimed to improve performance, not understanding how things work make it impossible for anyone to reasonably validate the claims and make wise decisions on the mods they chose.
Hence why I discuss this in generalities. Even in discussing the factory system, we know Chrysler had designed the system to function sufficiently adequate for the myriad of compromises and broad customer expectations that exist. On the other side of the coin, the bottom line purpose of bolt on performance is to make a profit. It's not uncommon for aftermarket manufacturers to exaggerate performance results in the hopes of making a sale.

We dont need to spin an engine at 6,000 RPM to know if a part is going to improve or hurt performance. We can look at a part and apply what I know about theory of operation and come to a general conclusion as to if a part will hurt or has the potential to improve performance.
I don't agree. It's not possible to just look at a part and determine based on looks, that it can add performance. If that were the case, any shiny part would add performance. As I said before, real engine builders take the time and effort to test and measure actual increases.

Say it out loud with me..."Engine theory of operation is NOT a random opinion... its science!"
My opinion isn't random

SPEED SAFE, AIR RAM PERFORMANCE
(Insert sales pitch)

Ed
 

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Does this mean that you were expecting a discussion on thermodynamics? If it was lost on you, allow me to clarify, my 'opinion' was based on theory of operation fundamental principals and is applicable not only to 4 stroke engines, but also 2 stroke engines, engines that have spark plugs and engines that don't, etc.



At no part of my response did I discredit how parts work together. If you go back and re-read my post, what I said was, not all performance parts are compatible with each other. Big difference!



Or you didn't grasp that I wasn't talking exact specifics but rather in generalities, meaning that what I was discussing could be applied to any engine, be it 2 stroke, 4 stroke, gas, diesel, or otherwise.
As such, by discussing it in generalities, it allows me to point out engine theory from a different point of view which should be beneficial to those who are open to discussion



I must have misunderstood you when you stated; "Anyway, I just like to discuss stuff..." But I'm sure you don't need a school lesson, you're the resident 4.7 guru here and we both know your business here depends on selling performance parts in a highly niche market.



It was clear that you didn't grasp the point that I was discussing in general terms and any points I made were applicable to all internal combustion engines. But lets quickly recap. What is HP? I say it is work/time. Am I correct or is that wrong? Next point, I said "work" in an engine is "torque" whereas the time element is measured in terms of 'RPM'. Is that right or is that wrong? So what was the point? It goes to engine theory, if you want to raise HP, you have to address one or both of the two elements of HP. And there are many ways to address them. I made no suggestion that the only way to increase HP was to increase CI & RPM though it could be one of many routes to more HP, so long as you use parts/machining that complement each other.



In terms of conversing in generalities, there was no need to get bogged down in a myriad of specifics like for example, a detailed discussion of thermodynamics. But to quickly comment, many people believe that once the piston reaches BDC on the end of it's power stroke, it's all over. The exhaust valve opens and the upward force of the piston pushes out the exhaust. But nothing could be further from the truth. At BDC there's still quite a lot of thermal energy present in the form of expansion. When the exhaust valve opens, that superheated gas "expands" out thru the exhaust system. In turbo charged applications, it's this untapped expanding energy which is harnessed to compress air for the intake charge (and which is why turbos are inherently more efficient than superchargers)

I am in total agreement with you, in that no engine was designed to benefit from back pressure. Unfortunately, back pressure is a compromise specific to daily drivers which must operate with long pipes of some given diameter, with mufflers and cats. It's unavoidable! Therefore the compromise is the engine is tuned to run with a given amount of back pressure. If you look at it this way, applying the definition of efficiency, we aren't gaining HP with headers and freer flowing exhaust, we are capturing what was lost to flow resistance. This is essentially why there is little to gain with just a header swap.



Hence why I discuss this in generalities. Even in discussing the factory system, we know Chrysler had designed the system to function sufficiently adequate for the myriad of compromises and broad customer expectations that exist. On the other side of the coin, the bottom line purpose of bolt on performance is to make a profit. It's not uncommon for aftermarket manufacturers to exaggerate performance results in the hopes of making a sale.



I don't agree. It's not possible to just look at a part and determine based on looks, that it can add performance. If that were the case, any shiny part would add performance. As I said before, real engine builders take the time and effort to test and measure actual increases.



My opinion isn't random



(Insert sales pitch)

Ed

Ed, I know you feel you may be the smartest one in the room because you are able to cut and past random google search results to boast up your opinons... Your kind is not new on these boards... you are saying the only
Does this mean that you were expecting a discussion on thermodynamics? If it was lost on you, allow me to clarify, my 'opinion' was based on theory of operation fundamental principals and is applicable not only to 4 stroke engines, but also 2 stroke engines, engines that have spark plugs and engines that don't, etc.



At no part of my response did I discredit how parts work together. If you go back and re-read my post, what I said was, not all performance parts are compatible with each other. Big difference!



Or you didn't grasp that I wasn't talking exact specifics but rather in generalities, meaning that what I was discussing could be applied to any engine, be it 2 stroke, 4 stroke, gas, diesel, or otherwise.
As such, by discussing it in generalities, it allows me to point out engine theory from a different point of view which should be beneficial to those who are open to discussion



I must have misunderstood you when you stated; "Anyway, I just like to discuss stuff..." But I'm sure you don't need a school lesson, you're the resident 4.7 guru here and we both know your business here depends on selling performance parts in a highly niche market.



It was clear that you didn't grasp the point that I was discussing in general terms and any points I made were applicable to all internal combustion engines. But lets quickly recap. What is HP? I say it is work/time. Am I correct or is that wrong? Next point, I said "work" in an engine is "torque" whereas the time element is measured in terms of 'RPM'. Is that right or is that wrong? So what was the point? It goes to engine theory, if you want to raise HP, you have to address one or both of the two elements of HP. And there are many ways to address them. I made no suggestion that the only way to increase HP was to increase CI & RPM though it could be one of many routes to more HP, so long as you use parts/machining that complement each other.



In terms of conversing in generalities, there was no need to get bogged down in a myriad of specifics like for example, a detailed discussion of thermodynamics. But to quickly comment, many people believe that once the piston reaches BDC on the end of it's power stroke, it's all over. The exhaust valve opens and the upward force of the piston pushes out the exhaust. But nothing could be further from the truth. At BDC there's still quite a lot of thermal energy present in the form of expansion. When the exhaust valve opens, that superheated gas "expands" out thru the exhaust system. In turbo charged applications, it's this untapped expanding energy which is harnessed to compress air for the intake charge (and which is why turbos are inherently more efficient than superchargers)

I am in total agreement with you, in that no engine was designed to benefit from back pressure. Unfortunately, back pressure is a compromise specific to daily drivers which must operate with long pipes of some given diameter, with mufflers and cats. It's unavoidable! Therefore the compromise is the engine is tuned to run with a given amount of back pressure. If you look at it this way, applying the definition of efficiency, we aren't gaining HP with headers and freer flowing exhaust, we are capturing what was lost to flow resistance. This is essentially why there is little to gain with just a header swap.



Hence why I discuss this in generalities. Even in discussing the factory system, we know Chrysler had designed the system to function sufficiently adequate for the myriad of compromises and broad customer expectations that exist. On the other side of the coin, the bottom line purpose of bolt on performance is to make a profit. It's not uncommon for aftermarket manufacturers to exaggerate performance results in the hopes of making a sale.



I don't agree. It's not possible to just look at a part and determine based on looks, that it can add performance. If that were the case, any shiny part would add performance. As I said before, real engine builders take the time and effort to test and measure actual increases.



My opinion isn't random



(Insert sales pitch)

Ed

Wow.. you really like to talk yourself up into a frenzy. I'm starting to think you're just posting trash to get your post count up. The question was about headers and if they are worth it on a 4.7L engine. Not about you and how much you think you know.

You made a essay babble post that failed to address a single question in the OP's post. Your response was not only off topic, from what I could see it failed to remotely answer the question.

If you have a first hand experience with headers and a 4.7L I would really enjoy to hear about it...

I included first hand REAL WORLD experience on the exact question/topic being asked. I have personally installed headers on my 2002 Dodge Ram 1500. I have actually installed every part ever made available into my 4.7L and DYNO tested nearly every single one of them as well... and at the time, my 4.7L 1500 was the quickest 4.7L NA QC 1500 in the country (9.49's in the 1/8th) debatable as quickest sure, but nobody ever posted quicker times or spoke up to debate them at that time...The single cab HEMIs where running 10.2s and 10.3s that same day my truck ran consistant 9.49s. And .07 at top end is about 4-5 truck lengths. Got to know a thing or two about a thing or two to do that back when it was considered blasphemy for anyone to claim a 4.7L beat a HEMI. <--- Great times!

You went on your attack accusing me for trying to sell something... please show me where I made an offer to sell anything at all. I love how you try to discredit my input on the topic as if I had an alternative motive. Because I own an operate a successful performance parts website I am forbidden to to participate in discussions? That's a very "Leftist" way to lean... cant beat them with knowlege and experience, just take the means of speech away! Sorry bud, I am not that guy you can swing that ugly stick someplace else. You chose to discredit and trash talk my responses... Im only responding to your bully tactics and babble.

If you take a peak at any of my past post (Ive made a few), I'm just as much as an enthusiast than anyone else... and more of an enthusiast than others. Heck, you may learn something if you do.

Just because I happen to own and operate a business founded on my knowledge and experience does not mean I am only hear to sell things. I did not post any links, I did not suggest that someone go to our website and purchase any parts... I just shared my experience supported by FACTS and REALITY. My experience and knowledge allowed me to turn it into a successful business... Thank you for the plug though.

And you know nothing about back pressure "Jon Snow"! I'm happy you jumped out to claim it as needed though, this way you cant go back and say you didn't say it. I do expect a tap dance around it though... looking forward to it. This is also why I didn't elaborate it in my first post... I wanted to hear your thoughts first.

Pencils out:
Back pressure is exactly what it sounds like... it is a restriction at best. NO engine has ever been intentionally designed to use, bennifit from or run with back pressure. Back-pressure is the term used by people who dont know or understand engine theory of operation. To them, loss of torque caused by to large of an exhaust system is a mystical anomaly that they are unable to articulate... so they just call it "lost back-pressure" and its concluded. But its not, because thats not how it works!

The science of exhaust flow and its effects on the intake charge into the cylinder (In a nut shell):
NA exhaust systems are designed to take advantage of the camshaft overlap.
What is Camshaft overlap? For a short duration the intake and exhaust valves are open at the same time... this is called "overlap". This is intentionally built into cam design specifically to take advantage of the vacuum created by the exhaust system. (All part of theory of operation - which does apply to ALL engines by the way)

A properly designed exhaust system will promote exhaust velocity at a desired HP/RPM...
If you go to large ID pipe you lose velocity.
If you go to small ID you gain your beloved back pressure.

A proper size ID of the exhaust is determined by the engine size, amount of power the engine makes and the targeted RPM range it makes that power. When the exhaust is the right size for its SIZE/HP/RPM, that exhaust WILL promote exhaust velocity, which creates a strong vacuum on the cylinder, and due to the camshaft overlap pulls on the intake side giving the intake charge a running head start into the cylinder. This in turn increases cylinder fill before combustion... this is also known as the "scavenging effect" and is responsible for increasing and decreasing low end torque. Again, this is why every NA cam has a decent amount of overlap designed into them.

So now when you hear about people who went to large of a pipe or added duals to there exhaust and they claim to have lost low end torque... know you know know why... and its not back pressure that they lost... they lost exhaust gas velocity within the system which caused them to lose the scavenging effect which led to lazy cylinder fill and a loss of low end torque.

All of this is important to understand when choosing performance mods. I personally prefer people to be informed with how things work before spending their money on parts that dont work or worse yet on parts that can hurt performance. You can spend lots of money on expensive parts and still make less power and be slower than someone who spent less and used the right parts...

Using this newly acquired information, you can now look at many exhaust parts and make an educated guess as to what to expect from them. You will at least know to verify your exhaust systems requirements based on the projected HP and RPM of that engine... you now know to at least ask the right questions before you buy.

Most lightly modded 4.7L engines will make between 220-250RWHP. That equates to about 285-315crank. Based on this, the majority of 4.7L engines perform best with a TRUE 3.0" exhaust starting with a high flow "Y" pipe...

Just a note: you're not going to be making 220-250RWHP without adding headers and replacing that "Y" pipe... this is not opinion... this is fact.
The great news is that the 5.7L HEMI trucks where belting out 250-260RWHP back in the day and those where considered rocket ships... So if your making 250HP+ with your NA 4.7L... You're doing well.

The factory "Y" pipe is two 2.25" pipes Crushed together and welded and forced into a single 2.75 system. Its truly a restrictive system...

Simply replacing the factory crushed "Y" pipe will with a high flow "Y" pipe and leaving everything else factory will net noticeable gains. However stepping it up to a true single 3.0" leaves you room to grow and will easily support over 300RWHP.

Bottom line, the factory "Y" pipe is the greatest restriction in the exhaust system... adding mods forward and aft of it without addressing it specifically will lead to disappointing results.

YES HEADERS WORK on the 4.7L however you must address the restrictive factory "Y" pipe to take full advantage of them.

SPEED SAFE, AIR RAM PERFORMANCE 😎
 

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Ed, I know you feel you may be the smartest one in the room because you are able to cut and past random google search results to boast up your opinons... Your kind is not new on these boards...
No, what makes me smart is my many years of experience. Google, no less the Internet, didn't yet exist when I learned about engines. I used books when they were in vogue.

Wow.. you really like to talk yourself up into a frenzy. I'm starting to think you're just posting trash to get your post count up.
Thats another thing that makes me smarter. I don't make false assumptions. I'd care less about post counts. I just post when I want to and have something to contribute

You made a essay babble post that failed to address a single question in the OP's post. Your response was not only off topic, from what I could see it failed to remotely answer the question.
This is why reading is fundamental... You said I failed to address a single question in the OP's post? This is what the OP asked;

"I've read countless of forums with mixed reviews on doing headers with a 4.7 and I'm looking for actual opinions from those who have done them. I have an 04 4.7, 08+ Intake, H.O cams, tuned, cold air intake, ignition and injector upgrades, 70mm TB, 3" to dual 2.5" exhaust and getting ready to do 4.56 gears. Would I benefit any from headers or should I stay away? Also how hard were they to install."

In my opening post, (Post #5) you'll note that I did mention that I have not added headers to a 4.7 but have installed headers on numerous other engines. I did address the difficulty of installing headers, as well as the general contribution that headers provide

So I just proven to you that, yes, I did respond to every question in the OP's post. That means either you didn't read it, ignored it, or you lied, so my question to you is why would you do that?

If you have a first hand experience with headers and a 4.7L I would really enjoy to hear about it...
Did I mention that I haven't installed headers on a 4.7? So now you're gonna try a disqualifier? Tell me, what makes headers for a 4.7 any different then a set of headers for say -a 390 Ford, 350 Chevy, 225 Slant Six or any other 4 stoke engine? Principal of operation is the same no matter which engine you're talking about.... And don't tell me it's any worse to install then it is on a 71-72 302 Maverick.

I included first hand REAL WORLD experience on the exact question/topic being asked. I have personally installed headers on my 2002 Dodge Ram 1500. I have actually installed every part ever made available into my 4.7L and DYNO tested nearly every single one of them as well... and at the time, my 4.7L 1500 was the quickest 4.7L NA QC 1500 in the country (9.49's in the 1/8th) debatable as quickest sure, but nobody ever posted quicker times or spoke up to debate them at that time...The single cab HEMIs where running 10.2s and 10.3s that same day my truck ran consistant 9.49s. And .07 at top end is about 4-5 truck lengths. Got to know a thing or two about a thing or two to do that back when it was considered blasphemy for anyone to claim a 4.7L beat a HEMI. <--- Great times!
Whats missing from this pat on the back is the actual numbers to back up your claims. So based on your own words, you said you dyno tested every part? Lets see the numbers on just the difference headers make.... I don't care about how fast your 1500 is, the question the OP had was if headers would be a benefit. Show him with pure numbers how they benefitted you

..... accusing me for trying to sell something... please show me where I made an offer to sell anything at all. I love how you try to discredit my input on the topic as if I had an alternative motive. Because I own an operate a successful performance parts website I am forbidden to to participate in discussions? That's a very "Leftist" way to lean... cant beat them with knowlege and experience, just take the means of speech away! Sorry bud, I am not that guy you can swing that ugly stick someplace else. You chose to discredit and trash talk my responses... Im only responding to your bully tactics and babble.
It makes your input biased. Even in just a paragraph above, you can't help but brag about your 4.7 beating Hemis. (and it's not the first time) It's called "hype" and it's also a type of sales pitch. You couldn't be a good salesmen if you had to say anything negative about the 4.7
You don't need to actively sell, you just need to actively participate and create a reputation
OTOH I can say positive things or I can say negative things about the 4.7 because I don't have any vested interests in it. I have no issue or conflict of interest about saying to you or anyone else that the 4.7 isn't anything special. Sure I'll give you major Kudos for attempting to address the lack of interest in this little forgotten engine and I do wish you mucho success but in the world of Chrysler performance, there is just so many better engines to pick from and therefore if anyone really wanted to kick butt with Dodge and lay waste to Chevies and Furds. I'd recommend other Chrysler engines before I'd ever suggest a 4.7

A Leftist way to lean is misrepresenting what someone else said, like saying something like, I didn't answer any of the OP's questions when I did ... Hmm! Lets Go Brandon

And you know nothing about back pressure "Jon Snow"! I'm happy you jumped out to claim it as needed though, this way you cant go back and say you didn't say it. I do expect a tap dance around it though... looking forward to it. This is also why I didn't elaborate it in my first post... I wanted to hear your thoughts first.
WTF? What does that all mean? You know all you need to do is do a quick search on just my handle RXT and you'll see I've been using it all over the internet for the last 20 yrs

Pencils out:
Back pressure is exactly what it sounds like... it is a restriction at best..................
Everything you said, from this point on I can agree with, but you left something out that without it being considered would cause confusion and misinformation. You left out the importance of RPM. The pressure waves or pressure pulses responsible for the scavenging effect is a constant. No matter the RPM, these pulses or waves always move at a constant rate. What doesn't move at a constant rate is the volume or flow of exhaust. At low RPM the exhaust volume is low and the pressure pulses do not coincide with the volume of exhaust flow leaving the valve area, and no scavenging takes place. The only range of RPM when scavenging occurs is around the mid to upper RPM (which also explains the importance of tube length) Which goes back to what I've been saying all along. Headers do not benefit power at the lower RPMs common at normal road speed and factory manifolds are just as effective. At much higher RPM, yes, you can gain a little HP. But for the average DD which spends more than 90% of the time at around 2000 RPM, it's probably not worth as much as the hype implies

SPEED SAFE, AIR RAM PERFORMANCE 😎
(Inject sales pitch)

Ed
 

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C'mon Dodge - NEW DAKOTA
2003 Dakota Club Cab Sport 4.7L
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This was amusing at first, but now it's simply annoying. Perhaps you can finish this elsewhere. The technical bits are worth reading, the personal attacks are not. And they all fall into the TLDR category now.
 
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I've read countless of forums with mixed reviews on doing headers with a 4.7 and I'm looking for actual opinions from those who have done them. I have an 04 4.7, 08+ Intake, H.O cams, tuned, cold air intake, ignition and injector upgrades, 70mm TB, 3" to dual 2.5" exhaust and getting ready to do 4.56 gears. Would I benefit any from headers or should I stay away? Also how hard were they to install.
You have a great set up with what seems to be the right parts.... The 08 intake with HO cams and 70mm throttle body is a GREAT set up and will make great power throughout the RPM range. And as I have mentioned above... YES headers can be a great addition to your 4.7L IF you address the restrictive factory "Y" pipe. Feel free to PM me with any questions or concerns, I will do everything I can to give you the right information to make the best possible decisions for your project..

SPEED SAFE, AIR RAM PERFORMANCE
 

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This was amusing at first, but now it's simply annoying. Perhaps you can finish this elsewhere. The technical bits are worth reading, the personal attacks are not. And they all fall into the TLDR category now.
I could not agree more.

SPEED SAFE, NICK
 
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