I've towed 39k# with mine and never had any heating issues except the brakes. Mind you we don't have 10% grades 20 miles long like out west.
get a tune with a airraid MIT tube, duramax air filter, and a muffler of your choice. If your wanting more just get some boost.

 

I believe the reason why you are completely wrong is that you are thinking that the power improvement from long tube headers comes from improved gas flow. That is in my opinion why it's so hard for a lot of people to understand why shorty headers don't do anything at all, because it is obvious that they have to flow more than stock manifolds.
Another name for long tube headers is tuned length headers. All of the power comes from the scavenging effect of the tuned length.
When I installed long tubes on my truck, it had the stock 6.0 with a blower. I kept the cats and repiped from the collectors to the cats with 3".
That was the straw that broke the camel's back for the 45 lb/hr injectors. With 60 lb/hr injectors and a retune, the power improvement from long tube headers was very evident.

 

To correct myself, I should not say that the improvement doesn't come from increased flow, because it does. My point is that it does not come from decreased restriction, it comes from the scavenging effect.

 

Not all long (or short) tube headers are tuned headers. Tuned headers have equal length primaries.

I said long tubes will help, they will. They have a better flow design. Shorties WILL help. The reason they won't help by doing them on their own (ON AN NBS), is because of the collector. That collector cuts airflow to 3/4 if it goes from dual 2.5" to a single 3", and it cuts the airflow in half if it goes from dual to single 2.5". THATS the reason that shorties alone do nothing. When you add long tubes, you are getting rid of the collector, and that is where the GIANT restriction is.

If our exhaust is a garden hose, and you change the front third and back third to a fire hose, it's still going to only flow as much as that garden hose in the middle can. Long tubes compared to shorts, take out some of the bend at the start, BUT MORE IMPORTANTLY, are going to be piped the rest of the way back, to get rid of that restriction at the collectors that's the major blockage of your air flow. They both help, (BUT SPECIFICALLY FOR AN NBS EXHAUST), making that garden hose entirely into a fire hose is going to do more than taking a little bend out of the start.

 

My setup is dual factory 3" into the single stock muffler. The only 2-1/2" was of course eliminated by the headers because it was only short lengths from the manifolds to the 3". I think that the stock muffler has to be quite a bit more restrictive than the dual 2-1/2" pipes that you say a 1500 has. Where did the power increase come from in my case, if not from the scavenging effect of long tube headers?
Explain the improvement that I got having two 3" pipes going to the single muffler, which has a severe restriction inside of it according to a picture I saw on this website.
The difference in long tube headers and equal length headers is miniscule, only due to fitment restrictions. Long tubes still work by the scavenging effect.
You are stuck on improved flow, and my example proves that power increases can come without removing the stock restriction (the muffler). Go ahead and keep spreading misinformation that the power increase of long tube headers comes from improved flow, I will continue to educate people that the increase is actually from the scavenging effect.

 

You are right in what you are saying but you are completely forgetting exhaust scavenging which is extremely important. This article explains it quite well if anyone is interested: https://www.onallcylinders.com/2015/...header-tuning/


That should close this one out.

 

Unlike a garden hose or fire hose, the medium going through is a gas not a liquid. The y-merge from dual 2.5" head pipes going to a 3" doesn't create a significant restriction because:

1. As temperature decreases along the exhaust path, the effective volume of exhaust gas is steadily decreasing from head (hottest) to tailpipe (coolest). I would call this a very small effect in the case of head pipes to y-pipe, not a main contributor. The bigger factor is:
2. A y-pipe merges the exhaust gas pulses from both banks (kind of like an x-pipe, but instead of separating back out, it stays into a single larger one), so there's a savaging effect at that point as well.

There's a lot more fluid dynamics happening beyond comparing total cross-sectional areas.

The advantages of long tube headers over shorties has been tested on many other configurations in the past for other cars, makes, etc. (true duals, duals with H pipe) with similar results. It's not a phenomenon specific to our trucks and their 2 into 1 setups.

 

You know, when I said that this post should close this one out I meant it.

 

Is that what you meant to say? Cause what you wrote is not true. Long tube headers MIGHT be equal length, and they might not. Equal length are going scavenge better. It's one of those things where you are paying that extra 20-50% for a 5-10% better product. It's more of an effort and amount of work to make them properly equal. Fitment restriction might be one of the reasons, but they require more bends and work to make them right.

Scavenging happens with shorties, and x pipes too, it's not limited to long tubes.

The only place a 1500 has dual 2.5" pipes (stock) is the cats up to the collector.

I'll respond to the rest, even though this is getting really sidetracked, Its just not clear about what your exhaust, was, is, and what you have done. Here's what you said:

Just so we're clear, I'm talking about the restriction from the collector, and you just said you don't have that right? I've said it at least twice in this thread, long tubes will help (this is the third time). They will usually have larger primaries, and the longer initial runners to allow more air get out of the combustion chamber without being restricted.

 

I missed what your point is on this, it sounds unfinished. What I've been trying to say is that long tubes help the most over short tubes, but the merge is the big problem. Long tubes overcome that with how the piping ends up going. So when you add long tubes, you are getting the benefits of the long tubes, AND removing the restriction. Just changing to short tube headers (with an otherwise stock NBS) exhaust will do next to nothing. It's not because shorties won't help, its because only changing those changes nothing about the main restriction in the exhaust.


I get what you are saying. I want to respond, but flat out, I don't know enough to know specific details.
1. I have no clue how much it is actually cooling, but I don't believe that it cools enough to compress itself into 3/4 of the space it was using just a few feet earlier. It's not pressurized, it's just cooling. It is flowing similar to water, but okay its cooling so its compressing, but not anywhere near the rate it would need to, to overcome that restriction.

2. I get the Y-pipe is scavenging, but once those pulses for each pipe take up more than 1/2 of the total volume of each, then when it merges, its being restricted. I THINK that you could figure out your actual volume use and requirements based on your combustion chamber size, type of fuel, amount of fuel, the expansion after combustion, etc.. but I don't know the details of what's needed in order to do the math.

3. If you're going to say cooling and scavenging, then once the air flow hits ANY kind of restriction it creates turbulence which hinders free flowing gases.

I get there's more. I think I can say I understand several of the concepts, but I don't know enough to know what I'm missing. HOWEVER, If there was no reduction in size along the piping, wouldn't that be enough to quickly solve all those concerns?

I also haven't pulled my cats off yet, but I'm thinking it's (2) 2.5" pipes merged into a single 2.5" pipe. Even a single 3" pipe is 3/4 of the volume. There is no way the air is cooling enough that quickly to offset the merge reduction.