When are 2" headers necessary?
 

Just like the title says when do 2" headers out due the 1 7/8" headers?

Any back to back dyno numbers?

They make more power everywhere even on a bone stock engine.

They are usually just used on FI cars

There was a test and the 2" did out perform the 1 7/8ths even on the stock tune. Not by much but when you go adding a cam ect. they are the way to go if you want to maximize what you have.

2" are the way to go nomatter how you slice it... wish i would ahve gotten them :facepalm:

This is a myth. One shop two years ago posted results of a test they did. If I remember correct, it was just they posted the peak numbers, not like a chart that shows power throughout the whole powerband.

I have been selling LSX parts now for 8 years, and have sold as many headers as anyone. 2" headers only sell for cars making 750+ rwhp. This is not my opinion..you call any major header manufacturer, and they will tell you the same. If 2" headers were better everywhere, why would header manufactuers bother making 1 3/4" and 1 7/8"? It would make life alot easier for everyone.

Everything you need to know about headers can be summed up in a garden hose. The idea of a header is the make the exhaust gas move faster. The faster the exhaust gas moves, the faster new air/fuel can replace it in the cylinder head, and the more efficiantly the engine can breathe.

Going back to the garden hose..if you replace your garden hose with a bigger garden hose...what happens? The water comes out the end slower because it is not as pressurized. The water will only move the same speed as the smaller hose if you turn the water up real high. Same thing with a header. If you put a big header on, it does not pressurize the exhaust gas as much initially, which hurts exhaust velocity. If the exhaust does not move as fast initially, you lose lowend power and TQ. You may see a same, or higher peak HP number witha 2" header, but that is because ones the engine is really wound up over 5K RPM, the bigger primary can flow it better.

Long and short is..you want the smallest diameter primary that can flow the maximum exhaust output of the engine efficiantly. if you go on LS1Tech, Corvette forums, or any of the other really technical LSX boards and say..I am gonan run 2" headers on my stock LS3, you will get laughed out the place.

I think it is time for another test;)

Jannetty did a comprehensive test showing the entire curve.

2 inch exactly matched the 1 7/8 all the way to 5-5500 and made 5 more rwhp peak. And this was on a stock ls3. 1 3/4 was down 10 rwhp peak and 5rwhp through most of the curve.

2 inch is the way to go regardless.

There has been a Test of header tube sizes on here by jenetty. I know the old saying the better it breaths it more power.

IF you are looking at a stock or a cammed Car the 1 7/8 looks to be your best bet.

If you have a pretty hot Forced induction car you can go with 2inch however I dont see that great amounts of hp coming out of 2inch.


I would go with them if I had a F1 car with a larger Cam.

I have 2" on my car, no tune and a home made cold air... I just ran 113mph sunday and pulls 112 about every pass, 12.60 on stock tires. I think they are working pretty well, they definitly wont hurt and if you have plans to make over 500rwhp they will be worth it.

And Micheal Jordan could score 30 pts a game with Hanes 3 sizes too big. Does not mean it is right. Again..if you step outside the Camaro5 Vortex..and look at some of the othe LSX boards, you will find a lot more info than 1 dyno test that a 2" header does not make sense untill you really turn the power up.

Again..no one has answered my question...if 2" is better everywhere..why would the header companies makes 3 different sizes and only recommend 2" for the most extreme applications? Bigger is not better with exhaust.

They make it because people buy it. If you think 2 s are better than jump On them. Not much of a difference, they are all better than stock.
I would like to think the big header companies have done their research, and thats what they have decided, but i do know better than that. They just posted what they thought and nobody has cared to disprove them.

so you guys saying the 2" headers are the best way to go, would you also say based on your experience that a carb sytle intake or fast 102mm would be the best intake for a 5.3L LSx?

Like i said... 2" headers make more power. Period. They arent as commonly used because they fit worse,and cost more, along with being heavier. Come up with all the stupid analogy you want, but the reality stays the same. 2" make more power, and the more mods you have, the more power they will make. I have 2" stepped to 2 1/8 staring at me in the garage for the new motor...