It was never explained in where headers (each size) do their work. For example, looking at dynos, I easily learned where TPI intakes help vs short runner intakes. (2,500-4,500 vs 4,000+)

No matter how many times I read this thread, I won't find anything more detailed than 1 5/8" start working lower than 1 3/4". Your post above proves you just like to argue.

While you were busily trying to get me to reread posts, everyone failed to recognize how simple my questions were. I understand (after looking around the couple of days) that 1 5/8" and 1 3/4" headers are the most readily available.

I still don't know where they really start helping (rpm-wise). Saying I need to go to school and become an expert -- just to get an answer to that question is.....

I know I won't get an answer. I know this thread does not contain that answer. OTOH, I know I will get an arguement.

I win.

gp

 

gregg, they start lower, thats all you need to know. you're not racing for the coveted -.001 win. your engine to too small and primitive to get into exotic discussions. its a car with a basic little truck engine, the 350 sbc.

get on that phone, order the 1 5/8", and you've nailed one major component of several you'll need to undo the semi-joke that the factory laughingly issued from its conveyerbelts for years......which at this point might as well be considered a millenia ago.

 

Like I posted above, it depends on engine size, heads, cam, exhaust system, etc. Length of the primary pipes, collector diameter and its length also. Same as the Intake manifold. You can get close but, you'd have to put your car on the dyno with each size and then compare, for exact numbers. 1 5/8" LT headers on a 350" probably start to "come on" around 15-2000 RPM over stock manifolds; depending. To add to your confusion, I've read articles where 1 5/8" made the most power on SBChevy motors as big as 406", up to around 6500 RPM. It depends on the parts combo.

 

That can't be answered. There are WAAAY too many possible variables. How high is up???


That is as detailed as possible. YOU can build the engines that meet your parameters and dyno them to get your answers. I like to argue? What point is it that I am arguing?

If the questions are so simple, so easy, why are WE the dummies for not having the answers? For EASY questions, you shouldn't need to study too hard.

Is excellent advice. Apparently common knowledge isn't specific enough for you. When you thoroughly know and understand it all, you can come back and enlighten the rest of us.


I retract the re-read advice as far as specific rpm switch on and switch off points are, because they aren't contained in this or any other thread. That isn't the way it works.

No arguments. Just statements of fact.

I agree. No argument. I just won't say WHAT you win.

RACE ON!!!

 

Maybe you should start over and think about what the answer you really need is?

If you want to know specific things about header designs, about testing two different sizes on the same engine, well as said, either start testing, or start reading. My guess is no one has taken the same engine and in a methodical way swapped on headers of different sizes, lengths, designs, etc to compare them, and then documented it in an article like the ones you've read on intakes. If you want that information, it sounds like you'll have to construct it yourself. I'd hardly call that a simple question.

But if your goal is to buy a header for your car, you don't need that. What you need is real-world feedback from people who have done the same thing. And you've gotten that, it seems to me.

As an aside, how useful are those rpm points you've found out for intakes? Do you think that means the same intakes on your engine will have the exact same rpm breakover points? Or that the differences will be of the same magnitude? Has any of that specific info actually helped you decide what you are going to do with your car? The way you make it sound, you should have the whole build nailed down except the headers, right?

It seems to me there is a body of information, both methodical like some of the magazine test articles, and some simply a test of a particular combo, available to you. From that I'd think your main options are:

- Use that body of info to find a proven combo that has a result similar to your end goal

- Wait for the body of info to get bigger

- Increase the body of info with a lot of theorizing and testing on your own

The option you are pursuing now of just asking "why, why, why" all the time does not appear (to me) to be productive. It doesn't appear that you are going to increase the body of knowledge through nagging. While it's a forum and you are welcome to ask questions, the only thing it seems to accomplish is to wear out the patience of those who could probably help you the most.

Just my take on it...

 

I wasn't trying to wear down anyone's patience. I was interested if headers started "working" in lower rpms ranges (like under 4k rpms). Maybe I got too wordy in the process.

It seemed the answers involved to much mumbo jumbo about the intracies and calculations involved. And, I hoped someone might know. Curveit seemed to answer the question on this page of the thread. I guessed the benefit could be fairly quickly (off idle) but had never seen that mentioned.

Most people build thinking top-end. Some do consider their street use as a bigger priority. That priority may be amplified due to two issues. I have active sidepipes and I already redid my exhaust maintaining emissions configuration. The cost exceeded $1k with used sidepipes, new "Y", and new hi-flow cats. Sidepipes is something I wanted and that's the config they made them in. At the time, I wanted to stay "legal" as well.

After removing the TPI, I got down-right pizzed at the AIR and EGR. I decided that ease of maintenance on an older car was more important -- especially if I could use tuning and other methods to keep it clean. That change in philoshpy ended up leading me to doing more mods.

Lawrence-Keech says sidepipes "breath well" for motors up to 450/500 hp. Maybe that's true, maybe that's bs -- like a lots of other companies are eager to do. But with side pipes, the money spent on exhaust, $2k set aside to do more, and the goal of keeping it a street car -- I felt it reasonable to be sure that introducing headers at this point in mods would REALLY be worthwhile.

Without reviewing threads I've read over the years, I seem to recall that exhaust upgrades could help around 35hp. But I also thought a lot of that was in the small 2.25" pipes, restrictive cats, and restrictive mufflers. Combined with the small size of exhaust valves vs intake valves, I guessed that headers weren't highly significant. Even with an upgrade to let more air in, the exhaust valves/ports seem relatively small on stock heads. This knowledge added to my perception that header on a stock motor might be somewhat overrated.

After looking around at header threads, posts, and websites again, my interest in them has renewed. Of course expaining to the wife why I have to spend MORE money on exhaust could be quite fun! And, it helps if I have REAL conviction!!!!

You might perceive my persistance as nagging. I see as a reasonable question. Too often people take the hype of what mods can do at face value. Look at how many have purchased chips, cold air intakes, TB dividers, and muffler bearings....

I'm not saying headers are in that category. But, I consider asking about their value and performance for lower rpm applications reasonable.

If it helps, I apologize if I sounded annoying/impatient, etc... I was merely parroting what my wife will say when I announce I need headers!!!



gp

 

This was a reference to the fact I new I'd receive more in the form of an arguement or debate or whatever you want to call it. And, I did.

OTOH, I was surprised that Curveit provided a more specific answer. Thanks!

Half the "fun" of posting here is the "debate". And, I got one!

BADDUCK once posted that I would argue with a fencepost. Why should I do that when I have you guys...

gp

 

I'd be surprised to see any engine with exhaust valves as large or larger than intake valves. Pushing a gas out and pulling a gas in are pretty different. It's a lot harder to pull something in through a small hole than push it out, because the pressure pushing out can be extremely high, the pressure pulling in can not be any higher than atmospheric pressure.

What I don't get is on one hand you pontificate about valve sizes and port sizes, and on the other real people put real headers on L98s just like yours. So you have two different conclusions, and you wonder which one is the right one?

 

People need to quit taking this SO literally and try to read intent.

Been reading posts on headers this evening. The second post above is one I read when it was posted last Fall. (It was a response to someone wanting to replace their manifold with shorties). To him, you called the stock manifold "shorties". OTOH, when talking to me you wanted to criticize my use of the phrase "stock headers" when referring to the stock manifold on my car. That's a good example of why I took this thread as argumentative.

Is the use of words becoming more important that the question or intention behind them?

Some of the responses here lead me to believe that. For example, Aurora's response above does too...

I clearly outlined some of the reasons for confusion/uncertainty. Yet he had to point out that it's crazy that I was confused. (Maybe it wasn't clear I was describing how my perception changed over a long period of time? And, with more reading).

As I stated earlier, this thread just plain turned argumentative. For my part, I already apologized. I can't do anything more than that!

gp

BTW: If I was confused enough before, try adding Neat's stock ZF6 L98 with a stock motor and 4:10 rear end to this mix. He claims the fastest stock L98 in this forum. And, he's using 1 3/4" headers with a TPI. (And, 4:10 gears "to boot"!) I'd call that a mis-match. But, for some reason, it seems to work. THAT's what's

 

BTW: If I was confused enough before, try adding Neat's stock ZF6 L98 with a stock motor and 4:10 rear end to this mix. He claims the fastest stock L98 in this forum. And, he's using 1 3/4" headers with a TPI. (And, 4:10 gears "to boot"!) I'd call that a mis-match. But, for some reason, it seems to work. THAT's what's [/QUOTE]

With the 6 gear and 4.10s he's keeping the RPM up where they can start making power. Really be "rowing" the gears, with that rear end, and the stock TPI making power at around 4800 (If it's all stock). I think 1 5/8" would be better anywhere else in the RPM band, and probably better at his top-end too. Maybe he uses them to kill off some bottom end, for traction?