Are Headers REALLY Worth It?

[RedHot85Vette]

Back in the late 50's and early 60's everyone's street/strip headers had cover plates capping the collectors..

Yeah! I've seen those on Rods. Let's just say I've whacked my head too many times in the grease pits of America, or that I'm just plain ignorant, but Isn't it sort of a "Y" pipe, where the Left part of the "Y" would have a Cap on it, and when one wanted their Rod to have more balls, and noise wasn't a problem, they'd pop the Caps off, thus allowing the exhaust to free flow the path of least resistance. I've seen things like that and often I'd see the capped off pipe sticking out below the rocker panels of the front doors. Even though still going through my classes at the school of kick-azz rodding science, I thought the simple no-brainer engineering of such an exhaust pipe system was brilliant and ideal. I always thought if I got a Rod like Milners '32, I'd do the same thing. Although you could do it to just about any car.

I have an '85 C4, so I'm thinking a set of long tube headers, the "Y" pipe cap-off thing, or whatever, and then the rest of the exhaust, whatever it may be, would do the trick, although that's just a bit of mind play. I don't race, I'd do it just for Fun and I think the project, adding a set of shiny stainless steel headers, would give a better awesomeness to my engine bay, and unimaginable level of Fun and automotive Uumphh when I took the caps off, possibly to show off. Just the other day, I was listening to the muffler elimination setup pipes on YouTube. But what if you have a Cat and have to have one due to laws... you still have an obstruction. The Cap-off pipe after the headers solves that problem because the Cat will no longer be a factor. Just How Easy and Cool is that?! It's the best of both ozone layer destroying worlds. More Speed, More Noise! (fewer debates, just slap them cap-off pipes on and Believe! Ha!) I bet there Would be a Difference, otherwise, why would they make 'em and why would rodders buy 'em and take the time to install 'em, and fuss with 'em at the track, or wherever, whatever. I bet when you paste the pedal from a dead stop, your car would launch with a lot more anger, and after all is said and done, you'd find a significantly deeper dent in your seat upholstery.

Rods are Fun, Vettes are Funner!

John

 

[toobroketoretire]

I have an '82 and the "header" pipes are only 1-3/8" diameter or just about big enough for a 4000 rpm engine.

 

[toobroketoretire]

Headers are only beneficial when they're "uncorked" and blowing to the open air. One of the closely guarded secrets of the header manufacturers.

For headers to produce any gain all three of the following conditions must be present:

1. Engine at full throttle

2. Engine at a high rpm

3. Headers uncorked

If any of the above three conditions aren't present headers are just expensive ornaments.

 

[toobroketoretire]

You will NEVER see a chassis dyno test that compares the stock "ram horn" exhaust manifolds to headers with the rest of the exhaust system attached. Why? Because the dyno test would show no gain whatsoever! First of all the stock exhaust system will easily handle the exhaust output from a 350 hp engine. It's only when the power output exceeds about 400 hp when the OEM mufflers begin holding the power back. When speaking about the L-88 Zora Duntov said the mufflers drop the power output by about 50 hp. Headers do have their place in off road track racing where mufflers aren't required but for street use headers don't produce any gain at all. They look pretty cool but that's all they do.

 

[kpic]

Scavenging and pulse timing work with the pipes open or closed. Pipes closed has more resistance to flow; however, headers still beats a stock cast iron exhaust.

Back in the 60s, we welded an adapter on the stock exhaust to mate up to the header's collector. I've seen those capped setups you mentioned. Yes, they help. However, no air, inlet or exhaust, although it will follow the path of least resistance doesn't appreciate turning sharp corners. Basic aerodynamics.

Point is, you're only kidding yourself and no one else here.

 

[toobroketoretire]

Yep! from a special magazine from 1985 about Vettes from '53 to '95, about the '82 said: "...and Stainless Steel FreeFlow exhaust headers..."

The magazine article about the '84 said: "blah, blah, blah...stainless steel exhaust system...".

Have you ever run an engine with the exhaust manifolds off? It just makes a pop pop pop pop pop pop pop pop pop. At 6000 rpm you'll hear 50 pops per second and those pops have to be routed thru the exhaust system to quiet them down and expel the gasses out the rear of the car. But over the years people have become convinced the exhaust gasses come BLASTING out like the exhaust from a jet engine; a WHOOSH and headers extract those whooshes much better and make a LOT of additional horsepower. Uh no, just a bunch of back-to-back pops and that's why not a single engine in the world has ever come equipped with headers. I'll have to admit headers do look awfully cool but that's all they do on a street engine.

 

[toobroketoretire]

People have been led to believe headers PRODUCE power when in fact open headers REDUCE the power loss by bypassing the restrictions of the exhaust system. To claim headers produce power is absurd because power is made inside the cylinder; not outside the engine. That's why none of the world's most powerful vehicles have ever left their factories equipped with headers. Headers are simply exhaust manifolds made from steel tubing and that's all they are. I feel sorry for people who shell out $700 for something that just looks cool because they have been duped by misleading advertising and dyno tests.

 

[RedHot85Vette]

Missing Post You Quoted (?)

pop pop pop pop pop pop pop pop pop... just a bunch of back-to-back pops and that's why not a single engine in the world has ever come equipped with headers. I'll have to admit headers do look awfully cool but that's all they do on a street engine.

Good Afternoon! I hope you're enjoying a pleasant one. I am unable to find the rest of the post you quoted... the one I wrote. There are a couple of valid references that I wrote in that post, that I'd like to copy, so I don't have to write them again. Also, isn't there a place in my account where my posts get saved?


Thanks,


John

Reference:
"Originally Posted by RedHot85Vette View Post
Yep! from a special magazine from 1985 about Vettes from '53 to '95, about the '82 said: "...and Stainless Steel FreeFlow exhaust headers..."


The magazine article about the '84 said: "blah, blah, blah...stainless steel exhaust system..."."

 

[RedHot85Vette]

Lotta Misleading, Money, Duping, & Dyno

People have been led to believe headers PRODUCE power when in fact open headers REDUCE the power loss by bypassing the restrictions of the exhaust system. To claim headers produce power is absurd because power is made inside the cylinder; not outside the engine. That's why none of the world's most powerful vehicles have ever left their factories equipped with headers. Headers are simply exhaust manifolds made from steel tubing and that's all they are. I feel sorry for people who shell out $700 for something that just looks cool because they have been duped by misleading advertising and dyno tests.

Your talking about Decades of Misleading, Lying, Conning Manufacturers, Millions upon Millions upon Millions of stupid people, Money in the Billions, Incorrect or Falsified Dyno Tests from installed junky lying misleading equipment equally tested and certified to be spot on true, and Duping by maybe the same Billions. For one thing you can get a set of headers for $95 bucks and up Brand New, and if one is patient, chump change on Craigslist or eBay. For another thing, right here on this very Forum, complete, there's gotta be 100s of Dyno Tests and cheap headers and people of sound mind with hot rods who've experienced performance gains and better horsepower by just slapping on a set of headers...

I also believe that when one says their headers "produce power", I believe what they're trying to say is that their new headers are giving or allowing them, their cars, their engines, better performance, more horsepower... maybe that the new headers have unleashed more available power from their engines... like a great set of spark plugs, or a new very breathable air filter setup... and maybe if one created a more breathable engine altogether with a new fancy air filter system and a new set of more breathable exhaust manifolds or headers... along with a can of MAF cleaner... wouldn't that help the engine to breathe better and produce more power, more horsepower...

I'm sure if I dig, I'll be able to find a couple or few of production speedster cars in this world, throughout history, maybe even recent history, that were manufactured with something resembling a pair of Headers. Shorty as they may be. Maybe those headers weren't called headers. If you were an engineer designing a sports car, maybe It might not make your bosses happy to say your putting a set of Headers on your creation, maybe it wouldn't work well with marketing to say you put a set of Headers in your design... Maybe it might make the EPA suspicious of you... Maybe in the past they didn't call them Headers and that they were called something else, but they were installed nonetheless... or Because they provided your car with better performance, you might want to call them something else for some reason or reasons unknown to anybody... But Trust Me, I won't be Duped into Digging!

Don't feel sorry... I'm sure some people, albeit maybe just a few, got something for their Money.

Best Regards,

john

 

[dougelam]

Well put John, he is insulting everyone of us millions of dupes. I'd bet that there isn't one person that was watching a Comercial and was instantly hypnotized to think
I NEED HEADERS
I NEED HEADERS
I NEED HEADERS

Come to think of it I believe my car runs better and faster right after a good wash and wax

Just another myth, I was duped by the wax manufacturer

Sent from my SM-N920P using Tapatalk

 

[kpic]

so why not prove to the world that headers are pointless and get some dyno testing done like kpic said. unfortunately being an engineer isn't proof that you are right.

The links I posted are with the headers closed as that is what they tested.

Antz81,
There are all kinds of engineers and toobroketoretire is a type I am totally unfamiliar with. It sounds as if his message is leave it stock and it will run faster. That has never worked for me.. Perhaps it has for him, who knows. A so-called engineer who doesn't get engineering seems unlikely.

It passes time in an amazing fashion. However, I have better things to do with my time.

 

[toobroketoretire]

More On Headers

As an engineer I have always thought it is hilarious how simple-minded people get convinced of a product's worth because of ADVERTISING. Headers are just another form of exhaust manifold but yet most people have been convinced they actually produce power. Uh uh, they are just fancy exhaust manifolds that cost 3-4 times as much and cook anything that is near them. Power is made INSIDE the cylinder and once the spent gasses get blown out of the cylinder head the power "event' is over. That's why none of the world's engines have ever come equipped with them.

 

[Antz81]

none of the world's engines have ever come equipped with them.

Except there are some that have. The BMW E46 M3 is one.

The reason most don't is cost. If long tube headers were to come as standard on a car then they would need to be installed by hand. So not only do you have the increased production cost of the header, but the extra labour involved with installing them, longer production times and fewer cars produced as a result. That starts to become big $$$.

 

[kpic]

Except there are some that have. The BMW E46 M3 is one.

The reason most don't is cost. If long tube headers were to come as standard on a car then they would need to be installed by hand. So not only do you have the increased production cost of the header, but the extra labour involved with installing them, longer production times and fewer cars produced as a result. That starts to become big $$$.

Cast iron is a lot less expensive and lasts longer than bent SS tubing. The additional heat retention of cast iron manifolds is better for emissions. The cast wall thickness is better for pass by noise. That being said, cost is the answer.


toobroketoretire
I was a power train design engineer for 34 years and a forced induction system engineer for 11. Your ignorance of the basic engineering disciplines is a cross between amazing and boring. Let's leave it at engineering and dynos are wrong and you're right.

You posted a carburetor chart which ignores cam lift and duration. Did you consider cam with your misleading calculations? Nah, all engines are the same no matter what cam or CR, huh. Now what real so-called design engineer would do that is the question. The answer is obvious, isn't it.

I like the people here and you are misleading them which is unacceptable.

 

[toobroketoretire]

My carburetor sizing chart isn't accurate? Volumetric efficiency is volumetric efficiency regardless of which cam is used. Summit Racing recommends 1-1/2 cfm per cubic inch of displacement for street engines which almost exactly matches the 85% column in my sizing chart. Only the hottest of street engines will achieve an 85% efficiency because of the restrictive exhaust system that is mandatory because of federal noise standards. I was a professional engine builder for the 20 years prior to me obtaining my engineering degree and I know firsthand racing engines and street engines are two completely different animals.

If I invented a new "performance" product I could easily run phony comparison dyno tests of the OEM product versus my product. I'd start by running the OEM product at 75% throttle and then run my product at 100% and guess what the dyno would show? It would show my product produced more power (how about that?).

Remember this: For headers to be effective they must be run OPEN because if they're not run OPEN they are just steel tubing exhaust manifolds with a fancy name and an even fancier price.

 

[toobroketoretire]

Please explain to me how I am misleading anyone by posting a 100% accurate street engine carburetor sizing chart based on 4 different volumetric efficiency's at 6000 rpm.

 

[dougelam]

If you were a REAL professional engine rebuilder/engineer you would have already known the answer

Sent from my SM-N920P using Tapatalk

 

[toobroketoretire]

If you were a REAL professional engine rebuilder/engineer you would have already known the answer

Sent from my SM-N920P using Tapatalk

There are two formulas to calculate cfm consumption:

1. 1-1/2 cfm per cubic inch displacement

2. Cubic inch displacement X maximum rpm divided by 3456

Both formulas and my chart give almost identical results so why do you have an issue with my chart? Or are you one of those thousands of people who have been led to believe street 350's need 750 cfm double pumpers?

 

[kpic]

I didn't see any consideration for lift and duration in the formula. An engine is a system, same as any system, one must consider all the components in the system.



"At high-RPM, the rules change. Air has weight, and thanks to Sir Issac Newton, we know that once it is moving, it doesn’t want to stop moving. This means that the air can continue to flow into and fill the cylinder, EVEN AFTER the piston has begun to travel UP the cylinder bore. This can allow an engine to exceed 100% volumetric efficiency, if even by a small amount."
Cam Gear Tuning - Tuning Advance, Retard, and Overlap for Power

"As piston speed increases less time is available for the cylinder to fill completely before the piston reaches BDC limiting RPM and proper engine breathing. Opening the intake valve slightly before the piston reaches TDC can increase high-speed volumetric efficiency. Rapid piston movement creates both a faster moving air charge and pressure differential in the cylinder. The piston’s rapid movement nonetheless surpasses air charge velocity. At higher RPMs the initial intake charge is lagging prior to building speed after the opening of the valve. Once moving the charge gains speed and continues moving rapidly. Keeping the valve open longer ABDC uses the inertia of the fast moving charge to make up for the slow initial fill. Remember if airflow movement is fast enough we can pack more air into the cylinder with inertia than the piston could ever “pull” in by itself."

"As duration is added, the opening and closing point of the valve are extended. This benefits breathing by placing the valve at a higher more useful lift as the induction stroke begins. Extending the duration also increases the responsiveness of the air/fuel mixture to piston location. At high RPM inertia of the air charge continues to fill the cylinder ABDC as the piston begins to ascend in the bore."
Valve Timing Events and the Order of Importance - Engine Builder Magazine

In engineering terms, it is called Inertia Charging:
Inertia Charging
Charging is used to aid in cylinder filling at higher RPM. Closing the valve later, well after bottom dead center (ABDC), allows the benefits of high momentum airflow granting one last gulp of air as it pushes its way past the closing intake valve. The higher the RPM the later the intake valve closing should occur to ensure proper cylinder charge into the compression stroke. High RPM race engines benefit immensely from a continuation of airflow (inertia charging), into the cylinder as the intake valve is closing and the piston begins traveling upward on the compression stroke. This is due to piston speed increasing the velocity of the airflow(pressure wave), that is not easily impeded once in motion

By maximizing the kinetic energy of the air flow into the cylinders with the inertia supercharging effect, the volumetric efficiency is improved along with engine power. Similar to forced induction, inertia charging on a balanced engine build can increase VE over 100%. While high RPM use benefits from inertia charging, low-to-mid range RPM operation may decline as cylinder pressure is pushed back into the intake manifold.


Valve Timing Events and the Order of Importance - Engine Builder Magazine

Oops, there went your formula.

The problem, or more accurately, your problem is ignoring the obvious.

 

[toobroketoretire]

You wouldn't last a single day in a factory engineering department because you can't comprehend what you read. Let's examine each of the formulas and see how they compare for a HOT 350" engine spinning 6000 rpm:

1. 1-1/2 cfm per cubic inch displacement: That would equal 525 cfm

2. Cubic inch displacement X maximum rpm divided by 3456.: So 350" X 6000 rpm = 2,100,000 divided by 3456 = 607 cfm

Of the two formulas the first one is the most reasonable for a street engine because that is based on an approximate 85% efficiency which is all you'll get out of a street engine because of the exhaust system. The second formula is based on a 100% efficiency which you will NOT get out of a street engine because of the exhaust system and is only valid for engines running open headers.

My chart shows the EXACT cfm consumption at 4 different efficiency's so it is far more accurate than any formula.


But thanks for your long-winded explanation of how duration affects volumetric efficiency; something all of us already knew.