Are Headers REALLY Worth It?

[kpic]

As I lasted from 1970 until 2015, in powertrain design engineering; sorry to disappoint you.

I suggest you take your formulae and figure out how the same displacement SBC or BBC made so many different power outputs. The answer is simple, it was engineering whether it was in the OEM's design engineering group or in an enthusiast's garage.

 

[dougelam]

The CFM chart is a duplicate, I know I saw that in publication years ago.

Personally I was not a racer by trade or hobby but most of my friends and work partners were and I didn't see any of them running 2 barrel carburetors with factory exhaust. Since we were GM guys the small block 350 was the engine of choice. NOT A 1 went right out and bought a 750 double pumper first thing, contrary to someone's belief. BUT I'll admit the double pumper was the goal of many. With that goal came high compression and large valves fed by ported heads controlled by very aggressive cam shafts.

NOW what toowhatever must have forgotten, MUST Have, The 750 double pumper worked very well when jetted properly through a high rise single plane intake Manifold. As kpic stated you MUST take the system as a whole when determining the air/fuel delivery, WAIT did I say fuel? All toowhatever talks about is CFM related to air flow when as he stated "power is only made in the combustion chamber" which "all of us know" without fuel the is no power.

He preaches to uncork the headers but then tells us to choke off the intake! WTF
He then shows us a picture of a 1960s muffler in 2016 again WTF

I believe it's common knowledge in the hot rod community that free flowing cold air systems with open headers unleashes ALL the power available!
Again OLD news

If I have 295HP, add headers for the 25HP "as quoted" =320HP Cork them off at half or so and if I get 305HP with a nice sounding car I'M HAPPY

You know if he says "all of us" or "everybody" or "most guys" again!
Bottom line, I believe he made all of these mistakes and assumes we are just as stupid!

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[toobroketoretire]

Eager To Argue But Unable To Comprehend

You guys are so eager to argue about something you didn't even bother trying to comprehend what I wrote. I posted a chart showing how many cfm an engine would consume at 4 different efficiency's. The 75% column representing most base engines like the L-48's, the 80% column representing say an L-82 with a longer duration cam, and the 85% column representing the L-88's, LT-1's, Z-28's with their even longer duration cams. And then I showed a 100% column representing the hottest engines running open headers. Since it's illegal to run open headers on the street the 85% column is the one that is most useful for determining how big a STREET carburetor needs to be for each of the efficiency's.

The mechanical secondary "double pumpers" are not suitable for street use because they are intended solely for high-rpm track racing conditions where the engine speeds never drop below about 4000 rpm. When operated at a wide open throttle at low rpm's they meter fuel very poorly and that's why none of the world's muscle cars ever came equipped with them. The only carburetors that are suitable for street use are the AVS or vacuum secondary designs as they limit the amount of throttle opening to prevent fuel standoff which kills power.

And headers? You have been conned into believing headers increase power when in fact they can only bypass the restriction of the exhaust system; resulting in a power gain but not actually PRODUCING power. When pushing thru the restrictive exhaust system headers are nothing more than steel tubing exhaust manifolds with a fancy name and an even fancier price. As China produces headers and sells them to our American vendors for only $50 a pair there is no reason why $60,000 Corvettes can't use them because of excessive cost.

 

[Crimson Thunder]

I must be really doing something wrong. My Corvette has headers, a double pumper carb, and I run 30 psi in all my tires.:L

 

[dougelam]

Me too Crimson, my ls1 flows upward around 1000CFM thru a 78mm throttle body and I never run it at 6000RPM

What a waste, I only need a 35mm to keep my less than 300HP and still make it to work!

WHY WOULD GENERAL MOTORS DO SUCH A THING?

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[toobroketoretire]

Me too Crimson, my ls1 flows upward around 1000CFM thru a 78mm throttle body and I never run it at 6000RPM

What a waste, I only need a 35mm to keep my less than 300HP and still make it to work!

WHY WOULD GENERAL MOTORS DO SUCH A THING?

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Your 78 mm throttle body may flow 1000 cfm but your engine sure won't. Do you even know what "volumetric efficiency" means? It is the engine's ability to fill it's cylinders at high rpm and street engines can barely achieve an 85% efficiency because of the exhaust system.

 

[kpic]

Not exactly correct.

The site is an excellent read on the subject and contains quite a few formulas, enjoy. Although you will ignore the following information; others will find it useful.

"In a four-stroke naturally aspirated engine, the theoretical maximum volume of air that each cylinder can ingest during the intake cycle is equal to the swept volume of that cylinder (0.7854 x bore x bore x stroke). Since each cylinder has one intake stroke every two revolutions of the crankshaft, then the theoretical maximum volume of air it can ingest during each rotation of the crankshaft is equal to one-half its displacement. The actual amount of air the engine ingests compared to the theoretical maximum is called volumetric efficiency (VE). An engine operating at 100% VE is ingesting its total displacement every two crankshaft revolutions.
There are many factors which determine the torque an engine can produce and the RPM at which the maximum torque occurs. However, the fundamental determinant is the mass of air the engine can ingest into the cylinders. The mass of ingested air is directly proportional to (a) the air density and (b) the volumetric efficiency. There is a remarkably close relationship between an engine's VE curve and its torque curve.
For contemporary naturally-aspirated, two-valve-per-cylinder, pushrod-engine technology, a VE over 95% is excellent, and 100% is achievable, but quite difficult. Only the best of the best can reach 110%, and that is by means of extremely specialized development of the complex system comprised of the intake passages, combustion chambers, exhaust passages and valve system components. The practical limit for normally-aspirated engines, typically DOHC layout with four or more valves per cylinder, is about 115%, which can only be achieved under the most highly-developed conditions, with precise intake and exhaust passage tuning.

(Remember, I did mention earlier that it's a system.)

Generally, the RPM at peak VE coincides with the RPM at the torque peak. And generally, automotive engines rarely exceed 90% VE. There is a variety of good reasons for that performance, including the design requirements for automotive engines (good low-end torque, good throttle response, high mileage, low emissions, low noise, low production costs, restrictive form factors, etc.), as well as the economically-feasible tolerances for components in high-volume production."

Volumetric Efficiency (and the REAL factor: MASS AIRFLOW), by EPI Inc.


"The required VE for that engine will be:

Required VE = (9411 x 300 x .45 ) / (134 x 5200 ) = 1.82 (182 %)

Clearly that's not going to happen with a normally aspirated engine. Supercharging will be required, and you can use the 1.82 figure to calculate the approximate minimum Manifold Absolute Pressure (MAP) needed (1.82 x 29.92" = 54.5" MAP, or 24.6 inches of "boost") for that power level."

The above is more my interest.

 

[Antz81]

Your 78 mm throttle body may flow 1000 cfm but your engine sure won't. Do you even know what "volumetric efficiency" means? It is the engine's ability to fill it's cylinders at high rpm and street engines can barely achieve an 85% efficiency because of the exhaust system.

This certainly has become in interesting read. And getting far beyond my knowledge. One thing i don't understand is why the exhaust system effects the volumetric efficiency.

 

[Vettehead Mikey]

This certainly has become in interesting read. And getting far beyond my knowledge. One thing i don't understand is why the exhaust system effects the volumetric efficiency.

You can't suck new stuff in if you can't push all the old stuff out first.

 

[kpic]

Antz81
Headers are performance parts and CI manifolds are utilitarian. If one adds more flow in, common sense says there is a need for more flow out. Back pressure prevents flow out. Aftermarket cams increase the flow of charge air; "hot" cams and scavenging increases inertia charging.
As I said earlier, it's a system. Focusing on any one part of a system can be very, very, misleading.

Sorry. it went towards the high end. As I've read your posts; ignore the malarkey and stay the course you know.

 

[kpic]

You can't suck new stuff in if you can't push all the old stuff out first.

That is the shortest form I've ever heard it said.

BTW, the wife spent many years in automotive design engineering also. You made 2 people with one sentence.

 

[toobroketoretire]

You can't suck new stuff in if you can't push all the old stuff out first.

Very well said and as long as the restrictive exhaust system is attached to the header's collectors the headers cannot do the job they were intended to do. Headers may look really cool on street engines but that's all they do.

 

[RedHot85Vette]

Very well said and as long as the restrictive exhaust system is attached to the header's collectors the headers cannot do the job they were intended to do. Headers may look really cool on street engines but that's all they do.

I recently sold my 64 Comet, January 2016, It had a 200ci Inline 6, Awesome Engine, wave the key at it and it starts, 1/2 a crank, and goes forever. There's a web site called classicinlines.com. You gotta see what some guys do with these engines. I had to sell my Comet for health reasons... I was no longer able to do all that needed to be done on it, nor bend over the fenders very well. My spine is now like a 4x4. My extensive research about the car, at Classic Inlines and at other sites and forums, told me that adding headers, just headers, of various types, gave at least 10+ HorsePower at the rear wheels. Back in the day, many hot rodders had to make their own headers or have them made... certainly nobody back in the 60s had headers for a Ford Inline Six.

Just one of the reasons why this disabled guy, with a spine like a chunk of 4x4, likes his Base C4 Corvette is that it's Low to the ground (not much reaching), easy to get in/out of (if you know how), keeps him tucked into his comfortable generally hard to find cloth covered cockpit seats with Torso, Thigh, and Lumbar support, 6 way adjustability, adjustable Tilt/Telescopic Steering Wheel... simple as possible, not even power door locks, the best handling/braking of most Any cool sports car available, affordable, other things I can't think of right now, but coolest of all... NO FENDERS!!! Ha! I can actually reach the whole engine and give it a Tune-Up, and other things as well, maybe even change the shocks or something. That Clam Shell is Awesome!!!

Once upon a time, a few very reputable guys in the Motoring business had an idea to Hop up one of those Ford 6 200's. As they went along, they Dyno tested before and after their modifications. One of the things they had to do was have custom made a set of headers... which added 10 HorsePower to the rear wheels. It's a very interesting & Fun article to read and you wouldn't believe how inexpensive and easy it was, back then, to add horsepower, bit by bit, by doing some of the simplest things. Classic Inlines has a summary of the article. I have the original Magazines from 1967 that it came in (2 parts/mags).

I believe slapping on a set of quality Headers on my Corvette, properly, professionally, and doing nothing else, I would get more Horsepower at the RW. I challenge anybody to prove me wrong.

And before any know-it-all shouts about how "you can't believe what you read in magazines"... first it was 1967, when people just naturally had more integrity. It was an article about a Ford 200 Inline Six for chrisake. Read the article! It was Huge Pro's in the business, having a good time, not advertising or trying to dupe anyone. The article has 110% integrity, just like MOST of the articles I've read in many of the HOT ROD magazines, that have been around forever, available then and now. Magazines that wouldn't be still around if they published bulldoody.

The Best Thing! Ask the man on the street, the Boys on any Forum, like this one. Here's a maybe post: "Did You Get More HP at the RW after installing Headers". Ask Forum People, that are not trying to sell or dupe anybody. Rather, they're just nice, fine, helpful gentlemen trying to help you upgrade your rod. Some are fashioning their own Headers, for whatever reasons, because they know they'll get more Horsepower with them. Ask them if Headers make a difference. Ask if they Dyno'd before & After. Of course you have to visit several forums, and weigh and question some of the answers. Research takes work and time but could save you hundreds of dollars, or get you off the fence running to the store to get a set of Headers. I wouldn't want to spend a Grand or more (maybe more for professional installation) on parts that did nothing or were actually performance robbing or harmful to my engine.

Here's something to think about too. I just had to add this. I think it's very important to anyone who wants more speed out of their car. A Pro guy in a Magazine once said something about a Weight/Horsepower ratio or something like that. He said that a great way to increase the performance of your car, get more speed out of it, was to lighten the load. I had a 91 Sunbird Convertible.The V6 3.1 engine ran great. Every Time I worked on the car, I found something to get rid of, even if it was just a nut, bolt, screw, miscellaneous wire. I also found HEAVY Things to change out for lighter Things. Power Door locks didn't work. Gone! Convertible top piston bad. all of the gear for it. Gone! Manual top worked fine for me. Hood insulation. Gone! Spare Tire & Trunk Mat and cardboard Junk. Gone! Inside trunk brackets. Gone! I sprayed the trunk floor with rubberized coating. I have my own fix-flat-kit, AAA Gold, never got a flat all my life.

All Over, Top to Bottom, your car has weird do nothing parts, brackets, wires, etc. Also look and see if you have any redundant or ridiculous gauges, decorations, accessories, Christmas Lights, license plate frames, and such that could go. Gigantor rock splitting Super HEAVY sound systems! Why?! Do you want FAST? along with better fuel economy? Or do you want every piece of your car to rattle along with your ears and brains? Look in your glove box and storage compartments for misc & garbage that could go. Ask the question: "why do I need that?".

If you think those little things don't make a difference... when you pile them all up... you would be Shocked! Look, Look, Look! Change out some hunk o junk heavy bracket for some tie wraps.... change heavy to light, and maybe change your cast iron manifolds for some lightweight plain ol headers, big Fat Ignition System, change those big fat 9-10 mm wires, separators, fancy looms... Hey! maybe some Aluminum Heads... and on and on...

My Sunbird 3.1 V6 Hauled Ass!!! Moving from Florida to NY State I got 31 MPG Average... and I mean Moving. And I still had the damn cast iron manifolds. They were going to go eventually as well (but I sold the car and that was that). Look Closely! When you select, change parts for your Rod, see if you can get weight stats to compare. Everywhere there's Weight to be lost. Real Racers Know This. Racing Spark Plug Wires: 5mm. The weight of every part is considered down to the tiniest fraction of an ounce. Thing is this, making no modifications to the engine, I got a lot more speed/perfomance AND economy out of my car. Something to think about. Horsepower isn't everything. Peal out at the stop light, red, green, Burn!!!... now try that with a 454 big block in your trunk.

If One could get more horsepower and a lighter load with a set of Light Headers (research, compare! your selections!), that would be a nice plus. When last seen, I bought a set of headers for my Ford 200/6. The original manifold that came with it was haunted. It was also way heavier in weight. It just always wanted to fall off the engine. It was a big problem for many owners. I was happy to find an affordable, lighter set of Headers for the engine. But I sold the car before I could install them. If you have the Very Heavy Cast Iron Rams Horns Manifolds, which if you compare them to the tubular manifolds of the 80s, first you SEE a big difference, then you feel a big difference. Those Iron things gotta be crap. Even if you install Headers that You can't even see in your engine compartment for the coolness effect, I'd chuck those Iron things anyway. Probably use them because they're cheap, easy to get in huge mass quantity, fit into anything, last forever, and once again, Cheap! It's all about Money!

Look at some of the cars from the 30s, 40s, 50s, some were Production Hot Rods (but weren't called that) with bigazzz "Pipes" of some sort, but not called "Headers". They weren't just engineered in there for show.

The Vettes of the early 80s, There's tons of evidence that Chevy/GM was building and selling out of their dealerships, genuine production race cars with "tubular exhausts" so they could win those races, not sure what they were called, for cars that were stock out of any dealership. Buy & Race! Prior to the 80's they used to lose all the time. Didn't look good. The 80s and McClellan came along and they won ALL the time, so much so, that ALL of the EuroTrash cars gave up and dropped out. Once a Pontiac Trans Am Won... but it was discovered that the car was modified... a Cheater! He was disqualified and the Vette got the prize. Eventually it became a Vette Only race.

I'm not sure when the Term "Headers" came to be, but before it did, there were production cars that came with "FreeFlowing Tubular Manifold Pipes" of some sort or another, and called "Whatever" as engineered with pencils by the Best of the Best of the Day... when Honorable American Men & Cars were made of Raw USA Steel and the only thing imported from china was chop-sticks.

As an Example, these guys took a lowly stock Ford 200ci Inline Six, and turned it into a V8 Killer, with the help of a set of Headers.

"Horsing Around With The Mustang Six," by Ak Miller, which appeared as a two-part article in the June-July 1967 issues of Hot Rod. Part I, which covered some very simple modifications and readily available parts from Ford and Lincoln-Mercury dealers, is presented in detail. Part II suggested some more ambitious modifications. Although any skilled mechanic could make them, they are only summarized here. Detailed information can be obtained from the July, 1967 issue of Hot Rod Magazine. ~ http://www.classicinlines.com/HA1.asp

For Reference and Qualifications/Integrity of Author:

"AK MILLER is a legendary figure in the world of modified performance vehicles. Ak was co-founder of the world's oldest hot rod club, and during his term as President of the Southern California Timing Association, the first Bonneville Speed Trials were run; the modern method of classification of cars with respect to cubic inch engine sizes versus body styles was established; and the first sanctioned drag strip competition was started. He was also one of the founders of the National Hot Rod Association, Ak has raced in events around the world, including specialized competition like the Pikes Peak Hill Climb where he holds a record of six wins in eight years in the sports car division. Ford is unique in offering the service of Ak Miller as a Performance Advisor; to aid in the selection and application of high performance equipment that will be compatible with your vehicle and personal driving habits. Ak regularly tells "inside" info about the latest in high performance in his "Flak by Ak" column in publications like "Hot Rod" Magazine. You can get personal answers to questions by writing:
AK MILLER
Ford Performance Advisor
Autolite-Ford Parts Division
Merchandising Services Dept.
P.O. Box 3000
Livonia, Michigan 48151"

~~~~~>>>>> via Hot Rod Magazine

I challenge anybody: professionally, properly, install Quality Headers, from a company that says, Advertises, Guarantees, they're claims, not lying, exagerating, or duping, on my Bone Stock, All GM Parts right down to the mufflers, as "Base" as you can get, no extra junk, not even power door locks, with just about a dozen meaningless RPO Codes, 1985 Corvette Coupe, Base. If I get more Horsepower, you pay for them, if I don't, I pay for them... but I don't know who's gonna' pay for the installation and testing... not me boy! I'm Lucky I got the Vette!

View attachment 23128
AK Miller at the Bonneville Salts
Number 13 Streamlined Ford Roadster

(as much as I tried increasing the size of the JPG 800x600, when uploaded to this post, that's as big as I could get (???) ~ JvB.)
​

PS. what happened to the "Smiley" with the American Flag? ~ signed John V. Brennan, United States Coast Guard Veteran.

"If your day is unpleasant, I hope it gets Vetter ~ JvB"​

 

[Tom Bryant]

"Horsing Around With The Mustang Six," by Ak Miller"

I remember that article. I used to read all the tech articles on 6s mainly because that's what most of us Chevy guys had in those days. A $75. to $150. '49 to '57 two door post was a very common thing that we could afford. My brother had a '62 Bel Air bubbletop. No, not a 409, although it probably is now, fully documented of course, but a 235 six stick. It got about 12.5 to 13 mpg driving back and forth to college every day. We put on a split exhaust manifold and duals and it went to 14.5 mpg and accelerated better. There wasn't any dyno around to test it on but the increase in mpg and pep was real.

Tom

P.S. in my signature photo below you can see the blue Bel Air Bubbletop in the background just above the headlight of my '59. This photo was taken in Sept. 1969.

 

[toobroketoretire]

With enough advertising and misleading and deceptive dyno tests you can sell anything to the gullible public.

 

[kpic]

You lack basic knowledge of exhaust systems, back pressure, pulse timing, scavenging, flow deficiencies and more..
Header Basics - How Headers Contribute to Horsepower - Car Craft Magazine


The mind is a terrible thing to waste; however, you are good at it.

 

[dougelam]

You lack basic knowledge of exhaust systems, back pressure, pulse timing, scavenging, flow deficiencies and more..
Header Basics - How Headers Contribute to Horsepower - Car Craft Magazine


The mind is a terrible thing to waste; however, you are good at it.

His basic knowledge is from the 60's

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[kpic]

He could profit from some reading rather than calling dyno operators liars.

Exhaust System Technology: Science and Implementation of High Performance Exhaust Systems

The above is a somewhat simplistic article; below is a highly technical book. Either is quite good.

"This book provides design assistance with the actual mechanical design of an engine in which the gas dynamics, fluid mechanics, thermodynamics, and combustion have been optimized so as to provide the required performance characteristics such as power, torque, fuel consumption, or noise emission."
Design and Simulation of Four-Stroke Engines

Here is a listing of other publications sold by the SAE. Who is Gordon P Blair?
Gordon Blair - Profile - SAE International

"Many people knew Professor Blair. He was quite well known throughout the world in the area of engine theory and design. Professor Blair achieved notoriety through his accomplishments in the research and publication of the fundamental study of two- and four-stroke engines. He was very passionate about engine theory and as such was perceived, at times, to be smug or condescending to some. The conviction he had for his beliefs and his experience became the foundation on which he stood his ground against anyone who debated fundamental engine theory. While Professor Blair may have been considered by some to be arrogant or snobbish, nothing could be further from the truth."

As one who debates fundamental engine theory, Toobroke would not have enjoyed Professor Blair.

This is also excellent although highly technical; however, at $109.95 it's a pricey date.

Toobroke...
SAE is the Society of Automotive Engineers, they are not given to publish bull manure or lies; however, you can accuse them also.

 

[Mac]

You lack basic knowledge of exhaust systems, back pressure, pulse timing, scavenging, flow deficiencies and more..
Header Basics - How Headers Contribute to Horsepower - Car Craft Magazine

That's a great link... plenty of easily understood info and well presented. Thanks!!

Mac

 

[toobroketoretire]

There is nothing wrong with headers. When they're used as INTENDED (open) they do a great job. But when they're corked they don't produce any gain at all which makes me wonder why they are so popular.