RedHot85Vette
Well-known member
Brilliant! Makes sense to me. It's great to have an explanation. I'm going to use it, show off a bit as necessary.
Thanks!
John
Are Headers REALLY Worth It?
- Thread starter toobroketoretire
- Start date
Brilliant! Makes sense to me. It's great to have an explanation. I'm going to use it, show off a bit as necessary.
Thanks!
John
- Thread starter
- #22
toobroketoretire
Banned
The only advantages of the 1-3/8" stainless steel tubing exhaust manifolds is their light weight and ease of connecting the smog pump piping. Other than that they offer NO performance gain whatsoever. Open headers do offer a performance gain in track racing applications but NOT when the rest of the restrictive exhaust system is attached for street use. But they do look cool and with the fancy name "headers" they can be sold for a lot more money.
dougelam
Well-known member
How do exhaust headers work to improve engine performance? | HowStuffWorks
Header Basics - How Headers Contribute to Horsepower - Car Craft Magazine
I didn't see the words "NO performance gain" anywhere!
Maybe I missed it?
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Header Basics - How Headers Contribute to Horsepower - Car Craft Magazine
I didn't see the words "NO performance gain" anywhere!
Maybe I missed it?
Sent from my SM-N920P using Tapatalk
- Thread starter
- #24
toobroketoretire
Banned
Simple logic tells me headers will only be effective after the restrictive exhaust system behind them is eliminated so the headers can blow to the open air. As the mufflers are the main source of the restriction how can headers do their job when the mufflers are still attached? Something to ponder anyway.
RedHot85Vette
Well-known member
I've watched a load of YouTubes, and read some magazines, dealer handouts, etc, and such, and the info I got out of it all is that while designing the "New Corvette", the 1984, the engineers were scrutinizing the car for where they could lighten the load. I'm looking now through my materials to see if and/or what was said about the exhaust system other than it was dual.
About them looking "cool" and along with the cool name "headers", I think you hit nail on the header! (sorry, i just had to say that). And if it's easy to install, that's a big plus too. I was a tech of many disciplines for over 33 years, but now I have disabilities (a spine with 15 fusions for one thing, sheesh!) that won't allow me to play with projects like that. There are a lot of auto repair shops around here, I guess I'd have to do some more research to find a mechanic worthy to work on my baby if I wanted a pair. I should probably do some research anyway for anything else comes up that I can't play with.
I always wanted a Hot Rod or a Corvette. A used car dealer couple of miles down the road often had 1 or 2 in his lot. I'd always check when I drove by. I just sold my 64 Comet. It was beautiful all over. Black & Red Interior, all original down to the muffler, 63K, like it just drove out of 1965. But after 50 years, rubber and stuff gets mushy. So it needed the whole front steering section replaced, and more. Not really a big job for just about anybody with a wrench or two. I can't do it. I'd end up in the hospital before I finished jacking it up. The fenders made it so I couldn't reach the 6 cyl. engine very well. All them cool old hot rods like the 30s, 40s, 50s, etc with big fenders were out of the question. The Corvette, especially the C4's with the Clamb Shell front end are a blessing, No Fenders! Ha! I can Tinker with things! I can reach across anything! Like for tune ups, light repairs, Washing & Waxing. It's Low and easy to get in and out of. I watched a video showing how to get in and out of a Vette real easy that I just modified a bit. And More! Like buying lots of "cool" accessories and stuff for it. It's definitely the only car for ME!
All I can say is...
God Bless The Vette, Baybe!!!
- Thread starter
- #26
toobroketoretire
Banned
Headers And Double Pumpers Are Intended For High Rpm Track Racing ONLY
Open headers WILL give a boost in power but they must be OPEN (duh). Somewhere along the line people got convinced headers are just as effective when they're corked thanks to VERY aggressive advertising. If people would use their uh "critical thinking" skills (of which very few people have) they would realize headers don't do diddly squat when the rest of the exhaust system is attached to them. It's the same with the so-called "double pumpers" that have become so popular thanks to aggressive advertising. Mechanical secondary carburetors are special purpose high rpm track racing carburetors that require engine speeds of at least 4000 rpm all the time and aren't suitable for street use regardless of the type of transmission used. When an engine is run at low rpms with excessive throttle opening a condition known as "fuel standoff" occurs in which the power goes flat until the engine can reach a high enough rpm to accept the additional throttle. I suggest you Google "Fuel Standoff You Tube Videos" and see what happens when too much throttle is applied at low rpm's. The fuel standoff is a fog of fuel that forms over the inlet of the carburetor and that fog kills the power until the engine is able to be revved higher and suck it in. I first learned about fuel standoff when I was an ignorant 17 year old kid with dual quads on my 283" Impala. I had low rpm/full throttle power problems so I took my '59 Chevy Impala to a chassis dyno shop in Los Angeles. As the dyno operator stepped on the throttle I saw a BIG fog of fuel form over the tops of my dual WCFB's and my engine wouldn't gain any rpm until he backed off on the throttle. He then disconnected the front WCFB and my engine took off like a rocket ship. Absolute proof of excessive throttle opening killing power at low rpm's. The $25 I spent for those two dyno runs was well worth it as I learned AVS or vacuum secondary 4-barrel carburetors MUST be used on street engines to prevent over-throttling at low rpm's.
Have you ever noticed how EVERY dyno run (engine dyno or chassis dyno) starts off at about 2000 rpm and then the engine is SLOWLY throttled up? Do you know why it's SLOWLY throttled up? It's throttled up SLOWLY to prevent fuel standoff from occurring and killing power. If the throttle was suddenly snapped open at 2000 rpm (with a double pumper) the engine would fall on it's face because of excessive throttle causing fuel standoff. That's why the QuadraJet was so successful for so many years because with it's tiny primaries and AVS secondaries it was virtually impossible to get fuel standoff. And because of it's AVS design it was used on the Pontiac inline 6 cylinders all the way to the 500" Cadillacs. Because of it's flexibility I would have to rate the QuadraJet as the best carburetor ever made.
Here's the CFM chart I made years ago that shows the actual amount of CFM an engine consumes at 6000 rpm at an 85% volumetric efficiency (which is about as high as any high performance street engine can achieve). Note how much less CFM is consumed when the engine has a full exhaust system attached and that's why smaller CFM carburetors are always recommended for street use.
Open headers WILL give a boost in power but they must be OPEN (duh). Somewhere along the line people got convinced headers are just as effective when they're corked thanks to VERY aggressive advertising. If people would use their uh "critical thinking" skills (of which very few people have) they would realize headers don't do diddly squat when the rest of the exhaust system is attached to them. It's the same with the so-called "double pumpers" that have become so popular thanks to aggressive advertising. Mechanical secondary carburetors are special purpose high rpm track racing carburetors that require engine speeds of at least 4000 rpm all the time and aren't suitable for street use regardless of the type of transmission used. When an engine is run at low rpms with excessive throttle opening a condition known as "fuel standoff" occurs in which the power goes flat until the engine can reach a high enough rpm to accept the additional throttle. I suggest you Google "Fuel Standoff You Tube Videos" and see what happens when too much throttle is applied at low rpm's. The fuel standoff is a fog of fuel that forms over the inlet of the carburetor and that fog kills the power until the engine is able to be revved higher and suck it in. I first learned about fuel standoff when I was an ignorant 17 year old kid with dual quads on my 283" Impala. I had low rpm/full throttle power problems so I took my '59 Chevy Impala to a chassis dyno shop in Los Angeles. As the dyno operator stepped on the throttle I saw a BIG fog of fuel form over the tops of my dual WCFB's and my engine wouldn't gain any rpm until he backed off on the throttle. He then disconnected the front WCFB and my engine took off like a rocket ship. Absolute proof of excessive throttle opening killing power at low rpm's. The $25 I spent for those two dyno runs was well worth it as I learned AVS or vacuum secondary 4-barrel carburetors MUST be used on street engines to prevent over-throttling at low rpm's.
Have you ever noticed how EVERY dyno run (engine dyno or chassis dyno) starts off at about 2000 rpm and then the engine is SLOWLY throttled up? Do you know why it's SLOWLY throttled up? It's throttled up SLOWLY to prevent fuel standoff from occurring and killing power. If the throttle was suddenly snapped open at 2000 rpm (with a double pumper) the engine would fall on it's face because of excessive throttle causing fuel standoff. That's why the QuadraJet was so successful for so many years because with it's tiny primaries and AVS secondaries it was virtually impossible to get fuel standoff. And because of it's AVS design it was used on the Pontiac inline 6 cylinders all the way to the 500" Cadillacs. Because of it's flexibility I would have to rate the QuadraJet as the best carburetor ever made.
Here's the CFM chart I made years ago that shows the actual amount of CFM an engine consumes at 6000 rpm at an 85% volumetric efficiency (which is about as high as any high performance street engine can achieve). Note how much less CFM is consumed when the engine has a full exhaust system attached and that's why smaller CFM carburetors are always recommended for street use.
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kpic
Well-known member
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- Mar 29, 2014
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- 2,292
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- Columbus, NC/NE Georgia
- Corvette
- 1997 boosted silver coupe
It is actually quite simple, cast iron manifolds are inexpensive to manufacture, they are stout and have great longevity. After tooling and pattern maintenance costs; castings are purchased by the pound + a profit. Looking at a header's complexity etc.; hopefully, no explanation is required why headers cost more to manufacture. In addition, due to hot exhaust gases moving at a high rate of speed; headers will not last as long as a cast iron manifold.
Cast iron exhaust manifolds are thick walled or there is less room for the exhaust gases to exit. As cast iron is thick, it retains heat well (great for emissions) and prevents heat from "leaking" to other parts. Cast iron manifolds create back pressure as the exhaust is dumped into a small area. Headers are smooth and the equal length insures the gases from each cylinder reach the collector separately, avoiding back pressure.
Headers are also more difficult to "package" than a short lump of iron into a single piece to tubing. The usual cast iron manifold dumps the exhaust gases with no consideration to pulse timing, scavenging etc.
Pulse timing, less back pressure, and scavenging work the same whether closed driving around town or open at the drag strip.
Independent header testing- ARH Longtubes/Pfadt Tri Y/Kooks Longtubes- Results Inside - Corvette Forum
Basically engines are an air pump; the more power they make, the more air they pump. Any restriction to pumping air lessens horsepower. Headers have less restriction so they increase power and it is just that simple.
Cast iron exhaust manifolds are thick walled or there is less room for the exhaust gases to exit. As cast iron is thick, it retains heat well (great for emissions) and prevents heat from "leaking" to other parts. Cast iron manifolds create back pressure as the exhaust is dumped into a small area. Headers are smooth and the equal length insures the gases from each cylinder reach the collector separately, avoiding back pressure.
Headers are also more difficult to "package" than a short lump of iron into a single piece to tubing. The usual cast iron manifold dumps the exhaust gases with no consideration to pulse timing, scavenging etc.
Pulse timing, less back pressure, and scavenging work the same whether closed driving around town or open at the drag strip.
Independent header testing- ARH Longtubes/Pfadt Tri Y/Kooks Longtubes- Results Inside - Corvette Forum
Headers Power Increase - Tech Article - Chevy High Performance Magazine
Basically engines are an air pump; the more power they make, the more air they pump. Any restriction to pumping air lessens horsepower. Headers have less restriction so they increase power and it is just that simple.
- Thread starter
- #28
toobroketoretire
Banned
Most novices just can't seem to understand track racing parts do NOT work well on street engines because of the extreme rpm difference. Before I got my mechanical engineering degree I was a professional engine builder for almost 20 years so when it comes to building high performance engines I am well versed. If you look back in history you'll find none of the world's most powerful muscle cars ever came with mechanical secondary carburetors because street engines can't swallow the HUGE amount of air a mechanical secondary carburetor can deliver at low rpm's. I have found the 750 cfm double pumpers are being put on L-48's with drastic results. Drastic because of the mechanical secondaries and drastic because of the 750 cfm being WAY too big for any 350" engine. A street 350" only requires 517 cfm at 6000 rpm so I can't understand why owners are putting those huge carburetors on their engines. Probably because well-meaning but ignorant people recommended them.
kpic
Well-known member
- Joined
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- Location
- Columbus, NC/NE Georgia
- Corvette
- 1997 boosted silver coupe
To be blunt, I stopped reading your post at novice.
I designed engines for 20 years, drive trains for 14 years and was involved with the design of forced induction systems for 11 years. In simple terms, that means I'm not exactly a novice.
However, as you brought the subject up and there are all kinds of engineers. I'm curious what sector of industry you worked in as an engineer?
There are dyno charts all over the web; look them up. As you don't believe them take your car to a dyno shop. For $50 bucks the shop I use will tie your car down and measure the wheel HP. You can watch them..
Then, have them install headers and tune the car. To get their interest, say if it makes more power at the tires; you'll pay them 2 or 3 times what they charge.
I designed engines for 20 years, drive trains for 14 years and was involved with the design of forced induction systems for 11 years. In simple terms, that means I'm not exactly a novice.
However, as you brought the subject up and there are all kinds of engineers. I'm curious what sector of industry you worked in as an engineer?
There are dyno charts all over the web; look them up. As you don't believe them take your car to a dyno shop. For $50 bucks the shop I use will tie your car down and measure the wheel HP. You can watch them..
Then, have them install headers and tune the car. To get their interest, say if it makes more power at the tires; you'll pay them 2 or 3 times what they charge.
dougelam
Well-known member
Well put kpic, he starts most of his posts with an insult to All of us in the auto profession.
20 years as a "professional engine rebuilder" ? I'll bet he doesn't know why Chevrolets have their timing marks both at 12 o'clock instead of aligned with each other like most others!
AND it's interesting that he never once mentioned the correct method for tuning an open header exhaust to back up his claim
I believe one would have to work in the field to recognize that he is condescending and insulting to our intelligence
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20 years as a "professional engine rebuilder" ? I'll bet he doesn't know why Chevrolets have their timing marks both at 12 o'clock instead of aligned with each other like most others!
AND it's interesting that he never once mentioned the correct method for tuning an open header exhaust to back up his claim
I believe one would have to work in the field to recognize that he is condescending and insulting to our intelligence
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- Thread starter
- #31
toobroketoretire
Banned
As an engineer I know headers won't do diddly squat unless they are uncorked and blowing to the open air. The moment the exhaust system is attached to the headers any gain you had gets lost as it's the mufflers that determine how much restriction there is in the system. Headers will certainly provide a meaningful gain when uncorked and used in full throttle high rpm track racing conditions but don't accomplish anything when used on street driven cars with street-legal mufflers. But oddly enough most people have been convinced headers are the easiest way to make BIG power for their street engines. If that were true every vehicle in the world would be equipped with them.
Antz81
Well-known member
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.
- Thread starter
- #33
toobroketoretire
Banned
Headers become very expensive ornaments when the restrictive mufflers get attached.
RedHot85Vette
Well-known member
Just stopped by the Holley "Brands" Web Site, which includes, Accel, Hooker, Lakewood, Mr. Gasket, MSD, and more... up pops a small box in the lower right which is somewhat related to this thread, and maybe some members here might want to get in on it... may increase your horsepower, or not...
Hooker BlackHeart 2 15 Mustang Giveaway - Holley Blog
I have an 85 Vette, I just got it Feb 20th, 16, it was a beautiful Saturday. Due to unfortunate circumstances related to spinal health, I only drove the car once, from previous owners home to mine, approximately 1 hour, 15 mins. I've been watching this thread and looking up stuff for my Vette, having fun finding accessories and such for it... I'm incapacitated at the moment and won't be moving around too much for the next year... but I can dream and use PayPal...been doing some reading, mostly of magazines, and advertising materials of the time. I'm an 'ol timey electro-mechanical tech of many disciplines, and an amateur mechanic not afraid to try anything. Although those days are over. I've read a lot of articles and technical data about other cars. Even the 64 Comet with Inline 6, single barrel carb, I just sold was said to have improved horsepower with headers. They did Dyno tests. It was a magazine artical from 1967. These 3 prominent car guys wanted to see what kind of performance they could get out of the inline 6, while spending the least amount of time and money. It was very interesting.
Everything they did boosted the horsepower, performance, and driving economy, bit by bit. The headers they had to get fashioned. There was no promoting there, and they made a big difference. They added a 2 barrel carb, then I believe they may have added multiple carbs, then later on in Part 2, they added some wicked cool side-draft carbs. In 1967 you could get really cool junk in the junk yard, dirt cheap. They got huge performance gains, spent very little money (1967!), comparatively speaking, and the time spent was also minimal, but really, 3 guys, pros of the industry, and all their friend-pros, with all kinds of equipment... I think the average tech would have to spend more time on it than presumed.
After every modification they did Dyno Tests. I believe the Headers made a big, maybe the biggest improvement on the Dyno tests. They entered some bizarre race and I believe they came in first and got about 30 mpg to boot. I had that same inline 6 in my Comet. The Exhaust Manifold was a problem from day 1. That engine was the greatest 6 cylinder ever built. Those Pro Guys just ranted and raved about it. Just wave the key at it in any weather and she starts with 1/2 a crank and goes forever. But the exhaust manifold, for me, was bad. I found a set of inexpensive headers to try on. I never got the chance because I sold the car but I do believe they would have given my car several benefits.
There's a Web Site called ClassicInlines.com where there's a nice photo gallery of modified and stock inline 6's. Some of the Mods are simply Outrageous. The 1967 Article I mentioned is also summarized there. They also sell headers and carbs and heads and just about everything to improve the performance of your lil ol Ford 6 banger to make it competitive and kick butt with the V8 Big dogs.
I'd like to see some articles or maybe some bonafide test data that shows that just adding headers to your existing exhaust system doesn't make an improvement. Open pipes is almost surely the Best way to go for racing, but it would annoy people in civilian use. I think John Milner in American Graffiti took his exhaust junk off before racing Harrison Ford's '55 Chevy. I see that they even sell muffler eliminator kits for Vettes and you can listen to them on YouTube. I wonder if those Muffler Eliminators will increase horsepower, performance, economy. I'm going to ask The Google and see what I come up with. Maybe someone can start a new thread: "Did Adding Headers to your existing Exhaust System improve Performance", something like that, and then in your message ask those who have it, to post their Dyno Data. Get the truth from the man on the street, and/or track.
RedHot85Vette
Well-known member
- Thread starter
- #36
toobroketoretire
Banned
Back in the late 50's and early 60's everyone's street/strip headers had cover plates capping the collectors. They'd arrive at the track, uncap their collectors, and go racing. At the end of the day they'd re-cap their headers and drive home with a quiet exhaust. Since those early days people have forgotten about using caps for their collectors and began connecting their restrictive exhaust system directly to their collectors; making their headers ineffective at making ANY additional power. In another forum I told the members this and immediately came under a fierce attack as the members claimed their headers are just as effective when the restrictive exhaust system is attached.
Vettehead Mikey
Well-known member
Can't say I've ever seen anyone hook up a set of headers to a restrictive set of pipes and mufflers.
Antz81
Well-known member
Are you able to explain why one of the guys at my work had a power increase of 16% just by changing to headers? (he had it dyno'd) he left the existing mufflers on the vehicle.
But Yes running open headers will give an increase compared with headers that run through a muffler.
But Yes running open headers will give an increase compared with headers that run through a muffler.
dougelam
Well-known member
You know Mike and ant I figured out that the author of these posts is stuck in the 60's
Its been years since I heard comments that he is making. Funny thing is None Of his comments are new, he is repeating what he heard forty years ago.
He doesn't know that HI Flow/Low restriction mufflers were designed in the 80's
Starting my automotive career in 1980 I grew up with Fuel Injection, I've had more than enough discussions with old timers on how we were doing it all wrong and didn't need all the electronics junk. I all but gave up on trying to educate them on how simular it was to carburetors.
If I had a dollar for every time I heard the "little old lady that bought a car with tilt that was in the up most position for years" story
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Its been years since I heard comments that he is making. Funny thing is None Of his comments are new, he is repeating what he heard forty years ago.
He doesn't know that HI Flow/Low restriction mufflers were designed in the 80's
Starting my automotive career in 1980 I grew up with Fuel Injection, I've had more than enough discussions with old timers on how we were doing it all wrong and didn't need all the electronics junk. I all but gave up on trying to educate them on how simular it was to carburetors.
If I had a dollar for every time I heard the "little old lady that bought a car with tilt that was in the up most position for years" story
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- Thread starter
- #40
toobroketoretire
Banned
Headers Are Just Steel Tubing Exhaust Manifolds With A Fancy Name
"Headers" are simply steel tubing exhaust manifolds with a fancy name so they can be sold for more. When they are used as intended headers do produce a gain in track racing applications where mufflers aren't required but for street engines using mufflers they don't provide any gain whatsoever. For street engines headers produce "perceived power" but in reality they are just ornaments that cook anything near them. But now there are ceramic coated headers that don't cook everything but they cost twice as much for the same zero horsepower gain. Good old American logic at work here.....................
"Headers" are simply steel tubing exhaust manifolds with a fancy name so they can be sold for more. When they are used as intended headers do produce a gain in track racing applications where mufflers aren't required but for street engines using mufflers they don't provide any gain whatsoever. For street engines headers produce "perceived power" but in reality they are just ornaments that cook anything near them. But now there are ceramic coated headers that don't cook everything but they cost twice as much for the same zero horsepower gain. Good old American logic at work here.....................
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