[Rookie]

If you've seen my other posts, you know I'm brand new to Chevelles, and cars in general. I see lots of people talking about how headers improve performance, but I'm not quite sure what they are, where they go, or what they do. Yeah, I'm an idiot, but I'm working on it. I appreciate y'all's advice, and if you don't mind, there'll be a lot more of these basic questions coming. I appreciate all the advice, it makes jumping into a _really_ complicated world a little bit easier.--Rookie

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'72 350 Malibu
Team Chevelle #528

 

[junglejimmie]

Welcome to our ranks "Rookie"!, To answer your question, "headers" are performance exhaust manifolds of sorts. What I mean is,they replace your normally restrictive exhaust manifolds by using free flowing tubing to go from your heads to your exhaust pipes. Check this out: http://www.flowtech.com/index2.html
you can see what they look like. Of course' this is only one of many styles/types.

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Jungle Jim #105 Gold
70SS396 & 70 Malibu~
"Fight the good Fight every moment, every minute,every day. Make it worth the price you pay!"

 

[Rookie]

So the heads are where the exhaust leaves the engine, and headers move it to the pipes quicker and faster to make more room for new combustion? How are headers different from normal exhaust? And to push it further, how does exhaust play a part in performance, and do dual/wider exhaust pipes mean more horsepower? Thanks for the input junglejimmie, I'm a babe in the woods. Fortunately, I have a great-looking car, makes the woods a little less lonely.

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'72 350 Malibu
Team Chevelle #528

[This message has been edited by Rookie (edited 01-29-2000).]

 

[Gene Chas]

Once you start checking out rides ( like at cruise events ) it becomes quite obvious. When I was a kid, headers sucked from a looks point of view becuase they were black and rusty. Now the cveramic coated ones look like an extension of my polished aluminum heads. Too cool.

The pipe/collector config of the headers vs. the "one tube" style of cast iron exhaust manifolds allows a scavenging effect, literally pulling the exhuast out of the head.

Headers also allow tuning the peak torque/HP rpm of an engine. For example, smaller tube headers generally shift the rpm at which peak torque occures down.

Chaas
Gold #62
67 SS396/L88

[This message has been edited by Gene Chas (edited 01-29-2000).]

 

[jmw]

Headers and bigger than stock pipes and low restriction mufflers decrease backpressure that the piston is working against during the exhaust stroke. Lower backpressure means less dilution of the next incoming charge of fuel and air with exhaust gases. That means more power from the same engine! Adding headers and the rest is one of the few real bolt on improvements that you can feel in the seat of your pants, especially big blocks. Look at the new Camaros and Rustangs, they have pretty much got factory headers now.
jmw

 

[Wes V]

Rookie;

Here is "header class 101A" (with a super bowl twist)

Think about the exhaust gas leaving the head as a "pulse". Not a constant flow until farther down the exhaust pipe. It has mass and also velocity (same as a football)

The pulses leave the engine in a sequence that is the firing order.

The smaller the pipe, the more resistance to the football. At first this would lead you to think that you want the largest pipes you can get, but it's not totally true.

As the football goes down the pipe, it creates a suction behind it. If the length of the header pipes are such, this suction can be used to pull the next football. This is the "timing" of headers that people talk about. You want the length such that as the pulse (football) hits the collector (where all the pipes come together), the exhaust valve is opening on the next cylinder to be exhausted. This will tend to suck out the cylinder!!!!!

If the header pipes are too large in diameter, you loose this suction action.

Happy superbowl

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Wes. Vann
Technical Reference section
Gold Member #5


[This message has been edited by Wes V (edited 01-29-2000).]

 

[Pat Kelley]

One more thing to add. Having separate tubes from each cyclinder keeps one exhaust pulse from interfering with other exhaust pulses from other cyclinders. With a log style manifold, all 4 cyclinders on one side dump into the same "pipe", so to speak. Exhaust pulses can, and do, interfer with each other.

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Pat Kelley
66 El Camino, daily driver
67 El Camino, STRIP/street

 

[larrym]

Hey Rookie, I like your questions a lot!

There a lot of us around who have an awful lot to learn and need to ask the same questions you've been asking.

For example, I've been working on cars in minor way for 40 years but I learn a lot about headers from the discussion that you initiated above. In fact, I'd guess that virtually everyone, who read it, learned something.

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Larry
Gold Member #245
Seattle WA

 

[Tedster]

Headers are only as good as the rest of the exhaust system. The least resistance that the exhaust gases (or footballs

) encounter, the more power the car will make. It doesn't matter how efficent your headers are, if the rest of the system restricts flow, you're losing power.

I'm assuming that this isn't the only question you have, so I'm going to try and explain the basics of the 4 stroke V8. This applies to every modern automotive engine ever made.

The reason they call it a 4 stroke engine is because there are 4 different phases to a complete combustion cycle. The 4 cycles are the intake stroke, the compression stroke, the power stroke, and the exhaust stroke.

The engine block is the foundation of a motor. It houses the crank, connecting rods, pistons, and oil pump. Heads, on the other hand, are the units on top of the block.

The heads mount to the block and they direct the air/fuel mixture to the cylinder through tunnels within the heads called "intake ports". The air/fuel mixture is sucked past the valves and into the motor on the intake stroke.

Then the piston travels up, compressing the air/fuel mix on the compression stroke. Now at the height of this compression stroke, the spark plug will ignite this mixture and force the piston down into the power stroke. Finally the exhaust valve is opened and the spent gases are pushed out of the motor by the piston on the exhaust stroke.

The spent exhaust gases are pushed into another set of tunnels within the heads called "exhaust ports" and are directed towards the headers, into the exhaust system and out of the car.

Now there is a little bitmore to it than that, but this should give you a general idea of how it's done. There are alot of well written books on engine basics and they should help explain the basic theory better than I can.

If there is one peice of advice I can give you, it would be to read everything you can get your hands on. Get a subscription to Hot Rod or Car Craft. Just read as much as you can. And don't be afraid to work on your car. That's how we all started.

This is a pretty cool site
http://www.autoshop-online.com/auto101.html

[This message has been edited by Tedster (edited 01-29-2000).]

 

[Buddy]

If your interested I can scan my small engines notes: its all about the strokes, oil system, and carburater
just e-mail me and lemme know

 

[catman]

Headers.... bent tube things that hook up to the big orange thing under hood

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John
Catapiller Mechanic
Salinas,Ca
70SS 454 Clone {in construction}

 

[plain 69]

Catman that is a very good explanation on what they look like.

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69 SS 454
69 Malibu 406
ACES Member #3635

 

[jmw]

Catman, I for one loved it! Laughed out loud.

Hey Rookie, another way I learned about motors was when my Honda CT70 broke down and I couldn't afford to fix it. The Honda shop had torn it down and they gave it back to me in a box, so I tried to put it back together ( I was in the 9th grade). It actually ran again, but I found out what those extra parts left over were when it wouldn't go into third gear!

jmw

 

[Dean]

They say (who ever "they" are) a picture is worth a thousand words, here's one worth... oh, maybe 25 or so.

http://members.primary.net/~cys.dean/images/headers.jpg


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Dean Call
Team Gold member #3
A.C.E.S. # 00235
N.C.O.A. # 4350
Mid America Chevelle Club #001
chevelles.net

oops, forgot can't use the tag here[/I][/B]
[img]http://www.chevelles.com/forum/redface.gif

[This message has been edited by Dean (edited 01-30-2000).]

 

[Cardiac]

Header: ...tripping on the rug while sneaking back into the house after a night on the town

Just razz'n ya Rookie

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Lowered '67 Elcamino
ZZ430HP / 4L60
"Canyon Carver"

 

[ETAYLOR72]

Welcome Rookie! Got a 72 Malibu myself. Plain old bench seat, Covert Tan painted, 350 sleeper. But all original....woohoo.

. Tell us a little about yours, if you don't mind. Again, welcome to the club!

[This message has been edited by ETAYLOR72 (edited 01-31-2000).]

 

[283v8]

For simplicity, think of any engine as an air pump. Getting air into and out of it are the keys to making power.
Bigger carb. , less restrictive intake manifold, bigger valves,"bigger" cam, better flowing heads, all help get air in.
Bigger exhaust valves,"bigger" cam, better flowing heads, less restrictive exhaust manifolds(Headers), and freeflowing exhaust all help get air out.
Headers are one of the common upgrades because factory manifolds are usually restrictive.

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Gotta have a Chevy !In Durham N.C.
Make it look the way you like it, forget what the other guys say!

 

[Rookie]

Thanks again for all the input, you've no idea how much it all helps. One more quick thing -- how can you tell by looking at an engine if it's got a factory exhaust manifold or headers? Do they look different to the eye?

ETAYLOR72, mine's a '72 Malibu, red with black stripes (didn't know when I bought it I was inadvertently an SS impostor), with a brand new Chevy 350 and TH350 transmission with a console shifter. The interior is black with buckets, new upholstery and carpeting. No stereo yet -- got to recover from buying the car first!

Like I said, thanks for the advice, and it sounds like you don't mind the stupid questions, so I'll keep 'em coming! Stay tuned for Rookie school part 2!

Buddy -- wow, I'd really appreciate the notes! Didn't see an email in your profile, but if you send me one I'll reply right away.

(and Cardiac -- yeah, that's what I THOUGHT it was!)

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'72 350 Malibu
Team Chevelle #528

[This message has been edited by Rookie (edited 02-01-2000).]

 

[lev]

Headers are very easy to distinguish from manifolds. Headers (usually) have 4 LONG pipies that meet underneath the car, where they bolt up to the exhaust, and manifolds have 4 very short pipes going into one long pipe on the side of the motor. That long pipe meets the exhaust pipe in the engine compartment, not underneath the car further down. I'm a headers guy. I'll always run them over exhaust manifolds.

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70 Malibu
350/300hp
Soon to be 396/325hp

 

[283v8]

Stock manifolds are almost always cast iron made all in one piece with a connection to the exhaust pipe up beside the engine.
Headers are made of round tubing, thus have 4 tubes on each side coming off the engine and going down below the engine where they connect together (in a "collector") at this point they connect to the exhaust pipe.
If the exhaust manifolds are compact, beside the engine, and all made as one piece, they are stock.

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Gotta have a Chevy !In Durham N.C.
Make it look the way you like it, forget what the other guys say!