Headers, whats the real gain?

[Lord Warlock]

Just wondering, back in the 70s and 80s the magazines touted headers as one of the few really good modifications for big blocks and other muscle cars.  But how much of a hp/tq improvement do they really make over the factory hipo manifolds?  For years I wanted to put a set on the car, now i'm pretty much going to live with the factory manifolds primarily for looks and that was the way it came when I got it,  but I always wondered what i was missing power wise from skipping the headers.  Which ones are popular? I remember Eagle, Hooker, thorson ? and a few other names from the past.  I can't argue a point I have no experience with.  I do know  how improving the exhaust systems have really improved how some of them ran in the upper RPM ranges, where they would nose over on stock systems, but never really had that problem with the charger when i did run it in the old days. 

[1974dodgecharger]

If u got the heads then headers work but if u yave stock heads minimal gains. I think some forum members did testing on some headers with stock 906 and saw only 5hp gains. 

Get tye heads right first as cooter and my uncle would say 3 tips first is heads, 2nd is heads, and 3rd well is heads.......

[Cooter]

Doesn't matter if it's only 10 hp. IT'S A GAIN. Headers are lighter, produce a better sound, better fuel mileage,  and make more power.

Drawback is headers are not stupid proof like manifolds. They will require periodic maintenance. (Poss. Blown/leaking gaskets)...
There aren't just "gains" of HP....

[myk]

Yup, I'll take a 10 hp gain and the improved sound/feel, stupid as that may sound...

[Ghoste]

Doesn't sound stupid at all.  One of the easiest mods you can make too.

[cudaken]

Few month ago I would have said they would only be worth about 5 HP. Someone had posted a link to where a stock smoggier 440 was used as a test mule on a dyno. With just the headers installed the 440 showed a 20 HP gain? 

If a car weight is 3600 pounds with 300 HP and the headers gave it 320 HP that would net around .3 tenths of a second. You will feel that kind of a differences.

But to really get that kind of power gain, more than likely you will need to rejet the carb.

Cuda Ken   

[heyoldguy]

From our dyno tests on a low compression (7.5:1) 440.

RPM.............HP manifolds.......headers

2500...............197 hp...............203 hp
3000................230..................239
3500................257..................266
4000................266..................280
4500................268..................281
5000................248..................257
5500................214..................223

We just swapped to the headers without doing any other changes like jetting.

[Ghoste]

All at 4000 rpm. 

[myk]

'Course, this takes us back to the 'ol "which header" debate.  I'm still aiming at Doug's or TTi's, but I'll probably do suspension 'mods first...

[chargd72]

Almost a 9% increase in HP for that low performing 440.  Not bad at all.

[Lord Warlock]

that was a low performing 440, how about the manifolds found on a stock 440 magnum with stock hipo exhaust manifolds? A 10hp improvement to me isn't really worth the effort unless i'm racing it, and in that case any improvement is welcome.  From what I read over the years the 67-71 440 magnum exhaust manifolds were actually pretty good performers compared to headers, although they did say headers would improve things.

On my 91 stealth I put an aftermarket downpipe which eliminated the catalytic converter and gutted the precats and put a borla catback on it and it woke up and screamed from 4000-7800 rpm where previously it would lose boost above 4500 rpm and kind of lost power above 5k.  Never hit the rev limiter on the car till after i put the exhaust system on.  I know they can be beneficial. 

[Challenger340]

I've seen close to 30 hp on the Dyno on a 440-6 pack Restoration Engine, pocket ported stock valve 906 Irons, 274H Cam, with 1 3/4" Headers from the HP Manifolds with 2 1/4" pipes.
THAT really surprised us ! it was very unexpected.
I don't think EVERY Engine would respond the same, but that one did. I am guessing with smallish resto style Cams a good average might be 10-15 ?

[BSB67]

Few month ago I would have said they would only be worth about 5 HP. Someone had posted a link to where a stock smoggier 440 was used as a test mule on a dyno. With just the headers installed the 440 showed a 20 HP gain? 

If a car weight is 3600 pounds with 300 HP and the headers gave it 320 HP that would net around .3 tenths of a second. You will feel that kind of a differences.

But to really get that kind of power gain, more than likely you will need to rejet the carb.

Cuda Ken   

Do you still have the link?  I'm always interested in the details of these comparisons.  Sometimes they are not apples to apples.  The balance of the exhaust system used on the dyno will also have an effect as well.  Valve timing even on smaller cams may favor headers more than other similar sized cam.

[green69rt]

I've always had my doubts about the HP gains on street engines (lots of advertising!!) but don't have any real numbers to back it up.   I'd like to see some really good comparisons.  For example: the low HP 440 in a previous post, if you worked the engine to get the best you could without the headers.   Like tune the carb really nice, make sure the ignition is running things as it should then swap in the headers and see the diff.   Then tune the engine with the headers in the same way.  What would be the results??  Someone, somewhere has probably done this.  I would just like to see the results.

On a different note, some of us don't have much choice.  Restoring a car means that sometimes factory exhausts are not available.

[heyoldguy]

We dyno tested the stock log cast iron manifolds and switched the the HP cast iron manifolds and gained 4 HP.

[1974dodgecharger]

Doesn't matter if it's only 10 hp. IT'S A GAIN. Headers are lighter, produce a better sound, better fuel mileage,  and make more power.

Drawback is headers are not stupid proof like manifolds. They will require periodic maintenance. (Poss. Blown/leaking gaskets)...
There aren't just "gains" of HP....

As cooter would say dont bring a knife to a gun fight....

[Lord Warlock]

I seem to remember reading articles where racers would extrude hone stock manifolds to smooth the insides as much as possible, if thats the right term, was somehow forcing a sludge thru the innards.  Saw before and after shots and it was impressive.  Not really sure about the sound being better argument, I still compare every other car I've ever owned to the exhaust note on the charger with a stock exhaust, nothing has ever come close to the right sound, love the sound of the 440 magnum at idle as well as on the road. 

[green69rt]

We dyno tested the stock log cast iron manifolds and switched the the HP cast iron manifolds and gained 4 HP.

This is the exact thing I wonder about... 4 or 10 or 20 HP at peak is important on the track but not so much on the street.  If you give me a good amount of seat-of the-pants kick then great.  For those of you who run your car on the track a few times per year or more, that's great.   But what of those of us who are boulevard cruisers??  I've had headers and also cars without (not much diff), other than bragging rights what are they worth??   Since I don't race (maybe a little stop light stuff) do headers really pay off??  I really don't know so can someone give me some guides??

[c00nhunterjoe]

http://www.youtube.com/watch?v=MGGuRdr18b0&list=PLCD53AA672390665D

Is it worth it? I think so. Exact numbers? You cant put a number on it. Varies with every engine combo. Compression, heads, cam, collector length and exhaust system all factor in. The bottom line is headers will make more hp and tq then manifolds.

[69wannabe]

Mopar muscle did a header comparison with extruded honed HP manifolds and short tube and long tube headers. I think the long tube headers were a 20 to 30 HP gain over the manifolds. When I read that the manifolds I had were gone the next day and headers were on the way!!!! 

[1974dodgecharger]

Headers look cooler than stock manifolds.....

[Brass]

But whether they sound better is subjective. 

[1974dodgecharger]

They do sound better in my opinion and they look cooler and u instantly gain street cred once the see it.

[randy73]

They do sound better in my opinion and they look cooler and u instantly gain street cred once the see it.

They do not always look cooler and if not done right, will rust out in 4-6 yrs. if someone believes headers are the end all, be all. Let me know, my friends sleeper will eat them alive. Love these types of threads, you can port some manifolds and get the same or close to the same HP numbers , as headers. People always boast wild HP numbers when they sell headers, just remember, the car breathes only as good as the worst choking point and to much headers are a bad thing and sometimes worse than stock manifolds. Had a friend w/350 LT1 and put headers w/1 3/4" primaries on a stock 300hp engine, the car fell on its ass, HP and MPG went down and he could not understand why. Like candy, to much of a good thing, is a bad thing.

[Lord Warlock]

do people really look for street cred while driving a 69 charger? you get about as much credit as you need just driving one compared to all the other rides on the road.  Noone really cares if its the fastest thing in town anymore.   About the only people that want street cred are the people that deserve none.  Sorry younger owners, some of us have outgrown that by now.  I build the car to suit me, not anyone else. 

If you have a non RT charger and you've put a big block in the car, by all means put a set of headers in it, it only makes sense.  Having a real R/T sometimes means we don't want to deviate from stock that much.  Maybe a cam, roller rockers, and an aftermarket carb as long as it can't be seen from the external view of the engine bay.  Almost every car i've seen headers on the headers are almost always rusted looking, they're never clean and nice looking.  I have to be willing to make concessions, I'm also not willing to swap out the rear 3.23 open rear in the car, whereas a 3.90 or 4.10 would easily make it quicker in the quarter, i'd much rather have a car that can be driven on the interstate at 75mph with rpms in the reasonable range.  Used to drive it long distances.

I also am more interested in real dyno numbers that show at the wheel hp and torque improvements than I am with just a motor.  I am sure they will add some power, as many tests in the 70s, 80s, and 90s proved that they do add hp, but they almost always tested cars with cams, intakes, and carb changes also which isn't a fair representation compared to the stock.  What do the stock class drag racers use on their cars? how do they get into the low 12s or 11s with an engine that appears stock on the outside? 

Unlike many here that have been driving their chargers, its been so long since my car has been on the street that I'll be happy just to be able to drive it to the store and back without something happening to it.  I certainly don't want to blow the motor up after having it survive 30 years of storage.  The engine only has 70k original miles on it when i stored it. 

[randy73]

do people really look for street cred while driving a 69 charger? you get about as much credit as you need just driving one compared to all the other rides on the road.  Noone really cares if its the fastest thing in town anymore.   About the only people that want street cred are the people that deserve none.  Sorry younger owners, some of us have outgrown that by now.  I build the car to suit me, not anyone else. 

If you have a non RT charger and you've put a big block in the car, by all means put a set of headers in it, it only makes sense.  Having a real R/T sometimes means we don't want to deviate from stock that much.  Maybe a cam, roller rockers, and an aftermarket carb as long as it can't be seen from the external view of the engine bay.  Almost every car i've seen headers on the headers are almost always rusted looking, they're never clean and nice looking.  I have to be willing to make concessions, I'm also not willing to swap out the rear 3.23 open rear in the car, whereas a 3.90 or 4.10 would easily make it quicker in the quarter, i'd much rather have a car that can be driven on the interstate at 75mph with rpms in the reasonable range.  Used to drive it long distances.

I also am more interested in real dyno numbers that show at the wheel hp and torque improvements than I am with just a motor.  I am sure they will add some power, as many tests in the 70s, 80s, and 90s proved that they do add hp, but they almost always tested cars with cams, intakes, and carb changes also which isn't a fair representation compared to the stock.  What do the stock class drag racers use on their cars? how do they get into the low 12s or 11s with an engine that appears stock on the outside? 

Unlike many here that have been driving their chargers, its been so long since my car has been on the street that I'll be happy just to be able to drive it to the store and back without something happening to it.  I certainly don't want to blow the motor up after having it survive 30 years of storage.  The engine only has 70k original miles on it when i stored it. 

while I agree with a lot you said, make no mistake. Dyno number do not tell the whole story about and engine or a car, I have seen many a car with great dyno numbers get blown off the track by cars with lesser numbers. Weight distribution, tire size and width and a lot more go into making a quick and or fast car.

[Lord Warlock]

for sure, my 300hp stealth would blitz the charger in the quarter, even before i upgraded the exhaust, bigger turbos or turned up the boost from 8psi to 16psi. It was no contest, awd makes a world of difference, as well as weight distribution.  Used to get challenged alot when i drove the stealth daily, and i used to race it often, never lost a race in it.  It surprised many car owners on the road who thought it was a heavy pig till they couldn't keep up with it.

Have no idea what the charger would actually run in the quarter, pretty sure it was in the 13s when I drove it regularly, and today it sits on 17x11 rear rims with 315 drag radials so it should launch a whole lot better than it used to.  If it ever gets driven hard again. 

[darkside]

imo when you pop the hood them big hp manifolds make the 440 look more massive so That's what i'll be running.I remember back in the day having to
unbold the drivers side engine mount  and jack the motor up to change header gaskets and starters and I ant doing that again.

[Ghoste]

while I agree with a lot you said, make no mistake. Dyno number do not tell the whole story about and engine or a car, I have seen many a car with great dyno numbers get blown off the track by cars with lesser numbers. Weight distribution, tire size and width and a lot more go into making a quick and or fast car.

All too true, what many fail to see is that the dyno is a tuning device and it is only looking at a portion of the overall package.

[myk]

imo when you pop the hood them big hp manifolds make the 440 look more massive so That's what i'll be running.I remember back in the day having to
unbold the drivers side engine mount  and jack the motor up to change header gaskets and starters and I ant doing that again.

How often were you having to change out gaskets and starters?

[1974dodgecharger]

imo when you pop the hood them big hp manifolds make the 440 look more massive so That's what i'll be running.I remember back in the day having to
unbold the drivers side engine mount  and jack the motor up to change header gaskets and starters and I ant doing that again.

How often were you having to change out gaskets and starters?

Gaskets can blow easy unless u use some kind of rtv on it.  I use Percy's alunmim with rtv nothing's blown now. Lol

[myk]

imo when you pop the hood them big hp manifolds make the 440 look more massive so That's what i'll be running.I remember back in the day having to
unbold the drivers side engine mount  and jack the motor up to change header gaskets and starters and I ant doing that again.

How often were you having to change out gaskets and starters?

Gaskets can blow easy unless u use some kind of rtv on it.  I use Percy's alunmim with rtv nothing's blown now. Lol

From what I gather from most here, it seems that leaking header gaskets is almost a common occurrence.  I don't like the sound of that; then again the Charger never gets more than 3K miles a year anyway, so....

[Ghoste]

If you ignore it yes.  Use a quality HEADER gasket with high temp sealant and then re-tighten the bolts once in awhile and you should not have any problems.

[tsmithae]

I know that Percy's is highly regarded around here and if mine fail, I intend to go that way.  However, I ran into Soupy's gaskets at a swap meet and I am very happy with them so far.  I haven't gotten a lot of run time with them, mostly just breaking in the engine on the test stand so far.  However, it is another alternative and I just thought I would pass it along.  High quality, thick, American made gaskets that are far better (so far) than the thin ones I have run across yet. 

http://www.ebay.com/itm/Chrysler-Big-Block-Exh-Gaskets-361-383-400-413-426-440-/120616430407?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item1c154cab47

[darkside]

imo when you pop the hood them big hp manifolds make the 440 look more massive so That's what i'll be running.I remember back in the day having to
unbold the drivers side engine mount  and jack the motor up to change header gaskets and starters and I ant doing that again.

How often were you having to change out gaskets and starters?

It was my daily driver and back in early 80's  paper gaskets sucked. 

[cudaken]

Far as header leaks, my Hookers Super Comp's on my 68 Road Runner are God, 32 years old?  I have never had a header leak! 

Far as changing starters, yea that still sucks. But over time I have found a few tricks.

My first set of headers where cheap Castlers and what POS they where!

While my Charger was pretty much stock I was fine with the HP Manifolds. It was a driver and a extra 10 to 20 HP did not make a differences to me. Then the Go Fast Bug Bite and I built a new 440 with the GMC 6-71, I added headers. 

Cuda Ken 

[Kern Dog]

These "Are headers worth it?" threads crack me up.
On one side you have the sensible guys that understand the dynamics of an internal combustion engine. They realize that an engine is like an air pump: The faster air can pass through the engine, the more power it will make.
THEN you have the stubborn old timers on the other side that actually believe that their iron manifolds make either the same or almost the same power. THESE same guys have the mistaken belief that an engine needs backpressure to run right.  

Headers do many things, two of the most important are the following:
1) They are less restrictive, allowing the exhaust to flow from the engine faster.
2) They have a "scavanging" effect. This means that as each cylinder fires and pushes out the exhaust, when that tube merges into the collector, it creates a suction that actually draws the exhaust from the next cylinder to fire. In simpler terms, each pulse, each cycle of spent gases that enters the collector creates a path for the next pulse.
No manifold does that.
If you install headers and lose power, you didn't tune the engine to take advantage of the headers.
If you install headers and get leaks, you probably did something wrong.

[Cooter]

^ yep. It in fact, many new cars run some form of tubular exhaust header. Only time I see a cast iron manifold today, it's usually in a high heat, or towing vehicle.

[1974dodgecharger]

I like to go in threads to say the opposite i said in another thread to see who responds and I'm right on who responds only to go opposite what I say, always.  I once said headers give u hp/tq the same person in this thread said no its worthless this time i say its worthless and those people say its worth it 

These "Are headers worth it?" threads crack me up.
On one side you have the sensible guys that understand the dynamics of an internal combustion engine. They realize that an engine is like an air pump: The faster air can pass through the engine, the more power it will make.
THEN you have the stubborn old timers on the other side that actually believe that their iron manifolds make either the same or almost the same power. THESE same guys have the mistaken belief that an engine needs backpressure to run right.  

Headers do many things, two of the most important are the following:
1) They are less restrictive, allowing the exhaust to flow from the engine faster.
2) They have a "scavanging" effect. This means that as each cylinder fires and pushes out the exhaust, when that tube merges into the collector, it creates a suction that actually draws the exhaust from the next cylinder to fire. In simpler terms, each pulse, each cycle of spent gases that enters the collector creates a path for the next pulse.
No manifold does that.
If you install headers and lose power, you didn't tune the engine to take advantage of the headers.
If you install headers and get leaks, you probably did something wrong.

[Lord Warlock]

Don't think i've ever said they're worthless, they have their place and in some cars where power is the only concern I would go with a full exhaust upgrade.  The whole point of this thread was just to find out how much power they would add over the stock magnum manifolds which were considered a decent design which evidently gave a 3 to 5hp increase over the lesser manifolds of the day.  Much of the advertising of the old days said headers would add 30 to 40hp which I've always thought was a little on the high side on an otherwise stock motor.  I figure a good set of headers should add 20hp, which is enough to feel it in the butt dyno but may not equate to much in quarter mile times.

I am an Old Timer, and I believe the stock manifolds weren't bad as far as flow goes, I do however believe that headers SHOULD improve the flow provided the design was an effective one, but am not stupid enough to think that every header will outperform a well designed manifold, not without a port job on the exhaust ports. 

Never put a whole lot of stock in the backpressure necessity part of the argument.  engines flow air in, and they pump it out, the more air the more power.  I have personally seen folks go too large on an exhaust system and had the car get slower in the quarter.   

[1974dodgecharger]

I had a paper gasket aluminmum foil hybrid type gasket always blew at #7 area...

imo when you pop the hood them big hp manifolds make the 440 look more massive so That's what i'll be running.I remember back in the day having to
unbold the drivers side engine mount  and jack the motor up to change header gaskets and starters and I ant doing that again.

How often were you having to change out gaskets and starters?

It was my daily driver and back in early 80's  paper gaskets sucked. 

[BSB67]

These "Are headers worth it?" threads crack me up.
On one side you have the sensible guys that understand the dynamics of an internal combustion engine. They realize that an engine is like an air pump: The faster air can pass through the engine, the more power it will make.
THEN you have the stubborn old timers on the other side that actually believe that their iron manifolds make either the same or almost the same power. THESE same guys have the mistaken belief that an engine needs backpressure to run right.  

Headers do many things, two of the most important are the following:
1) They are less restrictive, allowing the exhaust to flow from the engine faster.
2) They have a "scavanging" effect. This means that as each cylinder fires and pushes out the exhaust, when that tube merges into the collector, it creates a suction that actually draws the exhaust from the next cylinder to fire. In simpler terms, each pulse, each cycle of spent gases that enters the collector creates a path for the next pulse.
No manifold does that.
If you install headers and lose power, you didn't tune the engine to take advantage of the headers.
If you install headers and get leaks, you probably did something wrong.

To think that the right headers don't add power to any engine is just silly.  But I don't think anyone on this thread is suggesting otherwise. 

The OP did not ask: "is it worth it?" And of course the answer to that question is completely personal and subjective and only the OP can answer that for himself.

The answer to his actual question, "what is the real gain?" , based on the information he has given, has been answered as good as it can be.  5 to 40 hp.   There are so many unknown details regarding the OPs specific case that the right answer would simply be a lucky guess.

Here is my guess.  If the engine is 325 hp-ish, the cam is stock or has an overlap of 48° or less, and the exhaust system after the manifold/header flanges is identical, 10 to 15 hp. that would result in a 0.10-0.15 et, and 1.0-1.5 mph improvement at the track.

[cdr]

BSB67 , YOUR car & engine combination is VERY interesting. 

[ACUDANUT]

Does nobody give real advice anymore.
It depends. How much of a fight do you want putting them in. How many times do you want to replace a starter. How many times do you want to replace leaky gaskets.

[BSB67]

Does nobody give real advice anymore.

Heck, generally speaking, I thought the OP got some pretty good feed back.

[RECHRGD]

These "Are headers worth it?" threads crack me up.
On one side you have the sensible guys that understand the dynamics of an internal combustion engine. They realize that an engine is like an air pump: The faster air can pass through the engine, the more power it will make.
THEN you have the stubborn old timers on the other side that actually believe that their iron manifolds make either the same or almost the same power. THESE same guys have the mistaken belief that an engine needs backpressure to run right.   

Headers do many things, two of the most important are the following:
1) They are less restrictive, allowing the exhaust to flow from the engine faster.
2) They have a "scavanging" effect. This means that as each cylinder fires and pushes out the exhaust, when that tube merges into the collector, it creates a suction that actually draws the exhaust from the next cylinder to fire. In simpler terms, each pulse, each cycle of spent gases that enters the collector creates a path for the next pulse.
No manifold does that.
If you install headers and lose power, you didn't tune the engine to take advantage of the headers.
If you install headers and get leaks, you probably did something wrong.

So it's the "stubborn old timers" that don't know that headers do offer some hp gain!  Who the hell do you think first designed them?

[Ghoste]

Whoohoo!  By that rationale it means Im neither stubborn nor old.  Good thing I love headers. 

[cdr]

for me i love headers,as said in previous post lots of variations on the answer to the OP question,headers help fill the cylinder with a fresh intake charge during the overlap cycle of the cam,the intake & ex valve are open at the same time & the exhaust pulse & flow help to draw the intake charge into the cylinder,also intake runner length plays a part in how well the header works ,they can compliment each other or hurt each other,its all about the combination of parts & if the engine was built for headers or built for stock exhaust manifolds, by putting headers on an engine that was specifically built to run manifolds the gain would not be as great as an engine built with headers in mind. there are more variables that i want get into,but bottom line is the camshaft specs are the biggest factor on the answer.

[Homerr]

Almost a 9% increase in HP for that low performing 440.  Not bad at all.

Hmmm, my calculator says 3-5%.

[c00nhunterjoe]

Whats the real gain over manifolds? My rough opinions:

Bone stock- 5 hp
mild (mild cam, intake etc)- 10-15
Drag- (choppy cam, heads etc) 15-25
Race- (full build, 12:1, big heads, big solid roller etc) 30+

There, thats my opinion

[chargd72]

Almost a 9% increase in HP for that low performing 440.  Not bad at all.

Hmmm, my calculator says 3-5%.

Yep, I agree with you. It's actually almost right at 5%. That was my poor attempt at mental math.

[1974dodgecharger]

Whats the real gain over manifolds? My rough opinions:

Bone stock- 5 hp
mild (mild cam, intake etc)- 10-15
Drag- (choppy cam, heads etc) 15-25
Race- (full build, 12:1, big heads, big solid roller etc) 30+

There, thats my opinion

thats based on everything running optimal!

[c00nhunterjoe]

Whats the real gain over manifolds? My rough opinions:

Bone stock- 5 hp
mild (mild cam, intake etc)- 10-15
Drag- (choppy cam, heads etc) 15-25
Race- (full build, 12:1, big heads, big solid roller etc) 30+

There, thats my opinion

thats based on everything running optimal!

I figured that was a given. Maximun output doesnt come without a little tuning.