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.