Headers vs. HP exhaust manifolds...

[69Charger_440]

Hi,

I was hoping to get some input as to whether I should run headers or the HP exhaust manifolds that Year One sells.  The kind of input I am hoping to get is the pros and cons of the HP exhaust manifolds vs the headers.  Thanks in advance for any help that is provided.

Fernando 

[Chatt69chgr]

I think it depends entirely on what your goals are with your engine and your car.  If you are doing a close restoration, then you will want the manifolds.  I have a set and they look real good.  I need to get them jet hot coated before I run them.  But my goal was to put together a car that pretty much looks like it came from the factory------but I don't care about numbers matching since it is a RT clone.  Now if you are wanting to make 450 or up horsepower, then you will want the headers since they flow much better than cast iron manifolds.  And the engine is just an air pump in the final analysis and the more air it moves the more power it will make.  Headers have been improved to the point that they don't leak like they did and you can get them coated too to prevent rust too.  You would want to buy a good set of headers though.  I thiink the cast iron manifolds would be quieter.  And you wouldn't have to worry about heat radiated from them like you would the headers.  I think the mini-starter helps solve the header clearance issue and you can get insulation to wrap the starter as well as a heat shield for the master if necessary.  It really all depends on what your ultimate goal is with the car.

[Carl1]

I think you will soon get tired of the headers if you go that way. Nice stock ex manifolds are trouble free and don't have that awful tinny sound when hooked up to mufflers. If you need to go fast go to the race track and run unmuffled headers.

[69Charger_440]

I think it depends entirely on what your goals are with your engine and your car.  If you are doing a close restoration, then you will want the manifolds.  I have a set and they look real good.  I need to get them jet hot coated before I run them.  But my goal was to put together a car that pretty much looks like it came from the factory------but I don't care about numbers matching since it is a RT clone.  Now if you are wanting to make 450 or up horsepower, then you will want the headers since they flow much better than cast iron manifolds.  And the engine is just an air pump in the final analysis and the more air it moves the more power it will make.  Headers have been improved to the point that they don't leak like they did and you can get them coated too to prevent rust too.  You would want to buy a good set of headers though.  I thiink the cast iron manifolds would be quieter.  And you wouldn't have to worry about heat radiated from them like you would the headers.  I think the mini-starter helps solve the header clearance issue and you can get insulation to wrap the starter as well as a heat shield for the master if necessary.  It really all depends on what your ultimate goal is with the car.

So would I not be able to attain 450 hp with the manifolds?  I basically want a cruiser with a little umph when needed though I do know that headers/manifolds are not the whole answer when looking for hp.  What I am trying to find is an estimate of how much hp I will lose if I go with the manifolds.  On another not, is 450+ hp too much to be considered a cruiser?  Anyhow, those were my main concerns (the heat radiated, rust, and leaks.)  Thanks for your advice!

Fernando 

[69Charger_440]

I think you will soon get tired of the headers if you go that way. Nice stock ex manifolds are trouble free and don't have that awful tinny sound when hooked up to mufflers. If you need to go fast go to the race track and run unmuffled headers.

I'm leaning towards the manifolds, but I want to do a little more research before I buy them.  Thanks for your input!

Fernando

[8WHEELER]

If this is going to be a street bruiser, you will not have very many opportunities
to wind it up. So I put my HP manifolds back on, they will provide you more
torque for stop light to stop light fun. And yes, HP manifolds can provide
more than plenty torque and HP for street use, your cam choice is a huge benefit.

If I put headers on again, I will be spending a lot more money than I have in the last
26yrs of running headers. Much better fitting and more spark plug wire clearance
with the new headers compared to the $300.00 headers I ran in the past years 

Dan

[Ghoste]

Then again, some of us love the sound of headers on any vehicle and for us, it's always a worthwhile modification. 

[firefighter3931]

If you want to run manifolds the cam selection becomes more critical. Ideally, a cam with reduced overlap will run much better on a restrictive manifold type exhaust system. Look for a cam profile with 112* LSA if you want to use the HP manifolds. 



Ron

[69Charger_440]

Thanks for the advice, guys!!   

[is_it_EVER_done?]

You didn't state what the rest of your build is, but if you are only shooting for 450 HP, I assume that it's nearly stock heads, small cam, and a manifold. Correct me if I'm wrong.

At that power level stock manifolds are just fine, and might even be better than headers, and certainly are better than large tube headers.

The higher the intended power output of the rest of the parts (heads, cam, carb/manifold), the more use headers become, and on a race motor they are indespensible.

Somewhere I have saved a test of a "crate" small block Chevy engine with stock manifolds, on up through all the  different header sizes and lengths. I'll try to find it and if I do I'll post it, but the point is that the wrong headers cost the power as much as 40+ HP/TQ on an engine that put out about 400 HP overall! Notice I didn't say added, I said COST.

You can pick up a bit of power with small tube headers on a stock/mild build, but only if you are willing to tune everything on a chassis dyno or drag strip. Otherwise you may just as likely hurt overall performance instead of helping it. It all depends on what you are trying to achieve, and what your other parts consist of.

[tecmopar]

One thing you can look into, but I think its gotten expensive lately is to do a mild port/cleanup on the iron manifolds and them have them extrude honed. I've done this on quite a few of my cars and seen dyno gains of 10-15HP. Not as much as headers but I'm not a big fan of them anyway. It keeps the stock look, sound, heat in and low end torque and you don't have the problems associated that come with headers, good luck.

[dkn1997]

you can get 450hp with manifolds.    andy f on moparts got close to 500 on a low deck 451. He used unported eddys and the MP 528 solid cam.  some good flowing heads, proper cam, right converter and gear and it will kick ass on the street where nothing is as fast as anyone thinks it is anyway.  Now that mopar sells straight plug eddys, you can have spark plug clearance too.  brendan at 440 source is making heads coming out in feb that are aluminum and flow well and they will be 900 complete. 

My car sounded much better with manifolds vs headers.  with no other changes, it improved the sound. much deeper and sounds less "cheap"