Headers?

[cuda620]

Anyone ever compared the Schumacher headers to the high po exhaust manifolds? I ask because they’re small tube for figment and I’ve heard 475 hp is all. But someone on here got over 500 with just manifolds. He actually wrote a book. His name evades me now... I’d like to know before I spend the money. Thanks

 

[roccodart440]

YOu can get HP with manifolds. NOt easily...

it's not like, yeah, manilfolds cost you 10hp so no big deal just bolt them on. The guys that run them and make big power do head porting, special cams and even extrude hone the manifolds themselves.

Headers are easy and readily available.

 

[AJ/FormS]

I think HR magazine did a comparo and found over 40hp after bolting on long-tubes; with no tuning changes; hinting at more power lurking. I think they used the 284 Magnum cam. That is sortof like 2 cam sizes or dieting over 400 pounds out of your car.
Are long-tube headers worth it? Hunt up the article, and choose for yourself.
The more overlap your cam has, the greater will be the power difference.
Myself, for a performance combo, I would do whatever I had to, to get long-tubes on. Even smogger 318s like long-tube headers.
But shorties still provide a place for the hot, high-pressure gasses, to go when they burst out of the chamber, and at least some distance to get straightened out before they hit the head-pipes; and so the engine doesn't have to work quite as hard to push the exhaust out. That's gotta be worth something.

 

[cuda620]

I’m looking at a crower solid cam that has a bit more duration and more lift on tha exhaust side. I don’t think there’s muc more power lurking in the manifolds to warrant the expense of extrude honing though. Not easily done in my area anyway. Thanks

 

[Dartnut]

Just look at the times that the pure stock muscle car guys crank out and say it can't be done.
And on skinny bias ply tires i may add.
Yes, the science that goes into these cars is way beyond the average joe, but they show you what's possible........

 

[cuda620]

Just look at the times that the pure stock muscle car guys crank out and say it can't be done.
And on skinny bias ply tires i may add.
Yes, the science that goes into these cars is way beyond the average joe, but they show you what's possible........

Good point!

 

[AJ/FormS]

Extra exhaust duration of a split-pattern cam, also allows a little more flexibility in the installed centerline, before the effective overlap timing is cut off. This is really only important with long-tube headers, not important at all with logs, and IDK if the shorties can do much with this info either.But that wouldn't stop me from experimenting, or at least spending some time in research. Unfortunately, extra exhaust duration has to come from somewhere and the only available place is from Power Extraction, and in a street combo that means poor fuel economy on two counts 1),a portion of the energy of the expanding gasses goes straight out the exhaust pipe, and 2) when the exhaust finds it's way into the intake on the overlap cycle at lower rpms, that kindof makes a mess of the AFR,lol. And the logs just make it worse as pressure backs up under the carb;which we read as low idle-vacuum and vacuum that does not plateau until after 2000/2200. So anytime your TC locks you into operating down there, you are likely to be running rich, and wasting fuel. The shorties might act as a sortof escape-plenum for the exhaust, and ease that pressure effect some. But I guess you could always run a smaller cam.........still keeping a big split, say 10 degrees or more. And let the cubes do the work.
_________________________
FWI;
In my 367HO, I run a
276/286/110/61overlap cam. 230/237@.050
The compression duration is 116* and Power extraction is 104*, leaving a lot of energy in the pipes which is strong enough to make dust clouds in the gravel as I idle by. That is a pure waste of energy. On the other end; the 61* of overlap which makes a nice fat midrange, idles with; tons of EGR, a low idle vacuum despite the dualplane on it, and needs ~2000rpm to peak the vacuum, which makes that, the lower limit for my cruise rpm. So I set-up the cruise for 100kph/62mph @2150 in overdrive, so I'm ok. But even at this low cruise rpm, fuel economy is atrocious, because so much energy is lost to heating the exhaust, and so much energy goes right out the pipes. It was so bad I never bothered to calculate it.Well, I did one time, and promptly wadded up the paperwork,lol.
For a manual trans SBM streeter, My cam is approaching the upper limit of streetability. I did run the next smaller with which I was much happier. It was
270/276/110/53overlap.223/230@.050 ,I installed this one at 108,
The Compression degrees were 117*, the Power extraction was 110*
I was able to cruize this cam down to 65<1600, and was rewarded with 32mpgUS. With the same Scr,and 3.55s,she made a lil more torque than the 276/286, but didn't have the topend rush.
If you do the math on the exhaust side, you will see that the exhaust valve opens 6 later and closes 3 degrees sooner, and apparently when it comes to cams, small spec differences like this can make large operating changes.
All advertised specs are Hughes cams @.008 lift
Something nobody talks about is what amount of duration is left over. For a streeter, IMO this is pretty important. In the above examples I get 220* on the bigger cam, and 227* on the smaller. The smaller the cam,generally, the higher the number gets, and vice-versa.
227* is typical for a 110LCA cam streeter. But this is all you have and the compression and power cycles have to share it. So if your engine is down on Scr, you have to advance the cam to get some pressure going, so you can actually drive it at low rpms. But....... advancing the cam takes more of the 227, leaving less for extraction. So now the engine is responsive, but sucks gas, cuz there is not enough degrees left over to transfer all the pressure to the crank; some escapes out the pipes..
If you have to run this size of cam, the solution is to not have a low Scr, so you don't have to steal so much from the extraction cycle..
So what I learned was that at my Scr of ~11/1, 104 extraction degrees sucks gas. My first cam the 292/292/108 ran this and so does the current 276/286/110.
And I learned that the 270/276/110 cam had 110* of extraction, and with overdrive, can make really really good fuel mileage at that number.
So, I'm gonna guess that somewhere in between is where you want to be, if you are a streeter........ cuz gas is not likely to ever get cheaper. So I'm looking at a target of 107*. If you have enough Scr to run a 64* Ica, that leaves you with 116 on the compression side, for a grand total of 223; not much. So you need to pump up the Sdr to run less Ica, say 60*. Now the total is 227, about as small as a SBM wants to run.
So now you only have 720 degrees plus overlap to play with.
The range of street overlap is as little as ~40* and perhaps as much as ~70*.. The 292/292/108 has 76* overlap and IMO is too much for even a 360 streeter. But typically 55 to 65 are workable; 55 if fuel economy is important and 65 if not.
Lets do a couple of exercises, just math.
Lets go with 65*, because we already have 107 Extraction targeted.
Ok then 65+720 ( two crank revolutions)=785 total available degrees. Now subtract the 227 we already established, leaves 558 degrees for intake plus exhaust. Which I will give 8 extra to the exhaust. Leaving 550 to split, and so 275 to the intake and 275+8=283 to the exhaust. So there is your street cam; 275/283/116/117. The 65 overlap calls for a 214 Lsa, so here is your cam for a hi-Scr ;
275/283/116/107/114/65overlap.
Now compare that to a low-Scr engine which needs more compression degrees to make adequate pressure. Lets designate 122* to compression and still with the 107* extraction. for a total of 229*
And lets say you are power hungry and aim for 72* overlap. So now 720+72 less 229=563 for intake plus exhaust. Lets take 9* for the exhaust split, leaving 554/2=277 for intake and 277+9=286 for exhaust.The LSA will be (563/2 less 72)/2=104.75.. so your cam looks like
277/286/122/107/104.75/72overlap.

Now look at the intake numbers; 277 intake is bigger than 275, which is counter intuitive to making pressure. The exhaust everybody says who cares, as long as it's bigger than the intake for factory heads and logs. The extraction is the same. But then we come to the LSAs. 114 versus 104.75.. This is where the magic happens! Not really , this is just what we get when we select the other numbers,lol.
But we can make some inferences from this number as it couples with the overlap.For instance; the first cam has a wide 114LSA and 65* of overlap. Ica will be 64*, and a 360 cuber will need an Scr of ~9.8 to run it close to 160psi
The second has a tight LSA of 104.75 and at an Ica of 58* only need an Scr of 9.4 to accomplish the same 160psi.
The wider LSA will have a wider powerband, suitable for an auto trans, at the expense of absolute power, whereas the tighter LSA has a bit more overlap, which can lead to a higher specific power number,allbeit with a tighter powerband suitable for a manual trans which has tighter ratios.
BTW
the 292/292/108 has 212, and IMO is a terrible SBM street cam
the 340 cam has 220, and was a pretty good cam for an automatic
the 360 2bbl cam comes to 240*, and when you pump the compression up, you can tow a mountain with it.
I can't say how these numbers translate to BBs, as I've never played with one.

The point I'm trying to make is that nobody pays attention to Compression degrees plus Extraction degrees; it's like whatever.......................

 

[rumblefish360]

cuda620 said;

But someone on here got over 500 with just manifolds. He actually wrote a book. His name evades me now... Thanks

Member AndyF

 

[cuda620]

Ok.... Thinkin about the mopar 528 cam. Andy F had very high praises for thin cam. But I’m gonna use hi- po exhaust manifolds on my 451. No headers for me. Schumachers, while fitting my app great, won’t make anymore power due to very small tube design... imo. Thanks

 

[rumblefish360]

Skip opinion and investigate fact.

 

[68dodge]

Anyone ever compared the Schumacher headers to the high po exhaust manifolds? I ask because they’re small tube for figment and I’ve heard 475 hp is all. But someone on here got over 500 with just manifolds. He actually wrote a book. His name evades me now... I’d like to know before I spend the money. Thanks

Just for info my car makes 500HP with Schumacher headers. And ran best of 11.37s.

 

[oldkimmer]

The .528 cam is an awesome cam. It may not make 500 hp but it will run mid to low 11s in a 3200 lb car. Kim