Everything in header design

[6 cylinder puller]

Okay I have the basic idea how they figure the length and size of pipe. But what about collector size ?length? Angle ? The transition cone ? What about 4 to 2 to 1 headers and other designs that pair one header to the other side on certain cylinders. I remember seeing a drawing of a v 12 engine that had three collectors that were placed at different lengths on one bank to help the torque in three different rpm areas. How do you figure out these decisions are right for you build and what they need to be?

[77cruiser]

This might get you close. http://www.coneeng.com/pdf/Area_Calculation_Table.pdf
Then you have Pipemax, that will get you some more info.

[NewbVetteGuy]

And then there's the Easy Button, especially if you already plan on using a good merge collector: http://www.exhaustengineer.com/technica ... t-modeling.

I'm still VERY much a newbie, but from what I can tell you ask a detailed header question beyond PipeMax results, or a detailed valve job question, and the forum suddenly goes mostly silent or switches to insider whispers and hints only. (Other than the commenters stating that the finer details of the exhaust won't make an appreciable difference.)

Seems to be the areas where secrets are still held to tightly.



Adam

[6 cylinder puller]

I agree Adam I am pretty new myself but I am looking and dreaming about building a header for a pulling tractor. Which the heads and ports are extremely poor compared to car heads. So I am looking for all the splints I can physically use to help flow and velocity. Also trying to learn a few things along the way before I start my build.

[modok]

long, half length, short, venturi, megaphone, and AR collectors all have different properties. Which one is right depends on what the other primaries are doing or not doing, and how abruptly you can merge them depends on that too, and the collector can influence that....so So, the merge angle leading to them may be different depending on which one you choose. There are many rules and principles, and I don't keep secrets, but it's all INTERDEPENDENT. There is a lot to know, but all that does is narrow down your possibilities to a half dozen you can test. There is no replacement for testing. It's called tuning......and tuning is messing with something until it works. blindly or half blind, or getting the right results for the wrong reasons, it's still tuning.
Which one to choose? well, for one thing you should start with an engine with a definite number of cylinders and firing order. before you start building it, for sure, once you've done that, then IMo it depends on how hard you want to work. You can have a collector that is a megaphone of a particular angle and is a particular length and has a reverse cone on the end and and and.....it's so complicated, you could build 100 different ones to test, and still not know for sure.....
A straight collector you just have diameter and length, which narrows down reasonably fast.
Just tuning with a venturi choke, you have...just one size, so. that's easy too.

BUT, the primary size and length may not be the same for all possibilities....I don't want to make it sound impossible, but, once you've got the collector FIGURED OUT, it may be the done, or you may have come so far the primary size and length isn't ideal anymore!!

[PackardV8]

building a header for a pulling tractor. Which the heads and ports are extremely poor compared to car heads. So I am looking for all the splints I can physically use to help flow and velocity.

Would exhaust header extraction be analogous to turbo boost? The less the ports flow, the easier it is to build boost; better they flow, the less boost seen, but more power.

I do know flatheads, which can't breathe, intake and exhaust tuning is much less effective percentage-wise than on a freer-breathing OHC 4-valve.

Is it also the case on the exhaust side that it would be possible to build a very efficient extractor system which would outflow the port and thus "choke"?

So can anyone give guidance on how much exhaust effort/expense is likely to produce how much result on a strangled head design?

[modok]

the only way it would not work is if the exhaust port is too small for the rpms, and that probably isn't the case. Almost all old and industrial stuff the E/I ratio is generous, or maybe even both valves the same size, so the intake side will ckoke first.
The sooner you pull on the intake the more you can flow, the header you can use to start pulling before the piston has moved down. A most certain advantage. If it didn't work you did it wrong!!

[6 cylinder puller]

Well some of the head problems are that the exhaust throat is larger than the exhaust valve. It enlarges just passed the valve seat and the intake is a shared, one intake feeds two cylinders. 4 cylinders, 390 cubes , 3000 rpms 6.5 stroke 4.375 bore 14.5 comp. two valve head both intake and exhaust ports are on the same side of the head. So it’s not a cross flow. Thanks and I kinda figured on the tuning part but if I can try to limit my options to try, I ll put forth the effort. Thanks Jack I appreciate the fact you always help with most of my post !! But thanks everyone for the help also !

[hoffman900]

building a header for a pulling tractor. Which the heads and ports are extremely poor compared to car heads. So I am looking for all the splints I can physically use to help flow and velocity.

Would exhaust header extraction be analogous to turbo boost? The less the ports flow, the easier it is to build boost; better they flow, the less boost seen, but more power.

I do know flatheads, which can't breathe, intake and exhaust tuning is much less effective percentage-wise than on a freer-breathing OHC 4-valve.

Is it also the case on the exhaust side that it would be possible to build a very efficient extractor system which would outflow the port and thus "choke"?

So can anyone give guidance on how much exhaust effort/expense is likely to produce how much result on a strangled head design?

An Elston built header was worth no worst than 10% more power everywhere (12% at most) over a Stahl type header on an engine I would consider having a very compromised cylinder head.

[6 cylinder puller]

Okay well okay can we break this down a little. I have a few questions about a few of the options mentioned. Like how the firing order affects the header and how do you chose which cylinders to pair with each other ? How about I ve never heard of a straight collector and then placing different ventures in it ? How about I ve seen where a few change primary tube size. Like go from 2 inch to 1 7/8s at a certain length before the collector.

[77cruiser]

Give Calvin a call I'd bet he would be willing to help out.
http://www.elstonheaders.com/

[Tuner]

Well some of the head problems are that the exhaust throat is larger than the exhaust valve. It enlarges just passed the valve seat and the intake is a shared, one intake feeds two cylinders. 4 cylinders, 390 cubes , 3000 rpms 6.5 stroke 4.375 bore 14.5 comp. two valve head both intake and exhaust ports are on the same side of the head. So it’s not a cross flow. Thanks and I kinda figured on the tuning part but if I can try to limit my options to try, I ll put forth the effort. Thanks Jack I appreciate the fact you always help with most of my post !! But thanks everyone for the help also !

Perhaps protrude the pipe into the port to reduce the diameter of the port. Do the rules allow you to machine the head and change the angle at which the pipe enters the port to get a more direct exit from the valve bowl? I've seen cast iron Pontiac heads machined so the header primary tube slips into the head at an angle above horizontal, thereby eliminating the U-turn in the Pontiac exhaust port. I'm guessing that for a pulling tractor the pipes can be straight because bends are not required fit, as in a car. Consider making the primary like a stepped header but with the pipes able to slide over each other like a trombone, 1-3/4 inside 1-7/8 or whatever, so you can easily change the length to experiment.

[6 cylinder puller]

Tuner the port actually goes back to a normal size after the bowl. I should have said bowl not throat. But i can imagine velocity drops dramatically after the valve seat. I was actually wondering if I enlarger the valve till the bowl and seat was a smooth transition if there would be any benefit. But it would be quite the size jump flow would probably increase and velocity would probably be close to the same or slightly lower. Thoughts?

[cjperformance]

How much of an enlargement after the valve are you talking?
What diameter are valve and bowl?
A twist on what Tuner suggested, could you machine a combined seat and bowl insert , like a seat insert with a 'skirt' that protrudes into the bowl. May or may not be practical or even worthwhile.

[6 cylinder puller]

Guessing since I am out of town and can’t give you an actual measurement my guess is a half inch difference. Enough so that there is a flat area around the valve behind the seat that is parallel to the valve face. I like the idea thought ! Wish I could include pictures but again I am out of town.