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My guess is a proper merge collecter would lessen the benefits of a clocked header pattern. On a side note, I once had to clock a set of headers with a hammer a few times for steering shaft clearance . Worked well
 

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So for instance on an SBF, for 1-3 , if you are building a set of tri y's then you would want cylinder 1 and 2 paired together. Not cylinder 1 and 3 correct? Same with 6-5
 

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So for instance on an SBF, for 1-3 , if you are building a set of tri y's then you would want cylinder 1 and 2 paired together. Not cylinder 1 and 3 correct? Same with 6-5
The cylinders paired at the Y should fire as far apart in the order as possible... within practical reason.
 

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pairing based on firing order is totally different to clocking, i would have thought on a 4 into 1 you'd not want to be rotation so the flow is is not swirling losing energy. i think youd be splitting hairs though
 

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pairing based on firing order is totally different to clocking, i would have thought on a 4 into 1 you'd not want to be rotation so the flow is is not swirling losing energy. i think youd be splitting hairs though
When I referred to 'clocking' earlier... it was in reference to installing 4-2-1 collectors. You could turn, or 'clock' them for best efficiency in regards to firing order.

If installing the collectors one way paired two cylinders that fired one right after another, rotating the collector 90 degrees would often help.

Building Tri-Y headers from scratch, it's not usually that hard to pair cylinders for maximum efficiency. When installing 4-2-1 collectors, you only have two choices, so you turn/install them for the best compromise in regards to firing order.

https://www.ebay.com/itm/Maximizer-4-2-1-Exhaust-Merge-Collector-3-85-ID-4-OD-Outlet-2-2-ID-Inlet/232355534689

 

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Actually you are thinking backwards...... think of a toilet.... it swirls to make the water go down the drain faster correct..... same with a header in the correct firing order rotation..... now, put that together, with a great cam from say Chris Straub, and when you have valve overlap, the exhaust is drawing in more air and fuel and then you close that up and you have just put more powder in the BOMB to go BOOM and make more power....
 

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Actually you are thinking backwards...... think of a toilet.... it swirls to make the water go down the drain faster correct..... same with a header in the correct firing order rotation..... now, put that together, with a great cam from say Chris Straub, and when you have valve overlap, the exhaust is drawing in more air and fuel and then you close that up and you have just put more powder in the BOMB to go BOOM and make more power....
Swirling slows the flow down. The fastest path is the shortest path, which is straight. Toilets swirl to help keep the bowl cleaner.
 

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Swirling slows the flow down. The fastest path is the shortest path, which is straight. Toilets swirl to help keep the bowl cleaner.
I don't think they are talking about what would be good on a blower car.
 

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Depends on cam but we have seen as much as 12 on a stocker and on a 632, I have seen closer to 18hp gain....

Proheader
That's worthwhile in my book.
 

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I remember seeing a set of cleveland headers where a couple of the pipes crossed under the oil pan to the opposite side collector. I think they were for a Pantera but not sure.
 

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I remember seeing a set of cleveland headers where a couple of the pipes crossed under the oil pan to the opposite side collector. I think they were for a Pantera but not sure.
These are 180 degree headers... where all of the pulses fire 180 degrees from each other. To do this, some pipes from each bank need to be paired. Use to be fairly common.

https://www.hotrod.com/articles/180-degree-headers-help-v8s-low-midrange-torque/



From the article...

To achieve optimum exhaust scavenging on a four-stroke V8 engine, each cylinder should fire every 180 degrees of engine rotation; on a typical V8 with a cross-plane crankshaft and conventional headers, two cylinders on each bank end up firing consecutively, only 90 degrees apart. The way around this is crossing two primary tubes from each bank over to the opposite bank. For example, on an engine with a 1-8-4-3-6-5-7-2 firing order (with the odd-numbered cylinders on the driver side and even-numbered ones the passenger side), cross tubes from cylinder Nos. 3 and 5, and 4 and 6. Often termed a 180-degree header, this configuration makes the firing cycle seen by each collector occur 180 degrees apart, improving scavenging as well as low- and midrange torque by permitting a smaller collector outlet diameter than normal for a given combination.

The problem is packaging this bundle of snakes. Four tubes must cross either under the oil pan or around the front or rear of the engine. On a high-rpm race mill, it may be difficult to keep primary-tube length down to 32 inches or less.

If that’s not enough, try to arrange the tubes into each collector so they fire in a rotational firing pattern, as seen on Ford’s Indy engines and Le Mans race cars back in the 1960s. Such a rotational pattern further enhances scavenging: The exhaust gas exiting one tube, passing across the opening of the tube directly beside it, creates more signal on that tube than it would on a tube on the collector’s opposite side.

In theory, the ultimate solution to the V8 firing-order conundrum is the flat-plane crank (aka, a “180-degree crank”). Essentially, this makes the V8 act like two four-cylinder engines, allowing the optimized collector arrangement of a four-cylinder engine without the need to cross tubes. But flat-plane cranks cause such severe vibration they can only be used on a pure race car.
 

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Swirling slows the flow down. The fastest path is the shortest path, which is straight. Toilets swirl to help keep the bowl cleaner.
I read an article that a nascar team back in the 2000s basically said the same thing. All these fancy swirled idiotic headers that are "equal length" are junk. It said the straightest with the least amount of bends was the best .

What do you guys think
 

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I read an article that a nascar team back in the 2000s basically said the same thing. All these fancy swirled idiotic headers that are "equal length" are junk. It said the straightest with the least amount of bends was the best .

What do you guys think
I read the same article. I don't remember it saying anything about 'swirl'. It's main point was that making a bunch of crazy bends just to get the tubes exactly equal length didn't work as well as making them straight and free flowing.
 

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I read an article that a nascar team back in the 2000s basically said the same thing. All these fancy swirled idiotic headers that are "equal length" are junk. It said the straightest with the least amount of bends was the best .

What do you guys think
Equal length, least amount of bends is the best. It's not worth putting four 90 degree bends in a primary just to retain the perfect equal length. Every bend will have an effect on flow. Same amount of bends in each primary is a plus.
 

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I read an article that a nascar team back in the 2000s basically said the same thing. All these fancy swirled idiotic headers that are "equal length" are junk. It said the straightest with the least amount of bends was the best .

What do you guys think
Equal length, least amount of bends is the best. It's not worth putting four 90 degree bends in a primary just to retain the perfect equal length. Every bend will have an effect on flow. Same amount of bends in each primary is a plus.
How much does a few dents on the tubes hurt flow or power?
 

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How much does a few dents on the tubes hurt flow or power?
On the Engine Masters show on Motortrendondemand.com they did that very test. The beat the hell out of a set of headers, and they could barely see any power difference at all! lol

They test a lot of goofy stuff that you always wondered about, but people rarely ever took the time to check on a dyno. It's fun to watch.
 

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think of a toilet.... it swirls to make the water go down the drain faster correct.....
Toilets swirl because of the Coriolis effect, not because of any design feature. All drains do that automatically except those exactly on the equator.
 
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