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Discussion Starter #1
Any advantage to having the exhaust manifolds opened up a bit? Just curious
 

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Powerstroke Monkey
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I was just looking at a manifold with that in mind, but I didn't see any bad casting ridges or hard corners in it. Could you get it to flow better? Probably, but it would take a while (it's not aluminum) and the gain would seem minimal.

Would love to see if anyone who has done it has some flow numbers.
 

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I know nothing...
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Opening up w/o changing the E port would help with reversion/drive PSI. On the other hand thining the mass would disipate heat faster, less heat to exapand.


:popcorn:
 

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Dairy Mechanic
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2,198 Posts
Planning on having my builder do some "blending in" on both the ports.
 

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An Ancient view on life
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314 Posts
Porting the stock exhaust manifolds is like grinding inside of a large sewer pipe. Same result. Poop out the back side.

JonFord
 

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Dairy Mechanic
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I misunderstood, I could have the "manifolds" extruded honed" maybe.
 

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if you look at the heads, you can see the manifold is opened up more then the head .port the exhaust ports and get the exhaust out faster?
of spend 1000.00 for headers
 

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Country Boy Toy
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How much porting would need to be done? I will have to look cause I got the stuff to port the heads out.
 

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An Ancient view on life
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314 Posts
I guess my first comment about the cast iron manifold being the equivalent to a poop sewer didn't take, let me put it another way.

Porting the cast iron manifold on a Ford 7.3 is the same as standing facing a strong wind taking a leak. Not fun, gets all over you and worthless.

The confusion that goes on inside of that log manifold is unreal and does not promote anything like organized flow.

The cast iron exhaust manifold is designed for 3 reasons. It is easy to package, cheap to build and very durable to those who like to pull with diesels at very high egt's. They will last a long time under severe abuse.

My take on the Cast Iron Log Manifold supplied by Ford.

When the exhaust charge comes out of the exhaust port from the cylinder head and into a stock cast iron manifold, it enters an area much larger than the exhaust port, runs into a 90 degree wall, slows down because the area is so much bigger, cools off, get confused as to where to go and then to top it off, it gets slammed around by 3 other exhaust charges that are doing the same thing, plus looking for a way out. It is not until the exhaust charge gets to the up-tube that it finally gets uninterrupted direction. It is my opinion that at this point on its way to the turbo, it has lost 5 to 20% of its energy.

The last thing you want in a turbo system, is to slow, cool and confuse the exhaust charge.

If you want to see what all this looks like, take to water hoses and spray it at a 90 degree angle to each other and then add 2 more to the equation.

But then some people don't buy my theory. :pointlaugh:

JonFord

P.S. Enlarging the exhaust port in the head to match the opening of the cast iron manifold is a super bad idea.
 

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dont know how much this is the same or even comparable as i didnt do it on my 7.3, but on my 12v i port matched the exaust manifold to the same size as the gasket and took out a little bit on the inside corners of all 6 holes in the manifold. before the porting i couldnt see through # 3 or 4 very well, now its a strait shot pretty much... with out changing anything else on the truck but the prted manifold i got about 150 degree drop in egts at wot, about 150 rpm faster spoolup(used to light at 1700 after lit at about 1550, so it worked out good for me other than about 20 bucks worth of porting rolls and about 5 hours or so.... I do not know if it would work the same on a 7.3 due to the length of the pipes after it leaves the exuast port?
 

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An Ancient view on life
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314 Posts
The Dodge manifold is not really a log manifold. The 7.3 Power Stroke and 6.6 Dmax are excellent examples of bad log manifolds.

The Dodge exhaust manifold provides a good deal of direction and organization. It does cause some confusion when the charges enter the stream with the other exhaust charges, but at least they are pointed in the same direction.

Remember that air (intake or exhaust) does not like to turn a corner. When it has to, it looses velocity and in the case of exhaust it will loose temp also.

Now, just to confuse everyone, you can preserve some velocity in air flow by enlarging the area in a turn.

JayBuller, if you got that sort of EGT reduction, you must have done something right.

The really hard part of porting is to make sure that you balance the air flow evenly amongst the cylinders.

Believe it or not, the headers on my truck are 1 1/2 inch tubing on the outside. I am also planning on reducing the size of the up-tube from almost 2 inches to 1 3/4. With the headers on the truck at the 1/8 mile track I got .35 tenths of a second reduction in ET. It was still slow, but then this one is still stock. I cruise down the road with about 50 degrees less EGT and from all appearance, it looks like a 5% increase in fuel mileage. The jury is still out on the fuel use.

JonFord
 

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Don't EFN worry about it
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15,588 Posts
The Dodge manifold is not really a log manifold. The 7.3 Power Stroke and 6.6 Dmax are excellent examples of bad log manifolds.

The Dodge exhaust manifold provides a good deal of direction and organization. It does cause some confusion when the charges enter the stream with the other exhaust charges, but at least they are pointed in the same direction.

Remember that air (intake or exhaust) does not like to turn a corner. When it has to, it looses velocity and in the case of exhaust it will loose temp also.

Now, just to confuse everyone, you can preserve some velocity in air flow by enlarging the area in a turn.

JayBuller, if you got that sort of EGT reduction, you must have done something right.

The really hard part of porting is to make sure that you balance the air flow evenly amongst the cylinders.

Believe it or not, the headers on my truck are 1 1/2 inch tubing on the outside. I am also planning on reducing the size of the up-tube from almost 2 inches to 1 3/4. With the headers on the truck at the 1/8 mile track I got .35 tenths of a second reduction in ET. It was still slow, but then this one is still stock. I cruise down the road with about 50 degrees less EGT and from all appearance, it looks like a 5% increase in fuel mileage. The jury is still out on the fuel use.

JonFord
Let me correct all of you its a cummins designed manifold to work in that application as is the one for a school bus or whatever. Just sayen No back to the debate .
 

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An Ancient view on life
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Well I guess I am really messed up then. Ford = International, GM/Chev = Izusu and the wonderful old Dodge = Cummins. We all know what we are referring to, however I am so so sorry for the lack of proper credits.

GASP

But then I am old and don't give a $hit.

JonFord :evil:eek:fftopic
 

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Don't EFN worry about it
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Well I guess I am really messed up then. Ford = International, GM/Chev = Izusu and the wonderful old Dodge = Cummins. We all know what we are referring to, however I am so so sorry for the lack of proper credits.

GASP

But then I am old and don't give a .

JonFord :evil:eek:fftopic
My bad man !
 

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Yea maybe the price would drop to a more realistic price (if they did 50 or more sets at a time the price should come down) and more people would buy them. I can’t justify 1000.00 for a set of them! But they sure are pretty. 
 

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An Ancient view on life
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The flanges on my headers are made of steel and about 1/2 inch thick. The tubing is 304 stainless and is 3 mm thick (.120). Together, they weight about 28 lbs.

JonFord
 

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I think i saw somplace. the flange is 5/8
 
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