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ok so i am tired of trying to use stuff that won't work. these are a few studies of what i might make. i could use runners with 1 bend and cross ram them. the plenum will be split and i have a fellow who makes stacks looking into making 1" x 2.5" for me. if i weld in trumpets it will be a dry only of course.


let me say first that i am sick of trying to use parts that will never work.

so i quit trying and have purchased a brake and sheet metal, tubing to do the job.

the tubing is 1" x 2.5" x .064 aluminum tubes. the sheets of aluminum are .085 thick.



here are the basic parts. they are not welded so their shape is off a little. they are also just mocked up for this picture. the runners are 11" and 14". it will create two distinct torque peaks. one at ~3900 the other at 4700. one thing that shows up in the modulars is a torque loss at 2900-3600 with bigger than stock cams and 11" or shorter runners. i left the cmc plates in the lowers. if i change the pcm to an 05+ pickup truck part, the VCT and cmc will come in handy. they are wired open for now.









so there is the secret thingy.

also the runners are parallel and vertical so they can be cut and shortened or lengthened based on dyno results. the plenum will be exactly as tall as the 4.6 part or 8" tall before adding provisions for a TB on top. i can put the TB opening anywhere i want it. i will probably weld a square bore holley flange to the top. this is a wet manifold, so carbs can be used with an 8 psi fuel pressure regulator and 6an return line. or it can be used for fuel injection. i have 8 injector bungs ready to weld on. carburetor will require a TPS to be fitted to use my current PCM. otherwise an MSD unit will work.

i am going to fuel inject if first. -b
 

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What engine is this for? 2v? 3v? single or split-port 4v?
-Thomas
 

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Those bends will not be smooth so flow will suffer. Just do yourself a favor and buy one of these.



:hitit:

-Miller
 

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if anything borrow your design concept from that... im not an expert but kinky bends dont belong in intake runners. if your really want to go your route maybe use a compass and draw out a real smooth curve and cut it out with tabs that bend down to secure the inside and outside wall (top and bottom depends how you look at it) then give a a really smooth bend to said walls and weld that. kinks are bad. but like i said im not an expert.
 

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Those bends will not be smooth so flow will suffer. Just do yourself a favor and buy one of these.



:hitit:

-Miller

that is for the 2V motor, he has the 3V 5.4L truck motor.
 

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the 3v 5.4 is single-port correct? If so, those different length runners are a horrible idea. It will lean out 4 of the cylinders at low rpm's, and lean out the other 4 at higher rpm's. And they are right about the notching to create a curve, it will create a great amount of turbulence. You would have been better off using a sheet and cutting out a banana shaped wall, then bending the top and bottom walls at a curve and welding all the edges.
-Thomas
 

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I'm guessing that Logan intake is on a forced-induction engine, because of the short runners. On an N/A application, added runner length would be need to have any usable torque for street RPM range. That's the main reason why the 5.0 EFI engines were so torquey, very long intake runners.


cheers
Ed N.
 

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Discussion Starter #9
the 3v 5.4 is single-port correct? If so, those different length runners are a horrible idea. It will lean out 4 of the cylinders at low rpm's, and lean out the other 4 at higher rpm's. And they are right about the notching to create a curve, it will create a great amount of turbulence. You would have been better off using a sheet and cutting out a banana shaped wall, then bending the top and bottom walls at a curve and welding all the edges.
-Thomas
yeah i realize that. unless it is carb only it won't work. the idea is an extension of MMR's 5.4 3v intake. their intake has one bend in it instead of 3 like mine.

still. i am going to try different things. the hogan piece is not a street part.
 

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Discussion Starter #10

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I would be willing to bet that the MMR part, even though it has a bend, is smoothed out on the inside. They used cut box tubing, kind of like you did, but I bet it has a thicker side wall so the bends could be filleted. I would still suggest that you start over. You can try it out but I can tell you right now it won't flow worth crap.
-Thomas
 

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Discussion Starter #12
you know , when i ordered this tubing i considered thicker wall. i may just order some more. it goes up to .125.

.065, .085, and .125 wall.
 

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Discussion Starter #13
i was reading a paper on turbulent flow. according to the paper turbulence is created in ANY bend, whether smooth or sharp. the actual loss of flow resulted from the difference in velocites of air as the floor beging to bend, trying to follow the floor, while the air at the top continues along it's longer path. the resulting shear as the top tries to keep up with the bottom causes a low pressure area the acts to draw the inner bend air to join the upper flow. it results in vorticies that cause all kinds of turbulent flow. it is only after the airflow straightens out the laminar flow restarts. it also says the a 1.5 degree taper in a 12" pipe will outflow a staight pipe. even though the difference in crossection is only .002".

really no matter what shape i give it, a bent runner is a losing proposition. if the inside flow has a path with a large enough difference to the upper runner. thus tunnel rams have very little runner bend.

it was also suggested that cuts in the floor to slow down the inner flow would help turbulence by making the inner flow wait for the upper flow to catch up.

interesting stuff.


here is a link.

http://beautyofspeed.com/data/cylinder_headtech/
 

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the logan piece pictured above is on my friends mustang and its a true street car. he drives it to work and does a little driving on the 1320 too but its a street car.

and last i checked. keith has 5.4 intakes at the shop. not sure why they are not listed on the site.
 

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I would suggest picking up a text book on introductory fluid dynamics. The complex bends will result in minor losses, the magnitude may be calculated based on inlet velocity and relative roughness of the inside of the runner.This itself may or may not be relevant based on factors such as fluid velocity, hydraulic diameter and relative roughness of the inside of the runner. Your greatest losses will come from obstruction in the flow, that is, rapid discontinuity in the smoothness and shape of the runners.

Your discussion of laminar flow and entrance/ development length of the flow may of may not be of value. If your flow before the bend is already in the turbulent region, that is in this case, a Reynolds number of greater then approximately 4000, you will need to work with the "mechanical energy equation" and head loss principles to determine if the bend robs you of that much.

I hope this helps a bit. I don't know much about actual intakes, but fluid dynamics I am able to chime in about.

Steve
 

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good to hear from someone who knows about this very obscure area of science.....what is a good introductory book on fluid dynamics?.....mathematical complexity within the text need not be considered as I have great mathematical abilities :)
 

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Discussion Starter #18

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ok so i am tired of trying to use stuff that won't work.

the runners are 11" and 14". it will create two distinct torque peaks. one at ~3900 the other at 4700. one thing that shows up in the modulars is a torque loss at 2900-3600 with bigger than stock cams and 11" or shorter runners.
I'm sure this has been said before but the runners must be the same length, otherwise the tuning is going to be a nightmare, or you'll lean out one at idle and rich up the other, and lean one out at high rpms and rich out the other, I just can't see that much of a difference on half the cylinders per bank running properly, there would be so many lean and rich conditions that you would have to find a way to make work it doesn't seem worth it, the bends as well are too sharp, you want a smooth continuous bend, not sharp breaks like you have.
 

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yea thomas had mentioned that ealier......tuning this thing would be a nightmare, but i dont think its because certain cylinders will be leaner/richer than others at different times......i think spark advance will be the culprit of tuning nightmares........

when you have a short-runner system, at low engine speeds, it makes the cylinder more of a slow-burn type chamber, because the aircharge hurling thru the short length runner doesnt acquire enough momentum and velocity to really get the air and fuel mixted thoroughly, thereby needing more spark advance to get the most torque out of it (AKA: reason spark needs to be added when IMRCs are open on pre-98 4V B-head engines)......but at the same time, the aircharge going thru the long runners will gain the necessary momentum and velocity to make it a typical fast-bruning chamber that does not need quite as much spark advance to get a useful amount of torque out of it

so IMO, at low engine speeds, you will be limited to 'running on 4 cylinders', so to speak...the ones being fed by the long runners....because if you were to dial in the [greater] spark that the cylinders with short-runners need, the cylinders being fed with long-runners might knock due to too much spark advance because the combustion rate will be faster there......and at higher engine speeds, you'd also be 'running on 4 cylinders'......the short ones.......these will be the ones producing the majority of the power....and I feel you'd still be knock-limited when trying to get the most power, because some air will still be flowing thru the long runners, which will put a 'cap' on the timing advance which will be below what the cylinders with shorter-runners require

thats just me thinking out loud :)
 
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