Tom: What are your thoughts on this manifold? I understand the high velocity/low pressure idea to balance intake flow, but this seems extreme. In addition, we have the burst panel right over the rear intakes. I wonder how "clean" that panel is underneath. Wish we could see inside!
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The People who built this intake are not John Marcella (Marcella Manifolds) type people.

They have some good CNC Machining Skills when it comes making CNC parts, but believe that this might be their
first venture building a Twin Turbo Type set-up. I could be wrong though. They typically campaign a couple of
belt driven Supercharged Vehicles. Maybe they did it for easy access since that might make a few tuning mistakes initially with the new set-up and the twin turbos. Just guessing here.

Tom V.

 

Sorry for slow update. Not much progress, but there is some related to fuel and manifold.

Downstream injector seats are now pretty much done. Some tidy up to do (welding turned out discusting, like horror movie messy!) I keep telling myself that I would have needed to grind those welds down anyway because of the tight fit to the frame tubing...
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Front one was a very tight squeeze.
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Should be closer to the valves and angled a bit steeper, but I couldn't find a way... At least there is symmetry between front and rear ports.
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Well here's mine....impressions?

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Rear cylinders will get more air flow than the ones nearest the throttle body

 

Personally think that the "Flat Top" lid is not a good idea but Marcella has built them that way for the Corvette Guys.
https://www.corvetteforum.com/forum.../2774383-marcella-intake-finally-came-in.html

I agree that most of the air will pack up in the back cylinders, I wonder how Marcella is getting around that deal with the corvette intakes.

Tom V.

 

Lots of racing going on with the different teams but wanted to check in on how the intake manifold was going.

Tom V.

 

Internal injectors getting plumbed and fitted.

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Not sure how these fittings are supposed to be used (never used them before), but if drilled out to 13.5 mm the'll snuggly fit an injector...

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Chopped some threads off that swively elbow-thingy and made a spacer.

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Front cylinder, upstream injector, in place. If it isn't obvious yet; I am completley winging this and have no idea if this solution will hold fuel under pressure.

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Rear cylinder upstream injector is in there too, it's tight but the lid allows for its removal if needed.

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Almost done, some final welding left to do along with wiring and connector placement. Both downstream injectors will be plummed and wired externally.

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You never know until you at least try it one time.

Tom V.

 

You will need some kind of thread sealer on your cutoff AN hose fittings. Those threads are not meant to seal fluid. They just clamp the hose into the fitting.

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Question for you 3D printing guys. I've got a holley stealth ram and I want to make some spacers for it. Is there a plastic that's suitable for doing that I can use at home? Haven't gotten the printer yet but am working that direction slowly.

 

Most of the plastics used in home 3d printing are fairly low temp thermoforms (meaning if you heat them back to that temp they will melt again) You would need something like a UV curing resin and these printers are pretty expensive. If you came up with solidworks drawings for a 3 axis I could possibly CNC them for you out of phenolic... it would almost certainly be cheaper to buy the parts if they are available.

Your other option would be to print the parts in something like PLA and set it up for a mold, then make the parts out of something like carbon fiber, or pour your own reinforced resin.

 

At that rate I could also finish the foundry I have sitting in my back yard and convert the plastic into aluminum too. It would be amusing to make a say 8" tall section of it then just cut off what I want and have someone mill it flat.

 

Another possibility would be to build cad drawings and have someone local to you EDM or water jet cut them. These services are usually pretty inexpensive if your not trying to rush something. Your building a flat part so there are a ton of options for processing.

 

Been watching this thread for some time, searching and doing research. Ended up with the design below.
Not yet finished, but the guts of the design is there to see.

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LOOKS LIKE YOU HAVE A LOT OF THE THOUGHT PROCESS WORKED OUT AND THE FABRICATION OF THE INTAKE IS COMING ALONG WELL!!!!!!!

Keep up the good work.

Tom V.

 

Have a minor fitment issue with the first plenum feed.
Goal was 5x the inner diameter of the tube to allow the velocity and pressures to equalize before slamming into the roof of the plenum. But we cannot fit the length I wanted in the design, so it's short.
Throttle body is feed from the Passenger side, so the highest flowing tube is the 2nd in from the front, followed by the 3rd. 3rd flowing is the front, lowest flowing is the rear.
We are thinking of kicking the 2nd feed tube forward a few degrees to push the air from the front tube straight.

For reference:
Engine displacement : 302
Plenum pressure: 25-30psi (1500+hp), 85MM single turbo (peak boost comes in by 4500 if desired via tuning)
Head flow 320+cfm and 2.62 sq/in cross sectional area at the manifold feeding dual 38MM high flow valves.
TiVCT variable cam timing in tact with 240 degree intake, 211 (stock) exhaust. Peak power between 7500 and 8000 (projected).
Head intake runner length 4.9"
Manifold runner length 9"
Manifold runner cross sectional area at plenum 4.90 feeding a 2.25" OD .065" wall round tube transitioning to oval and matching the head. (4.90" velocity stack inlet to 3.52" transitioning to oval and a final neck down to 2.62")
Runner volume 34ci (each)
Projected plenum volume 675ci
Plenum height (inside from floor to roof) 3.75"
Feed tubes extending 2.5" up from the floor to reduce turbulence and keep the air straight when it slams into the roof.
Feed tube volume yet to be calculated, but total manifold volume will be over 1000ci.
Feed tube area (x4) matches throttle area.

So the debate is 'let it ride', or modify the design.
We can kick the 2nd tube forward just a few degrees, or weld in a 1/4-1/2" 'tray' on the roof around all the feed tubes to force the air together and lose further velocity before moving into the plenum (may have to lower feed tube height into the plenum to compensate).

Or we are open to ideas.
On a time crunch though. LOL SCSN is just a few weeks away and we need to test soon.

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Personally I think that you are over engineering the multiple feed tubes vs just using a single feed tube and having the air slam off the roof of the center of the plenum.
Depending on the air speed thru the tubes the flow will constantly change for each tube with multiple tubes.

Audi tried to do the same thing with their slotted feed tube which did not work any better vs a single center feed tube and in many tests was worse as far as uniform distribution. I personally did a lot of that testing program for my old employer. I retired after 39 years.

I know you have time into the intake the way it is but just giving you my experience having already done a 6 month flow bench/dyno engine test at work. Center feed does work. You can either try to slow the air down drastically with a forward T/B and a BIG plenum or you can kill the air velocity by slamming it off a wall (roof) of the intake.

Tom V.

 

I tested the cones. I had Conengeneering make 4 cones to my specs. Had a design laid out for dual cones feeding from either side of the plenum in an attempt to mute the inertia of the incoming air.

I tested the cone with 50mph airflow. Set it all up with the small end blocked like it would be in the manifold, set the slot up to the exact size specified across the entire length (12" in this case). Took my hand held weather station and measured air speed across the slot. To my delight the speed was constant across the entire slot!
However.......
Simply feeling the air with my hand told me the MASS of air was VASTLY different across the slot. Not only was more mass of air coming out of the small end, but the air was till going forward out of the small end of the cone (with the end blocked). The inertia of the air at a mere 50MPH was enough for me to scrap the design. I could only imagine what it would be like at Mach .5 air speed.
Next design was to turn one cone around, so one would feed from the front, the other from the rear. In this way I could even out the airflow, but that would induce massive swirl in the manifold, so that was scrapped.

It's the inertia of the air at massive speed and pressure (high mass) that we need to control.

I have a front feed manifold on the car now. The OEM 2013 Boss intake manifold. This design is quite good for a front feed as the runners are in the center and the shape of the floor (raised for the runners at an angle) forces the incoming air around the 'V' shape and into what could be called 2 smaller plenums. The problem is (again) with air mass and significantly higher air speed the inertia of the air over-feeds the rear cylinders.

I'm a spark plug reader and ECU tuner. With the Boss manifold at 20psi and 1200RWHP Cylinder #4 and 8 needed 10-12% more fuel, cylinders 3 and 7 I added 6-7%.
Upon disassembly of the engine (factory) the valves and chambers showed even that much added fuel was NOT enough, and even the #2 cylinder needed fuel added. (Hard to read plugs on Ethanol fuel)

I see *new* front feed designs for these engines, all with the same limitations and in most cases WORSE than the Boss manifold.
Those tuners that do not add fuel based on airflow distribution blow engines regularly.

Hell....even the Factory OEM 2013 F150 EcoBoost tune file adds 12% fuel to the rear cylinder at load. That's 18psi boost in a factory 3.5L flowing less than 50lb/min air. (see picture attached). The F150 maifold is much like the old 'Downs' intake on the Fox platform. Short runners and a box style plenum with 1-2" of runner in the box, fed from the front.
If the factory is adding 12% fuel at 50lb/min......what would it take at 150lb/min?

Perhaps you are correct that I am over thinking things.....or perhaps the problem is far worse than most realize, especially as we add MASS (via boost) and air speed (via higher flow heads/intake) to these small engines.

I've got some perforated aluminum sheet on the way. 51% open
Thinking about using it to create tube extensions on the 4 feed tube and welding to the roof. (2" or so solid runner and the rest perforated all the way to the roof).

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Also, as you can see in the screen shot and as you are well aware.
Airflow distribution changes drastically on these front feed inlets with RPM and airflow, making it extremely difficult to counter via tuning.
Same goes for any manifold design. A front feed plenum with a hump and throttle angle to bounce the air off the hump may work well at one RPM / Mass and horrible at another.