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Main issue I see really is the sharp edges at the entry to each runner.

Sharp edge = about 62% of the assumed flow from the pipe.

Put a nice radius on the enlet and you go to 98% flow.

(You mentioned that would were going to do that with air horns and a larger plenum.

NA plenum needs to be 80% of engine displacement. Boosted engine at least twice that number. or 160% of displacement of the engine.

Tom V.

 

Thanks for the input Tom!

What kind of radius should I be looking at? 3/8"? Not positive how I will go about it yet. Open to suggestions

I was planning on 120% plenum, I can probably go to 160 I have to start playing there

Thanks for any suggestion or input. I'm just winging it

 

3/8" radius on the inlet will work as well as a much wider bellmouth.

Volume is a rule of thumb deal. Boosted engines like more volume.

The volume is related to the rpm too but if you want to go 150-160% would be a good start.

Tom Vaught

 

thanks for the thoughts!

 

i have made more progress

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and throttle

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, i either only got 7 or lost one magically lol

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I do have a question. Fot the plenum, what is a better plan?


Something like this where extend the sides, and then cut a large tube in half and place it on top


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Or bend something like this up on a brake?

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I planned on using 1/8" material, or should I move to 3/16 for that much surface area?

 

If you are running a NA engine make the Plenum Volume about so that you are 1.5" away from the sides of the Air Horns and 3" from the top of the Air Horns with your bottom feed design. That 3" allows the air to bang off the roof and distribute properly to the runner air horns.

Boosted engine can go with a larger volume and 4" above the Air Horns as you have more air velocity with boost and with your Divider slots the velocity will be even higher due to the Nozzle effect.

Tom V.

 

Thanks tom. Your input is always appreciated!

 

Thats a pretty neat build Zac. I like it.

-Tony

 

Awesome thread!

AlkyV6, I like what you came up with for the Buick V6.

 

So am I wrong in thinking longer runners are used for low end and shorter runners for top end power?

Great thread btw! I am building a custom intake for my 4.6 2v mod motor.

 

Richard Holdener is a Bonneville Salt Flats buddy of mine.

He has written an excellent book on tuning 4.6L & 5.4L engines for NA and boosted applications.

In this book: http://www.barnesandnoble.com/w/bui...082&isbn=9781613250082&kpid=9781613250082&r=1

He gives some excellent information on Tuning intake manifold runners based on HIS dyno testing. Book is cheap vs the knowledge inside.

Tom Vaught

 

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Tom you might like this , its for the 302 engine they were made years ago when turbochargers and superchargers for the 5.0 came out , I had one myself the bottom used a short ram 2 x 4 carb intake with the upper welded on and injector bosses , back in the 90s this intake was 1000$ the original name was FLOmaster

here is the web site they have some nice stuff http://buildandtune.com/sheet-metal-intake-manifolds/

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Nothing wrong with the basic box on the top design.

The air goes thru the throttle body, "bangs off' the back wall, disperses to the front and rear carb mounting locations and goes thru the runners.

A Buddy of mine WALLY BEABER designed the Ford GT-40 302 Intake: http://www.allfordmustangs.com/foru...-gt-40-intake-tubular-varients-0325081041.jpg

Tom V.

 

This thread has a lot of very informative stuff I will adapt a lot of this into my build thanks for your hard work and all the support from the community.

 

I am going to hop in and ask for some expert guidance on this manifold design.

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I plan on doing velocity stacks on the runners. I also plan on blowing "up" thru an air to water intercooler so it will be from the top down ( plenum, intercooler, and then "hat"

 

Guess I should have posted here..

https://www.theturboforums.com/threads/378412-Intake-manifold-runner-entry-feedback-on-design

 

Moving forward

I like it a lot, I have quite a bit of volume now, just under 120%. Have my engine shortly so I can see how it will run

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