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Discussion Starter · #1 ·
I've been doing intake manifold for my K24 RWD build and wanted to share the progress so far and hear comments if there are easy improvements still to make.

The starting point was a RAA intake that got me the first about 7cm from the head flange.
https://flic.kr/p/2nMcaSa
Doing this whit saw was good exercise :)
https://flic.kr/p/2nMbKQB
This is the piece I got
https://flic.kr/p/2nM5KF9 https://flic.kr/p/2nMazgk
Then some cleaning was done to remove unnecessary stuff
https://flic.kr/p/2nMcaMf
First cylinder pipe pointed too much towards rear of the head so that was straightened
https://www.flickr.com/photos/[email protected]/52362354372/in/album-72177720302278278/

Not final weld
https://www.flickr.com/photos/[email protected]/52363294661/in/album-72177720302278278/

If the pictures work, I continue in the next post :)
 

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Discussion Starter · #2 ·
Repost with pictures now inserted

I've been doing intake manifold for my K24 RWD build and wanted to share the progress so far and hear comments if there are easy improvements still to make.

The starting point was a RAA intake that got me the first about 7cm from the head flange.
Glove Auto part Personal protective equipment Metal Safety glove


Doing this whit saw was good exercise :)
Automotive tire Gas Electric blue Auto part Soil



This is the piece I got
Automotive tire Bumper Eyewear Rim Motor vehicle



Then some cleaning was done to remove unnecessary stuff
Automotive tire Auto part Font Metal Automotive wheel system



First cylinder pipe pointed too much towards rear of the head so that was straightened
Automotive tire Vehicle Bicycle part Wood Rim



Not final weld
Gas Nut Fastener Auto part Nickel
 

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Discussion Starter · #3 ·
I got nice velocity stacks from Aliexpress, 3 euros each.
Fluid Gas Electric blue Metal Plastic



There was sharp edge in the velocity stack, so that was blended in with rest of it
Yellow Gas Circle Auto part Rim



Next was plenum modelling
Musical instrument Office supplies Household hardware Wind instrument Wood


Plenum is going to be made from two pieces of 3" aluminium boost pipes by cutting them to suitable pieces

Got some parts from a friend who works in a laser cutting company
Crankset Wood Automotive exterior Suspension Bicycle part



The pipes will be 50mm boost pipes. There is 90-degree angle, so I can cut a smaller, say 15-degree angle from it and put it towards the piece cut from the RAA manifold, to get the plenum to suitable place/height.
Scroll Leg Comfort Glove Thigh


More in next post
 

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Discussion Starter · #5 ·
Making plenum out of these
Tool Hand tool Bicycle part Monkey wrench Household hardware



Cutting the plenum pieces, inner/short curve
Road surface Asphalt Automotive tire Tints and shades Art



Longer curved piece cut and testing it to place
Automotive lighting Hood Wood Automotive design Automotive exterior



Straight aluminium pieces needed to complete the plenum
Wood Art Human leg Automotive tire Thigh



Cutting the pieces out
Wood Beige Bag Gas Luggage and bags



Plenum put together with tape
Window Gas Automotive lighting Composite material Nickel



Plenum is fed with 78mm throttle body, connection piece is made, will be welded to the plenum when welding everything together
Motor vehicle Automotive tire Gas Engineering Nut

Wood Gas Audio equipment Hardwood Auto part



Made heat insulation from 4mm bakelite.
Hood Motor vehicle Automotive tire Bumper Wood
 

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Discussion Starter · #6 ·
The velocity stacks and pipes have inner diameter of 46mm, velocity stack outer diameter is 70mm.
Length of the runners not decided yet need to get the engine to the car first.
"back wall" of the plenum is 100mm high and the "curved pieces" opened to 80mm so plenum is slightly "opening" towards the head.

Now I would like to hear if there are areas of easy improvements in my design.
And also recommendations of runner length.

Motor will be:
K24
Stock RBB head
Skunk stage 2 cams
about 12:1 compression
Boosted with E85, target about 500whp
K20 oil pump
No AC or PS

Since it's going to be boosted engine, the intake is made maybe a bit "small" to work well with low RPM.
 

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At very high boost and air flows, flow and pressure distribution within the plenum become an issue. You might consider using a dual chamber design with a feed slit from an asymmetric small inlet chamber into the symmetric main chamber.

Next, flat alloy plates tend to ballon and crack, plate and welds under cyclically applied boost. They either need to be strutted/braced, thick or also round.
 

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Discussion Starter · #8 ·
At very high boost and air flows, flow and pressure distribution within the plenum become an issue. You might consider using a dual chamber design with a feed slit from an asymmetric small inlet chamber into the symmetric main chamber.

Next, flat alloy plates tend to ballon and crack, plate and welds under cyclically applied boost. They either need to be strutted/braced, thick or also round.
Yes, the distribution of air might be a problem. Plenums are tapered from feed in to the other end just to combat this phenomenon. Air wants to "rush" to the end, so first cylinder would have less air (be rich) and last too much (be lean or knock) and therefore plenum is larger in the beginning to have more pressure to the first cylinders. My dimensions are a guess, so I might need to go to dual chamber design later.
I'm planning to measure individual cylinder exhaust temps (at least in dyno) to get understanding how well the distribution works.

Cracking is one issue as well, however I'm hoping with the modest boost of about one bar, the current design would live several years....

ps. realised that put this to N/A side of things although it's going to be boosted design, however the intake manifold experts are on this side, I assume :)
 
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