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PostPosted: Mon Jan 28, 2013 7:20 pm 
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Group N

Joined: Fri Mar 31, 2006 7:29 am
Posts: 447
Location: Up North
Car Model: ST205
I am going to have a go at making a dual plenum inlet for the ST205, I think I have everything figured out apart from the inlet trumpets, How do I figure out what is the best size to use...and how far into the second main plenum it needs to petrude???

Any advice would be great.

Nial

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PostPosted: Mon Jan 28, 2013 7:32 pm 
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WRC
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Joined: Tue Dec 09, 2008 6:51 pm
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Location: Austria
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Hi,

according the trumpets, d/r=1 should be your target to get the lowest pressure loss

but why do you want to built a custom manifold?

greetz

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PostPosted: Mon Jan 28, 2013 8:32 pm 
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Group N

Joined: Fri Mar 31, 2006 7:29 am
Posts: 447
Location: Up North
Car Model: ST205
Sunny wrote:
Hi,

according the trumpets, d/r=1 should be your target to get the lowest pressure loss

but why do you want to built a custom manifold?

greetz


Why not? Seems like fun. I want a side feed inlet manifold and I recon I could make one cheaper than buying a second hand caldina manifold.

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PostPosted: Mon Jan 28, 2013 8:48 pm 
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WRC
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Hi,

i think a good manifold isn't that easy to built, you need to seperate the air flow nearly equal to all cylinders, the worst case is a unequal tourque per cylinder which effects the
the crank resonance too
no that easy to handle without tests

a few time ago there was a TTE dual one available, but ain't not cheap :lol:

greetz

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PostPosted: Mon Jan 28, 2013 9:12 pm 
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Joined: Thu Jul 14, 2005 12:44 pm
Posts: 4067
Location: drinking devil fuel
Car Model: ST205
Didn't Dan make such a thing. I'm sure there was some CFD pictures back in this day when he posted here


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PostPosted: Mon Jan 28, 2013 9:22 pm 
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Food for thought

viewtopic.php?f=16&t=3518&hilit=manifold


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PostPosted: Tue Jan 29, 2013 9:30 am 
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Group N

Joined: Fri Mar 31, 2006 7:29 am
Posts: 447
Location: Up North
Car Model: ST205
I have been following Dans advice. I missed a trick though but now I think I have it.

Constant radius velocity stacks protruding half way into the plenum.

Does this mean I have to cut extra off the length of the runners? IIRC long runners = good low down power but less up top, short runners = less low down power but better top end. I want to keep the set up as close to Toyotas original set up with regards to runner length so I guess what ever length I add to the runners with velocity stacks I have to cut the same off the runners?

My only other question (or two) now is do i go with domed ends to the main chamber or flat ends?

Also for adding vacuum points I guess the big main chamber is the best place to add them?

I have all the bits sat in my garage, my cusion makes jet engines and rockets in his garage so has all the equipment needed to fab up pretty much any shape I could come up with, I have a spare 205 inlet manifold I can cut the runners off, plenty of alloy in various shapes.

Oh one other question......how thick a material should I use...I was thinking 4mm alloy to take the pressure...or is that overkill?

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PostPosted: Tue Jan 29, 2013 12:50 pm 
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I believe stacks are going to add to runner length so you would have to compensate accordingly

My understanding of stacks is that the plenum protrusion doesn't have to be huge but there's a magical minimum figure that gives nearly 100% benefit. It's been a while since I read about stack design - there was a huge article in RET including discussion on mouth shape and throat design. Have a mooch about on ret monitor and see if there's anything interesting. Or ask Don nicely if he can scan the section for you

4mm feels like about the size of the stock plenum. There's probably formulae that you use to work out deflection vs loading but tbh if you're going to use stock runners i'd just pick a similar wall thickness to make joining them easier
I assume "he of ape like features" has FEA software and he seems to have manifold models.......


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PostPosted: Tue Jan 29, 2013 12:56 pm 
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http://www.ret-monitor.com/articles/cat ... on-system/

Nothing specific to trumpet design though :(


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PostPosted: Tue Jan 29, 2013 2:07 pm 
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Group N

Joined: Wed Dec 10, 2008 5:23 pm
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Location: London
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Insanity-74 wrote:
Sunny wrote:
Hi,

according the trumpets, d/r=1 should be your target to get the lowest pressure loss

but why do you want to built a custom manifold?

greetz


Why not? Seems like fun. I want a side feed inlet manifold and I recon I could make one cheaper than buying a second hand caldina manifold.


I like your thinking :)


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PostPosted: Sat Feb 02, 2013 3:40 am 
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Joined: Sun Apr 29, 2007 9:41 am
Posts: 277
Location: Norfolkcestershire
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Nial, round off the ends, considerable circulation happens within the plenum, and square ends mess things up. As to the ideal height for the trumpets - try to get the lower edge/lip 10-15mm clear of the wall to allow circulation to occur, and suck the air from the central part of the plenum.


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PostPosted: Sat Feb 02, 2013 7:32 am 
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Group N

Joined: Fri Mar 31, 2006 7:29 am
Posts: 447
Location: Up North
Car Model: ST205
Cheers Dan. I will try and get some designs drawn up.

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