displaying posts 1 to 9 of 9

Author Subject: Inlet Manifold Design
sam1

Junior User

Location: Coventry

Registered: 11 Dec 2011

Posts: 51

Status: Offline

Post #1
Has anyone ever tried cutting down the trumpets inside the inlet manifold so they are flush with the plenum wall?

I'm currently doing my first xu10j4rs rebuild and was surprised by the manifold design. I imagine it is designed to improve mid range and bottom end performance??? but it would be interesting to see how much top end power would be gained by making it less restrictive.
Posted 3rd Feb 2012 at 18:37
phillipm

Seasoned Pro

Location: Rotherham

Registered: 15 Oct 2006

Posts: 20,601

Status: Offline

Post #2
None, and you'll loose a big chunk of midrange too.

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Posted 3rd Feb 2012 at 18:41
clen666

Seasoned Pro

Location: Co. Durham

Registered: 12 Feb 2009

Posts: 2,400

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Post #3
click

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Posted 3rd Feb 2012 at 18:43
sam1

Junior User

Location: Coventry

Registered: 11 Dec 2011

Posts: 51

Status: Offline

Post #4
ok, thanks

clen666 wrote:


reading through this now. I did a search but did not come across that thread
Posted 3rd Feb 2012 at 18:52
lewisdmz

Senior User

Location: plymouth

Registered: 25 Jul 2009

Posts: 504

Status: Offline

Post #5
I thought trumpets are vital for "getting air through stuff".
Posted 3rd Feb 2012 at 19:04
sam1

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Location: Coventry

Registered: 11 Dec 2011

Posts: 51

Status: Offline

Post #6
They are important, but are they occupying more than 50% of the space (edit: cross section area) in the plenum. From reading the wonderfully detailed thread above it seems that this mod has not so far been proven to work on a standard engine...
Posted 3rd Feb 2012 at 19:47
phillipm

Seasoned Pro

Location: Rotherham

Registered: 15 Oct 2006

Posts: 20,601

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Post #7
Because the airflow near the wall of a plenum is dire, and you've also got less area for the edge of the trumpets to draw from, so higher acceleration of the airflow and lower dynamic pressure at the intakes, which interferes with the resonance. Might work if you could lengthen the whole system first but it would still only come into its own at high rpms

________________________________________

- Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM me
Email me!
Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces.
Posted 3rd Feb 2012 at 20:37
sam1

Junior User

Location: Coventry

Registered: 11 Dec 2011

Posts: 51

Status: Offline

Post #8
makes sense. looks like improving the design would require significant R&D input then, trial and error, CAD, flow bench...
Posted 3rd Feb 2012 at 21:57
welshpug!

Capt Pedantic

Location: Bigend, Wales.

Registered: 27 Mar 2007

Posts: 25,808

Status: Offline

Post #9
yup!

just fit throttle bodies Thumbs up (with a decent manifold, not the off the shelf jenvey/maniflow/omex one either)

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Bring on the Trumpets.

Posted 3rd Feb 2012 at 22:01

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