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There has been discussion on improvements made to the intake plenum by MRDANGEROUS and I have been working on a CAD drawing to get something like this made up. I think it's best to break this discussion out from MRDANGEROUS's original thread but with link back to it so it all stays connected.

http://www.lotustalk.com/forums/f164/x180-improvements-246153/index17.html

His original design:
 

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A revised 3D render. Once again, this is very close to the cover dimensions but not exact. Just looking for costing from manufacture. I was on another call and has time to add radii to the inner area around the holes. This is 1" thick 6063 Al. The costs changed as follows:

3= $155
5= $143
10= $124

Each feature adds time to the water jet distance of the cut.

These costs are unfinished. A bead blast of the part adds $14 to each at qty. 5 = $157.

To add anodize is $$ on a qty of 5 pcs, the cost goes to $194 each!
 

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MRDANGEROUS; please also share:

1. What bolt sizes, etc. are needed

2. Care to elaborate on the curved pieces you put in the OEM intake which you welded it looks like? Worth it (outside this group buy)? Wondering if a non welder such as myself could fab up the two curved pieces and then attach via high temp epoxy/high temp JBWeld?
 

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Plenum spacer

And in addition can some advise if this spacer would benefit a 4 cyl. G car or is this for V8 only? Thx.
 

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Discussion Starter #9
This is just for 4 cylinder Turbo cars! V8 need not apply unless it lowers the overall goal cost

There is a benefit to increasing the airflow in the plenum. MRDANGEROUS will have to do some splainin for it to make sense.
 

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SIGN ME UP REGARDLESS OF QUANTITY!

MRDANGEROUS; please also share:

1. What bolt sizes, etc. are needed

2. Care to elaborate on the curved pieces you put in the OEM intake which you welded it looks like? Worth it (outside this group buy)? Wondering if a non welder such as myself could fab up the two curved pieces and then attach via high temp epoxy/high temp JBWeld?

GREAT ENERGY! BRAVO!

A1: M8x1.25 stainless Allen socket heads (button head looks good, too),
from Bolt Depot
https://www.boltdepot.com/Metric_socket_cap_Stainless_steel_18-8_8mm_x_1.25mm.aspx

Add 1" to the OE length of the bolts

A2: I thought that adding little bit of swirl would help re-distribution
of the fuel dumped in by enrichment injectors.
I would not use epoxy inside the plenum. I love JB-Kwick, but I had occasional failures when gluing smooth aluminum surfaces. Inside of the cover there are some significant turbulent forces which may dislodge the part.

Spacer: Please notice the chamfer above the diffuser slot. Material can be removed with a rotary burr and a hand grinder or added to the water jet operation (tip the nozzle ~30 degrees to Z axis).
 

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<SNIP>
A2: I thought that adding little bit of swirl would help re-distribution
of the fuel dumped in by enrichment injectors.
I would not use epoxy inside the plenum. I love JB-Kwick, but I had occasional failures when gluing smooth aluminum surfaces. Inside of the cover there are some significant turbulent forces which may dislodge the part.
<SNIP>
Looking again looks like you attached the curved pieces by brazing and not welding, correct? If so I can do that and yes, it would be better than epoxy.
 

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They look welded to me. I don't know ab out brazing aluminum...

I'm looking to make a drawing of this part to see if we can have it made too. I'm not making any promises.

John, was this made from 2 pieces of 4" tubing, cut up and then welded??
 

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I would like to ask the following:

- Does this fit the SE/S4/S4s engines too, or is it for the early injection engines or both?

- Does this require other mods to Work, such as bigger jets og special/different injection computer?

- Anything else to be changed?

Kind regards,
Redfox.
 

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I would like to ask the following:

- Does this fit the SE/S4/S4s engines too, or is it for the early injection engines or both?

- Does this require other mods to Work, such as bigger jets og special/different injection computer?

- Anything else to be changed?

Kind regards,
Redfox.
Yes, it just makes the plenum a bit bigger for better air distribution. As long as the plenum is the same shape, it will work. It need longer bolts, 1" longer since its 1" thick. I will specify the actual bolt lengths if we get there and order.

No no mods should be needed.

No changes at all

Jon
 

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I see a lot of respected folks here jumping in on this buy. I'm not trying to be a pain in the arse but I'm wondering what significant gain will I see by adding this 1 inch spacer? I would think that this is an incremental step which would not do much without polishing and and honing the entire intake. Am I missing something here? I appreciate anyone's efforts in improving the performance of our cars, I'm just curious.
Thanks.
 

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On pre 1998 cars you have no room to package anything wider than 1-1.25". There is an interference to the air filter box.

On SE/S4/S4s you may may go wider, see pic (4" spacer!).
Thicker spacer=larger plenum volume= higher VE at higher rpm.

Sometimes it is true:
"bigger is better", LOL
 

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They look welded to me. I don't know ab out brazing aluminum...

I'm looking to make a drawing of this part to see if we can have it made too. I'm not making any promises.

John, was this made from 2 pieces of 4" tubing, cut up and then welded??
YES,
I used sections of the 4" OD aluminum tube.
TIG welded everything.
 

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I see a lot of respected folks here jumping in on this buy. I'm not trying to be a pain in the arse but I'm wondering what significant gain will I see by adding this 1 inch spacer? I would think that this is an incremental step which would not do much without polishing and and honing the entire intake. Am I missing something here? I appreciate anyone's efforts in improving the performance of our cars, I'm just curious.
Thanks.
Pete,

It has been a lengthy development, which started in 2011.
It is very difficult to condense all the research, development and testing into one simple posting. If you are interested how this idea evolved, please read

Variable Volume Intake Manifold and Tuning - Engine/Ancilliaries - The Lotus Forums

412 BHP...THAT WILL DO NICELY...... - Esprit Chat - The Lotus Forums

and a chapter on IM variables in: Design Techniques for Engine Manifolds: Wave Action Methods for Ic Engines
by D. E. Winterbone, Richard J. Pearson, ISBN-13: 978-0768004823

AND, you're totally right!
Polishing and port matching of CAI and turbo ducts is highly recommended for best results.
 
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