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Discussion Starter · #403 · (Edited)
So Far, So Good

Well, it took a while for me to find the mounting bracket for my flow meter, but I took a quick set of max and average flow readings for a short drive.

The max reading was 1100 fpm at about 80mph. Based on the calibration and data from this post: http://www.lotustalk.com/forums/f15...-air-flow-study-59117/index4.html#post1059881, that implies a flow of around 715 cfm. With just fettling and the Cup roof, only about 275 cfm flowed through the I/C at 80mph. So if this data is accurate, I've increased the flow through my intercooler 2.6x, over a fettled clam with a Cup roof only.

That's very encouraging, but I'll need to run a full test, comparable to the original tests. Also, I took a quick infrared temp reading, after I'd shut the engine off. There was still a 20˚ difference across the I/C, even though no air had been flowing for at least a minute.

More to come...
 

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Well, it took a while for me to find the mounting bracket for my flow meter, but I took a quick set of max and average flow readings for a short drive.

The max reading was 1100 fpm at about 80mph. Based on the calibration and data from this post: http://www.lotustalk.com/forums/f15...-air-flow-study-59117/index4.html#post1059881, that implies a flow of around 715 cfm. With just fettling and the Cup roof, only about 275 cfm flowed through the I/C. So if this data is accurate, I've increased the flow through my intercooler 2.6x, over a fettled clam with a Cup roof only.

That's very encouraging, but I'll need to run a full test, comparable to the original tests. Also, a took a quick infrared temp reading, after I'd shut the engine off. There was still a 20˚ difference across the I/C, even though no air had been flowing for at least a minute.

More to come...

:nanner: :clap: :bow:
 

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Discussion Starter · #405 ·
Here's the first cut at a comparison...

The light blue regression line is the Cup roof without fettling
The violet regression line is the Cup roof with fettling
The red regression line is the Cup root with fettling, plus the two side intake ducts

There wasn't much data above 50mph, and the points above 80mph are definitely bad data (GPS errors), so this is just an early result. Even so, it looks like at least twice the airflow over the fettled clam, 2.4x over stock. I have a feeling some of the high speed data points are wrong, which would skew the regression downward... so there's a good chance with more and better data, the results will be even better.
 

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Great info! :up::up::up:

Thank you!!!!
 
G

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Cool! Looks like you've done what I've been "wanting" to do for a while, but haven't found the time.

I wanted to put the 3" inlets into the duct that mounts to the I/C, but never thought about the duct from the roof.

So you are maximizing the flow...

I estimate the input area on the stock Exige S roof to be 1.5" x 8" = 12 in^2

Adding two 3" ducts = 14.175 ^2 additional inlet area...

So you've more than doubled the potential inlet area...
 

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Discussion Starter · #408 ·
Cool! Looks like you've done what I've been "wanting" to do for a while, but haven't found the time.

I wanted to put the 3" inlets into the duct that mounts to the I/C, but never thought about the duct from the roof.

So you are maximizing the flow...

I estimate the input area on the stock Exige S roof to be 1.5" x 8" = 12 in^2

Adding two 3" ducts = 14.175 ^2 additional inlet area...

So you've more than doubled the potential inlet area...
Thanks... those were the numbers I was looking at too... at first, I wanted to plumb the ducts directly into the I/C shroud, but there are two problems with that... 1) there's very little room to work with on the shroud (the I/C on the Cup cars has even <b>less</b> room), and 2) if I change intercoolers, I have to redo the plumbing.
 
G

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Thanks... those were the numbers I was looking at too... at first, I wanted to plumb the ducts directly into the I/C shroud, but there are two problems with that... 1) there's very little room to work with on the shroud (the I/C on the Cup cars has even <b>less</b> room), and 2) if I change intercoolers, I have to redo the plumbing.
How did you get the mounts into the plastic duct from the roof? Were you able to remove it? I'm wondering how it is attached....
 

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Discussion Starter · #411 · (Edited)
Will you consider to make this part with CF to replace the whole OEM parts and sale it to us?
Unfortunately I can't manufacturer parts in CF (or even plastic), so no... sorry.

How did you get the mounts into the plastic duct from the roof? Were you able to remove it? I'm wondering how it is attached....
My roof duct was already cracked badly... probably from the engine rotating on the soft OEM mounts and exerting force on it. I knew I'd have to repair the cracks anyway, so I just used a Dremel to connect the cracks and remove part of the roof duct. I originally tried to get the whole piece to come out by wedging a putty knife under the duct, but it wouldn't budge.

Once the piece was out, I trimmed a set of NACA ducts to fit the contour of the roof duct, then cut holes out of the duct and epoxied the NACA ducts in place. I used RTV sealant to make sure the fittings were air tight. Then I epoxied the roof duct back in place, and resealed any air leaks with RTV.

A few pictures...

1) At left: original duct piece used to make side scoops and mating ducts, center: roof duct with cut outs and trimmed NACA ducts, right: high temperature silicone brake ducting

2) Roof duct after supplemental ducts were epoxied and sealed with RTV
 

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Im just wondering if those ducts were re angled to allow the airflow pointed through the ic instead of into the duct may have a better effect?
maybe more efficient and greater air speed through it which may have the effect of dragging air through the slot on the roof faster?
 
G

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Unfortunately I can't manufacturer parts in CF (or even plastic), so no... sorry.



My roof duct was already cracked badly... probably from the engine rotating on the soft OEM mounts and exerting force on it. I knew I'd have to repair the cracks anyway, so I just used a Dremel to connect the cracks and remove part of the roof duct. I originally tried to get the whole piece to come out by wedging a putty knife under the duct, but it wouldn't budge.

Once the piece was out, I trimmed a set of NACA ducts to fit the contour of the roof duct, then cut holes out of the duct and epoxied the NACA ducts in place. I used RTV sealant to make sure the fittings were air tight. Then I epoxied the roof duct back in place, and resealed any air leaks with RTV.

A few pictures...

1) At left: original duct piece, center: roof duct with cut outs and trimmed NACA ducts, right: high temperature silicone brake ducting

2) Roof duct after supplemental ducts were epoxied and sealed with RTV

Dang, I was hoping that piece would just unbolt off... :(

Nothing is easy in regard to more airflow to the I/C
 

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Discussion Starter · #416 ·
wow! looks good and great improvement. i hope you will be able to sell us a similar thing in the future at a reasonable cost. good luck!
I'm sorry if anyone's gotten the idea that I'm planning selling this as a kit... I'm just another Lotus enthusiast; but I'd be happy to share any information that would help others put something like this together on their own (i.e. parts sources, photos, procedures, etc).

Im just wondering if those ducts were re angled to allow the airflow pointed through the ic instead of into the duct may have a better effect?
maybe more efficient and greater air speed through it which may have the effect of dragging air through the slot on the roof faster?
Given the space constraints, I tried to angle the ducts in the direction of the airflow as much as possible. There's very little room between the duct and the rear window glass...

<img src="http://www.elisetalk.com/gallery/files//11391-ic_ducts5.jpg" alt="Modified Intercooler Duct" />

Great job, that's exactly what I had thought and planned for my next upgrade...
Thanks! Here are a few more pics:

1) Right side ducting... note how tight the space is below the hatch hinge and behind the window

2) Without a flash to illuminate the inside of the side scoop, the ducting is fairly subtle...
 

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Discussion Starter · #417 ·
Dang, I was hoping that piece would just unbolt off... :(

Nothing is easy in regard to more airflow to the I/C
Yeah, I can't imagine being able to get the roof duct out in one piece without removing the rear clam. If anyone has any experience with removing the duct, feel free to chime in! On the other hand, a brand new roof duct is only $82 or so from Lotus Garage... Lotus Garage - Chargecooler & Ducting
 

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apk, are you planning to log temperature? how about blocking off the roof opening? (could there be some backflow out through the roof opening?)
 

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Discussion Starter · #419 ·
apk, are you planning to log temperature? how about blocking off the roof opening? (could there be some backflow out through the roof opening?)
Yes, I have a track day Tuesday, and I plan to log IAT, ECT, and spark advance over a number of laps with both the side scoops blocked off, and open. I seriously doubt there is any backflow through the roof scoop; because of the bottleneck, it's very likely that the pressure inside the roof scoop is higher than the pressure in the roof duct... and air will not flow against a pressure gradient in that case.
 

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I don't understand how the side scoop flow is not just going to collide with the roof flow? What is stopping the side scoop air pressure from going out the roof and/or the roof air from going out the side scoops? Both will be paths of least resistance vs. flowing thru the IC itself which has a very high resistance to flow?

To make your side scoop design work efficiently, you'd need a three chamber (isolated) IC shroud (think exhaust headers). What you've done here is most likely got side scoop air flow with higher volume pushing air out the roof scoop (some will go thru the IC, but it might be worse than what the roof scoop alone could do).

I think your design would work MUCH better if you ran the side scoop ducting directly into the IC shroud with 3 isolated chambers in the shroud - left chamber for left side scoop, center chamber for roof scoop, and right chamber for right side scoop. Isolate the chambers on the IC surface using rubber/foam molding (you would need to figure out how to mold plastic for each internal shroud chamber). This way, the only path for the air to flow in all 3 cases is thru the IC regardless in the differences of pressures between all 3 paths of air flow.

Not trying to knock your design because heat soak is a problem and the more air one can flow over the IC the better. I think you're on the right track, just needs some refinement.

Rob.
 
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