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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.
Not sure I buy your argument...

the flow from the roof scoop will also be under pressure from airflow being forced in at speed.

Total effective outlet area of the IC (taking out all the area blocked by the bars and fins, etc.) is still going to be greater than the area of the roof scoop.

This could further be assisted by some fans pulling through the IC
 

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Discussion Starter · #423 · (Edited)
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.
I've taken a few courses in aerodynamics, but I'm by no means an expert... but here's how I see it. The three sources of cooling air are all coming from front facing scoops, so essentially they're all seeing the same velocity air. The outlet of the I/C is into the engine bay, which is likely to be at a slightly lower than atmospheric pressure due to high speed air flowing over the vented hatch (I've actually measured this effect).

So my analogy is as follows: imagine three sources of water, all at the same height (potential energy). They have pipes (of possibly different diameters and complexity) leading them into a common plenum, which has a single outlet at a lower height than the three sources. Yes, they'll all mix in the plenum, but they're all still drawn out through the lower outlet.

EDIT: I'm pretty sure the 2-11 has two side ducts directed to the intercooler... I don't know if there's any separation between the ductwork, but I'm going to guess no. Maybe someone with a 2-11 can verify? :D
 

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EDIT: I'm pretty sure the 2-11 has two side ducts directed to the intercooler... I don't know if there's any separation between the ductwork, but I'm going to guess no. Maybe someone with a 2-11 can verify? :D
I haven't opened up the collector, but I'm pretty sure that there is no separation between the ductwork. ;)
 

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Not sure I buy your argument...

the flow from the roof scoop will also be under pressure from airflow being forced in at speed.
I agree completely.

the air wont be flowing out the roof scoop, no way. Exiting through the IC is definitely the easiest route.

I still prefer the setups using the naca ducts inside the roof scoop area though.
 

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Discussion Starter · #428 · (Edited)
Better Data, Better Results!

OK, this is the latest airflow data, taken today with some freeway driving to get better high speed numbers. As I expected, the results are better... the new configuration flows 2.36x the fettled-only configuration, and almost exactly 3x better than the stock Cup roof configuration.

Here's the data comparison (as you can see, much more linear data on the last run)
 

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Sorry if this has been asked before, but what are you using to measure air flow across the IC fins and out the other side? From your CFM data is does indeed look like the IC is the path of least resistance.

I still feel the flow dynamics are more efficient when unequal air pressures are not colliding with each other. Unless you have a perfect direct head wind, all air pressures from all 3 entry points will never be the same.

But it sounds like you'll be gathering Air Charge Temps this Tuesday from a track day? I'll certainly be interest to see those air charge temps. But the bigger question is, will this do anything to improve engine performance (and lap times) thru a session or will you be fighting increased drag.

I hope I'm not sending the wrong signals, I'm glad your doing this -- my questioning is purely from a scientific aspect. That's what science is about, always under scrutiny (question everything) and that's what makes it work. So please don't take my comments in the wrong way.

Rob.
 

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don't confuse flow with pressure

the roof scoop may be low flow but it has a high pressure differential mixed with a bottleneck(mail slot) so air will never flow out the scoop
 

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Discussion Starter · #431 ·
Sorry if this has been asked before, but what are you using to measure air flow across the IC fins and out the other side? From your CFM data is does indeed look like the IC is the path of least resistance.

I still feel the flow dynamics are more efficient when unequal air pressures are not colliding with each other. Unless you have a perfect direct head wind, all air pressures from all 3 entry points will never be the same.

But it sounds like you'll be gathering Air Charge Temps this Tuesday from a track day? I'll certainly be interest to see those air charge temps. But the bigger question is, will this do anything to improve engine performance (and lap times) thru a session or will you be fighting increased drag.

I hope I'm not sending the wrong signals, I'm glad your doing this -- my questioning is purely from a scientific aspect. That's what science is about, always under scrutiny (question everything) and that's what makes it work. So please don't take my comments in the wrong way.

Rob.
I have an OBD-II datalogger, which will allow me to log IAT (intake air temperature, from the sensor at the "cool" end of the I/C), ECT (engine coolant temperature, to make sure I'm not trading off cooler charge for a hotter block), and spark advance (to see whether the ECU is pulling timing due to heat soak). In addition, I'll have my Traqmate logging laptimes, speed, RPM, G-forces, etc. I'm looking forward to getting some interesting answers...

EDIT: Don't worry, you're not sending the wrong signals... I think that it's great that I can get thoughtful feedback on mods like this...

don't confuse flow with pressure

the roof scoop may be low flow but it has a high pressure differential mixed with a bottleneck(mail slot) so air will never flow out the scoop
Exactly! :up:
 

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Discussion Starter · #433 ·
For sure the air flow will be much more and cooler than the cup roof, but how about the original function of the engine bay cooling...
True, that's why I installed a set of much larger carbon fiber side scoops from TWRD... that way I still get proper airflow to the engine bay, as well as having extra capacity to augment the intercooler airflow...
 

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I nominate this thread as Most Valuable Thread Ever.

xtn (who doesn't even have forced induction, but recognizes the value anyway)
 

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Yes...but...

What data seems to be missing is the most critical. What is the temperature differential from one side of the intercooler to the other. While it may matter which direction the air flows or just how much flow there is...what really matters is the temperature...that is the reason its there.
 

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Excellent, looking forward to your data. :up:

Rob.
 

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Discussion Starter · #438 ·
What data seems to be missing is the most critical. What is the temperature differential from one side of the intercooler to the other. While it may matter which direction the air flows or just how much flow there is...what really matters is the temperature...that is the reason its there.
Excellent, looking forward to your data. :up:

Rob.
I've just finished configuring the OBD-II logger to log RPM, speed, IAT, ECT, spark advance, and MAF flow. That's in addition to the Traqmate data logger, so there should be lots of information to digest after tomorrow.
 

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The guys in Australia are having good result with water mist sprays as well. This combination with a water mist would be very interesting to see.
Yes, I'm having great results with water/methanol injection combined with water/methanol (very light mist) sprayed externally on the intercooler. I have data logs posted elsewhere. http://www.lotustalk.com/forums/f25/really-light-stuff-water-methanol-injection-55666/index2.html#post1091074

I'm using 50% distilled water / 50% methanol by weight.
 

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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.
First I like to thank apk919 for thinking outside the box and come up with all these great ideas to try and solve the dreaded IC heatsoak issue that we have. We need more people like you in our Lotus community.

I agree with Rob that a modified IC shroud might be the best solution. The air flow from the side scopes will be at a much better angle. Installation is easier since all you have to do is replace the IC shroud. Having the IC shroud molded with three internal chambers is also a great idea. Now we just need someone to actually manufacture one. It can be sold as a kit along with the side ducts and scope. I'm sure every Exige S owners will want such a kit since it can't be all that expensive to manufactuer.
 
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