2007 Exige S Intercooler Air Flow Study

[apk919]

Originally Posted by turbophil

I'd seriously consider putting a duct on the drivers side c pillar and see if that helps. I think it would look pretty cool. You can't see both side of the car at the same time so whycare about symetry

Frank found that the mesh blocks a heck of lot of air on those side scoops, so I would certainly remove that jazz...

The reality is that you need a lot more air to really get some good efficiency out of those ICs and I think you've shown that the big issue is that little opening. If you can double the size of that hole, you'll probably double the air... If I were you, I'd start doubling

Best,

Phil

Agreed, the mesh on the side scoops is finer (i.e. blocks more airflow) than those on the radiator and hatch...

Also, and not surprisingly... the flow through the intercooler seems proportional to the smallest cross section in the ductwork... so doubling would be good...

[Jack]

Originally Posted by turbophil

Frank found that the mesh blocks a heck of lot of air on those side scoops, so I would certainly remove that jazz...

Best,

Phil

Took the mesh out some time ago -- definitely helps with engine cooling.

[turbophil]

Originally Posted by Jack

Took the mesh out some time ago -- definitely helps with engine cooling.

You see, another reason the Elise is a better performer than Exige, it has no air restricting mesh!

[Mag]

Originally Posted by lwein

I have also felt the hot air that comes over the windscreen,it is from the heat of the radiators in the nose,and it is suprisingly hot.
I looked into fans a while ago,and the tiny fans that would fit don't come close to pulling enough air,pushing is not a good idea,either. the only place where fans might help on this car is when it is in traffic,but how much horsepower do you need in traffic? I am still thinking that a scoop on the drivers side "sail" panel(opp side of the fuel filler door)--or a NACA duct ---run into the stock air duct along with the roof might be the answer. It could be replaced with another gas filler door(screwed shut)if desired should the need arise. If you wanted to remove the top,you would still get air into the IC from the top scoop on the clam and the new sail panel air inlet. All of this is just mental masturbation on my part until somebody gets temps and meaningful data. Where is Jim Hall (Chaparral) when we need him?

I ordered 2 small motorcycle fans from SPAL to be mounted push inside the shroud. Just going to use a simple on off switch routed through the fire wall somewhere in the cock pit. I think the pre-IC shroud location provides a good vacuum seal aiding fan efficiency as opposed to fans in the open trying to pull air through. At idle standstill in street, or slow speed hairpins on track, this should help.

I know there are concerns that it would block airflow but in this case and it's just my own guess, since the bottleneck at the rear clam opening is so great, the fans can only help. At speeds, (cup roof) air rams through but is choked at the fettle location, my theory is the fans help pull that stream and push through the IC.

The fans I chose, if mount the way I want them to, on both sides will still leave a small open unobstructed IC space in the middle. Im no pressure engineer but imagine there's some turbulance on eighther side of the shroud, and the fans for the IC (for the exige config) can only help. I'm hoping innovate will come with the IAT parameter update soon so I can log this. I have some thermo couple but don't want to put these direct in the charge stream if dont have to...

On a seperate note, I wonder how much timing changes from the ecu are a result of IAT and how much are result of other parameters like ECT... ?

[simon_komo]

My comment with the 240S roof are as follows :

- When the car is at speed... will the heat from the radiator rise, glide on the windscreen and go straight into the roof ?? this is just my theory, but if you are driving and stick your hand out the windscreen (i tested my theory), you can feel the heat is passing thru, which questions will more hot air be going into the engine bay than cold air ??

I am sure the Lotus guys have windtunnel tested the roof but I am unsure if its cold air we are catching
though

[Drmike]

Discussion on use of fans after intercooler:-



LotusClubSG • Login

[Mag]

Originally Posted by Drmike

Discussion on use of fans after intercooler:-



LotusClubSG • Login

"You are not authorised to read this forum."

i even registered.

[arobot]

This may be a little over the top, but has anyone tried a setup whereby a small jet of atomized distilled water is injected into the cooling airstream? Maybe injection could be automated as a function of boost?
A liquid->stream phase change absorbs lots of heat...

BTW- how much HP difference are we dealing with (say between an optimally cooled IC versus no IC at all?)

[Mag]

Originally Posted by arobot

This may be a little over the top, but has anyone tried a setup whereby a small jet of atomized distilled water is injected into the cooling airstream? Maybe injection could be automated as a function of boost?
A liquid->stream phase change absorbs lots of heat...

BTW- how much HP difference are we dealing with (say between an optimally cooled IC versus no IC at all?)

search RLS aquamist, one of the members here is selling a kit. I've bought one but not hooked up yet.

[Pestodude]

Originally Posted by apk919

So, given a decent 20% increase in flow due to the first fettle, I thought I'd see how much more fettling was possible, as well as sealing leaks and smoothing flow.

There wasn't much more material to be removed, given the size of the ducting (see pics). There were gaps between the opening in the clam and the duct work though, and I sealed them with silicone caulking. Also, I worked on making the roof gaskets (for both the Cup and stock S roofs) seal more tightly with the clam opening. It's interesting that Lotus designed the gaskets differently... the Cup roof gasket goes over the top of the duct, the stock S roof goes under. On my S, there was a gasket attached to the clam to seal the gap above the duct. I don't know how a Cup car's clam gaskets look (pics anyone?). So I removed the gasket from the clam, and added a gasket below the duct for the Cup roof, and above the duct for the stock S roof. See pics...







































Now I need to road test... maybe tomorrow...

Pic #1: After completing the fettling.
Pic #2: After sealing the ductwork with silicone.
Pic #3: Cup roof mating gaskets.
Pic #4: Stock S roof mating gaskets.
Pic #5: Replaced the crappy hose clamps (Jubilee?) with decent slotted band hose clamps (Tridon). They're much easier to take apart, put together, and tighten down on the snorkel to the ductwork. Highly recommended if you ever take it apart.

I can't tell, did you also fettle the roof where it meets the clam? If not then that is a bottle neck that fettling the clam alone won't overcome. Is it even possible to fettle the roof?

[apk919]

Originally Posted by Pestodude

I can't tell, did you also fettle the roof where it meets the clam? If not then that is a bottle neck that fettling the clam alone won't overcome. Is it even possible to fettle the roof?

The thickness of both roofs at the clam interface is no thicker than the rubber gaskets used to mate them to the clam... so it really doesn't seem that there would be any practical benefit to fettling the roof.

Without changing the external dimensions of the roof or the clam, I think I've gone about as far as possible be fettling alone. If I were designing the roof and the clam from scratch, I'd definitely make the "mohawk" cross section wider and/or taller.

[Pestodude]

Originally Posted by apk919

The thickness of both roofs at the clam interface is no thicker than the rubber gaskets used to mate them to the clam... so it really doesn't seem that there would be any practical benefit to fettling the roof.

Without changing the external dimensions of the roof or the clam, I think I've gone about as far as possible be fettling alone. If I were designing the roof and the clam from scratch, I'd definitely make the "mohawk" cross section wider and/or taller.

Then, to my mind, if the roof is only allowing x amount of air to pass into the clam and there's no way to open up the roof any wider, it might flow more air WITHOUT the roof or with a roof sans a scoop. Then (correct me if I'm wrong) you could fettle the clam opening even larger because you wouldn't have to worry about a mating surface (to seal against a roof).

[apk919]

Originally Posted by Pestodude

Then, to my mind, if the roof is only allowing x amount of air to pass into the clam and there's no way to open up the roof any wider, it might flow more air WITHOUT the roof or with a roof sans a scoop. Then (correct me if I'm wrong) you could fettle the clam opening even larger because you wouldn't have to worry about a mating surface (to seal against a roof).

I'm planning on getting flow data with the roof off... but if I were to guess, I'd say it would flow a little less than when the Cup roof is on. The inlet of the roof presents a larger cross section to the air flow than the clam opening does, and a small "ram air" effect probably increases the flow (with an obvious cost in aero drag).

If you look at the photos though (http://www.lotustalk.com/forums/atta...-duct_seal.jpg), the ductwork leading to the intercooler is already smaller in cross section than the opening in the clam... I think you'd have to change the ductwork too.

[wildwhl]

Originally Posted by Smoky

Would love to see pics and a writeup of how the fans are located, installed, and wired-in to function. Are they always on when the car is running? Are they strapped to the i/c? Or elsewhere? Do the fans replace the function of the roof scoop, or supplement it?

I've seen several references to using fans on this forum but have never seen evidence of anyone actually doing it.

These are 2 of the 4 fans I'm using. They are Spal fans, 5.2" diameter if I recall correctly, 2 push and 2 pull (obviously, the pushers are inside the shroud). The controller is a Spal PWM 2 speed controller. The set points are end user adjustable/programmable. I tapped into the IAT sensor for an input. I have the low point set for ~100 degrees IAT (otherwise, sitting in the sun, well, anyway...) and the high point is not far above that, about 120 degrees. The switch up top turns the fans off - they are noisy and not always necessary/welcome.

I do not have any data logs to support my conclusion that they work. They do. It can and will be improved when I have full use of my tattered right arm again (titanium rocks!). The fans move a reasonable amount of air, and dropped IAT's about 30-40 degrees at the track.

My total expenditure was under $200 (purchased all from Ebay gradually over the winter) and they were very, very easy to install. 2 beers on a 6 beer scale.

If you're confused by the white stuff - that is dust. She hasn't been driven in about 2 months...

[qball]

For those interested, I have the same fans as WildWhl... you can get them at the SPAL clearance center for $38 each...

[Mag]

Originally Posted by qball

For those interested, I have the same fans as WildWhl... you can get them at the SPAL clearance center for $38 each...

ah man... i just paid double that, using the same, 5.2" ATV fans.

i just hooked up my innovate system to watch the OBD2 IAT Pid. Before car's started, reading is a bit higher than ambient so appears to be accurate. IAT mid 30C's. Ambient is low 30C's. Infrared temp gun aimed at the IAT from exterior confirm similar temps.

Once warmed up and running, IAT is consistantly around 42C. When full throttle through one gear, it'll quickly rise to 43C+. LOnger durations, 44C. In traffic, idling if the car is hot can get up to mid 40C's.

Not sure how to analyze the info but it's interesting, that at highway speeds, no matter how fast I am going, the IAT doesn't appear to move much. the range is more or less 1-3C and correlation appears to have more to do with throttle rather than speed.

higher speeds which normally = higher flows which = lower IC charge temps are normally reflected by IAT changes that are in line with speed variations/flow unless in cases where the higher speeds do not = higher flow. I guess making a new rear clam/hatch mold for the SC exiges was too expensive to fit in the lotus 2006 budget. When ever i have the roof off, I laugh shake my head at the fettle bottleneck location. Having owned several modified FI cars in the past, I've witnessed the fundamental importance of an efficient IC.

I'm hoping the IAT Pid is accurate (via innovate's OT1 obd2 reader). Have purchased the complete RLS WI IC system and 2 Spal fans outlined above to be installed inside the shroud pushing. Climates in HK are hot and humid so should be a good testing environment. A thermocouple in the roof scoop would also be ideal for the data log but that's still in the works. (If anyone knows how to make a thermocouple for this application that yields accurate readings, please feel free to clue me in. Currently I have the wire(s) run, soldered one inch exposed, stuck in the shroud but temps are about 10C higher than they should otherwise be.)

[ocelot27]

It's great that people are trying this. Spal has a new controller out now - I've been waiting for it - basically a minor update of the current one. I have 2 6.5" fans which will push though from the front side - I plan to ditch the duct on the intercooler entirely and just have the roof duct directed at the IC (an RLS). IMO the bottle neck is the roof duct and bypassing it will allow much more air flow. I don't think drawing air from above the engine will be horrible especially when the car is moving. I'll log some IAT's once I get the whole thing up.
john

[serpentor]

whats the CFM on those fans?

[ocelot27]

6.5" = 330cfm at 6.3A

[Mag]

specs on the 5.2"
http://www.spalusa.com/fans/automate.../3013-3011.pdf