[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

 

[ocelot27]

6.5" = 330cfm at 6.3A

 

[ocelot27]

All thermocouples need to be calibrated! It's impossible to make the weld between the two metals the same in every one. K-type TC's are linear over a broad range so you really only need two calibration points. Is there a way to calibrate your instrument? You just need an accurate thermometer to calibrate - john.

 

[ocelot27]

I'm just really surprised we haven't devised a foolproof, easy-to-install solution to get lots of cold air from the passenger side scoop to this friggin intercooler.

Even if someone makes a new shroud out of fiberglass that has two extra round inlets on that side...

Run some of this...

And one or two of these inline...

If someone wants to go the ducted fan route there are very powerful units available for electric model airplanes:

Electric Ducted Fans from Hobby Lobby!

I don't know what 20 oz of thrust equates to in cfm but it's gotta be loads more than our Spal fans.

The other problem with the roof duct is that the roof gets really hot in the sun - has anyone studied this aspect of the design?

-john.

 

[ocelot27]

John -

far too many year$ $pent with model airplane$ to admit thi$ - but at the designed *thrust* levels the motors have relatively short lifespans. Certainly not suitable for continuous use on a car. Then you need to drive the controller...but i digress...

WW

Good point. I drove my car pretty hard tonight - it always seems faster when cool. The RLS IC definitely helps enormously but the weakness is the lack of airflow to the IC with the factory design... got my Spal controller today... now I need to get everything to fit and with that I would warn people about mounting fans on aft side of the IC - you could definitely run into issues with the strut. I've removed mine entirely but no fans will safely clear the engine cover with the current motor mounts - the engine moves like 2-3 inches.... fans going on front side of IC sans duct.

-john.

 

[ocelot27]

Anyone know what the four wires are on the IAT - there's orange, blue, brown and yellow. TIA - john.

 

[ocelot27]

Yes...

http://www.ontronic.com/products/doc/Sensors.pdf

Forget the part number...but you're looking at it!

WW

Call me a tart but I looked at that PDF and it seems to only describe the thermistor part (two leads) but there are four leads going into the housing of the IAT (Bosch part# 0 261 230 042). I would take my multimeter to it but there's no good access to the leads because of the environmental seals - can you simply tell me which colors are what? Or simply which lead provides the variable voltage from the thermistor? Also what's the most convenient source of +12v (ignition on) to tell the fan controller when the ignition/engine's on and off - my guess is that one of the leads going into the IAT is +12V? - TIA - john.

here's the image from my engine:

 

[ocelot27]

John -

You are a tart.


That link is about (xxx) pages long. Look for page 37, connector configuration #3 (or diagram #3).

There are (also) 2 fuse blocks in the engine bay. I simply probed the leads until I found one that was +12V key on for the relay/fan control.

Signed,

your fellow tart.

WW

Ahhhh - I missed that page - silly me just going by the index. So in my pic it would be the orange wire, right? The fuse blocks are above the ECU correct? - john.

 

[ocelot27]

ok cars all set up. the issue with the temp differences had to do with technical problems with the gauges. Laptop temps are accurate. Will do a test tomorrow and log the data.

Close up of thermocouple. these things are really cool.

Attached to scoop entry.

sensor inlet side

IAT and other obd2 parameters via Innovate OT1 and AF ratio via Innovate LC1.

Seeing all those yellow connectors reminds me of thermodynamics lab... not something I want to be reminded of. At last we'll have meaningful data about the Exige's charge cooling system. We just need to measure the MAF through the duct then we have all the pieces - john.

 

[ocelot27]

I downloaded the manual and service notes back in February... it included a lot of '08 updates, including '08 schematics, launch control, new instrument panel, etc.

I wonder if there's still some way to make use of the temperature sensor part of the TMAP sensor on the intercooler. I noticed on Ocelot27's picture that it's actually tapped into the IC/intake manifold tube, where on my '07 its tapped into the intercooler itself... I'm assuming on your '08 it's tapped into the tube as well?

EDIT: I just realized that Ocelot27 has the RLS intercooler and tubes... so that's probably why his TMAP sensor is in a different location than stock

OK... are you sure of the wires on my pic and are you sure they aren't using this sensor for IAT - it makes absolutely no sense to measure IAT pre-compression?????? Charlie or Thomas HELP US!!!

I just want to know what wire to use to control the fans for my IC - there's conflicting info here and before I go cutting wires I'd like to know for sure what's what.

Also, you're right the RLS setup relocates the IAT sensor to the post-IC tube for those doing water/meth.

-john.

 

[ocelot27]

From the '08 MY schematic:

You're looking at the TMAP Sensor...
Yellow (Y) is ground
Brown/Green (NG) is the temp signal
Slate (S) is MAP +5V
Orange/Green (OG) is MAP signal



If I'm reading the schematic correctly, IAT is taken from the TMAF sensor, which would put it pre-SC. The temperature signal from the TMAP sensor (post-IC) is not used...

Could they mean that the temp from the MAF isn't used in SC cars - this makes a lot more sense??? Plus why would they wire up the whole TMAP shebang and not use it???

-john.

 

[ocelot27]

Well, I'm as sure as I can be in the accuracy of the schematics in the Lotus service manual.

You saw this excerpt from the schematic, right?

The wire color codes match up... and as far as I can tell the note about not using the TMAP temperature sensor is accurate...



I suppose they're using the pressure sensor part of the TMAP, just not the temperature sensor... without a schematic of the ECU itself (and it's software), I couldn't say what parts of the sensor are being used.

Yes, of course I saw the schematic - the temps from both sensors are plugged into the ECU according to the schematic - correct? Even if the IAT is from the MAF I should still be able to use the correct lead (i.e. the "NG" colored one) from the TMAP to control the IC fans as several have done previously in this thread...
-john.

 

[ocelot27]

Sorry, I wasn't sure if you'd seen the earlier post. If the temperature sensor of the TMAP is not used at all, then I suppose you could tap into it without causing any other issues...

EDIT: If I'm reading the Bosch spec sheet properly, it's a thermistor and not a thermocouple. I think that actually makes it easier to deal with for making a fan controller than a thermocouple.

Yeah - the Spal controller is really cool - will read just about any signal - you just tell it at what voltages to turn on and off.... and it's dynamic fan control!
-john.

 

[ocelot27]

I'm going ahead with my plan to ditch the duct on the forward side of the the IC and install the biggest fans that will fit in its place - whatever minimal air does go through the duct will still get to the IC if the fans are on. Massive airflow is the solution and sucking air through the duct with fans is not going to give massive air flow. The duct is the bottle neck - I would bet that disconnecting the duct system entirely and just using big fans will level things out nicely; I also think this will work better than an air/water IC - same soak issue with this solution only it just takes longer to saturate the systems water volume with heat - better just to blow the heat right the hell out of the engine bay with big fans.

-john.

 

[ocelot27]

Assuming the water to air has a sufficient heat exchanger and pump, why would this happen? The engine water temps are kept at a constant level with a properly functioning system, why wouldn't the same apply to a water/ air intercooler utilizing the same principles?

Every time you transfer heat from one medium to another you loose efficiency. Going from air to aluminum to water to aluminum to air is much less efficient than going from air to aluminum to air... if the air your using for cooling is about the same temp. So, ultimately, it is the mass air flow over the heat exchanger and the temperature difference that determines how much heat can be removed - regardless of which method you use.

You're right, if you have a big enough heat exchanger and... big fans... and lots of water flow you could get great cooling with the added benefit of much greater thermal capacity in the large volume of water. Thermodynamically in our scenario its better to cut out the middle man and just do two transfers - especially considering that the air used to cool the IC is roughly the same temp as the air used to cool the water in a water cooled IC. The only reason the water systems work better is that they remove the heat from the whole system by using a large well-cooled heat exchanger - we already have a good heat exchanger - it's just not well-cooled.

-john.

 

[ocelot27]

"the water to air has a sufficient heat exchanger and pump"

Water transfers heat better:
Here, water has a sizeable advantage—its specific heat capacity of 4.184 J/gK is more than four times higher than air's 1.005 J/gK. Water looks even better when we consider thermal conductivity, which describes a material's ability to conduct heat. Thermal conductivity is measured in watts per meter Kelvin, and again, higher values are better. Water's 0.6062 W/mK thermal conductivity dwarfs that of air, whose thermal conductivity is only 0.0262 W/mK.


THat said:
I think ultimately using water2air exhanges the volume of air that passes the an air2air system with a fixed volume of water. On a normal air to air with access to flow, the ambient temp air is limitless. In a water system, it's recycled and it would take a lot of water to replicate the same consistent ambient temp'd water. How to get rid of that transfered heat?

On an engine coolant system, the ambients are far lower than target water temps so this might be one reason this kind of system works well.

Exactly - you still have to get rid if the heat using air so why not just use air to start with and eliminate the inefficiencies of multiple heat transfers; you may need lots of air, however (we need to know how much).

If we had the specific heat transfer specs of the IC's in use we could calculate everything and do some "real" engineering... or, ultimately, through trial and error the best and easiest improvement will be determined.

I think by either modifying the existing duct system (expensive, more complicated to fab and less effective in a nonmoving car) or by adding some big-ass fans (cheap, less complicated to implement and works regardless of speed) will definitely show improvement in IATs - how much and how significant in terms of gained HP is another issue. It would be cool to use the temps from the right location (the TMAP) and have Charlie, if possible, write the ECU using this sensor and maybe get a whole different dynamic out of the tune?

This is all very exciting and I'm eager to se what different people come up with.

-john.

 

[ocelot27]

Has anyone measured the mass air flow through the IC roof duct vs speed? We could used a properly calibrated off-the-shelf MAF sensor but it would have to be placed in an area of the duct with laminar flow - somewhere between the roof scoop and the mail slot would probably be ok. I'd be very interested in knowing the cfm vs speed for the 07s, 08s, and with and without fettling the mail slot. Also some 08s have screens in the inlet of the roof scoop and some don't - mine did and I promptly removed it.

On another note those of you who haven't cleaned out your IC should take a look inside. When I installed the RLS IC I noted the factory IC which (had about 1000mi on it) had a pretty good collection of bugs plastered on the fins.

-john.

 

[ocelot27]

yea i found a lot of debris in mine too.

my guess is the only way we'd get accurate data is to drill a hole in the scoop and stick a sensor thru, otherwise the sensor itself would taint the results. I've heard of air speed sensors that race cars use like this one that might work. Racing Data Acquisition Sensors

Something like this would be ideal:

Traceable Hot Wire Anemometer/Thermometer with NIST Certification, Control Company - Mfg# 4330

All you need to know is the cross-sectional area of the conduit where the probe is to calculate cfm - assuming the probe is in an area of laminar flow.

Pricey though - that's one of the cheapest ones I was able to find...

-john.

 

[ocelot27]

You mean something like this?

Airflow was measured downstream of the IC, but since there's no place for the air to escape, it's essentially the same flow in cfm as any cross-section of the scoop or ductwork.

So two 6.5in Spal fans would essentially double the air flow.... neglecting head loss across the IC - which is probably significant.

-john.

 

[ocelot27]

Assuming that their rated cfm wouldn't be compromised by the same bottleneck that affects the roof scoop's ability to provide air flow...

I'm talking about ditching the roof duct entirely and putting the fans on the front of the IC - cool air would still come down through the duct towards the fans - essentially the rubber boot and the duct adapter that connects the IC to the boot would be replaced by two fans...

-john.