2007 Exige S Intercooler Air Flow Study

[charliex]

I've always heard it 3rd party (mainly from evo/subbie guys) but the rumour is a lot of tracks won't let you run if you have stuff spraying out of the car, even if it is mist, but i don't know the facts on that one.

Looking at that turbo prius, pause for a moment, the temp drop doesn't look like all that much, its already fairly low, the ability of the water to cool will drop off as everything gets hotter, so the percentage difference will drop too, i didn't see any other sheets on it so it might not be the best example, you can see on the sheet that the temps are beginning to converge.

[robains]

You could be correct on the rules - I didn't see anything in the rules that prevented this, but there are many pages and I didn't necessarily digest every detail.

Charliex, not great data, they do post more data on other links. But after reading more about the water pumps, there doesn't appear to be a really good pump to accomplish track type situations -- one would have to set a long delay between triggers to keep the pump from overheating with the high PSI needed to create the mist.

[ocelot27]

Originally Posted by robains

You could be correct on the rules - I didn't see anything in the rules that prevented this, but there are many pages and I didn't necessarily digest every detail.

Charliex, not great data, they do post more data on other links. But after reading more about the water pumps, there doesn't appear to be a really good pump to accomplish track type situations -- one would have to set a long delay between triggers to keep the pump from overheating with the high PSI needed to create the mist.

Thomas looked into this approach instead of injecting water (or water/methanol) directly into the intake post IC and I seem to remember him saying it helped lower intake temps but couldn't hold a candle to water/meth injection directly into the intake... this of course makes perfect sense. If you wanted to be conservative, however, you could use the same pumps that are used in water/meth injection systems and just locate the sprayers in the IC's cooling duct somewhere. I think if your going to spend the $$$ on such a system it's best to just use it as designed and inject water or water/methanol directly into the intake.

-john.

[robains]

From what I've heard, direct water/meth injection isn't helping these cars much either -- the heat soak is just too much.

I believe I was seeing 176F at ButtonWillow for IAT (according to EFI software and that was 15 minutes after I had been out on track) -- which is WAY hot. I had to let the car sit for a long time before I could even touch the pipes with a rag and gloves ON!

I hope someone comes up with a good solution for track worthiness. But I would have to say the large roof scoop appears to be more about looks than function. I'll continue on the sprayer and relocating the IC up and back and opening the mail slot as much as possible, but I'm honestly not expecting much.

[Thomasio]

Originally Posted by robains

From what I've heard, direct water/meth injection isn't helping these cars much either -- the heat soak is just too much.

I'm seeing 20 degrees F or more drop in IAT temps w/ 50/50 injection.

[qball]

The best I can figure is to mount to NACA ducts to either...

a) the plastic wheel well liner
b) inside the side-scoops (with some sort of velocity stack)

Run some 3" aeroduct hoses to the back of the intercooler shroud

Build a modified intercooler shroud to accept two additional 3" inputs

I figure the inlet on the roof is roughly 8" x 1.5" square, giving a total inlet area of 12 sq. inches

Two additional 3" ducts of air into the back of the I/C would provide 14.13 sq. in. additional area for air to enter.

So that would more than double the airflow...

(This is basically what the guy in France did)

I'm just not sure about the airflow inside the wheel wells.

[Mag]

Originally Posted by qball

The best I can figure is to mount to NACA ducts to either...

I'm just not sure about the airflow inside the wheel wells.

yea lots of bends.

enlarged side scoops to sealed collector would probably be best but who makes these in 3inch? and then what about the intake?

[Mag]

thomasio took a heat source to the stock MAP IAT and the mongoose obd2 reacted accordingly on 07 S car. May be a misprint in the manual? I'll do the same test next week to double confirm for innovate on 240.

[apk919]

Originally Posted by Mag

thomasio took a heat source to the stock MAP IAT and the mongoose obd2 reacted accordingly on 07 S car. May be a misprint in the manual? I'll do the same test next week to double confirm for innovate on 240.

I'm beginning to think that the manual describes the n/a IAT accurately and not the s/c IAT. If charliex says that the s/c IAT is taken from the TMAP sensor, I'm inclined to defer.

Hey Mag, I just got my Innovate OT-1, TC-4, and DL-32 delivered. I'm hoping to set aside some time this weekend to at least get a "breadboard" install done. I've also gotten my hands on an infrared thermometer and a Fluke temperature probe to verify temps.

[robains]

Is that a dent I see in the IC??? Hehe...does anyone not have a dent in the IC?

I'm hoping to be a protoype for a new solution to these extremely high IAT values.

[L 33 HAW]

I know iv mentioned it before, but i just wondered if there was any plans to study airflow and intercooler temp/effeciency with the roof removed? Alot of owners are running the car like this, and there is alot of descussion, with no firm answer as to the effects/safety of this.

Any ideas?

Thanks

[Mag]

Originally Posted by L 33 HAW

I know iv mentioned it before, but i just wondered if there was any plans to study airflow and intercooler temp/effeciency with the roof removed? Alot of owners are running the car like this, and there is alot of descussion, with no firm answer as to the effects/safety of this.

Any ideas?

Thanks

I'll do this as well once got the sensors hooked up correctly

[Mag]

Originally Posted by apk919

I'm beginning to think that the manual describes the n/a IAT accurately and not the s/c IAT. If charliex says that the s/c IAT is taken from the TMAP sensor, I'm inclined to defer.

Hey Mag, I just got my Innovate OT-1, TC-4, and DL-32 delivered. I'm hoping to set aside some time this weekend to at least get a "breadboard" install done. I've also gotten my hands on an infrared thermometer and a Fluke temperature probe to verify temps.

hehe ... its a good system once it's hooked up, then calibrated. good luck, if need any tips PM me.

[Thomasio]

The PID called SAE.IAT *is* the temperature from the intercooler IAT sensor (the Bosch). 2007 Exige S.

Here is what happened when I unbolted the Bosch IAT sensor from the intercooler and assaulted it with a hairdryer.

[apk919]

Originally Posted by Thomasio

The PID called SAE.IAT *is* the temperature from the intercooler IAT sensor (the Bosch). 2007 Exige S.

Here is what happened when I unbolted the Bosch IAT sensor from the intercooler and assaulted it with a hairdryer.

Well, that doesn't seem to leave much room for confusion...

I wonder what's up with the schematics in the service manual then?

[lwein]

Originally Posted by L 33 HAW

I know iv mentioned it before, but i just wondered if there was any plans to study airflow and intercooler temp/effeciency with the roof removed? Alot of owners are running the car like this, and there is alot of descussion, with no firm answer as to the effects/safety of this.

Any ideas?

Thanks

This is just based on my personal experience-------I have no data to support these conclusions.
I was driving my 240S around without the top,and while I was sitting at a light-ambient was about 85F-I could actually feel warm air-certainly warmer than ambient-coming out of my air intake. This was not a track day,and I was not driving it hard at all. Based on this,I have got to believe that the loss of HP is fairly severe without the top on. Again,I have no data to back this up. The wind buffeting(which I really don't care about) is much more pronounced in an Exige with the top off than it was with an Elise under the same conditions,which makes sense----and I am sure that the airflow to the wing is totally upset. If only someone made a scoop to use while the top is off,that might help. I can't imagine safety being a concern-do you mean in a rollover?
That said, on a beautiful summer or spring day,these things don't bother me-----For a track day,they would be a serious concern. This is on a totally stock 240S,I have Thomasio's intercooler but haven't installed it yet.
I still like the idea of a NACA duct on the drivers side sail panel,and the photo of the ducted air to the IC duct would also seem to be viable,but,of course,only when the car is in motion. I also noticed with the top off,when moving, the air coming over the windscreen is indeed warmer than ambient,but at the center of the windscreen(where the scoop would pick it up) it is actually cooler than the other spots!

[ericwgexige]

Yes, with the top removed, and at any speed, the hot air from the engine compartment will definitely back up through the IC and then exit backwards out of the ducting in the rear clam. Verified this today on my S.

[ericwgexige]

A little off topic, but how did you guys dent your IC, so that I may avoid doing this also?

[qball]

I suspect that IF the air is indeed flowing back out, then it is also with the top on too! You just can't feel it because the roof inlet is not easy to reach.

However, I see no physical reason why the air would back out with the top on versus off.

I suspect you are just feeing heat rising from the engine compartment over the roll-bar, or heat is just rising out of the roll-bar inlet due to convection.

There is some data in the thread below, showing that the it's actually BETTER for the I/C to get air flow with the top off (less restriction) then with the roof and scoop. End even better with a soft top on and NO SCOOP.

Exige S intercooler thermal measurements

[apk919]

Originally Posted by ericwgexige

Yes, with the top removed, and at any speed, the hot air from the engine compartment will definitely back up through the IC and then exit backwards out of the ducting in the rear clam. Verified this today on my S.

Originally Posted by qball

I suspect that IF the air is indeed flowing back out, then it is also with the top on too! You just can't feel it because the roof inlet is not easy to reach.

However, I see no physical reason why the air would back out with the top on versus off.

I suspect you are just feeing heat rising from the engine compartment over the roll-bar, or heat is just rising out of the roll-bar inlet due to convection.

There is some data in the thread below, showing that the it's actually BETTER for the I/C to get air flow with the top off (less restriction) then with the roof and scoop. End even better with a soft top on and NO SCOOP.

Exige S intercooler thermal measurements

Sorry guys, but at any speed above 5mph I've seen no evidence of reverse air flow though the roof scoop. I've put a data logging air flow meter at various points behind the intercooler, and have taken a few hours worth of data at various speeds and weather conditions. I haven't taken data with the roof removed, so it's possible that reverse flow can occur at higher speeds without the roof... but given the data that I've logged, I'm very skeptical that there's any reverse flow at any significant forward speed with either the "S" roof or the Cup roof.