911

I have an STi V3, stock IC on the engine and an RA waterspray set to run on my demand, so not linked to the ecu.It is not very good as I cannot get it to atomise the water, just spray.
I hill climb the car seriously, and you wait ages in the que for the startline. This means the IC soaks up a lot of heat and you cannot get it cool before a 60 seconds flat out run. In the recent hot weather it is even worse.
So-
Would you all think I might benefit if I run the cold air from the air conditioning (!)on the car into a plenum which covers the whole top surface of the IC (sealed) so I get very cold air delivered at pressure to pass through the IC so cooling the inlet air????
Such a plenum would take the place or lay inside the bonnet scoop.
I am realy only interested in power on the track rather than the road.
I know that running the A/C takes bhp, but would I not see a nett gain?
Who is still good at thermodynamics out there?
The plenum could be fibreglass and have a simple inlet to run along the edge of the IC to distribute the air right across the IC.

Hope I've explained this clearly, but before I start, am I crazy?

Graham.

Butty

iTrader: (2)

Why not take along a freezer bag of ice and dump it in the IC when in the queue. You'll have to judge it right that its not all melted while waiting, but remove it before your go as it will block the air flow while moving?

Nick

911

Thanks for the idea! Problem is I'm all strapped into the car, helmet on and all that, and you don't know how long you will be standing there, but, the top of the IC may be cold, but the base will be hot! Need to cool all the way through....hence the idea of the cold air blast which i can turn on/off to suit.
Thanks for the reply though!
Graham.

GariYaRally

Thermodynamics ehh...

Thermodynamics states that you can't get something from nothing (refer Carnot's cycle)

The amount of power the engine will use to cool the air will be a lot more than the power gain due to the cool air on the IC.

Although, if you were to cool the IC whilst you're waiting with the AC and then switch the AC off just before your run, there will be a huge difference in the power.

I've seen a couple of guys modify fuel rails on their cars. You get a long length of copper/aluminium pipe and wind it round a canister and fill the canister with "dry ice". This drops the fuel inlet temp. thus increasing the power.

Pavlo

You can't get something for nothing, but you can work on dumping the "something" somewhere other than the intercooler.

C02 liquid spray on the intercooler would be a good one, although N20 is cheaper and works more effectively. A small bottle should be light enough for the weight penalty to be overcome by the improved temps

Paul

dnb

Why not fix the water spray first. I expect that it's running at low pressure. IIRC, this sort of spray system needs to see 3 to 4 bar to be effective.

I have thought about using the AC system to cool some working fluid in a seaed system while cruising (when there's power to spare) and then use this to cool the charge when power is required. Sort of like a temporary charge cooler. Never got around to testing it though.

Unfortunately, I have a feeling that the extra weight of such a scheme would be prohibitive.

911

Yes, this is the next step. I think the volts to the RA sourced motor is low, but it is a real IC spray motor, so I thought it would all be ok.Whole system is off an RA, pipes nozzels etc.
The A/C idea is a source 'instantly' available which is bloodt cold and with a force to get through the IC matrix. My realy problem will be to get into the system behind the dash and bring it to the IC itself.
Thanks for the comments.
Graham.

911

Paul, Some people are starting to use 'plumbers icer' an aerosol spray used to freeze water pipes. They liberally spray the fin pack just before a run to quench the IC, but it cannot cool the collector end caps in time due to their mass. Again, this is why I think the A/C route provides a lot of very cold air in a limitless way, on driver demand , for however long you need! Bliss?
Any idea how much bhp is lost to an A/C pump at full chat verses the power gain by running the air cooler into the engine?
If the a/c is 8 bhp and the gain 12 then it is not worth the bother!
Graham.

LHD Ver1

Why not just get a water-air intercooler. joking

Or put larger endtanks over the current end tanks and run tubing from the AC lines into the larger endtanks. So the intake air flow will not change, the fins will not be covered. So you will have a casing around the end tanks like a water to air IC but the fins will still be used to cool the endtanks while in motion and the AC will cool the tanks while sitting still.


[Edited by LHD Ver1 - 8/14/2003 9:15:52 PM]

911

Wow, you Yankies sure think laterally!An interesting idea, but I am looking to cool the whole IC not just part of it!
For hill climbs, the road speeds are not realy that fast so airflow via the scoop is limited, I still thinkI can get a good result using a/c system.
Keep it coming guys!
Graham.

AJbaseBloke

A couple of guys I saw at a gymkhana a while back had installed GDB STi Spec C water tanks (12ltr jobs) that sit in the boot + upped the pump size for more flow (or maybe it was better pressure?). One guy I saw chucking ice in his tank, and another had ice in to cool the stuff in there, then a few packs of ice on a cold plate to cool the water further...dunno if it works much, but he was certainly fast!

And yeah, I've heard of a few peeps doing the fuel cooling trick too (I think both guys the day I went were doing that).

911

Just got back today from the race day hill climb, 3rd in class...
Tried ice cold water, about 3 deg above freezing. Soaked the now larger IC on the engine. ambient was about 28 deg C.
The colder water onto the matrix seemed to help as i went faster with the water full on on the last 3rd of the track, drenched the IC.
STILL think the masses of very cold air under pressure over the matrix is the answer provided from the A/C side of things.Just can't quite see how to get into the system under the dash board and get a duct through to the IC etc. Winter project!
Keep the comments/ideas coming in guys!
Graham.

911

Just got back today from the race day hill climb, 3rd in class...
Tried ice cold water, about 3 deg above freezing. Soaked the now larger IC on the engine. ambient was about 28 deg C.
The colder water onto the matrix seemed to help as i went faster with the water full on on the last 3rd of the track, drenched the IC.
STILL think the masses of very cold air under pressure over the matrix is the answer provided from the A/C side of things.Just can't quite see how to get into the system under the dash board and get a duct through to the IC etc. Winter project!
Keep the comments/ideas coming in guys!
Graham.

Zeolite

Get helper to chuck the ice water on the ic just before you pull up to the line. It seems to be simpler than a technical solution.

911

Tried that on a race on Saturday. Filled the reservior with ice cold water, about 3 deg C, and drowned the IC with same temp water. Turned the 'spray' on just after the run started until the run was done, about 35 secs duration. Kept it cool, but only the matrix not the end caps which are not sprayed on, but got a good time never the less!
Maybe low tech rules after all.....
Graham.

Mark A

iTrader: (1)

FMIC calling Graham
You know it makes sense. Your winnings should cover the cost ;-)

Mark A

Pavlo

might introduce inwanted lag on a hilclimb car, especially one without anti lag.

unless you can get one with very short pipe runs, so something like the pace, or completely custom, might be worth uprating the top mount

Paul

911

Gentlemen, have just fitted a BRD huge TMIC instead of the STi unit 3 days before last weekend's race. It weighs twice as much as the STi so a lot of aluminium to cool.....
A friend has just fitted a FMIC to his hillclimb RA which gives about 350bhp (I had his old BRD IC) and he has noticed more lag immedeatly! Still went quicker than me the bas*ard.....
What is all this 'prize money'? The only direction money goes in motorsport is out to someone else's pocket!
I think i must follow the mist spray of ice cold water but would like to spray the 'hot' side of the IC collector chamber to cool the air as well as the core/matrix.
There were 2 WRC Scoobies at Shelsley Walsh hill climb last weekend, the real thing. Both had FMIC but done by Prodrive so very short pipes and a reversed inlet manifold. Great great cars, BUT my STi was quicker up the same hill the day before!!!!They must weigh a lot more?
Graham.
Pavlo, those Kumho's are killer tyres!

rex11

You also might want to try a alcohol/water mix in your spray system. While water allon has a high latent heat of vaporization, the evaporation rate of the alcohol is much much higher...blah, blah...the alcohol will evaporate very quickly when it hits the intercooler fin surfaces, which is where practically all of your heat transfer is taking place. The higher the concentration of alcohol the better the "instantaneous cooling" will be. Just be careful of running pure alcohol, as it might be a fire hazard. Running somewhere between 70/30 and 90/10 alc/H2O.

With this set-up you don't have to worry about the liquid temps, as it is the phase change energy (liquid to gas)that will drive the cooling, not just a liquid/air temperature difference. Just my thoughts, anyone else?

911

REX, great info, I think i've read this somewhere before, but was worried about the fire hazard as the turbo will be very hot during a full run. Are you sure about the mix ratio? Can you buy pure alchohl I wonder?
Great idea, thanks!

rex11

you can buy both pure and 70/30 through chemical retailers (www.vwrsp.com), but the 70/30 will be less expensive. It should also be ok for use around the exhuast.

911

Great, and thanks for your help, will try to get some as the 'season' here is just 4 races more then I am back into the garage, so can get some more trial in during these races.
Will let you know how I get on.
Regards, Graham.

-=uk99=-

tri this m8 mine is on order now looks good

http://www.subarustore.com/deicry02taan.html

[Edited by -=uk99=- - 8/25/2003 11:37:57 AM]

911

Wow! Just been on thier site, quite a set-up! I bet this is the G Force package? I wonder if you can get the bottle here in UK?
Thanks for the lead!
Graham.

911

In an attempt to get the most of my present 'set-up' I substituted the STi 'spray' nozzels for simple Hozelok garden mist sprays.
For £3.90 you get 6 nozzels with th 360 degree spray pattern. They happen to inset into the subaru hoe tube exactly, but I secured them with very small cable ties and fixed them on wire supports allowing me to adjst their position directly ofer the IC's face.
These generate a mist of water so it will evaporate quickly and take the heat away. The STi units 'sprayed' like a hosepipe in comparison.
Do you think this will help?
Graham.

Mark A

iTrader: (1)

Surely all you'd need to order is the kit and not the bottle. C02 is available in very small bottles for welding, if not let me know as I can should be able to get hold of one but it might be a bit bigger and it will be heavier, a la BOC bottles.

Mark A

PS not ordered tyres yet as intercooler etc in bits at present.

911

You havn't got those tyres yet?! Tut tut, don't know what you are missing......
I'm a prat for not thinking about CO2 welding bottle! The Kit looks realy good, and is quite cheap if ordered direct. they do one with full temperature/pressure control so delivery is only when needed.
just need to get a few more brownie points with the 'boss' so I can do it over Xmas, might even get it as a present!
Was Harewood good? Would like to do that hill next year as part of the British Open Championship.
How can you have an IC in bits?
Regards, Graham.

carlos_hiraoka

spraying CO2 into the TMIC works really well ..... at least for drag racing it does

BUT be careful as it can reduce the inlet temps drastically, which would lean your AFR's , that is why on the cars that use it for the 1/4's we have the regular AFR's a little richer (nothing that a simple adjustable fuel pressure regulator wouldn't solve ).

Carlos H.

Mark A

iTrader: (1)

Graham,

Missed Harewood, bread knife had other plans. Trying to fit a bugeye IC into a classic, it looked so simple when I started but now its turning into a real nightmare. Plus while the IC's off decide to try the fuel rail mod. All this is being done on the street as I turned down the offer of a garage thinking it was a half day job, Muppet.

Mark A

911

Carlos, thanks for the tip! On a hillclimb I don't think the engine will demand a constant cooling of CO2, and the USA kit has sensors to trigger the charge on inlet temp.
I used to drag race here in the early 70's so understand the demand will be different to hillclimb (I think). A typical UK hillclimb is all of 50 seconds long with lots of on/off accelleration in relatively short blasts.....so i may be wrong!
Graham.