V mount why only on RXs ?

[Prof]

It does work...but only on something that emits water. So when we sweat the wind causes the evaporation. Likewise we blow the coffee because the molecules that are bouncing up and down at the top of the surface are blown away.
 
Doesnt work on metal though. But would do if you used an intercooler spray

Actually blowing on hot metal objects does cool them (that\'s what CPU fans are for in your PC), because as someone has twigged - you are replacing the heated air in contact with the metal with cooler air that will more readily accept the heat. What you\'re thinking is heat lost by evaporation, rather than heat lost through convection/conduction (radiant heat loss will not be significant in comparison)

[DRAGON]

Doesnt work on metal though.  But would do if you used an intercooler spray

So air passing over metal does not cool it!? :rolleyes:

[AtomicRex]

So air passing over metal does not cool it!? :rolleyes:

Nope...not in my world!

[DRAGON]

Nope...not in my world!

How do ICs work then?

[AtomicRex]

How do ICs work then?

Magic
 
I was being sarcastic!!
 
I didnt quite mean what I was saying...of course the metal radiate heat...otherwise our houses would be a tad cold....All I was meaning is that blowing cold air over it wasnt the most effective way of cooling them down.
 
Anyway...we spend all of this time and energy debating the best way of putting the coolers....and forget about the LIMs....had a car in the other day that the LIM was too hot to touch!  kind of makes the IC a bit pointless!!

[DRAGON]

I dont think you were being sarcastic, just stupid.

[AtomicRex]

I dont think you were being sarcastic, just stupid.

Thanks...

[soldave]

I\'ve got real figures from my ARC intercooler replacement verses the stock intercooler - and the improvements are marked - but I would not consider a top mount for drifting or any activity where the car is sat idling for any length of time and then expected to perform as the heatsoak will cost you valuable horsepower.

Can I ask to see the figures you\'re talking about?  Not Disputing what you\'re saying but I\'d love to see some evidence of the improvement an ARC top-mount might make.

[trotter]

Actually blowing on hot metal objects does cool them (that\'s what CPU fans are for in your PC), because as someone has twigged - you are replacing the heated air in contact with the metal with cooler air that will more readily accept the heat. What you\'re thinking is heat lost by evaporation, rather than heat lost through convection/conduction (radiant heat loss will not be significant in comparison)

As previously mentioned, its the differential temperature which is the driving force for heat transfer. So a greater dT between objects will permit a greater heat flow from one to t\'other.

The other factors in heat transfer (in no particular order) are:

1) Area
2) Heat capacity of the transfer fluid
3) Thermal conductivity of the object
4) Thickness of the object
5) Various fouling co-efficients

Intercooler are actually (in relative terms) very poor heat exchangers - the reason being that air is not very good at transferring heat either to or from objects. On of the reasons why those big cooling towers you see at power stations are so big - to overcome the inefficiency of the process.

Just my two penneth - spend a lot of time working on heat exchange problems at work!

graeme

[Prof]

Can I ask to see the figures you\'re talking about? Not Disputing what you\'re saying but I\'d love to see some evidence of the improvement an ARC top-mount might make.

These figures are taken from the emanage / temperature display which I built - there\'s a project thread on here somewhere for that, but suffice to say it reads the intake air thermistor (the one in the throttle inlet) and reports the temperatures in deg C on the display.  I built it just before switching the intercoolers - so I got some details from the stock intercooler for comparison purposes:
 
Ok - some figures I have - these are the range of temperatures I took from the engine Intake temp sensor. In the first 2 cases, the car had been on idle for some time prior to the runs - so there is a lot of heat already in the system. Ambient temperature was high 20\'s (80+ Farenheit).

I took readings from the car with the stock intercooler and Rad:

The temp range for the engine inlet sensor 52.2 - 63.6 (125 F - 146F), temp at max boost (11.7 psi) was 54 C (129F). The inlet temps drop on higher boost because of the airflow, but after coming off boost and into trafic they went up to the max figure !!

With the ARC intercooler and stock Rad:

Almost identical conditions to the last run - e.g. idling for a long time, followed by the same run on the same bit of road :

Temp range was 47.6 - 54.1 (117 F - 129 F), temp at max boost (8.6 psi) was 50.9 (123 F).

Then I took some runs with the rad changed as well, these runs were from \'cold\'

Temp range was 30 - 46.2 (86 F - 115 F), temp at max boost (10.4 PSI) was 43.8 (110 F).

The ambient temperatures were give or take 1-2 degrees C on all these runs, the difference in the last run was it was from engine cold, with boost being built after 10 mins of running - water temps upto 80\'s ( >176 F )

I\'m in no doubt the ARC intercooler is more resistant to heat soak, brings temps down much quicker from standing heat, and is returning running temps at least 10 degrees C lower than the stock intercooler. Changing the rad also helped with heatsoak.

[soldave]

Nice figures.  How did you take measurements from the intake temp sensor?  You using a datalogger or aftermarket EMS?

Wondering if the ARC TMIC might be a decent investment for me to go alongside the Ron Davis radiator I have.  Would ideally get a V-mount but am really unsure of the work involved in fabricating one of those.

[Prof]

Nice figures. How did you take measurements from the intake temp sensor? You using a datalogger or aftermarket EMS?
 
Wondering if the ARC TMIC might be a decent investment for me to go alongside the Ron Davis radiator I have. Would ideally get a V-mount but am really unsure of the work involved in fabricating one of those.

I can log temps with the emanage, which piggy backs onto the IAT and water temp signals, but in fact I found the emanage loaded the outputs enough to cause rich running - so I built a buffer amp for it. Seeing as I had the signals available, I have a small microcontroller that converts the temp signals to a serial datastream for display on an LCD - which is accurate to about 1-2 degrees. So basically I am using the stock temp senders the ECU uses, but just hijack the signal.
 
This is the unit in action:
 
http://i112.photobucket.com/albums/n197/dcr1tch/temp_display/DSC00312.jpg
 
http://i112.photobucket.com/albums/n197/dcr1tch/temp_display/th_MOV00316.jpg (http://s112.photobucket.com/albums/n197/dcr1tch/temp_display/?action=view¤t=MOV00316.flv)

[soldave]

That\'s pretty cool.  You fancy making me one of those

[slater1982]

Ok,
 
I\'m no genius but physics A level teaches you that the bigger the pressure difference flowing through the smallest path between the 2 areas measured means the greater the volume of air flowed, therefore the higher the cooling effect across whatever the air passes through, be it rad or ic, so making the biggest pressure difference is the best???:confused:

[Aubec]

Ok,
 
I\'m no genius but physics A level teaches you that the bigger the pressure difference flowing through the smallest path between the 2 areas measured means the greater the volume of air flowed, therefore the higher the cooling effect across whatever the air passes through, be it rad or ic, so making the biggest pressure difference is the best???:confused:

Biggest pressure difference would be by having an I/C that had no holes through it, and that wouldn\'t cool at all.  You need to balance the pressure difference with maximising flow through - you want maximum VOLUME of air reaching the front of it, and enough pressure difference that it flows through quickly enough to take the radiated heat away.  One way to do that is to reduce the pressure on the engine side - V-mount and a properly vented bonnet will likely do that (reducing pressure) better than a front mount (but the trade off is reduced VOLUME of flow through the I/C because the air is split with the rad).

All about compromises, which is why no one can agree on what is \'best\'.

From what I\'ve seen, the biggest downside to a V-mount is that when you take an off track excursion you end up filling the space between rad and intercooler with grass and mud.