Its a rather niave view on heat transfer, showing a lack of real understanding of whats going on.

 

Amen

 

Intercoolers aren't heat-sinks. They can get heat soaked but that's a different thing altogether. If it gets heat soaked then it's not big enough.

The purpose of the IC is simply to transfer heat from the charge to the cooling air as efficiently as possible.

Daz

 

here is the linky

so i'll save my money on their 'intelligent' water spray then!

 

Here is my version

First normal intercooling.

When the charge is at a higher temperature than the outside air temperature heat flows from the charge through the core and into the outside air. The rate of heat flow is governed by the difference in temperature, area available for heat transfer, and the resistance to heat transfer Q=UA(Tcharge-Tout)

The resistance to heat transfer, U, is made up of the combined effects of transfer of heat from the charge to the core, transfer thru' the core, and then transfer from the core to the outside air.

There is a layer of air next the core, both sides, this layer of air doesn't move, it is very thin and is known as the boundary layer.

As air is a very poor conductor the resistance to heat transfer will be dominated by the boundary layers of air. An intercooler normally has more transfer area on the outside, therefore the inside boundary layer will have the greatest effect. This means the temperature of the inside surface of the core will dictate how much the charge is cooled.

Under steady state conditions the temperature of the core would remain constant, however, we don't have steady state conditions. So the core temperature will rise during boost, then cool again when off boost.

Under harder driving conditions the core has less time to cool back down again, so in that sense the original statements are correct. But the fact that the engine is working harder will results in more heat soak of the various components ,turbo, pipework, etc, this will increase the inlet charge temp, meaning more cooling is required.

I have monitored my blower outlet temp and with successive boosted runs the outlet temp increases.

Now, water spray intercooling

The effect being taken advantage of here is evaporative cooling, the air flowing over the outside of the intercooler evaporates the water being sprayed onto the intercooler - this removes a tremendous amount of heat and minimises the core temperature, thus maximising transfer of heat out of the charge.

Matt

 

A much more scientific and informed view of what I was trying to say Matt

Daz

 

yeh- wot he said...............rushes off to dig out old uni books- hang on ive got some becks to finish off

 

so i still need to work on getting better airflow *through* my cooler then !

what do you reckon is the best strategy for water spray onto the intercooler - just a simple inlet manifold air temp switch? or throttle position / boost pressure switch, something like that?

 

so i still need to work on getting better airflow *through* my cooler then !

the best way of doing that is getting a 90-96 Honda Civic/Integra/DelSol rad, If you get a VTEC one it's dual core, and crucially they're half the width of the 5 rad, so you'll actually get *some* airflow through the rad!

the BBR design for the inercooler is really poor IMO

 

I would switch on air temp and either MAP or TPS.

 

Actually, I'm going to stick my head over the parapet and agree with the OP that intercoolers are heatsinks.

Or at least, the way they generally get used on the road, they are. The car might only be in boost for a few seconds at a time, with time enough to cool down in between.

It's been a long time since I did the sums, but starting with back-of-an envelope estimates for temperature, airflow and the mass of aluminium in an intercooler core, plus the specific heat capacities of air and aluminium, I worked out that a quick boosted run will only heat the core by a few degrees.

 

John, Richy is spot onIMO. The BBR 'cooler' is nothing more than a heat exhanger taking conducted/radiated heat from the rad while being 'cooled' by second hand air that has already been warmed by the rad on its passage. All this you already know but suffice to say there is not easy solution other than to remove the impediment of the rad from in front of the BBR cooler via a Honda rad or (more plausibe IMO) find a way of front mounting the self same intercooler. The BBR stage 3 cars acually used the same tiny cooler but mounted it in front of the rad to good effect. Whether this reversal resulted in cooler intake temps but coolant overheating is still unproven, but Peter Jones stage 3 car seemed to do alright. A much better solution of course is to front mount just about any other intercooler whatsoever, the BBR one really is that poor IMO.

 

putting location to the side, what's the difference between the bbr one and any other that i can pick up - basically, in what way can one intercooler be better than another?

i like the idea of a front mounter but wouldn't that then impede flow to the rad too much? i think i'd prefer the half width rad...

 

That is a fair question and I guess it boils down to how much internal surface area the intake air can contact with, without being impeded excessively. Instinct says that up to a point, for a given flow, a larger cooler with appropriate finning and flow channels will offer more surface area for conduction to the IC than a smaller one and the BBR design is very small compared to most others and of course it depends on the temp delta as noted above by MI5 (good explanation btw): to maximise the delta you minimse the IC airflow temp. As I noted above, the BBR design does work a hell of a lot better front mounted on the stage 3 cars like Peter Jones' without causing overheating of the engine coolant (and Peter has run at 130mph for extended periods) but a larger IC may of course block more of the rad. My gut instinct is that the std BBR location is basically as good as useless ie about as useful as no intercooler at all whereas a front mount of the self-same IC would probably knock 20degC off and a front mount of a better design may knock ~40degC off (I used to see 70degC plus whereas on the FM I see 30-40degC). All my 2pworth base on my experiences with my 10psi BBR, and 12 years of listening to the comments of others of course.

 

I looked into the IC spray kits when i decided to go the IC route.

I'd narrowed it done to this 1:
http://www.turbobits.co.uk/acatalog/elabtr...ater_spray.html

Thing is though i've not noticed any heatsoak problems so far.
So i feel at the min it might be a little overkill with WI already installed.

Cheers
Mark

 

where does the WI come - pre intercooler? if so i'd be surprised if you needed both...

 

John - buy the custom rad Rich Smith was selling in the classifieds, he specifically made it shorter to do EXACTLY what you want.

 

mate do you have any details? i've looked in nutz for sale section (and the oc and pistonheads just in case!!) but can't find it. do you know if its thicker than stock to make up for lost width?

cheers

 

I was talking to greg (packers) about Ic's at masrat the other month and where i see intake temps of generally 10 degrees more than ambient (give or take some) he regularly sees intake temps on the link of over 45-50 degrees.

my intake has rarely seen over 30 degrees, with current weather its around the late 20's.

I am 12psi and greg is 8psi non intercooled.

prob bugger all to do with the topic but hey, wortha mention

 

i just thought that after the intercooler the air might not be hot enough to evaporate the water?

 

If that were the case, then you'd find the injected water condensing inside the intercooler. Might build up a significant amount of liquid in there which would pose a risk if a decent amount got slurped out at some stage.

 

WI should be after the intercooler.

If you've managed to evaporate it before the intercooler you wont remove as much heat with the intercooler (lower driving force).

Better to have a fine mist of non-evaporated water getting into the cylinders where it can do its job properly. You do not need the water to evaporate in the intake.

Also, the mist of water entering the intercooler would impinge on the fins and you would soon end up with a puddle.

 

ahhhh

cheers!