There was a posting on here a while back asking why you couldn't use the aircon to cool down the charge temps.. obviously everyone was stating the power drain of using aircon etc...

... anyone else spotted that Ford (IIRC) in EVO(IIRC#2) magazine have a reservoir that can be chilled using aircon, giving a 50BHP boost for about 40 seconds ??

yes I did.


but the point is it stores it when power isnt being used.

There is no question that the air con could be used in this way, but the system costs power for sure so is meant to charge when power isnt required, such as on cruise etc.

Did you also not that it takes 2 mins to charge but 40 secs to use, so it could only ever be used i bursts.

I was susprised to see the claim of 50bhp though, seems awfully optimistic.

Was on a car with about 600bhp in the first place. Equates to approx 8% increase in power. Would equate to approx 16bhp on a scoob, they reckon a/c uses about 2bhp. Putting all this together, if run continuously, it could be an advantage, however for bursts, overall power consumption would be approx the same!!!!

forgive my stupidity.. but I was taught at school 'You cant get something for nothing' ??

David

Hence the short burst thing...

david, using stored energy is not the same as getting something for nothing.

and to whoever it was that said it is a percentage, that is true in some respects but not in others.

yes it will be affected more by the temp, but equally at 600bhp, it will be flowing a lot more air, so the amount of cold stored charge needed will be greater on that engine as it will need to get rid of more heat than it would on the impreza.

In short, two mins charging on our cars would last longer than it would on theirs.

This tank must be huge though, as 40 secs at WOT is a massive amount air.

isnt it something like 1bhp:1.5cfm roughly.

meaning 900cf/min.

there would need to be enough cold air stored to cool down 600cubic feet of air, thats quite a bit!

I'm feeling a bit bemused as well - something along the lines of conservation of energy and perpetual motion... So it couldn't be used to increase power all the time.

In fact, it would take energy from a time where you don't need it, and allow you to use that energy (less a bit for inefficiencies) when you require it.

I expect that you could use an AC compressor to cool a working fluid in a tank while the car is cruising, and then shut the compressor off and allow the fluid to flow round a charge cooler circuit when you need to accelerate...

The question then is not "will cooling the fluid cost more power than the gains from the charge cooler?" but "will the power taken to pump the fluid be less than the power gain from the charge cooler?" (I guess the answer is "yes" for the right fluid for the second question and a definite "No" for the first.)

Hmmm, maybe have to do some DIY trials :) - could be a better mod than IC water spray!

I'll stop rambling and go back to work now....

Adam - it doesn't have to be stored air. EG. The specific heat capacity of water is quite big, so a small vol. of water can cool quite a bit of air...

I have a few issues to work out, but a plan is forming :D

Can it work the same way a supercharger works? In terms that it takes a few bhp to drive the supercharger, but it gives you more bhp in return? Could the few bhp it takes to drive a compressor release more bhp in the cold charge it produces? I suppose if the answer was yes it would have been done ages ago.

http://www.autospeed.com/cms/article.html?&A=0436

EDIT: Subscription required - have mailed you the article to your address in your profile.

[Edited by GavinP - 2/10/2003 3:57:52 PM]

IMHO, I doubt the +50bhp on the car in EVO mag is purely from charge temperatures. I would guess that the extra cooling allows the engine to safely run more boost (and therefore also adds more fuel)without risking det. This could then also solve the "something for nothing" arguement?

I may of course be completely wrong! :p

Edit due to double negative confusing things :rolleyes:

[Edited by hades - 2/10/2003 7:08:38 PM]