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home made charge cooler?

2K views 16 replies 7 participants last post by  JohnA 
#1 ·
how feasible would it be to make a charge cooler using the internals from an aircon heat exchanger, then fit the compressor, the condenser and other bumph from a car with aircon. that would give the engine some really nice COLD air to play with. could the cooler matrix from one of these flow enough air to supply a 1.7 td at full revs, or would it need to be enlarged? is there any benefit from cooling the air any more than a normal water charge cooler would? would it give more than 5 bhp increase, which is what i`m told the compressor loss is?
 
#2 ·
ive often wondered about this, and why it hasnt been done before...

i spoke to Richard Bell at the Interpro RR,

we thought it could be because it would be too cold. ie ice?????

i know motorbikes have had to have heated carbs before, to stop them icing up.
 
#7 ·
would it give more than 5 bhp
I would think so I have seen two different charge cooler fitting guides (r5 and rst) and both cars saw gains of 20bhp or over with nothing else done. Fueling was checked to ensure niether were running lean.
 
#13 ·
cavvysri said:
how feasible would it be to make a charge cooler using the internals from an aircon heat exchanger, then fit the compressor, the condenser and other bumph from a car with aircon. that would give the engine some really nice COLD air to play with
This idea is not new. Ford even has a prototype based on this principle (loosely)

In your case, in a nutshell, it won't work.
The amount of energy you'll consume cooling the charge will always be greater than the extra bhp due to the cooler intake temps.
Just try to calculate the airflow of your engine at high revs, and you'll soon realise that the aircon setup won't do much at all. It was never meant to deal with this kind of cfm...
 
#15 ·
Using a conventional evaporator from an air con system will not suffice. What you'll need is a heat exchanger, such as a shell and tube or counterflow.
Problem will be is that the evaporating temperature will be too high, this means it will not be able to exchange energy between the refrigerant and the charge quick enough due to the high flow rate of the charge. The only way to overcome this is reduce the evaporating temperature even further, or increase the size of the heat exchanger which isn't really practical due to under bonnet space.
This means the plant will have to be larger to cope with the demand, the compressor will have to me more powerful, hence sapping more power from the engine. You'll also probably have to change refrigerant, and unfortunately the most effective ones are usually the most volatile and flammable!!
By the time you've done a mass energy balance of the system, you'll find that the refrigeration plant is actually using more energy that your gaining in engine output. As a general rule, compressors are only around 75% efficient.

So basically to do it, you'll have to have a unit off a refrigerated articulated trailer to cope with the cooling you'll need
 
#16 ·
thanks everybody, after the info youve all told me and what my mate said i`m just gonna leave it. ho hum large black intercooler it is then. how about fitting a couple of tiny water jets to spray on the intercooler body wired up to a switch in the dashboard. would that be effective?
 
#17 ·
cavvysri said:
.....how about fitting a couple of tiny water jets to spray on the intercooler body wired up to a switch in the dashboard. would that be effective?
Yes.
In the summer, this can increase the efficiency of the i/c by around 10%. So if the intercooler has an efficiency of 70% giving you 40 extra bhp (both realistic figures), then while the i/c core is wet and moist (...) the efficiency will be (say) 77% and you'll have yet another 4bhp.
If it's really hot and dry and you're stuck in slow-moving traffic, your intercooler's efficiency will be closer to 50%, and the spray will be even more helpful.
Make sure the water jets point in the right direction towards the core, when you're on the move (the airflow will deflect them, so you have to compensate for that)
 
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