Water-Air Intercooler using AC??

I'm looking for a cheap ($20XX Budget friendly) way to cool the intake charge for a 2003 MINI Cooper S.

The car suffers from heat sink, with the air/air intercooler mounted right on top of the engine, so it can soak up plenty of heat, and not flow air through it like it needs.

I was just going to build a bigger air scoop, but then I got to thinking...

This car is going to stay on the street, so I am not pulling all the AC stuff. But I DON'T need a functional AC unit at the Challenge.

So, could I modify a small double or triple pass radiator, mount it in the intake charge stream, and valve the AC unit to circulate the refrigerant through the radiator in a manner that would be reasonably effective?

This car will never see real class racing, so it's OK to think outside the box.

Thoughts?

Been done in an OEM application by just running the air charge through the evaporator. Phase-change intercooling!

Alternatively, you use a water/air intercooler and put the evaporator in the water tank. No water radiator. This would be a little more stable if the compressor can't handle the instantaneous loads. Pre-load the system with ice water before competition starts.

I wouks think the draw feom the compressor would negate any gains. U would always just hook up a sprayer and use the washwr squirtwrs or something.

Jaxmadine wrote: I wouks think the draw feom the compressor would negate any gains.

It can't take any more than ~10hp to drive the A/C compressor given the limitations of belt drive. Will intercooling allow more than 10hp gain? I'd bet it does

I think the laws of physics dictate that this won't work.

You would be further ahead to rig up an intercooler sprayer.

93gsxturbo wrote: I think the laws of physics dictate that this won't work. You would be further ahead to rig up an intercooler sprayer.

Explain how.

You can also use the laws of physics to say turbocharging doesn't work. Exhaust manifold pressure is generally 2-3x intake manifold pressure when under boost, therefore there is an increased resistance to mass flow through the engine, therefore the engine makes less power...

Supposedly been done to a few CTS-Vs by a local shop. Mostly for drag racing, not sure about autoX/street.

This will work for drag racing or autocrossing f you use an air to water setup and a decent sized reservoir. A cooler with ice water in it would work and probably be easier. Does the AC compressor shut off at full throttle? That would keep it from sucking power when you want it most.

In reply to SVreX:

It is certainly possible for this to be effective. I would recommend something like Knurled described - putting the existing IC in a water tank with an AC evaporator. You could use the AC to cool the water before each run, then turn it off right before heading out on track.

IIRC a recent hot rod ford had a factory pre cool setup using the AC.

93gsxturbo wrote: I think the laws of physics dictate that this won't work.

That's incorrect. It's certainly possible to get a system like this to produce a net increase in power. It's just not going to be the cheapest/lightest way to do it.

JohnyHachi6 wrote:

93gsxturbo wrote: I think the laws of physics dictate that this won't work.

That's incorrect. It's certainly possible to get a system like this to produce a net increase in power. It's just not going to be the cheapest/lightest way to do it.

At constant full load-no it won't work, but with a pre cool period and varying loads you can get a limited time increase in full throttle power.

MrJoshua wrote: At constant full load-no it won't work, but with a pre cool period and varying loads you can get a limited time increase in full throttle power.

Why not?

The horsepower gains are not from something silly like using an alternator to drive an electric motor on the crank. What is happening here is, a compressor is used to supercool the intake charge so that the engine may make more power through reduced tendency to detonate.

It would most likely be a net loss on a nonturbo car, but on detonation-limited turbo cars where there is a large temperature gradient, large power gains can be had.

Your car's A/C system is probably more powerful than your house's. Cars are horrible for cooling down, they're drafty and they have a lot of window area.

In reply to Knurled:

Overunity :D

Yeah, this discussion has come up on this board before. It's definitely possible from a conservation of energy & laws of thermodynamics perspective to show that a vapor-compression (A/C) charge cooling system can produce a net increase in power, even in steady state. It's just not usually a good solution since you can get that cooling for free with a big air-to-air heat exchanger.

93gsxturbo wrote: I think the laws of physics dictate that this won't work. You would be further ahead to rig up an intercooler sprayer.

It will work the same as a power drawing supercharger does.

I think you're right about the sprayer though.

Methanol sprayer is the most effective of the cheap ways of improving intercooler efficiency. It's VERY cheap too. You basically reroute/modify one of the washer fluid systems. Few new parts involved.

There were a lot of studies about this subject back in the day ('04-05'ish) and basically it was found there were diminishing returns in increased HP trying to go nuts cooling the intake charge. I think it had something to do with the ECU and fueling (it's been years since I cared much about any of this, so I'm going by spotty memory - do an archive search on NAM). Essentially: the "heat sink" is more theory than practical reality.

To be honest - contact Jan at RMW. Be sure to mention why you're trying to keep the budget down so he doesn't think you're a crack-pot. He's been playing with these cars pretty much since the beginning and if there's a cheap way to increase power, he'll know it.

Jaxmadine wrote: I wouks think the draw feom the compressor would negate any gains. U would always just hook up a sprayer and use the washwr squirtwrs or something.

You guys might be surprised but it can work. I work in a power plant that has a 7,000 ton A/C unit to cool the intake for two gas turbines. The electrical load for the A/C is 7MW and the turbine output gain is 30-50MW (depending on ambient conditions)

But doesnt the intake air in the power plant go through the evaporator to cool it? I xould see that possibly working if he makes a tiny evap that fits in line. Just just throwing some coling coils on the intercooler isnt going to be as effective. Just throw some ice on it when not running.

djsilver wrote:

Jaxmadine wrote: I wouks think the draw feom the compressor would negate any gains. U would always just hook up a sprayer and use the washwr squirtwrs or something.

You guys might be surprised but it can work. I work in a power plant that has a 7,000 ton A/C unit to cool the intake for two gas turbines. The electrical load for the A/C is 7MW and the turbine output gain is 30-50MW (depending on ambient conditions)

I guess the issue we all have stems from the truth that you can't get something for nothing. The reality in your (and Paul's) situation is that you can enable the current system to take MORE energy IN without melting/breaking and the allow you'll get MORE energy OUT. It's not a closed system: we are consuming gasoline and this might allow you to consume more.

I'm not suggesting getting something for nothing.

I'm suggesting correcting some big existing inefficiencies, and am perfectly willing to put more fuel (and other resources) into a system to enable more power.

There are a couple of things some of you are missing...

1- It's a MINI. It is cramped as heck. Big coolers are not an option.

2- The original design sucks. Well, sort of. It was a compromise design to facilitate a very specific aesthetic look which is extremely restrictive on air flow and put the intercooler in the only place possible- sitting on top of the engine. It actually exhausts air flow through the front, which is a little like putting 2 fans facing each other and wondering why nothing is happening.

3- I'm not going to remove the AC system. So, I am trying to take an existing component that uses energy, and re-route that energy for a different purpose temporarily. Inefficient, sure. But are there any gains given the circumstances (That the AC system will remain).

4- The methanol spray is a likely choice, but I'm open to other stuff too. Bigger scoop, raise the hood hinges, whatever. Cheap cooling is the goal. If I can use the existing AC for some useful gain, fine.

5- This is the $20XX Challenge. Weird stuff is normal.

Because it is the Challenge and I'm not restricted by aesthetic design considerations or class rules, I am trying to apply some basic horse sense and creativity.

I am not trying to out-engineer BMW engineers, nor racing legends.

But there is nothing telling me I have to keep the shape, appearance, or stock anything.

If I can improve the airflow by fabricating hood hinges that raise the hood so I can duct air over the windshield for a worthwhile gain, why not?

At constant full load-no it won't work, but with a pre cool period and varying loads you can get a limited time increase in full throttle power.

Thank goodness for a reasonable summary! I strongly feel this is the correct response.

I think a good distinction was made: You literally cannot make such a system give the engine more power with the same amount of fuel input. You possibly COULD make such a system allow you to burn more fuel and make more power that way. However, it's a lossy and overcomplicated way to go about it.

Now, i think there IS a way to do this on some vehicles that ties in to MrJoshua's take. On vehicles with and air to water intercooler system, and a orifice-tube-metered AC system where there is a post-orifice and pre-evaporator section of AC line in the engine bay, you can wrap a coil of tubing around that section of the AC line (and preferably wrap and insulate that whole shebang) and run the coolant for the IC through that tube. When the AC is running and you arent boosting often, it will gradually chill the coolant for the IC system, making it work better, briefly, for the periods you are in boost. This works well on the street because you run the AC often and rarely boost for more than a few seconds. Most modified boosted cars cant be floored for more than 10-15 seconds without going over 100mph anyway.

So that is a situation where this idea works. But, trying to use the AC to cool the charge in an Air-to-air intercooler system would be much harder and less efficient. I wouldnt even bother with it. I agree with the other suggestions.. Take some liquid with a low evaporation point and spray it through rerouted windshield sprayers.

screw this, I'd rather not do anything that might make my air conditioner not work

Ford was going to use in on the Lightning pickup like a decade ago, but decided not to for some reason..

the last time it was discussed here, i proposed to use the AC to cool a tank of water, which would then be used to cool the intake charge... the AC compressor would be hooked to a switch that disengages at about 3/4 throttle or whatever, and the stored "coldness" would cool the charge while at WFO. the compressor would kick back on once you lifted off the throttle, with the a slight benefit of the drag helping to slow the car down a bit as more "coldness" is added for the next use of WFO...