AC Intercooling?

[RedMist]

Been thinking about how to effectively intercool a 35psi engine in a tight constraint package. Specifically thinking about the use of a water to air intercooler and an ice box. In an endurance situation an ice box is next to useless, ice melts, no cooling effect. But what if you could keep that water cold by using an engine in it's off throttle moments.

Specifically was thinking of running an AC system with the AC core embedded in a traditional ice box. When the throttle is above say 60% the AC clutch is engaged to free up the power needed. An additional trigger would need to also disengage the clutch when IAT's increased due to being WOT for an extended period of time.

Effective? Useless? Issues?

[iOnic]

Not sure what sort of racing you do so sorry if this is way off but have you looked at how much time you spend under 60% throttle position (as an example) to figure out whether such a system would be worth it's weight (literally)?

I'd have imagined that a Water/Meth injection system coupled with a W2A intercooler with ice (dry ice? - get your pit boy to put it in ) would be closer to gaining the results you're after but I could be wrong.

[RedMist]

Offroad racing. Endurance racing up to 6 hours constant. National events at 3 hours.
With the Cosworth engine (more torque, more linear power curve, bigger engine than the 2ltr engine I'm looking at installing this system on) throttle utilisation between 90-100% was only 4% of total time.
Greatest time percentage was the 40-50% throttle utilisation.
I believe that I could run the compressor for over 80% of all time in racing.

[Akane]

How are you gonna go about still utilizing and not hindering the normal water-to-air system when the a/c is not on? Post radiator cooling? Another water bath after the normal front radiator?

you're looking at adding some serious weight in a decent aircon system that can utilise the most of your off throttle time. You'll want a big system that cool as much as possible in the least possible time......

[Malcolm]

I would wonder how much heat you could take out with an AC system, and whether it was any more efficient than say water sprayers on the intercooler radiator, considering the masses of each system and the secondary effects like additional fuel required to drive the AC and how much extra fuel you'd have to carry (or whether you'd have to stop more frequently). Also since you'd have to have a radiator for the AC mounted somewhere, would that space be better utilised with an additional or larger radiator for the w/a system?

My guess is that you're unlikely to see worthwhile benefits from the system.

[sergei]

The AC system in the car is only capable of moving a few kw of heat. While the turbo can make tens of kw of heat.
As Malcolm said - you are far better of using bigger W/A radiator, since you are going to have same area used for A/C system.

[Burning Angel]

Ford had a "supercooler" i the F150 SVT Lightning which would give a 50hp boost for like 30 seconds but then had to recharge for a period of time before being usable again. This was using aircon technology.

I dont think a freon system would work that well, but a c02 system would be awesome, just that you cant get compressors small enough to go on cars.

We use them at work but for freezing warehouse sized freezers.

[Malcolm]

The amount you'd have to cool the air to get a 50hp increase in power output (from a ~300hp engine?) would be pretty immense, in fact if you assume the power gains are proportional to density then you'd need to drop the temperature by roughly 50 degrees C

[Mr Revhead]

I would imagine the best it would do is slow the melting process a bit.

I think water to air is the best for your application though.
Having helped scooped mud out of ducts in your car before, doing anything to not use radiators is a good idea!

I would think a large capacity water to air system would work best. You are pretty free on where you can put the water tank, you could stick it in the front for example. I guess weight is the next consideration.
If you ran it from the air heat exchanger to a radiator mounted out of the way, say with a fan behind the cockpit then into a large tank in the front, that may work. It's a matter of making sure the capacity isn't overwhelmed by the heat...

Possibly you could use aircon to blow on the water rad? that might have more of a positive effect than trying to cool a large volume of water with it.

[gasman]

why not a normal air to air intercooler?

[Mr Revhead]

Mud. LOTS of mud. Then some more mud. And then force some more in there...

[Malcolm]

I would imagine the best it would do is slow the melting process a bit.

I think water to air is the best for your application though.
Having helped scooped mud out of ducts in your car before, doing anything to not use radiators is a good idea!

I would think a large capacity water to air system would work best. You are pretty free on where you can put the water tank, you could stick it in the front for example. I guess weight is the next consideration.
If you ran it from the air heat exchanger to a radiator mounted out of the way, say with a fan behind the cockpit then into a large tank in the front, that may work. It's a matter of making sure the capacity isn't overwhelmed by the heat...

Possibly you could use aircon to blow on the water rad? that might have more of a positive effect than trying to cool a large volume of water with it.

All adding capacity does is slows the heat soaking process, but it also slows the cooling. If you want stable temps you need to be able to shed as much heat as you put in to the system.

I think your final suggestion may require infringement of the 2nd law of thermodynamics to be successful

[gasman]

Mud. LOTS of mud. Then some more mud. And then force some more in there...

but wouldnt mud be a problem with the radiator for the water to air set up too?

[Mr Revhead]

Yep, I was aiming for that! Slowing the heating process to allow the cooling to be more effective. The issue in this application is finding the cooling.

Yeah I wasn't suggesting the aircon be the sole cooling, but rather a help. As in it could be used on say a rad placed between the air heat exchanger and water tank to help cool the water before it joins the tank.
Whether or not it will be enough of a help to be worth while is another thing...
I guess it will depend on what kind of compressor you can find and the power it will use to make X amount of cooling.

[Mr Revhead]

Mud. LOTS of mud. Then some more mud. And then force some more in there...

but wouldnt mud be a problem with the radiator for the water to air set up too?

yes, but being used to cool the water for a water to air means you have a lot more freedom on where and how you place it. Whereas with an air to air you are quite limited.

[gasman]

Mud. LOTS of mud. Then some more mud. And then force some more in there...

but wouldnt mud be a problem with the radiator for the water to air set up too?

yes, but being used to cool the water for a water to air means you have a lot more freedom on where and how you place it. Whereas with an air to air you are quite limited.

guess so.

water to air it is then. i would think the ac option would be too complicated for the gains you would manage to achieve with it.

[Mr Revhead]

I think so too.
but some times by talking shit out loud you come up with something

[RedMist]

Mud. LOTS of mud. Then some more mud. And then force some more in there...

but wouldnt mud be a problem with the radiator for the water to air set up too?

yes, but being used to cool the water for a water to air means you have a lot more freedom on where and how you place it. Whereas with an air to air you are quite limited.

You got it brother. It's all about packaging. The V6 twin turbo led to brilliant packaging running a A to A intercooler in each sidepod (I just need to keep developing the screens and ducts to the sidepods to minimise mud egress.
The straight four... (ummm... ummm... Honda) doesn't lead to such good packaging. With W to A I can run a rad infront of the existing rad and duct air into it using "evo ears" without too much mud egress. It also allows me to run the rear facing Honda intake (or performance replacement) in a mid engined solution.
In addition the pipework involved in putting a common A to A intercooler on her will mean a bit more lag (which is a killer in offroad racing).

Sounds like AC is a no goer. The complexity of the solution and the minmimal gains don't appear to be worth the effort. I'll stick with an icebucket for short course and just run lower boost for endurance. It would however be good to get rid of the 175c BW Matchbot is predicting as compressor outlet temp.

As an aside was amazed at what can be had from the B series engines. From the dyno's I've seen, keeping the engine reasonably quiet will result in around 500 hp.

As a second aside... anyone played with the BW EFR's yet? They appear to be god of all turbo's on paper!

[RedMist]

I think so too.
but some times by talking shit out loud you come up with something

I think the best idea is to keep it pretty much the standard w to a with a ice box. Just think I'll have a very cold arse converting the underseat 20 litre drinking water tank to an ice box!

[nzhogrider]

The A/C system isn't going to work in a fundamental failure kind of way due to ;
I) you wanted it to be cooling under 60% throttle, but most of the heat will be generated at 100% when the compressor is obviously working hardest
II) why exactly do you aim to reduce intake temps therefore generating more power when you estimate that you are at or below 60% power for 80% of the time and on 100% power for a mere fraction of the time? Sounds like you have enough power to get by on
III) any power gains appear to be at a cost to weight and/or complicated system lending itself to being prone to unreliability or inconsistency of cooling (most likely to be least effective when most required i.e. 100% power)

I would opt for a simple water to air system with the biggest capacity you can afford without giving away too much in the way of a weight penalty. Could try mounting the radiator for the system as high as you can to avoid the worst of the mud at the back of the car, try a reverse airflow setup ducting the air through 180 deg. before impinging on the rediator that way you can eliminate the biggest bits of dirt which are too heavy to change direction with the airflow, only the lighter dusty shit would remain, so avoid water sprayer as it will just create it's own mud to block radiator in conjunction with dust. Volume of tank required for water sprayers etc. due to being a total loss system would be unrealistic due to weight penalty too either that or you would need to stop more often to refill.

Just my ramblings, hopefully something helpful in there though.
Sean