Going out on a limb....be nice!

At risk of asking a dumb question and receiving a bashing, I am going to have faith in my Viper brothers to be nice.

Question: If colder improves combustion and HP, why wouldn't someone develop a way to plumb the cold air from the air conditioning system on the car into the intake system, or into an intercoolers for turbo or supercharged engines?.......BE NICE!

Not enough volume to keep up with demand from engine. You'd need 4L or air every rotation. At 3k rpm that's 12KL of air or about 450cfm of air - that's a lot more than the little squirl cage blower in the car can produce (maybe 25-50 cfm on a great day - The airhandler in your house only blows on high around 1000cfm, now go look how big it is) - then there is the flow rating/ability of the evaporator box itself....blah, blah, blah....

Basically you'd need and evaporator coil the size of your radiator which would require a condensor the size of a 4x8 sheet of plywood and a compressor the size of a VW engine to pump the 30+ pounds of freon around - I'm NOT exaggerating. Then you need a carpet/floor blower to keep up with the air demand of the engine...and a box to package it nicely under the hood

Sorry...

FastZilla said:

Not enough volume to keep up with demand from engine. You'd need 4L or air every rotation. At 3k rpm that's 12KL of air or about 450cfm of air - that's a lot more than the little squirl cage blower in the car can produce (maybe 150 cfm on a great day) - then there is the flow rating/ability of the evaporator box itself....blah, blah, blah....

Basically you'd need and evaporator coil the size of your radiator which would require a condensor the size of a garage door and a compressor the size of your engine to pump the 100 pounds of freon around - I'm NOT exaggerating. Then you need a carpet/floor blower to keep up with the air demand of the engine...and a box to package it nicely under the hood

Sorry...

Click to expand...

Great answer.
I thank you for that!

PS. That was a good question.

....Guilty!

I too have pondered this one!

Same Here !!!! Thanks for the answer!

Some guys used to claim that the Cool Can helps the fuel aspect...

Moroso 65125 Moroso Insulated Cool Cans

You're forgetting some other aspects of physics. Let me start with a trick, not so trick question.

If you open the door of your refrigerator in a closed room, will the average temperature go up or down?

It will go up, because refrigeration is not a 100% efficient process. Therefore, more heat is generated as a byproduct than cool is generated as a wanted product.

So what about the energy drain on the engine to run the cooling system? Will it use more energy than the HP will increase? The energy gain? What about the weight of the system and the energy required to transport it?

So, in short, it could just boil down to (regardless of the CFM demands...) that it takes more power to run it than it adds to the engine output.

I believe a couple years ago Ford offered such an option. It was only intended for quick burst of additional hp.

Idea was to run your AC and some cooling was routed to the intercooler. This allowed the charge to cool the intake air for 10 seconds or so for a quick hp increase.

One of the SoCal members patented such a system, but don't think it ever went commercial.

Make sure you separate, in your thinking, the concept of the a/c feeding cold air directly into the intake, versus the a/c cooling the intake plenum, or cooling an air to air heat exchanger, like an intercooler. The trade off of the energy used to the energy gained is different for each method. As describer above, the a/c cannot supply enough CFM and pressure, so that's out. What it can do, is cool the intake air by some form of heat exchanger. Some cars have the coolant routed around the thottle body, to reduce intake temps. If that's viable, then cooling the intake with a/c air, (or even the R14 in a liquid to air heat exchanger), would be even better. Sure, it takes power to run the a/c, so you might write it off as a zero sum game, but remember that concept doesn't apply universally. A roots supercharger can take 100hp to run at redline, (case of the Ford GT), but the power added gains exceed the power drained. That's not a zero sum game. What you would have to study is the limits of sustainable gains in varying designs or liquid-to-air or ait-to-air heat exchangers, the heat soakability of the a/c system. Of course its going to get loaded down beyond its design parameters, but what gains can be had, and for how long? Those questions need to be answered before the idea is written off. Or you could do like some drag racers do, and load a block of dry ice onto your intake manifold just before a run. (Not the same thing, I know, I know)

Dave hit the nail on the head - it boils down to laws of thermodynamics. Automotive AC systems are nowhere near 100% efficient, so, for example, a 1000 Btu AC system is going to take around 1200 Btu to run it (just numbers pulled out of nowhere to illustrate). Even if the decreased air temperature going into the engine led to a thermodynamically perfect increase in air density and available oxygen for combustion, you're still going to be losing from an overall energy standpoint. That's not to mention all the other things in an internal combustion engine that you're fighting to keep the intake charge cold - everything in an engine wants to heat up that air, and as that heat is being transferred from the engine to the air charge, the engine's cooling system is doing it's job by just letting the engine heat up more to maintain it's operating temperature. As noted above, to counter that, you'd need a MASSIVE cooling engine.

The example of a roots type blower taking 100HP to run it yet developing much more than 100HP is true, but it's a slightly different situation. With a blower, you're increasing the air density through mechanical compression and the energy to compress the air comes directly from the engine. It's not a net-sum-gain process, though - the extra power comes from the ability to burn extra fuel and the overall (adiabatic) efficiency of the engine actually goes down.

There's 3 different "methods" described above - some seem valid.

I know Treesnake has a CO2 system set up on his car to do essentially this same thing. Mayber he can let us know how effective it is.

I'm not a fan of temp or limited power adders like NO2. I prefer the power be available all the time without having to have a ticker on the dash telling me I can only make "X" more runs before I'm outta juice.

For example - you goofing around on a long Hwy with another car - the kind of goofing that goes on for 5-10 minutes. Basically you're out of NO2, your temp burst of cold air is gone, and your engine is heat soaked.

IMO ONLY - I feel it's a bit dyno queen'ish to only be able to make 2-3 runs before you out of "juice" and you're worried about detonation, heat soak, etc.

Martin said:

The example of a roots type blower taking 100HP to run it yet developing much more than 100HP is true, but it's a slightly different situation. With a blower, you're increasing the air density through mechanical compression and the energy to compress the air comes directly from the engine. It's not a net-sum-gain process, though - the extra power comes from the ability to burn extra fuel and the overall (adiabatic) efficiency of the engine actually goes down.

Click to expand...

Quite so. The example was only to illustrate that not every thing that takes energy to make energyis a net loss, or zero sum.

You wouldnt need to extract BTU's from the engine, thats a definite no-no, like powering your sail boat with a fan mounted to the deck. Thats worse than zero-sum, its a net loss. But you dont have to cool the engine itself, just the intake air, below ambient. You could have an air-to-R14 exchanger, mounted out in the front fascia. Maybe all thats needed is to cool the temp of the incoming air to net a gain. How much is the question, and there hangs the whole issue.

You ever notice how your car is faster at night?

I don't think chilling the outside of your intake pipe will do much with an r14 system, but could work if you have heatsink fins inside cooled by a 400 watt peltier cooler.

I could be wrong, I don't know much about thermodynamics

I assume that no existing exchangers would be suitable, + a special one would need to be designed. Let's see, 12hp to run the compressor.....hmm

dave6666 said:

You're forgetting some other aspects of physics. Let me start with a trick, not so trick question.

If you open the door of your refrigerator in a closed room, will the average temperature go up or down?

It will go up, because refrigeration is not a 100% efficient process. Therefore, more heat is generated as a byproduct than cool is generated as a wanted product.

So what about the energy drain on the engine to run the cooling system? Will it use more energy than the HP will increase? The energy gain? What about the weight of the system and the energy required to transport it?

So, in short, it could just boil down to (regardless of the CFM demands...) that it takes more power to run it than it adds to the engine output.

Click to expand...

Up north here, in my house, it goes down when you open the door. Even my freezer goes down this time of year. Guess where my freezer is?

As a side thought on this, what if you chilled the fuel and air?

WOT! said:

Guess where my freezer is?

Click to expand...

In the freezer?

dave6666 said:

In the freezer?

Click to expand...

Ok Dave...It IS officially after noon here in the great state...On that note I'm cracking my first one!

Lol YEARS ago someone TRIED TO MARKET one of the above for Gen 2s (heatsoaked AFTER 1 RUN )

Yes there are systems out there that do this very thing. In fact about 10 years ago there was a system for the Viper. Before the Roe and Paxton kits became available.

No it is not a zero sum situation as some indicate. Changing the inlet charge temperature allows advanced ignition timing and/or compression ratio due to reduced detonation sensitivity (more power from a given amount of fuel and air) and more charge due to the density increase (effect similar to a supercharger or turbocharger).

It is an expensive way to add power, with relatively low practical limitations, especially on a N/A engine where inlet temperatures are not that high to begin with. However it is feasible and can add net power. Impossible to state the overall impact on thermal efficency however as two factors would increase it (advanced ignition timing and increased compression ratio) while the A/C thermal efficiency and mechanical losses would lower it.

I believe on any of these cars, the optimal solution would be to have an intake manifold made out of a phenolic material (have no clue if I spelled that right...). By keeping the air temp roughly the same at the intake valve site on the head as it was outside the car, you'd be picking up a lot of power over what you lose due to heat soak in the current manifolds. Especially the Gen I and II manifolds - those things look like they were designed to heat up the incoming air charge...

It would be interesting to actually see what could be done with an engine pre-cooler that drove off the AC unit. I know that when my AC unit is low on freon and it cycles on and off every once in a while, I can definitely feel the drag on the engine when it cycles on. If a different timing curve could be developed that maximized the cold air and that increased power beyond what the AC unit is dragging on the engine, I'd be really curious to see the numbers. Something tells me that, even if there was an overall gain, it would be small enough that I'd rather keep the AC unit blowing cold air into my cabin and not the engine...

There's an article in the March Motor Trend, page 35, describing "sorbtive generators", that use the engine's heat to air condition the cabin. It has powdered carbon surfaces so porous, that one gram has 3.5 ACRES of surface area. Is that what is known as nano technology? No power input is required at all for this heat exchanger, its done by evaporating R134a using the FM priciple. (You know, Freeking Magic?) Two 6x6x6 sorbtive generators can air condition the cabin of a Focus. Now how about build that technology into a specially designed intake manifold, that cools the intake charge using the engine's own heat? Its like a free lunch. Inventions are mere Science fiction one day, an idea the next, posed by silly dreamers, bitterly opposed by "sensible" nay-sayers, then becomes everyday reality tomorrow. Isn't this the genesis of all great ideas?

I know what you mean - I used to be one of those dreamers I had an idea about carefully controlled direct water injection into a lean-burn engine to not only control detonation, but also increase power due to the expansion effects of the water. My advisor thought it was novel enough to let me work on it, but for whatever reason, we just couldn't get funding to see the project through. I still think I could make it work. Just think about all that waste heat going out of the cylinders after combustion. Wouldn't it be nice to use some of that waste heat to create power? Water expands to thousands of times its liquid form when it vaporizes, and if you inject it into the combustion chamber at just the right time, you can get a lot of free power by using that waste heat to vaporize the water. Oh well, I'll keep dreaming. If any other dreamers out there want to give it a go, PM me I'm tired of not being an engineer anymore.

Years ago I wanted to take a 1" aluminum carb spacer and drill the body of the spacer with holes to create an internal passage. I surmised that if plumbed it with a small pump and an Ice water cooler it would effectively prevent the engine heat from transferring to the carb. I never did test my theory out, but I can bet it would work wonders on a HOT So Cal Summer day at the drag strip.