Crazy Dream: Bleed cold air from A/C into engine

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I had a crazy dream two days ago. Car manufactures were designing vehicles to have a tube from A/C duct behind dashboard and plumb directly into intake manifold / throttle body. It was a low cost way to improve engine performance with Turbo / Supercharging. Any body thinks this is a crazy idea.... or its possible to 'bleed' cold air (40 degrees) from duct and directly into engine for better performance ? shrug
 
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It's the same as a project that I thought of at 14...put motors on the back of a car, and a bigger generator on the front of a car, and it would go faster and faster...Mr Ludwig (she survived Mt St Helens) was my science teacher at the time and explained that it wasn't possible, and I would learn more later. Unless there's a latent heat process involved, you can't gain more shaft power than you put into the AC compressor.
 
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Originally Posted By: Mr Nice
I had a crazy dream two days ago. Car manufactures were designing vehicles to have a tube from A/C duct behind dashboard and plumb directly into intake manifold / throttle body. It was a low cost way to improve engine performance with Turbo / Supercharging. Any body thinks this is a crazy idea.... or its possible to 'bleed' cold air (40 degrees) from duct and directly into engine for better performance ? shrug Whatever you're on, I want the recipe.
 
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You CAN dry ice the heat exchanger on the turbo before a drag. Buts that's just good for a couple seconds .... Now I heard naphtha mothballs in the intake box improve gas mileage. Ive never hear one way or the other ..
 
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The situation you describe would dump the waste heat about 18 inches ahead of the air intake you hope to cool. The AC condenser sits in front of the car radiator, so that heat interferes with the water cooling efficiency. (The thought is that AC performance impresses car owners more than the last few horsepower on a hot day.) They could, and do, cool the intake manifold to try to get colder, denser air for more power. The "newer" Corvette V8 has an opposite rotation water system, sucking cold radiator water first through the I/M, then the block, instead of the other way 'round.
 
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Maybe you could build up a reservoir of some super cooled fluid and pump it through a water to air intercooler for a momentary power boost? My Focus seems to have a near perfect CAI and even with the air at -32C, the extra power of cold dense air isn't all that impressive. Perhaps if you went from +32C to -32C instantly it would stand out.
 
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Air conditioning doesn't put out enough volume, as mentioned earlier in the thread. What does work, however, is leaf blower supercharging - same idea as your A/C feed but from a leaf blower. The motortrend guys did it on a Monza, before and afters on a dyno, and made impressive power gains
 
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Originally Posted By: Spazdog
Sounds like a neat concept to further downsize the engine. (just don't go up a steep grade for more than 45 secs in your 1.5 liter engine). And the wife will want to know how come the a/c temperature increases when you step on it? I always wondered though, if cooler air means more hp, why doesn't my rate of acceleration increase as it gets cooler? Seems like if you get 10% more hp by chilling intake to 30 degrees, then the effect should be even greater at zero or below?
 
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Is the ambient air that's forced in at high speed/velocity THAT much warmer? Imagine high performance driving in the winter.Now there's temps of 0-30 degrees F....do you pick up that much power and fuel economy?
 
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I've also wondered about this for many years, but have never done any calculations to see if it's feasible. But thinking about in superficial terms, I think it would be. Supercharging definitely works, but I'd bet the first guy to suggest it was laughed at because others said: "Why would you want to waste power from the engine to drive an air compressor? It won't make any more power because the compressor will absorb all the extra power produced." We all know that is not the case. Engines make useful power because they burn fuel, and the air that is required for burning that fuel is relatively easy to manipulate for temperature and pressure. I think the fundamental question to be answered is: "Will the system for refigerating the charge air absorb more power than is added by burning the additional fuel enabled by higher intake manifold density?" Unfortunately, I don't know doodly-squat about how much power refrigeration systems absorb for a given amount of cooling and mass flow. But I can give some ballpark numbers for engine airflow conditions. Let's say that we have a 2.0L turbocharged engine running 15psi boost with a 90% effective intercooler on a 77F day. At 5500 rpm and 30% thermal efficiency, the engine would produce 302 HP. The heat rejection from the intake airflow of 1600 lb/hr would be 1011 BTU/min. Then add a refigeration system to the intercooler loop with an assumed media temperature of 30F, and keep the same assumptions for engine performance as above. Intake mass flow would increase to 1732 lb/hr, and intake air heat rejection would increase to 1387 BTU/min. Power would increase to 327 HP just by decreasing the intake manifold temperature, an increase of 25 HP. I don't think that a refrigeration system would absorb all that additional power. Are there any HVAC engineers out there that can ballpark some numbers on the refrigeration system?
 
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I will state that my wife's legacy gt wagon (WRX motor) does feel slower on really hot days at times from a standstill. I think the intercooler does not work unless car is moving.
 
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Originally Posted By: NHGUY
Is the ambient air that's forced in at high speed/velocity THAT much warmer? Imagine high performance driving in the winter.Now there's temps of 0-30 degrees F....do you pick up that much power and fuel economy?
It isn't the velocity that increases the temp, it is the compression. look up adiabatic compression.
 
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Originally Posted By: A_Harman
Let's say that we have a 2.0L turbocharged engine running 15psi boost with a 90% effective intercooler on a 77F day. At 5500 rpm and 30% thermal efficiency, the engine would produce 302 HP. The heat rejection from the intake airflow of 1600 lb/hr would be 1011 BTU/min. Then add a refigeration system to the intercooler loop with an assumed media temperature of 30F, and keep the same assumptions for engine performance as above. Intake mass flow would increase to 1732 lb/hr, and intake air heat rejection would increase to 1387 BTU/min. Power would increase to 327 HP just by decreasing the intake manifold temperature, an increase of 25 HP. I don't think that a refrigeration system would absorb all that additional power. Are there any HVAC engineers out there that can ballpark some numbers on the refrigeration system?
A few decades ago, I got a wild idea about using a water spray system to cool the intercooler on my SAAB 900T. I picked up another windshield washer tank + pump and was going to install it on the opposite fender well. Then use a drip-system spray head to produce a fine spray to cool off the IC. Evaporating water absorbs a lot of heat. When it's > 200° under the hood, the Tx asphalt is 140° and the air temp is right at 100°, anything helps. Turns out I would have to move some other things to make room for the water tank. In that sled, the IC was separate from the radiator & A/C condensor, but it still heat soaked during most of the year. I also considered installing a 10" fan on the backside to pull air through it.
 

Mr Nice

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In my original post... I meant to say *without* Turbo / Supercharging. In my dream, Eddie Van Halen was a mechanic that was working on a crate engine sitting on a pallet that had the A/C tube to intake manifold set up. My alarm clock rang at 5:00 AM and I woke up, but I thought it was a neat hypothetical A/C to engine design. Like I said before, it was a crazy dream.
 
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Years ago I tinkered with an idea I thought would give short duration boost to a car engine. It didn't work, or at least gave no appreciable results. In the end I came to realize a car engine is basically a very big air pump. In order to have an appreciable affect on the air charge being drawn into an engine it requires some serious power. The flow rate was surprisingly high. It depends on the engine and RPM, but the flow rate could easily be a couple of hundred CFM.
 
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