If one had the means of drastically cooling incoming air, through the use of some form of very special intercooler, what kind of gains could you expect?
I'm talking of cooling the air well below the ambient air temp.
I know that cooler air aids in preventing detonation, but does cooler = less detonation and possible timing advance, or is there a rough air temp that below that cooling the air more really doesn't help?
Also, would cooling the air pre-charger (of course below ambient temp =)) help the charger push more air? (more 02 per volume)
on a turbocharged car, sure, an air/water ic would possibly do this.......but on an n/a car you're talking about using some sort of power to do so....which will probably make the gains negligible
I know that cooler air aids in preventing detonation, but does cooler = less detonation and possible timing advance, or is there a rough air temp that below that cooling the air more really doesn't help?
Also, would cooling the air pre-charger (of course below ambient temp =)) help the charger push more air? (more 02 per volume)
cooler air is more dense. since we have a finite volume in the cylinders, the cooler the air, the more mass of air fits in the cylinders so you can burn more fuel and make more power. I guess the only point of it being too cold would be the point where it makes stuff break (thermal stress and crap).
cooling the air pre-charger (assuming pre-turbo/blower) is also benefical. Compressor power is directly related to air inlet temp. Assuming the same mass flow rate and pressure ratio (boost pressure), the compressor with the lower air intake temp will require less power. Or you can look at it this way, it'll flow more air or compress the air more (more boost) given the same amount of power compared to if the air intake temp is higher.
I understand that colder air is better, but at what point does the coldness of the air really not make a difference? Is this temp well below what a standard intercooler can do, or would being able to cool well beyond this temp efficiently be worthwhile?
Sorry, I'm having trouble wording my question.
I understand, your asking at what temp does the cold air become as dense as it can get. I don't know the answer, but if you live near a college, go ask a meteorology major, or some one in the physics lab.
And if you have found a way to chill your intake charge, my guess would be just above 32 degrees farenheit(spell). No scientific proof to back it up, just a guess.
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Quote:
Originally Posted by James
future uncertain... i see a car with monkeys working on it... torque is coming to me.... 120ft/lbs... 9000rpm....
get it as cold as you can, until it starts causing probs with the other parts. of course, you have to use something to chill the air. so the question becomes, do you lose more power in cooling the air than gaining power from the cooled air. Thermodynamics book is your best bet for understanding air properties
Oh, consider this, air is about 79% nitrogen, and liquid nitrogen forms at
-320.4 F
Last edited by spdracerUT : May 12th, 2004 at 10:04 AM.
I understand that colder air is better, but at what point does the coldness of the air really not make a difference? Is this temp well below what a standard intercooler can do, or would being able to cool well beyond this temp efficiently be worthwhile?
well i don't know the exact point that the density of the air would become neglibile but considering all things said previous, I would think there is a point where it doesn't matter because the air is restricted more by the size of the piping and TB and MAF and such, much before the air turns into a solid state!
yes this temp is WELL below what a standard or super-standard intercooler can do!
There may be a problem with chilling the air below the dew point. At that temperature the water in the air will condense in the intercooler. It will collect somewhere and must be handled somehow. Just think of the amount of condensate your A/C drops out.
There may be a problem with chilling the air below the dew point. At that temperature the water in the air will condense in the intercooler. It will collect somewhere and must be handled somehow. Just think of the amount of condensate your A/C drops out.
Lew
And now I think you understand where he might be going.
I've thought about this too. If you could cut into the A/C unit and use the available coolant there in conjunction with a vacuum line, there wouldn't be a negative power loss to produce more power. All you'd be doing is sending the air on a longer route and the bennefits could be huge!
The graph at the bottom shows the maximum I.M.E.P. or the Indicated Mean Effective Pressure inside the cylinder that can be maintained before a potential for engine detonation occurs plotted against inlet air temperature for various running conditions. Under specific power conditions, each engine has an IMEP above which detonation occurs.
Consider a turbocharged engine running, for example, 10psi boost. The turbocharger heats the air. If the ambient air is 80*F the air is heated to 165*F at 10psi. It is possible that this inlet air temperature exceeds the IMEP threshold for detonation. By cooling the charge with a conventional intercooler with 70% efficiency, the inlet air temperature is reduced to 106*F. This may result in an IMEP below the detonation threshold, depending on the particular engine.
Note that the relationship between inlet air temperature and IMEP is not linear, and the effect of decreasing intake air temp is less as the temperature drops. (there is a 100 degree IMEP difference by dropping from 300 to 200, but a 40 degree IMEP difference by dropping from 200 to 100).
So... what's the importance of this for our engines? It allows a higher boost to be run without detonation if the intake air temperature is dropped. But the effect is not extremely great, perhaps 10-20% allowable increase in going from 100 to 0*F.
The graph at the bottom shows the maximum I.M.E.P. or the Indicated Mean Effective Pressure inside the cylinder that can be maintained before a potential for engine detonation occurs plotted against inlet air temperature for various running conditions. Under specific power conditions, each engine has an IMEP above which detonation occurs.
Consider a turbocharged engine running, for example, 10psi boost. The turbocharger heats the air. If the ambient air is 80*F the air is heated to 165*F at 10psi. It is possible that this inlet air temperature exceeds the IMEP threshold for detonation. By cooling the charge with a conventional intercooler with 70% efficiency, the inlet air temperature is reduced to 106*F. This may result in an IMEP below the detonation threshold, depending on the particular engine.
Note that the relationship between inlet air temperature and IMEP is not linear, and the effect of decreasing intake air temp is less as the temperature drops. (there is a 100 degree IMEP difference by dropping from 300 to 200, but a 40 degree IMEP difference by dropping from 200 to 100).
So... what's the importance of this for our engines? It allows a higher boost to be run without detonation if the intake air temperature is dropped. But the effect is not extremely great, perhaps 10-20% allowable increase in going from 100 to 0*F.
Linear Mode
