OK so been wondering about this question...

All else being equal (what theoretical proposition does not start with the required disclaimer), would a IC core be more restrictive when trying to pump hot air through it or cold air?

So hot air (higher pressure, higher temps, less density) being pushed through a core - would the air flow more easily than a colder (lower pressure, lower temp, more dense) air charge?

I am talking about nett amount of air molecules passed and then also in ccm's ...

I suspect more molecules will pass with the cold air, while the ccm flow will be constant in the sense that the same restriction will be applied by the core relative to the ccm's, regardless of temps?

Also I assume molecules are more important the ccm's.........

 

Good question. I'm not an engineer, but I will take a stab at it. Simply, do you make more power on a warm day or a cool day? There you go! In this example, the cfm capacity of the ic core has not changed but horsepower has increased. The assumption here is that the ic core is the greatest restriction in the intake path. Are there other factors which come in to play in this simple example, yes.
So, I'm guessing that you are considering placing a water/alcohol nozzle before the ic core.

 

hahaha you are psychic!

Thats exactly what I am thinking about. I think my logic is sound in that hot or cold the flow in ccm is constant however in terms of molecules its not. So cold air or hot air will flow the same, its just cold air will be more dense and cooler providing more power - the scenario you alude to.

Also I think the I/C is more efficient cooling cooler air than cooling very hot air... more to do with its size than anything else - were it a larger core this I think could be the opposite. e.g. if air into the I/C was 100degC it might drop by 30deg, but air coming in at 80 deg may be dropped 40deg due to better efficiency at that temp... but again I could be wrong and this could in fact be the reverse - just not sure.

Anyhow looks like I will be going down the HFS-6 route ... got the install mapped out in my head now and itching to get it done.

 

Here is why I would advise you not to go down that path. First, accessibility. If you have a leak at the nozzle, the whole ic has to come back out. As well, if you want to change your nozzle size, the whole ic has to be removed. Second, with water/alcohol injection, you have the capability to lower IAT temps below ambient. In turn, you could actually being pulling heat from the ic core. Let imagine your ic fluid temp is 50* but with sprayer on your air temp before the core is 45*. In this case, the ic core will raise your air temp slightly.
IMHO, let the ic core do as much work as possible, then inject the least amount water/alcohol to get your IAT temps in check.

Going back to your theory on the ic being more efficient at lower temps, I have to disagree. The ic will create the greatest temperature drop when the delta temp increases. Delta being the difference from ambient temp and discharge temp from the s/c.
Whatever you decide to do, I wish you good luck.

 

Hmm ok many good reasons there... How much space is there btwn the IC end and the IAT sensor? I just want to make sure the air and water is fully mixed by the time it reaches the sensor and does not send fluctuating values to the ecu ...

Thx for the help here much appreciated...

 

IMO the ease of simply mounting the nozzle before the blower far far outweighs any benefit you would get by mounting it after the IC's or under the blower. I concede that you may actually "waste" some cooling capacity pulling heat out of the IC, but I doubt it would ever be enough to make the slightest bit of difference.

 

Here is what Snow has to say about mounting the nozzle:

16. Where can I mount the nozzle?
Pre- or Post- throttle body/carburetor?

• Performance: It makes almost no difference. Before or after the throttle plate(s) won’t change the effectiveness of the fluid. A given amount of fluid will absorb a given amount of heat, whether it is done more before or after the throttle plate really doesn’t matter.
• Installation: It is usually easier to inject pre-throttle body in the intake tube. Easy access, no solenoid required (unless rear-mounting a reservoir). On a carburetor, it can actually be easier to use the #40050 carb spacer plate and a #40060 solenoid for a bolt-in installation. These components are included in our RT and MC series systems.
• In a blow-through carburetor setup with an air-box enclosure around the entire carburetor, injecting after the carburetor is preferable.

Pre- or Post- Supercharger/Turbocharger?

• Centrifugal/Turbo: (Procharger, Vortech, Paxton, Powerdyne, Rotrex, etc.) Never mount an injector nozzle before a centrifugal supercharger or turbocharger compressor. Sending fluid through the compressor wheel that spins anywhere from 50,000rpm to 250,000rpm can erode the leading edges of the fine aluminum, as well as serve to reduce the atomization. Instead of a fine mist, the compressor housing will create a river of fluid along the outside wall that means we get less benefit and use more fluid.
• Positive Displacement Supercharger: Roots style (B&M, Eaton, Magnuson, etc.) or twin screw (Lysholm, Kenne Bell, Whipple, etc.) Mounting the nozzle before this style of blower is perfectly safe and actually provides some additional benefits. The small amount of water-methanol fluid isn’t harmful to any rotor seals or surfaces or coatings, and it helps to seal the clearances and condense the air some more, resulting in a more efficient output. Additionally, it keeps the rotors and housing MUCH cooler, which reduces heat transfer to the rest of the intake and air charge.


Now the engineer in me agrees with the above statement that you want the inter-cooler to see the GREATEST Delta T, to get its best potential, aka heat absorption.

The idea of the meth cooling the supercharger intrigues me, but it also scares me in the same way. Although in theory the meth is atomized, if it would puddle for any reason, aka clogged screen, injector line, build up on nozzle, etc, etc, it could cause the rotors to lock. Causing a pretty hefty repair bill.

I have talked to KB numerous time about this, and they feel it is SAFE to run it BEFORE their blower, which has the same tolerances as the Lysholm found on our cars.

My bet is that if you were to dyno your car with a pre blower, post blower, or after IC nozzle, that the results would be almost identical. The difference would be that your IC recovery time would be greater with the last option due to it having to work harder.

It would be great if ANY of the vendors here could do such a test and post up the results. But alas, the cost and return on investment I would bet will make this all point less.

Good luck and please, please post up your results for all of us to see.

THANKS

 

All things being equal, a hot gas has more friction by definition so it will resist flow more than a cold gas would.

The larger the delta between gas and IC temperature, the more efficient the exchange of kinetic energy at each collision between gas molecules and IC walls. At the same time, molecules in a hot gas will have more chances to have collisions and give up their energy.

These distinctions are inconsequential with the temperatures you're dealing with here. Surface area of the heat sink and the temperature delta have the biggest impact. The trick is to optimize those without adversely impacting flow, at which point engine power improvements from lower air temperature are hindered by the inability to move a sufficient mass of air.

/physicist

 

Surface area, surface area, surface area. Then TD (temperature differential). Then velocity over the surface area. The shorter the time of contact with the surface area results in a lower rate of heat exchange. You cannot add cold, you can only remove heat.