Hot VS. Not: Two tips on intercoolers/heat exchangers for your turbocharged vehicle
1.) PROPER TERMINOLOGY:
You’ve heard it called an “intercooler” However it is technically a “Heat exchanger”
An intercooler is an air-to-water device that cools the intake air charge with liquid.
A heat exchanger is an air-to-air device that cools the intake air charge with outside air flow.
Get it right people!
2.) PROPER FLOW DYNAMICS:
stock < side flow < cross flow < air-water
Power to weight ratio ruins everything!
An air to air heat exchanger will rise to a peak operating temperature while at idle just like an intercooler. In the graph below it demonstrates the difference between both in the following aspects:
At-speed
At idle
power to weight ratio change
and power to weight ratio in relation to performance
3.) Which one wins?
An air-to-air heat exchanger will increase its cooling efficiency at higher speeds just like an air-to-water intercooler. The rate of temperature change is faster with an air-to-air heat exchanger, as the change is direct to the core in relation to speed and air flow. An intercooler will have a liquid heat exchanger mounted in place of the air-to-air heat exchanger and will receive the same at-speed cooling benefit. The difference is that water is many times more dense than air. Because of this fundamental difference, it requires more cooling to reach a certain temperature, but then remains at that temperature longer than an air-to-air intercooler will be capable of. (in this case a heat exchanger releasing heat energy)to change.
In the scenario that two otherwise identical
vehicles were running side by side at speeds of 100+ mph, it would take longer for the air-to-water vehicle to cool its air charge, while the air-to-air vehicle would benefit almost instantly from the improved cooling capacity of the intercooler at speed.
Once these vehicles have both come to a stop however, the core temp of the air-to-air unit would quickly rise back up to an at idle temperature, while the air-to-water units intake air charge and water temperature would remain at a stable temperature and rise many times more gradually, giving it the raw horsepower benefit of cooler air over the air-to-air unit, but only for a finite time. If the light turns green and the two cars accelerate, the air-to-water car would be making more power from a stand still.
How about turning that WATER TO ICE?
In an intercooler, adding an ice box does exactly as it sounds. It makes the intake air temps frigid! but once the ice melts, there is nothing left but heated water! This throws a monkey wrench into any potential comparison against the air-to-air options, but may still come to a loss if the added weight of an icebox reverses or equals any power gains seen by its use.
And power to weight ratio?
The air-to-water units are almost always heavier when you factor in the pump, heat exchanger, reservoir, piping, etc…
And installation vs. packaging?
The air-to-air unit is always simpler to install. No wiring, and less fabrication is usually the benefit. The strength of an air-to-water unit is that parts are more compact and easily spread out. The air-to-water unit can be made compact, with a strong pump, reservoir, and heat exchanger to make up for a packaging constraint.
Power to weight vs. performance?
You make think that making more power at the wheels will make you faster, but not if your air-to-water intercooler and 50 gallon reservoir weight 100+ lbs! There is a line that needs to be drawn. Even if you make an equal gain, you are adding both weight and power. With air-to-water Your car may simply not handle as well as it usually would (relative to installation engineering), but you would see a benefit in the straight away sections in a track setting, while an air-to-air unit will always be doing something even while cornering at slower speeds. Lets add another factor. The air-to-air unit will have an average higher cornering speed in a track setting than a slightly heavier air-to-water car. These differences are negligible and irrelevant when driver skill is factored in. so choose at will.
If you want greater control of your intake air temps you would go with air-to-water.
-Installation is more involved
-Adds complexity to the vehicle (more things to break)
-Heavier than air to air units in most cases
-added power :) added weight :(
-Preferred for drag racing and highway pulls in Mexico.
If you want a reliable solution that always does its job with no supervision? air-to-air.
-Simpler installation
-Mother nature controls intake air temps
-Cools great at speed
-Not so good at a stop light
-Cheaper!
-Preferred for drift and circuit track/autocross
